MiniMax NT LowNOx

Rev. B 4-5-02 P/N 472089

11

FOR YOUR SAFETY - READ BEFORE OPERATINGWarning: If you do not follow these instructions exactly, a fire or explosion may

result, causing property damage, personal injury or loss of life.For additional free copies of this manual; call (800) 831-7133.

Do not store or use gasoline or other flammable vapors andliquids in the vicinity of this or other appliances.

For YourSafety

Warning: Improper installation, adjustment, alteration, service or maintenance cancause property damage, personal injury or death. Installation and service must beperformed by a licensed qualified installer, service agency or the gas supplier.

MiniMax® NT Low NOx SeriesPOOL & SPA HEATERS

OPERATION & INSTALLATION MANUAL

WARNING

WHAT TO DO IF YOU SMELL GAS• Do not try to light any appliance.• Do not touch any electrical switch; do not use any phone in your building.• Immediately call your gas supplier from a neighbor's phone.

Follow the gas supplier's instructions.• If you cannot reach your gas supplier, call the fire department.

WARNING

U.S. Patent Numbers6,295,980

5,318,007 - 5,228,6185,201,307 - 4,595,825

Pentair Pool Products, Inc.1620 Hawkins Ave., Sanford, NC 27330 • (919) 774-4151

10951 W. Los Angeles Ave., Moorpark, CA 93021 • (805) 523-2400

1

ToConsumerRetain For

FutureReference

P/N 472089 Rev. B 4-5-02

2

Table of Contents

Introduction ............................................................................................................... 3

Important Notices ...................................................................................................................................................................... 3

Code Requirements ................................................................................................................................................................... 3

Warranty Information ................................................................................................................................................................. 4

Operation .................................................................................................................... 4

Safety Rules .............................................................................................................................................................................. 4

HSI (Hot-Surface Ignition) Lighting/Operation - Natural Gas ..................................................................................................... 5

Installation Instructions ............................................................................................ 6

Specifications ............................................................................................................................................................................ 6

Installation — Electrical ............................................................................................................................................................. 7

Installation — Remote Hook-Ups (2 and 3 Wire) ....................................................................................................................... 8

Installation — Operating Controls .............................................................................................................................................. 9 - 10

Installation — Troubleshooting (Controls) .................................................................................................................................. 10 - 11

Installation — Wiring Diagram ................................................................................................................................................... 12

Installation — Water Connections .............................................................................................................................................. 13

Installation — Plumbing ............................................................................................................................................................. 13

Installation — Gas Line ............................................................................................................................................................. 14

Pipe Sizing Chart/Gas Pressure Requirements ......................................................................................................................... 14

Regulated Manifold Pressure Test ............................................................................................................................................. 14

Venting — Indoor Installations ................................................................................................................................................... 15 - 18

Venting — Outdoor Installations ................................................................................................................................................ 19

Basic Operation — General Description .................................................................................................................................... 20

Basic Operation — Safety Controls ........................................................................................................................................... 21

Basic Operation — HSI Ignition Module .................................................................................................................................... 22

Maintenance ............................................................................................................................ 23

Maintenance Instructions ........................................................................................................................................................... 23

Pressure Relief Valve ................................................................................................................................................................ 23

Maintenance (Water Treatment) ................................................................................................................................................ 24

Trouble Shooting ....................................................................................................... 25

Troubleshooting (General) ......................................................................................................................................................... 25

Troubleshooting (Service Checks - Ignition Module) ................................................................................................................. 25

MiniMax NT Low NOx Parts List & Exploded View (Dual Voltage) ............................................ 26-27

Warranty Information ................................................................................................. Back Cover

Rev. B 4-5-02 P/N 472089

3

MiniMax® NT Low NOxPool and Spa Heaters

Congratulations on your purchase of a MiniMax NT Low NOx high performance heating system. Properinstallation and service of your new heating system and correct chemical maintenance of the water willensure years of enjoyment. The MiniMax NT Low NOx is a compact, lightweight, efficient, induced-draft,gas fired high performance pool and spa heater that can be directly connected to schedule 40 PVC pipe. TheMiniMax NT Low NOx, also comes equipped with the Pentair multifunction temperature controller whichshows, at a glance, the proper functioning of the heater. All HSI (hot-surface ignition) MiniMax NT LowNOx heaters are designed with a direct ignition device (HSI) which eliminates the need for a standing pilot.The MiniMax NT Low NOx requires an external power source (120/240 VAC 60 Hz) to operate.

IMPORTANT NOTICES

...For the installer and operator of the MiniMax NT Low NOx pool and spa heater. The manufacturer’swarranty may be void if, for any reason, the heater is improperly installed and/or operated. Be sure to followthe instructions set forth in this manual. If you need any more information, or if you have any questionsregarding to this pool heater, please contact Pentair Pool Products, Inc. at (800) 831-7133.

These heaters are designed for the heating of swimming pools and spas, and should never be employed foruse as space heating boilers, general purpose water heaters, in non-stationary installations, or for the heatingof salt water.

Do not use the heater to protect pools or spas from freezing if the final maintenance temperature desired isbelow 60° F. as this will cause condensation related problems.

CODE REQUIREMENTS

The installation must conform with local codes or in the absence of local codes with the latest National FuelGas Code, ANSI Z223.1, and the latest edition of the National Electrical Code, NFPA 70.

Installation in Canada to be made in accordance with the latest CAN/CGA-B149.1 or .2 and CSA C22.1Canadian Electric Code, part 1.

Introduction

P/N 472089 Rev. B 4-5-02

4

Operation

This instruction manual provides operatinginstructions, installation and service informationfor the MiniMax NT Low NOx high performanceheater. The information in this manual applies tothe MiniMax NT Low NOx 200, 250, 300, and400 natural gas models.

It is very important that the owner/installer readand understand the section covering installationinstructions, and recognize the local and state codesbefore installing the MiniMax NT Low NOx.History and experience has shown that most heaterdamage is caused by improper installation practices.

SAFETY RULES

1. Spa or hot tub water temperatures should neverexceed 104° F. A temperature of 100° F. isconsidered safe for a healthy adult. Specialcaution is suggested for young children.

2. Drinking of alcoholic beverages before or duringspa or hot tub use can cause drowsiness whichcould lead to unconsciousness and subsequentlyresult in drowning.

3. Pregnant women beware! Soaking in waterabove 100° F. can cause fetal damage during thefirst three months of pregnancy (resulting in thebirth of a brain-damaged or deformed child).Pregnant women should stick to the 100° F.maximum rule.

4. Before entering the spa or hot tub, the usershould check the water temperature with anaccurate thermometer. Spa or hot tubthermostats may err in regulating watertemperatures by as much as 4° F.

5. Persons with a medical history of heart disease,circulatory problems, diabetes or blood pressureproblems should obtain their physician's advicebefore using spas or hot tubs.

6. Persons taking medication which inducedrowsiness, such as tranquilizers, antihistaminesor anticoagulants should not use spas or hottubs.

Should overheating occur or the gas supply fail to shut off, turn off the manual gas control valve to the

appliance. Do not use this heater if any part has been under water. Immediately call a qualified service

technician to inspect the heater and to replace any part of control system and gas control which has been

under water.

WARNING

WARRANTY INFORMATION

The MiniMax NT Low NOx pool heater is soldwith a limited factory warranty. Specific details aredescribed on the back cover of this manual and acopy of the warranty and warranty registrationcard are included with the product. Return thewarranty registration card after filling in the serialnumber from the rating plate inside the heater.

Pentair Pool Products’ high standards of excellenceinclude a policy of continuous product improvementresulting in your state-of-the-art heater. We reservethe right to make improvements which change thespecifications of the heater without incurring anobligation to update the current heater equipment.

Operation

Rev. B 4-5-02 P/N 472089

5Operation (Lighting)

FOR YOUR SAFETY: READ BEFORE LIGHTING

A. This heater is equipped with an ignition devicewhich automatically lights the main burners.Do not try to light the burners by hand.

