Water and Space Heating - Heschong Mahone Group

California Statewide Utility Codes and Standards Program

12/9/2010

1

Water and Space Heating Nonresidential HVAC Stakeholder Meeting #2

Heschong Mahone Group, Inc.

Portland Energy Conservation, Inc.

CTG Energetics

Taylor Engineering

December 9, 2010

CALIFORNIA STATEWIDE UTILITIES CODES AND STANDARDS PROGRAM

12/9/2010 CA Utilities 2013 Title 24 Stakeholder Meeting for Proposed Code Changes

ACM Update-Water & Space Heating, VRF

● Summary of current code requirements

● Typical practice

● Summary of code change proposals

● Data/findings

● Specifics of code change proposals

● Remaining data collection and analysis

● Specific stakeholder requests

2 2


Water & Spacing Heating, VRF


Current Code Requirements

● ACM for Hydronic Space Heating

● Distribution pipe heat loss

● Different methods for DHW and Hydronic heating – pipe loss

included in boiler efficiency calculated as AFUE

● Very limited capabilities of modeling controls

● Hydronic heating modelling – optional capability

3




● Standard Design for Hydronic Space Heating

● Res hydronic heating system compared to central

furnace with duct loss


4

Air Dis Table R3-1 – Summary of Standard Design HVAC System

Proposed Design Standard Design

Heating System Cooling System Heating System Cooling System Detailed Specifications

Through-the-wall heat pump Same equipment as proposed design with no air distribution ducts

Equipment efficiency determined by CEC Appliance Efficiency Regulations

Gas wall furnace with our without ducts and/or circulation fan

Any Same equipment as proposed design with no air distribution ducts

Split system AC with air distribution ducts

Any other electric heat including electric resistance, water source heat pump, etc.

Any Split system heat pump with air distribution ducts

SEER per Package D

Verified refrigerant charge (prescriptive requirement)

No credit for sizing

No credit for cooling coil airflow

No credit for reduced fan power

All other gas heating Any Split system air conditioner with gas furnace and air distribution ducts.

Note: The standard design cooling system is also used for the proposed design if the proposed design has no air conditioning




● Standard Design for Hydronic Space Heating

● N Res hydronic heating system compared to 4-pipes

fan coil system with duct loss


5




● VRF technologies not recognized by ACMs

● Treated as heat pump with minimum

compliance efficiency

● Waived from federal testing requirements


6




Typical Practice

● Hydronic heating, including combined hydronic

heating, are used in MF and in nonres. Buildings (18% in Low Rise, 7% in High Rise according to PG&E California

Multi-Family New Homes program)

● DHW and hydronic system control technologies

are commonly used

● VRF technologies have relatively low market

share; they have high part-load efficiencies and

have no duct losses

7




8

Code Change Proposal #1

● Distribution Pipe Heat Loss

● Hourly pipe heat loss calculation

● Consistency DHW and Hydronics Space Heating

● Algorithms for controls

● Temperature modulation

● Flow variation

● Default distribution system layout

● Hydronic system fuel consumption calculation




Data / Findings – PIER DHW Research

● In-depth understanding of central DHW

distribution system based on field

performance study of 30+ MF buildings

● Monitoring of HW & CW flows, temperatures, and

pressures; gas flows

● System controls study and cool down tests

● System heat balance and energy flow analysis

● DHW recirculation loop modeling

9

Water Heater

Losses Distribution Losses

End-Use

Energy 30%

30%

Branch

Losses* Recirculation

Loop Losses Include pipe inside and

outside of dwelling units




Data / Findings – Pipe Heat Loss Model

● System model includes two heat transfer modes

with consideration of transition

● Pipe heat transfer with HW flow

● UA, water temp & flow, ambient temp

● Pipe without HW flow - cool down

● UA and pipe/water thermal capacity

10




Data / Findings –Model Validation

● Based on actual building DHW recirculation loop

configurations

● Compare modeled vs. measured HWR Temp, and

energy losses

11

2

3

4

9

5

6

7

1 10 11 12

8

1 2

3

4

10

5

7

8

9

11

12 13

6




12

Control type Measured

Data

(Btu/day)

Model

Results

(Btu/day) %Difference

Continuous Pumping 639732 643487 0.6%

Temperature Modulation 633433 616266 -2.7%

Timer 600803 562822 -6.3%

Demand control 411903 453556 10.1%

Data / Findings –Model Validation




Specifics of Code Change Proposals

Distribution pipe heat loss – Existing DHW ACM

13

● Recirculation Loop ● Plumbing layout based on

building geometry

● HW Draw patterns; or HW flow

rates for hydronic heating

● HW temp: 135F for HW; vary

for hydronic heating & Control

Hourly

Standard

End Use

Hourly

Adjusted

Recovery Load

Distribution

Loss

Multiplier

Solar

Savings

Multiplier

Hourly

Recirculation

Distri. Loss

Hourly

Jacket

Loss

Implement monthly variation

Inside dwelling unit:

