Ds 824 Controller Datasheet

8/2/2019 Ds 824 Controller Datasheet

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The DS-824 is an advanced low voltage version of the

DS-8. It is primarily designed for hydronic and low volt-

age guer, downspout, and roof ice melng applica-

ons. It can also be used on exisng buildings where

retrong high voltage wiring would be to dicult.

The 24VAC/VDC supply means less expensive wiring, norequirement for conduit, and lower installaon costs.

The unit is housed in a two gang PVC enclosure. The

overall dimensions of the DS-824 are 4(120) x 7(178)

x 2(70). The unit weighs 2 pounds. The user may

access all electronics by removing the four front cover

screws. The remote precipitaon sensor includes 10 feet

(3 m) of interconnect cable. A weatherproof LED indica-

tor on the base of the unit provides a method of check-

ing power and trigger status when the unit is mounted

in a hard to reach locaon. Steady OFF indicates no

power to the unit. Steady ON indicates power is being

supplied but no snow or rain trigger is acve. A blink-

ing LED indicates the DS-824 is triggered and connected

equipment has been acvated.

The DS-824 can be powered from a 22-28VAC/VDC

source. Peak power consumpon is 15 VA at startup,

8.5 VA steady state triggered, 5 VA steady state untrig-

gered. Power input is polarity protected for a DC supply.

The unit provides a single 24VAC/30A or 24VDC/20A

normally open load contact set. This contact set is paral-

leled with a low power contact set to provide remote

control and acvaon monitoring. Operaonal tempera-

ture range is -40C to +85C.

CONTROLS & MONITORING

THE DS824 RAIN/SNOWSENSOR CONTROLLER

Designed for Low Voltage Hydronic

and Baery Powered Systems

Automac Acvaon means Lower De-icing Costs

Reliable Rain and Snow Detecon

24VAC/VDC Operaon, Only 20 VA Required

Full 30A @ 24VAC Control

Replaceable Remote Precipitaon Sensor

8 Dierent Funcons, 1 Part Number

Adjustable Temperature Trigger Point

Exclusive Adjustable Sensivity Control

Selectable Low Temperature Cuto

Smart Manual On Operates for One Delay O Cycle

High Power, Low Price!

(866) 635-8123

www.thermaltechusa.com


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The table on the next page outlines the operang

modes for the DS-824. Trigger Temperature (TT) is

adjustable from 34F-44F using an on-board control.

When ambient air temperature (AT) is below this trigger

point precipitaon is assumed to be snow or freezing

rain. When above the trigger point, precipitaon is as-

sumed to be rain.

Delay O refers to the internal drying cycle mer of

the DS-824. The mer is used to allow the DS-824 to dry

the heated surface through evaporaon once precipita-

on has stopped. The drying cycle reduces the chance

that moisture le behind by the melng process will

refreeze into ice. This mer is restarted by each precipi-

taon detecon. Therefore, the DS-824 will connue to

operate as long as precipitaon and trigger temperature

is detected, then for the Delay O me once rain or

snow stops. It is assumed that, when operang as asensor, the DS-824 is supplying an acvaon signal to an

external control system. All sensor modes provide a

minimum 2 minute closure, reducing cycling of the ex-

ternal controller. The Delay O cycle has been extended

for hydronic applicaons and is determined by the Long

Delay (LD) switch seng, DEL switch seng and the DEL

adjustment. Delay O is 30-90 minutes in non-LD con-

troller mode and 2-6 hours in LD controller mode.

An environmentally sealed control switch is provided.

The Manual On funcon acvates the controlled

equipment for tesng and special operaonal condi-ons. The Automac posion allows the DS-824 to

handle all detecons and control. The Standby/Reset

posion disables triggering and can also be used to clear

the delay o mer (see next page) from true or test

acvaon. If the switch is placed in Manual On for less

than 2 seconds, then switched back to Automac the

controller will execute one delay o cycle. This allows a

controlled manual acvaon of the snow melt system

without the fear of forgeng and leaving the system

in Manual On for an extended and potenally very

expensive period of me. Standby/Reset can sll be

used to clear this delay o cycle. Remote control and

monitor up to 1000 feet away is also available when the

oponal CS-1 C/M cable listed is installed. The DS-824

is also compable with the DP-7B, DP-7EX, and CDP-2

remote control/status panels.

The Low Temperature Cuto (LTC) opon is typically

used on de-icing or snow melng systems with limited

output capacity. If selected, the sensor will not trigger if

precipitaon is detected below 15F. However, if the de-

icing system has been acvated, precipitaon connues,

and the ambient temperature drops below 15F, LTC will

be ignored. This assures that water le behind on thesurface during the heang cycle will not immediately

refreeze into ice as a result of deacvang the de-icing

system.

The DS-824 also features a new innovaon, a Trigger

Sensivity Adjustment. Previous units have always

detected and triggered on the rst drop of rain, the rst

ake of snow. While this has always provided a highly

reliable detecon it may create nuisance triggers in

some installaons. Snow blowing o a roof or falling

from a tree could cause the system to acvate for adelay cycle when its not needed, increasing operat-

ing costs. The sensivity adjustment allows seng

the number of seconds the precipitaon grid must

see connuous rain or snow before the sensor is trig-

gered and ranges from 3 seconds to 4 minutes. A higher

sensivity seng assures quick detecon no maer the

condions. A lower sensivity seng will allow a few

stray drips of rain or akes of snow to be ignored but a

heavier downfall will trigger the system.


(866) 635-8123



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DS824 SPECIFICATIONSDimensions 4"(120) x 7"(178) x 2"(70)

Weight 2 Lbs. (0.9 Kg)

Operang Temperature -40F to +185F (-40C to +85C)

Enclosure Rang NEMA 3R

Supply Power 22-28VAC/VDC 15VA maximum, 5VA typical

Trigger Temperature 34F-44F (1.1C-6.6C) Field Selectable

Delay O (Sensor) 2 Minutes

Delay O (Controller) 30-90 Minutes/2-6 Hours Field Selectable

Load Contact Capacity 30A @ 24 VAC/100,000 operaons minimum at full load

Monitor Contact Capacity 24 VDC/VAC 400mA 10W total

FUNCTION

AMBIENT

TEMP AT

DELAY OFF

LD OFF

DELAY

OFF

LD ON SUGGESTED APPLICATION

Snow sensor w\o LTC AT < TT 2 Min 2 Min Snow and ice alert, Sensor for external deice/snow melt con-

troller (unlimited heat)

Snow sensor w\LTC TT>AT>15F 2 Min 2 Min Sensor for external deice/snow melt controller (limited heat)

Snow controller w\o

LTC

AT < TT 30-90 Min 2-6 Hrs Stand-alone controller for electric/hydronic snow melng

Snow controller w\LTC TT>AT>15F 30-90 Min 2-6 Hrs Stand-alone controller for electric/hydronic snow melng

Precipitaon sensor Not Used 2 Min 2 Min Snow, ice, and rain alert, Ku band rain and snow diversion

Precipitaon controller Not Used 30-90 Min 2-6 Hrs Snow, ice, and rain alert, Ku band rain and snow diversion

Rain sensor AT>TT 2 Min 2 Min Rain alert, Ku band rain diversion

Rain controller AT>TT 30-90 Min 2-6 Hrs Ku band rain diversion, intake and exhaust fan control

(866) 635-8123


Documents

Ds 824 Controller Datasheet