B. BEFORE OPERATING, smell all aroundthe heater area for gas. Be sure to smell nextto the floor because some gas is heavier thanair and will settle on the floor.

WHAT TO DO IF YOU SMELL GAS- Do not try to light any heater.- Do not touch any electrical switch; do not use

any phone in your building.- Immediately call your gas supplier from a

neighbor's phone. Follow the gas supplier'sinstructions.

- If you cannot reach your gas supplier, call theFire Department.

C. Use only your hand to push in or turn the gascontrol knob. Never use tools. If the knob willnot push in or turn by hand, don't try to repair it.Call a qualified service technician. Forced orattempted repair may result in a fire or explosion.

D. Do not use this heater if any part has been underwater. Immediately call a qualified servicetechnician to inspect the heater and to replaceany part of the control system and any gascontrol which has been under water.

E. The MiniMax NT Low NOx incorporates thePentair temperature controller to aid you in theoperation of the heater, and to assist indiagnosing a failure in the heater’s function.

MINIMAX NT LOW NOx HSI ELECTRONIC IGNITION LIGHTING/OPERATION - NATURAL GAS

1. STOP! Read the safety information above.2. Set the thermostat to the lowest setting.3. Turn off electric power to the heater.4. This heater is equipped with an ignition device

which automatically lights main burners. Donot try to light the burners by hand.

5. Remove the control access door.6. Push in gas control knob slightly and turn clock-

wise to “OFF”. (If not on “OFF” position.)7. Wait five (5) minutes to clear out any gas. If you

then smell gas, STOP! Follow "B" in the safetyinformation above. If you don't smell gas, go to thenext step.

8. Turn knob on gas control counterclockwiseto “ON”; see Figure 1.

If you do not follow these instructions exactly, a fire or explosion may result causing personal injury, loss of lifeand property damage.

Do not attempt to light the heater if you suspect a natural gas leak. Lighting the heater can result in a fire orexplosion which can cause personal injury, death, and property damage.

WARNING

9. Replace the control access door.10. Turn on the electrical power to the heater.11. Set the thermostat to the desired setting.12. If the heater will not operate, follow the instruc-

tions "To Turn Off Gas To Heater" and call yourservice technician or gas supplier.

OPERATING INSTRUCTIONS

TO TURN OFF GAS TO APPLIANCE1. Set the thermostat to lowest setting.2. Turn off all electric power to the heater if

service is to be performed.3. Remove control access door.

4. Push in gas control knob slightly and turnclockwise to "OFF". Do not force.

5. Replace control access door.

Gas control knob shown in “ON” position.Figure 1.

OFF

ON

Gas

Inlet

P/N 472089 Rev. B 4-5-02

6

Installation Instructions

IMPORTANT NOTICE: These installation instructions are designed for use by qualified personnelonly, trained especially for installation of this type of heating equipment and related components. Somestates require installation and repair by licensed personnel. If this applies in your state, be sure yourcontractor bears the appropriate license.

SPECIFICATIONS

24.05

2 in. SOCKET

"A" DIM.

8.846.64

30.63

LEG

LEG

14.50

3.50

4.875

MODEL

200

250 24.63

21.63

"A" DIM.

15.50

300

400 34.13

27.63

7.35

24.05

"A" DIM.

8.846.64

30.63

LEG

LEG

14.50

3.50

4.875

INDOOR VENT ADAPTOR

4 in. KitP/N 460506

5 in. KitP/N 460507

15.50

7.35

Ø4.88

Ø5.88

4 in. KitP/N 460506

2.00

5 in. KitP/N 460507

MODEL

200

250 24.63

21.63

"A" DIM.

300

400 34.13

27.63

OUTDOOR VENTILATION

INDOOR VENTILATION

Figure 2.

Figure 3.

DIMENSIONS IN INCHES

DIMENSIONS IN INCHES

Rev. B 4-5-02 P/N 472089

7Installation (Electrical)

ELECTRICAL, for MiniMax NT Low NOx Heaters

Electrical Rating 60 Hz 120 / 240 Volts AC, single phase

NOTEThe MiniMax NT Low NOx heater is prewired for 240 volt AC connection using the “RED/BROWN” female connector and the

“WHITE” common male connector; see below, Figure 4. If you require the heater to be connected to 120 volts AC, remove

the “RED/BROWN” female connector from the “WHITE” common connector; now locate the “BLUE” female connector and

plug it into the “WHITE” common connector.

When connecting the home wiring to the “Line Terminal Block” inside the junction box, follow the polarity as shown below.

Connecting to 120 VAC, make sure that you connect the positive wire to the positive terminal (L), the neutral wire is

connected to the neutral terminal (N) and the ground is connected to the ground terminal (GND); see below, Figure 5.

NOTEIf any of the original wiring supplied with this heater must be replaced, installer must supply (No. 18 AWG, 600V, 105° C. U.L.

approved AWM low energy stranded) copper wire or it’s equivalent. Thermal fuse wiring must be replaced with 18 AWG, 600V,

150° C. temp. rating.Interconnecting wiring to appliance must conform to the National electrical Code or supersede local

(wiring) codes.

In Canada: wires must be CSA approved.

WARNINGThe heater must be electrically grounded and bonded in accordance with local codes or, in the absence

of local codes, with the latest national electrical codes ANSI/NFPA No. 70.

In Canada: CSA standard C22.1 Canada Electrical Code Part 1 and/or local codes.

Always use crimp type connectors when connecting two wires.

LINE TERMINAL BLOCK

RED/BROWNFM CONNECTORFOR USE WITH

240 VOLT AC

BLUEFM CONNECTORFOR USE WITH

120 VOLT AC

WHITECOMMON MALE

CONNECTOR

TERMINAL BLOCKFOR AC INPUT

120 / 240 VOLT SINGLEPHASE "See Figure 2"

L

N

GREEN WIRE

WHITE WIRE

BLACK WIRE

GROUNDCONNECTION

NEUTRAL / WHITE 120 VACLINE #1 FOR 240 VOLT AC

POSITIVE LINE FOR 120 VOLTS ACLINE #2 FOR 240 VOLT AC

INTERNALFACTORY WIRES

Figure 4.

Figure 5.

P/N 472089 Rev. B 4-5-02

8Installation (Remotes)

Figure 6.

Figure 7.

SPA COM POOL TPROBE

OUT RETURN

24 VAC HILMT IGNITION MOD

EX

T S

WIT

CH

THERMOSTAT CIRCUIT BOARD

JUMPER REQUIRED IF NO 2 WIRE REMOTE SWITCH

POOL/OFF/SPA

FRONT PANEL

THERMOSTAT SELECT SWITCH

TFUSE VALVEPRESS

SPA COM POOL TPROBE

OUT RETURN

24 VAC HILMT IGNITION MOD

EX

T S

WIT

CH


JUMPER REQUIRED IF NO 2 WIRE REMOTE SWITCH

POOL/OFF/SPA

FRONT PANEL


TFUSE VALVE

REMOTE POOL/OFF/SPA


PRESS

NOTE: When connecting a remote control to the MiniMax NT Heater, you must install the low voltagethermostat wires in separate conduit from ANY line voltage wires. Failure to follow theseinstructions will cause the thermostat relay to react erratically..

REMOTE SWITCH DUAL THERM IID ONLY

3 Wire Remote

2 Wire Remote

Rev. B 4-5-02 P/N 472089

9Installation (Operating Controls)

Knob Stopper

Screw A

OPERATING (CONTROLS)

Dual Temperature Control SystemFor convenience and economy all MiniMax NTHeaters are equipped with two thermostats on thefront of the heater control panel; see Figure 8.

Figure 8.

Figure 9.