DLMk =1 + (SDLMk-1)*DSMk

DSMk =1 for MF

SSMk should be applied to HRDLk

as well; however, it depends on

how SSF is rated

● Branch ● Depend on HSEUk

should be a multiplier

to HSEUk

● Modify DLMk to include

heat loss from

branches outside of

dwelling unit

Proposed Improvement





Proposed Recirculation Distribution Pipe Heat Loss

14

Hourly ambient temperature

for pipe section, n

Hourly average water

temperature for pipe section, n

Average water temperature

during pump-off period

Average water temperature

during pump-on period

● Assess hourly average pipe temperature to calculate heat loss

- Replace the table of UL with explicit calculation

● Average pipe temperature is weighted between two modes, which

depend on control schedule

Weighting factor depending

on control schedule

● Each control strategy has a 24-hour schedule




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TIMER

p Pump

off

Time

TS

1 2 135

1 3 135

1 4 135

1 5 135

1 6 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

0 0 135

1 1 135

TEMPERATURE MODULATION

p Pump

off

Time

TS TS

With cont.

monitoring

0 0 110 110

0 0 110 110

0 0 110 110

0 0 110 110

0 0 120 120

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 135 125

0 0 120 120

DEMAND CONTROL

p Pump

off

Time

TS

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

0.8 0.125 135

Continuous Pumping

Hour p Pump

off

Time

TS TS

With cont.

monitoring

1 0 0 135 125

2 0 0 135 125

3 0 0 135 125

4 0 0 135 125

5 0 0 135 125

6 0 0 135 125

7 0 0 135 125

8 0 0 135 125

9 0 0 135 125

10 0 0 135 125

11 0 0 135 125

12 0 0 135 125

13 0 0 135 125

14 0 0 135 125

15 0 0 135 125

16 0 0 135 125

17 0 0 135 125

18 0 0 135 125

19 0 0 135 125

20 0 0 135 125

21 0 0 135 125

22 0 0 135 125

23 0 0 135 125

24 0 0 135 125



12/9/2010 CA Utilities 2013 Title 24 Stakeholder Meeting for Proposed Code Changes 12/13/2010

16


Hydronics heating and Central DHW ACM update

Supply

Return

Boiler

Room

n=1 n=2 n=3

n=6 n=5 n=4

● Current ACM requires user input of pipe length for three

pipe sections

● Proposed changes

● Supply and return each has three sections –

● Unconditioned, conditioned, (semi-conditioned), underground,

● Return pipes behave dramatically different from supply pipes under controls

● ACM generate default system layout to check/adjust user input

(details to be discussed after ACM algorithms)





Recirculation Distribution System Pipe Layout

17

• Building Story, floor area

• Number of apartment/guest room

• Boiler room Location

• Number of Loops

• Supply and Return Loop section

locations and length

USER INPUT

• Recirculation loop path

• Branch length and number

• Pipe diameters (Follow UPC)

• Pipe insulation thickness

ACM Generate Default Loop

Configuration

Low

Rise

High

Rise

Recirculation

pipes at

different levels

All recirculation

pipes in the

same level

Input

Validation

Reasonable Unreasonable

Use user input Adjust user input

Calculate

Default

Pipe

Length





Example 1: Low Rise

18

A 50

100

Loop 1

Loop 2

Supply Return

Loop 1 35 ft 35 ft

Loop 2 35 ft 35 ft

Total 140 ft

Generate ACM

Default

Total Length <

85% of ACM

Default?

A 50

100

User Inputs

Return Recirculation Pipe

Section #1

30

Section #2 Section #3

10 /

Supply Recirculation Pipe

Section #1

10


30 /

Uncondition

ed Space-

Bottom

Level

Conditione

d Space-

Bottom

LeveL

/

2 stories

2 loops

Yes No

Conditioned

Space-

Bottom

Level

Unconditio

ned Space-

Bottom

LeveL

/

Keep

user

input

ACM Default

Adjust

user

input

Option 1: Increase total length to ACM default

Option 2: Increase branch length

Branch number / length




19

User Inputs

Return Recirculation Pipe

Section #1

30


10 /

Supply Recirculation Pipe

Section #1

10


30 /

Uncondition

ed Space-

Bottom

Level

Conditione

d Space-

Middle

Level

/

4 stories / 2 loops

Conditioned

Space-Top

Level

Uncondition

ed Space-

Bottom

Level

/

A

Ceiling level 3

Ceiling level 2

Loop 1

Loop 2

Supply Return

Loop 1 80 ft 80 ft

Loop 2 80 ft 80 ft

Total 320 ft

Generate ACM

Default

Total Length <

85% of ACM

Default?