THERMOSTAT KNOB STOPPEREach thermostat is equipped with a mechanical stop thatcan be locked or unlocked with use of a screwdriver toprevent temperatures in excess of that desired by the user;see Figure 9.The maximum setting can be adjusted by loosening the screw"A" and turning the stopper dial to desired maximum setting.Lock the setting by tightening the screw. The Mechanicalstop is under the knob. Ensure that the knob is stopping at thecorrect position when the knob is rotated clockwise from alower temperature position. (See Thermostat Adjustment.)

NOTETo eliminate error due to piping heat losses,measure pool temperature with an accuratethermometer directly at the pool or spa.

THERMOSTAT ADJUSTMENTThe knob with locking feature eliminates the need forconstant thermostat adjustments. Set the knob pointer tothe desired pool or spa temperature.If further adjustment is needed, rotate the knob until thedesired temperature is obtained. This knob positioncorresponding to your desired maximum pool or spatemperature may now be preset (locked) by the knobstopper which prevents the knob from being turned beyondthe maximum temperature you set.

POWER (THERMOSTAT SELECT) SWITCHThe Pool/Off/Spa switch allows the heater to be turned offwhen heating is not desired.

1. “Pool” position - Maintains selected pooltemperature.

2. “Off” position - Heater will not come on regardlessof drop in pool or spa temperature.

3. “Spa” position - This allows separate control of spawater temperature.

INDICATOR LIGHT DESCRIPTION

The MiniMax NT Heater provides nine status indicator lights, six can be seen from the front of the control panel whichhelp you understand the operation of the heater. If something should go wrong, the lights will aid in troubleshooting theproblem. Three additional lights can be seen after opening the control panel. These three lights give the service technicianadvanced troubleshooting capability. All the LED lights are green with the exception of the red service LED.

POWER LIGHT (POWER)

The light is on at all times, in any switch position, indicating24 VAC power is being supplied to the control circuit. If itfails to light, no other light will be on. Possible causes are:a) external power to the heater is disconnected, checkservice panel circuit breaker or fuses; b) local circuitbreaker inside the transformer has tripped -- investigatecause before resetting; c) transformer has failed.

THERMOSTAT (TSTAT)

This light is on when the thermostat contacts close, signaledby the water temperature falling below the setpoint, callingfor the heater to fire to maintain the desired watertemperature.

AUXILIARY (AUX)This light is on when it indicates the remote switch contactsare closed. This allows you to observe if your remote switchis properly closing the heater control circuit. When shippedfrom the factory a jumper is installed to maintain closedcircuit in the absence of a remote switch.PRESSURE (PRESS)This light is on when Spa/Pool Selector switch is on,indicates the circulation pump is running properly. Ifpressure light fails to light, the pump may have lost itsprime or water flow may be restricted by an inadvertentlyclosed valve or clogged filter or pump basket. If you havedetermined that there is no water flow restriction to theheater, you should call a qualified serviceman.

P/N 472089 Rev. B 4-5-02

10Installation (Operating Controls, cont’d.)

PWR TSTAT RMT PRESS

SRVE

HI TEMP TFUSE

GAS VALVE

MV

MV

IGNITION MODULE

IND GND VAL

MV HEAT

CLOSE IFNO MV

THERMOSTATRELAY

REMOTE PRESS TFUSEHI TEMP

LIMIT SWITCHESBREAKERCIRCUITTRANSFORMERINCOMING

LINE VOLTAGE


LIMIT SWITCHES

HI TEMP

NO MVCLOSE IF


TRANSFORMER

LINE VOLTAGEINCOMING

PWR

CIRCUITBREAKER

TSTAT RMT

RELAYTHERMOSTAT

REMOTE

PRESS

SRVE

PRESSHI TEMP

MVTFUSE

TFUSE

HEAT

IGNITION MODULE

IND GND VALGAS VALVE

MV

MV

WATER AT SELECTED TEMPERATURE.... NORMAL OPERATION

THERMOSTAT CALLING FOR HEAT - PUMP OFF(NO PRESSURE) BLOCKS FIRINGNORMAL OPERATION

SYMBOL TABLE

LED LIT LED OFF

SWITCH OR DEVICEOPEN CIRCUIT(BLOCK CURRENT)

SWITCH OR DEVICECLOSED CIRCUIT(PASS CURRENT)

THERM

AUX

PRESS

HEAT

POWER

SERVICE

FRONT PANEL LEDS

FRONT PANEL LEDSHEAT

PRESS

AUX

THERM

SERVICE

POWER

OR POOL/OFF/SPA THERMOSTAT SELECT SWITCH OFF.... NORMAL OPERATION

HEAT (HEAT)The heat light is on any time the thermostat hassignaled a call for heat which initializes the ignitionsafety firing circuit -- the light comes on to indicatesuccessful firing of the main burners.

SERVICE (SERVICE)The service light is off during normal operation ofheater. The light only comes on if a problem with acontrol has occurred or when the heater is firstfiring. The problem must be investigated by theserviceman prior to attempts to fire the heater again.

The diagrams that follow give examples of troubleshooting a malfunctioning heater using the assistance ofthe indicator lights.

TROUBLESHOOTING (CONTROLS)

Example of troubleshooting with the assistance of the indicator lights.

Rev. B 4-5-02 P/N 472089

11

PRESS

PRESS

HEATER FIRING - NORMAL OPERATION

NOTE: SERVICE LED LIT FLAGS PROBLEM, TFUSE LED OFF SHOWS PROBLEM

PRESS

PRESS

THERMOSTAT CALLING FOR HEAT - BLOWN THERMAL FUSE BLOCKS FIRINGFRONT PANEL LEDS

HEAT

PRESS

AUX SERVICE

TRANSFORMER

THERM POWER

INCOMINGLINE VOLTAGE

FRONT PANEL LEDS

PRESS

HEAT

AUX

THERMOSTAT

PWR

CIRCUITBREAKER

TSTAT

RELAY

RMT

REMOTE

TRANSFORMER

THERM

INCOMINGLINE VOLTAGE

THERMOSTAT

PWR

BREAKERCIRCUIT

TSTAT

RELAYRMT

REMOTE


NO MVCLOSE IF

IGNITION MODULE

SRVE

HI TEMP

LIMIT SWITCHESHI TEMP

TFUSE MV

IND

TFUSE

GND


GAS VALVE

HEAT

VAL

MV

MV

IGNITION MODULE

SRVE

CLOSE IFNO MV

HI TEMP

LIMIT SWITCHESHI TEMP

TFUSE MV

IND

TFUSE

GNDGAS VALVE

HEAT

VAL

MV

MV

POWER

SERVICE

IS IN THERMAL FUSE CIRCUIT

SYMBOL TABLE

LED LIT LED OFF

SWITCH OR DEVICEOPEN CIRCUIT(BLOCK CURRENT)

SWITCH OR DEVICECLOSED CIRCUIT(PASS CURRENT)

TROUBLESHOOTING (CONTROLS) - Continued

Installation (Operating Controls, cont’d.)

P/N 472089 Rev. B 4-5-02

12Installation (Dual Voltage Wiring)

MiniMax NT Low NOx - HSI Electronic Ignition Wiring Diagram(DUAL VOLTAGE w/6800 Control Board)

GR

N

IGN

MO

DU

LE

IGN

ITO

RH

OT

SU

RF

AC

E

BU

RN

ER

GN

D

VA

L

TH

IGN

L2L1IGN

/240

Min

iMax

NT

Lo

w N

Ox

Du

al V

olt

age

W/6

800

Co

ntr

ol B

oar

d W

irin

g D

iag

ram

OR

G

WH

T

GR

N

OR

G

RE

D

TH

ER

MA

L F

US

E

WH

T BLU

RE

D

SW

ITC

HW

AT

ER

PR

ES

SU

RE

SP

ST

EX

TE

RN

AL

SW

ITC

H

GA

S V

ALV

E

RE

DW

HT

BLU

RE

D

HIG

H L

IMIT

115˚

F

1 2 3 4 5

321G

RN

AIR

PR

ES

S. S

W.

BLU

RE

D

WH

T

BLO

CK

TE

RM

BLO

CK

TE

RM

WH

T

WH

T

BLK

WH

T

BLK

WH

T

OR

G

OR

G

WH

T

WH

T

WH

TW

HT

BLO

WE

R

BLK

/WH

T

BLKR

ED

/WH

TRE

D

PU

ROR

G

WH

T

BLK

WH

T

IGN

/120

FS

WH

T

BLK

120

VA

C

OR

240

VA

C

BLK

WH

T

BLK

YE

L

CO

N-F

EM(B

LU)

CO

N-M

AL(

WH

T)

LOW

GA

S

F1

F2

24 V

AC

WH

T

PO

OL

JUM

PE

R R

EQ

UIR

ED

J6

PR

OB

ET

EM

P.

VLV

TP

RO

BE

J5J8

24VJ4

J7

IGN

MO

DU

LE

J10

J11

IND

PR

ES

SU

RE

SW

.

IF O

RIG

INA

L F

AC

TO

RY

WIR

ING

MU

ST

BE

RE

PLA

CE

D,

INS

TA

LLE

R M

US

T S

UP

PLY

UL/

CS

A A

PP

RO

VE

D W

IRE

WIT

H 1

8 A

WG

, 600

V, 1

05˚

C T

EM

P. R

AT

ING

.

ORG

OR

G

SW

/HL/

TF

US

E

J9P

OO

LS

PA

CO

M

WH

T

WH

T

OR

G

BLK

WH

T

WH

T

GR

N

GR

N

OF

FS

PA

J2J3

TH

ER

MA

L F

US

E W

IRIN

G M

US

T B

E R

EP

LAC

ED

WIT

H

INT

ER

CO

NN

EC

TIN

G W

IRIN

G T

O A

PP

LIA

NC

E M

US

T

CO

NF

OR

M T

O T

HE

NA

TIO

NA

L E

LEC

TR

ICA

L C

OD

E O

RS

UP

ER

SE

DE

LO

CA

L(W

IRIN

G)

CO

DE

S.

WH

TW

HT

WH

T

WH

T

IF N

O R

EM

OT

E S

WIT

CH

RE

D

RE

D/W

HT

BLK

BLK

/WH

T

WH

T

WH

T

WH

T

BLK

YE

L

BLU

OR

G

OR

G

HIG

H L

IMIT

150˚

F

18 A

WG

, 600

V, 1

50˚

C T

EM

P. R

AT

ING

.

FOR

120

VAC

CO

N-F

EM(B

RN

)FO

R 2

40 V

AC

AT

TA

CH

GR

OU

ND

WIR

EH

ER

E

GR

N

(ON

TH

E S

IDE

JA

CK

ET

)G

RE

EN

SC

RE

W

PU

R

OR

G

YE

L

BLK

WH

T

FR

OM

TR

AN

SF

OR

ME

R

BLK

WHT

BLK

WH

T

WH

T

BLU

WH

T

YEL

4720

82 R

EV

.B

P4

P7

P10

P11

MV

MV

P9

P1

P2

TH

ER

MO

ST

AT

CIR

CU

IT B

OA

RD

(680

0)

Rev. B 4-5-02 P/N 472089

13

PLUMBING CONNECTIONS

The MiniMax NT Low NOx heater has the uniquecapability of direct schedule 40 PVC plumbingconnections. A set of bulkhead fittings is included withthe MiniMax NT Low NOx to insure conformity withPentair’s recommended PVC plumbing procedure.Other plumbing connections can be used.

CAUTIONBefore operating the heater on a new installation,

turn on the circulation pump and bleed all the air

from the filter using the air relief valve on top of the

filter. Water should flow freely through the heater.

Do not operate the heater unless water in the pool/spa is at the proper level.

MANUAL BY-PASS

Where the flow rate exceeds the maximum 120GPM, a manual bypass should be installed andadjusted. After adjustments are made, the valvehandle should be removed to avoid tampering.

WATER CONNECTIONS

Reversible Inlet/Outlet ConnectionThe MiniMax NT Low NOx heater is factoryassembled with right side inlet/outlet waterconnections. The inlet/outlet header can be reversedfor left side water connections without removing theheat exchanger.

Reversing Water ConnectionsTools required:

1/4 in. Screw Driver9/16 in. Socket and Wrench1/2 in. & 9/16 in. Open Wrench

1. Remove the right and left large inspection plates.2. Disconnect all wires from the high-limit

switches except the short jumper wire.3. Disconnect the pressure switch wiring.4. Remove the temperature sensing bulb from the

inlet/outlet header. Note: If needed, you may cutthe wire ties holding them together.

5. Remove the 16 bolts holding the main inlet/outlet head and return head in place, exchangethe heads, using the new tube seals suppliedwith the heater, re-install the 16 bolts usingmoderate torque.

6. Install the temperature sensing probe by passingthe wires through the hole provided on the leftside of the brace panel. Route wires through thesupport bracket.

7. Reconnect all the high limit wires and thepressure switch wiring, routing the wiresthrough the same hole as the thermostat sensorwires.

8. Re-install the two large inspection plates on theappropriate side.

PLUMBING

VALVES

When any equipment is located below the surface ofthe pool or spa, valves should be placed in thecirculation piping system to isolate the equipmentfrom the pool or spa.Check valves are recommended to prevent backsiphon.

CAUTIONExercise care when installing chemical feeders so

as to not allow back siphoning of chemical into the

heater, filters or pump.

ledoM )MPG(.niM *)MPG(.xaM

002 02 021

052 03 021

003 03 021

004 04 021

dednemmocermumixamehtdeecxetonoD*.gnipipgnitcennocehtrofetarwolf

Installation (Plumbing)

BELOW POOL INSTALLATION

If the heater is below water level, the pressureswitch must be adjusted. This adjustment must bedone by a qualified service technician. See Page 21,Figure 21.

PUMPFILTERPOOL

HEATER

CHECKVALVE

MANUALBY-PASS

TOPOOL

GATEVALVE

CHECKVALVE

FROMPOOL

Figure 10.

P/N 472089 Rev. B 4-5-02

14Installation (Gas Line)

GAS CONNECTIONS

GAS LINE INSTALLATIONS

Before installing the gas line, be sure to checkwhich gas the heater has been designed to burn.This is important because different types of gasrequire different gas pipe sizes. The rating plate onthe heater will indicate which gas the heater isdesigned to burn. Table 1, shows which size pipe isrequired for the distance from the gas meter to theheater. The table is for natural gas at a specificgravity of .65.

When sizing gas lines, calculate three (3) additionalfeet of straight pipe for every elbow used.

When installing the gas line, avoid getting dirt,grease or other foreign material in the pipe as thismay cause damage to the gas valve, which mayresult in heater failure.

The gas meter should be checked to make sure thatit will supply enough gas to the heater and any otherappliances that may be used on the same meter.

The gas line from the meter will usually be of alarger size than the gas valve supplied with theheater. Therefore a reduction of the connecting gaspipe will be necessary. Make this reduction as closeto the heater as possible.

The heater and any other gas appliances must bedisconnected from the gas supply piping systemduring any pressure testing on that system, (greaterthat ½ PSIG).

The heater and its gas connection must be leaktested before placing the heater in operation. Do notuse flame to test the gas line. Use soapy water oranother nonflammable method.

A manual main shut-off valve must be installedexternally to the heater.

Pipe Sized For Length Of Run In Equivalent Feet

ledoM

.ni4/3 .ni1 .ni¼1 .ni½1 .ni2

saGlarutaN

002 '03 '521 '054 - -

052 '02 '07 '052 '006 -

003 '01 '05 '002 '004 -

004 - '02 '001 '002 '004

REGULATED MANIFOLD PRESSURE TEST1. Attach the manometer to the heater jacket.2. Shut off the main gas valve.3. Remove 1/8 in. NPT plug on the outlet side of the

valve and screw in the fitting from the manometer kit.4. Connect the manometer hose to the fitting.5. Turn on the heater.6. The manometer must read 4 in. WC for natural gas,

while operating.7. For adjustment, remove the Regulator Adjustment

Cap and using a screwdriver turn the screw clock-wise to increase - counterclockwise to decrease gaspressure.