Yes No

Keep

user

input

ACM Default

Adjust

user

input

Option 1: Increase total length to ACM default

Option 2: Increase branch length

Branch number / length

Specifics of Code Change Proposals Example 2: High Rise




20

Default Pipe Sizing

● Based on IAPMO Uniform Plumbing Code

● Maximum water velocity limit of 5 ft/s determines sizing

# of Dwelling Units Line Size

1 0.75

2 1

3 – 4 1.25

5 – 7 1.5

8 – 20 2

21 – 42 2.5

43 – 67 3

68 – 100 3.5

101 – 144 4





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Data / Findings - Branch Model

● SDLM – expand current ACM formula to include heat

loss from all branches and twigs

● SDLM has two components; correlate both to HSEUk

● Pipe heat loss during usage = (GPHk/Numbranch)∙ ∙Cp∙ Tbranch

Tbranch= 0.25F [Insulated Pipe] or 1F [Uninsulated Pipe]

● Water waste = NumWait∙Cp ∙ ∙(fwait∙Volbranch) ∙(Tsupply,branch-Tcoldwater)

NumWait: to be determined based on NREL HW draw event tool

fwait: multiplier reflecting the effects of flow mixing + extra waiting




22

● For hydronic heating, pipe loss in conditioned

spaces contributes to space heating

● Only consider pipe loss in unconditioned space

● Return pipe starting temperature:

● Temperature and flow controls can be modeled

similar to DHW controls

Conditioned

Space

HourlyLoad Supply Return

TS,end TR,start





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● Hydronic system fuel consumption calculation

Effective AFUE:

Accounting for pipe

losses

AFUE: Boiler/water

heater efficiency

converted in AFUE

PL:

Hourly pipe loss rate, calculated

based on annual estimates using heat

transfer equation

RI:

rated input of the gas water heater

FurnFuel:

Hourly water

heater/boiler gas

consumption

NetHLoad:

Hourly space heating load

Hourly distribution pipe

loss rate, calculated with

the new methodology

Water heater efficiency

Water heater gas consumption

Exis

tin

g

Pro

po

sed




24


● Space Heating Standard Design for Gas Heating


Current Proposed

Gas wall furnace with or

without ducts and/or

circulation fan

Same equipment as

proposed design w/o

air distribution ducts

Fan assisted wall furnace

w/o

air distribution ducts

Hydronic Heating

Split system air conditioner with

gas furnace and air

distribution ducts.

Standard design hydronic

system (TBD, w/o air

distribution duct loss)

All other gas heating Same as current

Air Dis Table R3-1 – Summary of Standard Design HVAC System


Heating System Cooling System Heating System Cooling System Detailed Specifications

Through-the-wall heat pump Same equipment as proposed design with no air distribution ducts

Equipment efficiency determined by CEC Appliance Efficiency Regulations

Gas wall furnace with our without ducts and/or circulation fan

Any Same equipment as proposed design with no air distribution ducts

Split system AC with air distribution ducts

Any other electric heat including electric resistance, water source heat pump, etc.

Any Split system heat pump with air distribution ducts

SEER per Package D

Verified refrigerant charge (prescriptive requirement)

No credit for sizing

No credit for cooling coil airflow

No credit for reduced fan power

All other gas heating Any Split system air conditioner with gas furnace and air distribution ducts.

Note: The standard design cooling system is also used for the proposed design if the proposed design has no air conditioning




25

● Central System

● hydronic heating with baseboard/radiator - no ventilation/no fan

● hydronic heating with baseboard/radiator w/ fan assisted

circulation - no ventilation/no fan

● hydronic heating with baseboard/radiator - 2 pipe fan-coil system

for AC

● hydronic heating with baseboard/radiator - 4 pipe fan-coil system

● Combined hydronic heating - pipe and WH efficiency

● RTU/split AC system with central furnace

● Distributed system

● Fan assisted furnace

● Gravity based furnace

Data / Findings – Potential Standard Designs




Data / Findings – Standard Designs

● Central DHW distribution plumbing designs –

baseline distribution system design

● Distributed systems : Fan Wall furnace

26




27


● Introduce VRF modelling capability in

ACM

● Validate manufacturer proposed

models




Data / Findings – VRF

● VRF model developed by EnergySoft for:

● Mitsubishi

● Daikin

● Sanyo

● LG

● Proposed Compliance Option submitted by

manufacturers

● VRF model can be validated by certified test

data using AHRI 1230

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Remaining Data Collection and Analysis

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● Pipe distribution heat loss

● Refine branch heat loss model

● Perform energy savings analysis

● Hydronic heating standard design

● Survey hydronic heating design practices

● Cost effectiveness study of different design options

● Cost effectiveness study of fan-type wall furnace vs.

gravity-type wall furnace

● Market penetration study of hydronic heating, combined

hydronic heating, and wall furnace heating systems

● VRF validation procedure




30

Specific Stakeholder Requests

● Hydronic heating system design practice

● Market penetration of wall furnace and hydronics

heating, including combined hydronics

● Test Data from VRF manufacturers



Water & Space Heating, VRF

31

QUESTIONS & COMMENTS

?

Documents

Water and Space Heating - Heschong Mahone Group