Table 1.

Natural

Maximum inlet gas pressure 10 in. WCMinimum inlet gas pressure **5 in. WCNormal manifold pressure 4 in. WC

*All Readings are taken with the heater fired. Any adjustmentsor readings made with heater off will give incorrect readings.** 6 WC for 400 model

OFF

ON

Regulator Adjustment Cap

1/8" NPT Plug(Manifold Press)

1/8" NPT Plug(Inlet Press)

Figure 11.

CAUTIONThe use of Flexible Connectors (FLEX) is NOTrecommended as they cause high gas pressure drops.

MINIMAX NT LOW NOx GAS PRESSURE REQUIREMENTS*

WARNINGDo not install the gas line union inside the heater

cabinet. This will void your warranty.

Rev. B 4-5-02 P/N 472089

15

INDOOR VENTING—General Requirements

The vent pipe must be the same size or larger. The MiniMax NT Low NOx heaters are capable of a 360-degreedischarge rotation and operate with a positive vent static pressure and with a vent gas temperature less than400° F. The total length of the horizontal run must not exceed the length that is listed below in the tables.

Please note the allowable vent runs for each stack pipe diameter are different and can not be exceeded.

Note that each 90-degree elbow reduces the maximum horizontal vent run by 8 feet and each 45-degree elbowin the vent run reduces the maximum vent run by 4 feet. See the tables below for the maximum vent lengthsusing a 90-degree and 45-degree elbows. The MiniMax NT Low NOx induced-draft pool and spa heater usespositive pressure to push flue gases through the vent pipe to the outside. This requires a completely sealed ventsystem—single wall vent pipe with sealed-seams and joints may be used. Flue gases under positive pressuremay escape into the dwelling with any cracks or loose joints in the vent pipe, or improper vent installation.The vent pipe must be of a sealed-seam construction such as those listed for use with category III appliances.Alternately, single wall or double-wall type B duct which has had duct seams and joints permanently sealedusing cements or other suitable means which are rated for use at the flue gas temperatures of 325° F. and arepermanent are acceptable. The use of listed thimbles, roof jacks and/or side vent terminals are required; and theproper clearances to combustible materials must be maintained in accordance with type of vent pipe employed—in the absence of a clearance recommendation by the vent pipe manufacturer, the requirements of the UniformMechanical Code should be met. The ventilation air requirements for the MiniMax NT Low NOx heater andcan be found on page 17. It is recommended that vent runs over 18 feet be insulated to reduce condensationrelated problems and/or the use of a condensate trap in the vent run close to the heater may be necessary incertain installations such as cold climates. The MiniMax NT Low NOx is suitable for through-the-wall venting.

Recommended sources for Side-wall vent hood terminals include: The Field Controls Co. (2308 Airport Road,Kingston, NC 28501, (800)742-8368) and Tjernlund Products Inc. (1601 Ninth Street, White Bear Lake, MN55110, (800) 255-4208)—consult manufacturer for model information and availability.

CAUTIONDo NOT combine exhaust vent pipes to a common exhaust vent in multiple unit installations. Run separate vent pipes.

).tf.viuqE(tnev.D.O.ni5,nuRtneVmumixaM.tf54

swoble°09lanoitiddA

wobletsrifretfa


wobletsrifretfa

ytitnauQ .xaMdecudeR ytitnauQ .xaMdecudeR

)latot2(1 73 )latot2( 14



).tf.viuqE(tnev.D.O.ni4,nuRtneVmumixaM.tf22


wobletsrifretfa


wobletsrifretfa

ytitnauQ .xaMdecudeR ytitnauQ .xaMdecudeR

)latot2(1 .tf41 )latot2( .tf81

)latot3(2 — )latot3( .tf41

)latot4(3 — )latot4( —

Installation (Indoor)

P/N 472089 Rev. B 4-5-02

16

INDOOR INSTALLATION (USA ONLY)

OUTDOOR SHELTER INSTALLATION (CANADA)

See page 17 for (Indoor) Vent Adaptors

All products of combustion and vent gases must becompletely removed to the outside atmosphere througha vent pipe which is connected to the stack adaptor. Avent pipe extension of the same size must be connectedto the indoor stack adaptor and extended at least 2 feethigher than highest point of the roof within a 10 foothorizontal radius, and at least 3 ft. higher than the pointat which it passes through the roof, or as permitted bylocal code; see Figures 12 and 13. The vent shouldterminate with an approved vent cap (weather cap) forprotection against rain or blockage by snow. Double-wall vent pipe and an approved roof jack shall beemployed through the roof penetration.

The heater must be located as close as practical to achimney or gas vent.

CAUTION

The heater should be installed at least 5 feet away

from the pool or spa.

The heater must be placed in a suitable room on a non-combustible floor or on a non-combustible base and inan area where leakage from heat exchanger or waterconnections will not result in damage to the areaadjacent to the heater or the structure. When suchlocations cannot be avoided, it is recommended that asuitable drain pan with adequate drainage, be installedunder the heater. The pan must not restrict air flow.

Installations in basements, garages, or undergroundstructures where flammable liquids may be stored musthave the heater elevated 18 inches from the floor usinga non-combustible base. The following minimumclearances from combustible materials must beprovided.

Side Front Back Top

Water Connection 18 in. 24 in. - -

Remaining 6 in. - 6 in. -

Ceiling Clearance - - - 18 in.*

*To ceiling or roof.

��

VentCap

Ridge

Chimney

3 ft. min.

2 ft. min.

10 ft.

RoofJack

AIR SUPPLYVENTILATION

AIR SUPPLYGAS COMBUSTION

OPTIONAL SIDE WALL VENT NT

VENT CAP ANDRISER FURNISHEDBY INSTALLER


The heater should not be installed closer than 6 inches toany fences, walls or shrubs at any side or back, norcloser than 18 inches at the plumbing side. A minimumclearance of 24 inches must be maintained at the front ofthe heater.

DO

OR 6"

6"

24"

18"

Figure 14.

Figure 12.

Figure 13.

Rev. B 4-5-02 P/N 472089

17

.oNtcudorP .aiDtneV

605064 .ni4

705064 .ni5

Figure 16.

YLPPUSRIADERIUQER

ledoMnoitsubmoCrofriA

.nI.qS

noitalitneVriA

.nI.qS

002 002 002

052 052 052

003 003 003

004 004 004

ledoM tiKesaBelbitsubmoC-noN

002 169174

052 905064

003 069174

004 805064


NOTEThe heater requires two uninterrupted air supply

openings; one for ventilation and one to supply

oxygen for proper gas combustion. The air supply

openings should be sized according to Table 2.

Air supply requirements below apply to allMiniMax NT Low NOx heaters*.

CAUTION

Chemicals should not be stored near the heater

installation. Combustion air can be contaminated by

corrosive chemical fumes which can void the warranty.*NOTE

The openings listed in Table 2 are free open vent

area—if the vents incorporate restrictive louvers,

the vent openings must be increased to

compensate for the area blocked by the louvers

(or grills).

b) Construct a non-combustible base from masonryblocks as illustrated, see Figure 15.

INSTALLATION ON FLOORS CONSTRUCTED

OF COMBUSTIBLE MATERIALS

The heater may be placed on a “combustible floor”using either of the two methods listed below:

a) Use Listed Factory Non-combustible Base Kitfor use on combustible floors.

INDOOR VENT ADAPTORS

(FITS ALL MODELS)

The proper draft hood and adapter must be installed onthe heater as shown below and on pages 15 and 16:

BASE FOR USE ON COMBUSTIBLE FLOORS

24 GA. (MIN.) GALVANIZED SHEET METAL.FOR AIR CIRCULATION). COVER BLOCKS WITH(LAID WITH ENDS UNSEALED AND JOINTS MATCHEDHOLLOW MASONARY BLOCKS, NOT LESS THAN 4" THICK

SHEET METAL

BLOCKS

6" Min

.

6" Min

.

Figure 15.

Indoor VentAdaptor

Table 2.

P/N 472089 Rev. B 4-5-02

18

Det

ail H

IND

OO

R IN

STA

LL

AT

ION

SM

INIM

AX

NT

LO

W N

Ox

VE

NT

ING

GU

IDE

LIN

ES

��

��

vent

term

inat

ed a

tle

ast 2

4" a

bove

any

obje

ct w

ithin

10

ft.

Ven

tC

apR

idge

Chi

mne

y

3 ft.

min

.

2 ft.

min

.10 ft

.

4'

7'

4'

Air

Sup

ply

Ven

tilat

ion

Air

Sup

ply

Com

bust

ion

Ven

t Hoo

d

Wal

kway

3'

1' m

in.

1' m

in.

1' m

in.

abov

e gr

ade

Ven

t Hoo

d

Ven

t Hoo

d

EH

D

F

G G

F

BC

A

mus

t ext

end

at le

ast 3

ft. h

ighe

r th

an th

e po

int a

t whi

ch it

pas

ses

thro

ugh

the

roof

, or

as

perm

itted

by

loca

l cod

e.

mus

t use

a d

oubl

e-w

all v

ent p

ipe

thro

ugh

the

roof

pen

etra

tion.

mus

t ter

min

ate

with

an

appr

oved

(lis

ted)

roof

jack

, sto

rm c

olla

r, an

d ve

nt/w

eath

er c

ap.

mus

t be

not l

ess

than

7 ft

. abo

ve p

ublic

wal

kway

s.m

ust b

e at

leas

t 3 ft

. abo

ve a

ny o

utsi

de a

ir in

take

loca

ted

with

in a

10

ft. r

adiu

s.m

ust

NO

T b

e w

ithin

3 ft

. of a

n in

side

cor

ner

of th

e st

ruct

ure.

mus

t be

at le

ast 1

ft. a

bove

gra

de.

mus

t be

loca

ted

the

follo

win

g di

stan

ces

away

from

any

doo

r, w

indo

w, o

r gr

avity

air

inle

t:4

ft. b

elow

4 ft.

hor

izon

tally

1 ft.

abo

ve

Air

Su

pp

lyS

ee A

ir S

uppl

y R

equi

rem

ents

Tab

le.

BA

D E F

J K L

C G

Ven

t te

rmin

atio

n fo

r si

de

wal

l in

stal

lati

on

s:

mus

t be

the

sam

e di

amet

er a

s th

eve

nt c

onne

ctor

.

mus

t be

suita

ble

for

use

with

cat

egor

y III

appl

ianc

es w

hich

hav

e flu

e ga

s te

mpe

ratu

res

of le

ss th

an 4

00 d

eg. F

.

may

use

a s

ingl

e w

all v

ent p

ipe

with

pe

rman

ently

sea

led

seam

s an

d jo

ints

.

Ven

t p

ipe

exte

nsi

on

:

Ven

t fo

r ro

of

pen

etra

tio

n in

stal

lati

on

s:

L

J K

Rec

omm

ende

d so

urce

s fo

rsi

de w

all V

ent H

ood;

see

pag

e 15

,S

ectio

n V

entin

g.

(Ta

ble

2 o

n p

ag

e 1

7.)

Fig

ure

17.


Rev. B 4-5-02 P/N 472089

19

VENTILATION

OUTDOOR INSTALLATION ONLY (Outdoor Shelter Installation in Canada, see page 16)

For outdoor installation with built in vent, the heater must be placed in a suitable area on a level, noncombustiblesurface. Do not install the heater under an overhang with clearances less than 3 feet from the top of the heater. Thearea under an overhang must be open on three sides.

IMPORTANT!In an outdoor installation it is important to ensure water is diverted from overhanging eves with a

proper gutter/drainage system. The heater must be set on a level foundation for proper drainage.

Maintain minimum clearances as indicated below. Install a minimum of 4 feet below, and 4 feet horizontally from anyopening to a building, see Figure 18.

IMPORTANT!When locating the heater, consider that high winds can roll over or deflect off adjacent buildings

and walls. Normally, placing the heater at least three feet from any wall will minimize downdraft.

NOTEThis unit shall not be operated outdoors at temperatures below -20o F. for natural gas.

Installation (Outdoor)

MINIMAX NT VENTING GUIDELINESOUTDOOR INSTALLATION

B

C

D

E Check local building codesfor setback requirements.

Property Line

4'

1'

4'

4'

Walkway

3'

A

E

Figure 18.

CAUTION

If installing the heater next to or near an air conditioning unit or a heat pump, allow a minimum of 24 in.

between the air conditioning unit and the heater.

P/N 472089 Rev. B 4-5-02

20

GENERAL DESCRIPTION

The MiniMax NT Low NOx Pool and Spa Heater is a fan-assisted induced draft appliance. The MiniMaxNT Low NOx is available in 200,000, 250,000, 300,000 and 400,000 btu/hr. capacities and are certified forboth indoor and outdoor installations. The MiniMax NT Low NOx version natural gas pool heater must beused for installations in the South Coast Air Quality Management District (SCAQMD)—these heaters arecertified to comply with SCAQMD Rule 1146.2 and also meet Ventura Co. APCD Rule 74.11.1.

The MiniMax NT Low NOx is designed to operate both in stackless outdoor installations and in indoorstack vent installations—the indoor installation may be made using Kit 460506 or 460507; see pages 6 and 17,vertical vent pipe or with a horizontal vent pipe and a Listed side-wall vent.

BASIC SYSTEM OPERATION

TO OPERATE HEATER

1. Start pump, make sure the pump is running and is primed, to close water pressure switch andsupply power to heater.

2. Set thermostat to lowest setting .

3. Set the thermostat rocker switch to the center “OFF” position.

4. Open the access doors.

5. Push in the gas control knob slightly and turn the knob clockwise to “OFF”.

6. Wait (5) minutes to clear out any gas. If you then smell gas STOP. Follow the safety information(stated earlier in the lighting instructions section). If you don’t smell gas, go to the next step.

7. Turn the knob on the gas control counter clockwise to the “ON” position.

8. Replace the doors.

9. Push the thermostat select switch to “POOL” or “SPA” to start the heater.

10. Set the thermostat to the desired temperature.

a. Fan motor starts, which closes draft proving switch.

b. Ignition module is energized and the prepurge cycle is started approximately 15 seconds.

c. Check for powering up the (glow coil) hot-surface ignitor by viewing through the opening holeson the face plate.

11. The ignitor will warm up and then gas valve opens to ignite the main burners.

12. Heater will operate until desired temperature is reached.

Basic Operation

Rev. B 4-5-02 P/N 472089

21

SAFETY CONTROLS

AIR PRESSURE (FAN) SWITCH

The air pressure switch is a safety device used to insurethat the blower (fan) is operating and has beendesigned to monitor the vacuum (negative) pressurewithin the blower housing. The air pressures switchis factory set and is in the ignition module circuit—the ignition module does not operate unless the airpressure switch and all safety switches are closed.

WATER PRESSURE SWITCH

The water pressure safety switch closes when there isa sufficient flow of water to the heat exchanger tosafely operate the heater. The switch operation mustbe verified during initial operation of the heater afterinstallation—the switch is set at 1 PSIG and the switchcontacts must not be closed in the absence of waterflow. NOTE: See, Below Pool Level Installationinstructions on page 13. The switch may remain closedwith no water flow if there is more than a 3 ft. elevationdifference between the heater (heat exchanger) andthe pool water line—if this is the case, the waterpressure switch must be reset to maintain open switchcontacts with no water flow.

NOTE

If the pool is more than one floor above or one floor

below the heater, the pressure switch may have to

be replaced with a flow switch.

LOW GAS PRESSURE SWITCH

(LOW NOx Versions Only)

The MiniMax NT Low NOx heater uses a low gassupply pressure switch, ahead of the gas valve, toprevent operation of the heater when the gas supplypressure is below the minimum required for properoperation of the burners. The switch is factory set. Inthe event that the switch does not close and preventsthe firing of the heater, the cause of the low gas supplypressure must be corrected. Typical causes areundersized supply piping, undersized gas meter or lowgas regulator setting (gas supply regulator and gasmeter problems are typically corrected by your localgas company).

Basic Operation

AIR PRESSURE SWITCH

Adjustment Knob

Typical Water Pressure Switch

Low Gas Pressure Switch

Figure 19.

Figure 20.

Figure 21.

P/N 472089 Rev. B 4-5-02

22

SAFETY CONTROLS, (cont’d.)

IGNITION MODULEThe Ignition Module is microprocessor based and operates on 24 VAC supplied by the transformer. Thecontrol utilizes a microprocessor to continually and safely monitor, analyze, and control the proper operationof the gas burners. The module with the presence of the flame sensor/ignitor or remote sensor, using flamerectification, allows the heater to operate.

HIGH LIMITSA “High Limit”, is a safety device that opens the electrical circuit and shuts off the heater based on atemperature set point within the “High Limit Device”. The MiniMax NT Low NOx series of heaterscontains three (3) high limit devices, two (2) are located on the main inlet / outlet header, one sensing theinlet water temperature and one sensing the outlet water temperature. The third high limit is located on theexhaust outlet and senses the temperature of the flue gas.

OPERATION OF IGNITION MODULE

HEAT MODE

• When a call for heat is received from the thermostat supplying 24 VAC to the module terminal, thecontrol will perform a self check routine, for up to four seconds and begins the safety timing ignitionsequence. After the fan prepurge cycle, the hot surface ignitor is activated for a heat-up period followedby energization of the gas valve for the trial for ignition period.

• When flame is detected during the trial for ignition, the ignitor is deactivated and the gas valve remainsenergized. The thermostat and main burner flame are constantly monitored to assure the systemcontinues to operate properly. When the thermostat is satisfied and the demand for heat ends, the mainvalve is de-energized immediately.

FAILURE TO LIGHT LOCK OUT

Should the main burners fail to light, or flame is not detected during the trial for ignition period of(7) seconds, the ignition Module will stop the ignition sequence and the gas valve will be turned off.The ignition module will go through this sequence three (3) times, if full ignition fails after the third try, themodule will go to full lock out. To restart the ignition sequence, turn the main electrical power off to theheater, using the switch on the bottom of the junction box, for a period of one minute, then turn the powerback on, the heater will again try to light.

FLAME FAILURE—RE-IGNITION

If the established flame signal is lost while the burner is operating, the control will respond within 1 second.The gas valve is de-energized and the control starts a new ignition sequence in an attempt to relight theburner. If the burner does not relight, the control will go into lockout, requiring a manual reset.

Basic Operation

Rev. B 4-5-02 P/N 472089

23

LOW-NOx

MAINTENANCE INSTRUCTIONS

It is recommended that you check the following items atleast every six months and at the beginning of everyswimming season.1. Examine the venting system. Make sure there are no

obstructions in the flow of combustion andventilation air.

2. Visually inspect the main burner and the hot surfaceignitor. The normal color of the flame is blue. Whenflame appears yellow, burners should be inspectedand cleaned. Check ignitor for damage.

3. Keep the heater area clear and free fromcombustibles and flammable liquids.

Pressure Relief ValveIn some installa-tions, a pressurerelief valve (PVR)is required on theMiniMax NT LowNOx. To install aPRV, carefully drilla 3/8 in. hole incenter of 3/4 in.NPT port (on mainheader) beingcareful to drill onlythrough wall at bottom of 3/4 in. NPT port and nodeeper—now thread in the 3/4 NPT PRV. NOTE:(A.S.M.E. version varies from illustration. It is of bronzeconstruction, and is supplied with the A.S.M.E. SectionIV, pressure relief valve pre-installed at factory.) Test therelief valve at least once a year by lifting up lever.

ENERGY SAVING TIPS

1. If possible, keep pool or spa covered when not inuse. This will not only cut heating costs, but alsokeep dirt and debris from settling in the pool andconserve chemicals.

2. Reduce the pool thermostat setting to 78° F. orlower. This is accepted as being the most healthytemperature for swimming by the American RedCross.

3. Use an accurate thermometer.

4. When the proper maximum thermostat settings havebeen determined, tighten the thermostat knobstopper.

5. Set time clock to start circulation system no earlierthan daybreak. The swimming pool loses less heat atthis time.

6. For pools that are only used on the weekends, it isnot necessary to leave the thermostat set at 78° F.Lower the temperature to a range that can beachieved easily in one day. Generally, this would be10° F. to 15° F., if pool heater is sized properly.

7. During the winter or while on vacation, turn theheater off.

8. Set up a regular program of preventativemaintenance for the heater each new swimmingseason. Check heat exchanger, controls, burners,operation, etc.

SPRING AND FALL OPERATION

If the pool is being used occasionally, do not turn the heatercompletely off. Set the thermostat down to 65° F. This

WINTER OPERATION

will keep the pool and the surrounding ground warmenough to bring the pool up to a comfortable swimmingtemperature in a shorter period of time.

If the pool won't be used for a month or more, turn theheater off at the main gas valve. For areas where there isno danger of water freezing, water should circulatethrough the heater all year long, even though you are notheating your swimming pool. The MiniMax NT LowNOx should not be operated outdoors at temperaturesbelow 0° F. for propane and -20° F. for natural gas.

FOR PRVINSTALLATIONDRILL THRUTHE NPT PORT

REMOVE FLOW VALVE BEFORE DRILLINGTHE NPT PORT Figure 23.

Figure 22.

Maintenance

Where freezing is possible, it is necessary to drain thewater from the heater. This may be done by opening thedrain valve, located at the inlet/outlet header, (see Figure23.), allowing all water to drain out of the heater. Itwould be a good practice to use compressed air to blowthe water out of the heat exchanger. (See additionalnotes under Important Notices in Introduction.)

P/N 472089 Rev. B 4-5-02

24Maintenance (Water Treatment)

RULE: 7.4 to 7.6 is a desirable pH range. It is essentialto maintain correct pH, see Table 4.

If pH becomes too high (over alkaline), it

has these effects:

1. Greatly lowers the ability of chlorine to destroybacteria and algae.

2. Water becomes cloudy.

3. There is more danger of scale formation on theplaster or in the heat exchanger.

4. Filter elements may become blocked.

If pH is too low (over acid) the following

conditions may occur:

1. Excessive eye burn or skin irritation.

2. Etching of the plaster.

3. Corrosion of metal fixtures in the filtration andrecirculation system, which may create brown, blue,green, or sometimes almost black stains on theplaster.

4. Corrosion of copper in the heater, which may causeleaks.

5. If you have a sand and gravel filter, the alum used asa filter aid may dissolve and pass through the filter.

CAUTION: Do not test for pH when the chlorineresidual is 3.0 ppm or higher, or bromine residualis 6.0 ppm or higher. See your local pool supplystore for help in properly balancing your waterchemistry.

RULE: Chemicals that are acid lower pH. Chemicalsthat are alkaline raise pH.

Heat exchanger damage resulting from chemical

imbalance is not covered by the warranty.

CAUTION

Muriatic Acid has a pH of about 0. Pure water is 7(neutral). Weak Lye solution have a pH of 13-14.

pH ChartTable 3.Strongly Acid Neutral Strongly Alkaline

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

ALKALINITY High - Low:

"Total alkalinity" is a measurement of the total amountof alkaline chemicals in the water, and control pH to agreat degree. (It is not the same as pH which refersmerely to the relative alkalinity/acidity balance.) Yourpool water's total alkalinity should be 100 - 140 ppm topermit easier pH control.

A total alkalinity test is simple to perform with a reliabletest kit. You will need to test about once a week andmake proper adjustments until alkalinity is in the properrange. Then, test only once every month or so to be sureit is being maintained. See your local pool dealer forhelp in properly balancing the water chemistry.

7.26.8 7.0 7.4 7.6 7.8 8.0 8.2 8.4

Add Soda, Ash orSodium Bicarbonate

Add AcidMarginalIdealMarginal

pH Control ChartTable 4.

CHEMICAL BALANCE

POOL AND SPA WATERYour Pentair Pool Products pool heater was designedspecifically for your spa or pool and will give you manyyears of trouble-free service, provided you keep yourwater chemistry in proper condition.Three major items that can cause problems with yourpool heater are: improper pH, disinfectant residual, andtotal alkalinity. These items, if not kept properlybalanced, can shorten the life of the heater and causepermanent damage.

WHAT A DISINFECTANT DOES

Two pool guests you do not want are algae and bacteria.To get rid of them and make pool water sanitary forswimming - as well as to improve the water's taste, odorand clarity - some sort of disinfectant must be used.Chlorine and bromine are universally approved by healthauthorities and are accepted disinfecting agents forbacteria control.

WHAT IS A DISINFECTANT

RESIDUAL?

When you add chlorine or bromine to the pool water, aportion of the disinfectant will be consumed in theprocess of destroying bacteria, algae and other oxidiz-able materials. The disinfectant remaining is calledchlorine residual or bromine residual. You can determinethe disinfectant residual of your pool water with a reliabletest kit, available from your local pool supply store.You must maintain a disinfectant residual level adequateenough to assure a continuous kill of bacteria or virusintroduced into pool water by swimmers, through the air,from dust, rain or other sources.It is wise to test pool water regularly. Never allowchlorine residual to drop below 0.6 ppm (parts permillion). The minimum level for effective chlorine orbromine residual is 1.4 ppm.pH - The term pH refers to the acid/alkaline balance ofwater expressed on a numerical scale from 0 to 14. A testkit for measuring pH balance of your pool water isavailable from your local pool supply store; see Table 3.

Rev. B 4-5-02 P/N 472089

25

Possible Cause Remedy

Heater will not come on

Automatic ignition system fails Check if electrical connections are

correct and securely fastened –

If YES, call serviceperson.

Pump not running Place pump in operation

Pump air locked Check for leaks

Filter dirty Clean filter

Pump strainer clogged Clean strainer

Defective wiring or connection Repair or replace wires

Defective pressure switch Replace switch

Defective gas controls Call serviceperson

On-Off switch in "OFF" position Turn switch to "ON"

Heater Short Cycling (Rapid On and Off Operation)

Insufficient water flow Clean filter and pump strainer

Defective wiring Repair or replace wiring

Defective flow valve or out of adjustment Call serviceperson

Defective hi-limit and/or thermostat Call serviceperson

Heater Makes Knocking Noises,

Make sure all valves on system are open

Heater operating after pump has shut off Shut off gas supply and call serviceperson

Heater exchanger scaled Shut off gas supply and call serviceperson

Troubleshooting - General

SERVICE CHECKS—

IGNITION MODULE

skcehCecivreS

motpmyS eruC/esuaC

daeD.1 deriwsiM.A

dabremrofsnarT.B

dabrekaerbtiucriC/esuF.C

lortnocdaB.D

noitingion—notatsomrehT.2 deriwsiM.A

lanimrettaegatlovontatsomrehtdaB.B

noitingion,noevlaV.3 rotingievitcefeD.A

deriwsiM.B

)rotingitaegatlovkcehc(lortnocdaB.C

noitcaevlavon,norotingI.4 nepoliocevlaV.A

eriwevlavnepO.B

)egatlovkcehc(lortnocdaB.C

gnirudyakoemalF.5

,)IFT(noitingIroFyrT

)IFTretfa(esnesemalfon

rotingidaB.A

seriwdaB.B

renrubtadnuorgrooP.C

)tnerrucemalfkcehc(emalfrooP.D

P/N 472089 Rev. B 4-5-02

26

MINIMAX NT LOW NOx HEATER - (Dual Voltage)

1

4

3

5

7

8

9

11

28

30

35

36

38

51 50 48 46 4445

40

39

17

16

15

14

23

13

34

41

26

27

2

6

10

24

25

22

18

31

33

32

37

47

43

42

12

29 19

20

21

MiniMAX NT Low NOx Heater(Dual Voltage w/6800 Controller)

49

Rev. B 4-5-02 P/N 472089

27

ITEM DESCRIPTION QTY. 200 250 300 4001 Exhaust Grill 12 Gasket, Exhaust Grill 13 Top Cover 1 471885 471692 471886 4715914 Exhaust Assy. 1 4720135 Blower 1 471938 4718846 Gasket, Blower 17 Flue Collector Assy. 1 472008 472007 472006 4720058 Return Manifold Assy.Non-ASME 19 Bolt, Heat Exchanger, Non-ASME 16

10 Washer, Heat Exchanger 1611 Fire box Assy. 1 471904 471835 471922 47182112 Heat Exchanger Assy. Non-ASME 1 471910 471785 471928 47183813 Baffle, Heat Exchanger 8/16(200,250,300/400) 471642 471641 471896 47164014 Thermistor Probe 115 HI-Limit Thermostat-115° F. 116 Hi-Limit Thermostat-150° F. 117 Water Pressure Switch 118 Main Manifold Assy. Non-ASME 119 Main Header Assy. Non-ASME 120 Main Manifold Bottom 121 Cap, Main Manifold Bottom 122 Adapter, Bulkhead Ring 223 Adapter, Bulkhead, 2 in. 224 Gasket, Fin Tube, Seal 1825 Flow Valve Assy. 126 Gas Pressure Switch 127 Sub-Manifold, Gas Supply 128 Gas Valve-Natural Gas 129 Burner Tray Assy. 1 471905 472016 471923 47198130 Igniter 131 Gas Manifold Assy. 1 472004 472003 472002 47200132 Burner 4/5/6/8(200/250/300/400)33 Face Plate 1 472069 472068 472067 47205234 Jacket, Upper Panel, Left 135 Jacket Corner 436 Jacket Divider 1 471827 471651 471826 47158037 Jacket, Lower Panel, Left 138 Base 1 471829 471645 471828 47157339 Jacket Back 1 471861 471669 471874 47157440 Bracket, Jacket Side 241 Jacket, Upper Panel, Right 142 Jacket, Upper Subplate, Right 243 Jacket, Lower Panel, Right 144 Base Heat Shield 1 471831 471646 471830 47157945 Control Box Assy. 146 Air Pressure Switch 1 471747 47156947 Module, Ignition Control 148 Temperature Controller Assy. 149 Bracket, Controller 150 Right Door Assy. 151 Left Door Assy. 1 471900 471659 471918 471726NA Gas Orifice, 0-2000 Ft (Not Shown) 4/5/6/8(200/250/300/400)NA Thermal Cut-off (Not Shown) 1NA Transformer, 40 VA (Not Shown) 1

Note: Some parts are not listed above, please contact our Customer Service Department for details.

��

471610

471991471622

472014471883

471592471701

072184

471566471587471694471672471993

274440471441

471992

471420471419

471581

471647

471575

070951

471696

471668

471597471601

471750471506

471571

472086

472087

471984075173

471852

472015

472080471743

471768471576(Non-ASME) ; 471697(ASME)

471767471577

P/N 472089 Rev. B 4-5-02

2840

HEATER SERIAL NUMBER

(Please Fill In)

Pentair Pool Products, Inc.1620 Hawkins Ave., Sanford, NC 27330 • (919) 774-4151

10951 W. Los Angeles Ave., Moorpark, CA 93021 • (805) 523-2400

Documents

MiniMax NT LowNOx