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Multifamily Program Gas Water Heaters: Sealed Combustion Crossover Products

Abstract

The purpose of this paper is to document the benefits of using crossover gas water heating products that

combine the benefits of instantaneous and storage units for use in the Investor Owned Utilities

Multifamily Upgrade Program (MUP), California Multi-Family New Homes (CMFNH) or the California Tax

Credit Allocation Committee (CTCAC) program. This paper uses the HTP RGH-75F Condensing Sealed

Combustion 20 gal water heater to demonstrate the benefits of the crossover configuration which yields

substantial performance improvement and energy savings. Acceptance of these units into the multifamily

programs will encourage the use of ultra-low NOx certified tank type water heating units with significantly

improved efficiency, reduced energy cost, reduced greenhouse gas emissions, reduced utility space

requirements, and the elimination of combustion appliance safety testing for water heating.

At this time there are no sealed combustion water heaters available to California multifamily housing

builders with an energy factor (EF) rating. The acceptance of these 20 gallons units, with an energy factor

rating of .83, where 40 or 50 gallon units are typically required will allow the specification of higher

performing modulating condensing sealed combustion units for use in multifamily housing projects for

domestic hot water, including hot water and space heating combinations. These units provide a higher

First Hour Rating, lower energy use, reduced devoted space requirements and the safety of sealed

combustion.

This paper demonstrates the project energy savings available with crossover units using two completed

multifamily projects as examples. The savings are calculated under the projected scenario where the RGH-

75F is approved for the MUP program and specified for use on these projects rather than the actual lower

efficiency units installed. The enhanced performance of these units would benefit residents, multi-family

housing operators and project developers through better indoor air quality, lower capital and operating

expenses, and reduced construction testing requirements.

Description of need

The renovation of multifamily projects presents the opportunity to reduce energy cost, reduce

greenhouse gas emissions and enhance life safety. However, the currently approved units for supplying

hot water for occupant use and space heating all have an Energy Factor (EF) less than .71 for the capacities

of 75kbtu or less. A standard tank type unit specified for the MUP is limited to an EF equal to 0.71 or less.

Instantaneous water heaters have higher Energy Factors but are typically not viable for these projects as

they require supply lines greater than existing .5” diameter gas lines. Replacing the lines is typically

impractical and cost prohibitive for these applications. Additionally, some areas of California have very

hard water where instantaneous gas water heaters are not recommended.

Furthermore, the use of water heater units that are not sealed combustion run the risk of leaking

combustion gases into the living spaces. Costly and time consuming combustion appliance safety testing

is required for these units to ensure life safety. The use of sealed combustion units provides a cost

effective alternative that resolves this issue.

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Description of opportunity

The need to reduce energy costs and to eliminate installations requiring combustion appliance safety

testing can be addressed by allowing the use of crossover units similar to the RGH-75 residential water

heaters for program certification in place of the required 40 gal or 50 gal standard units. The use of these

units will allow the specification of better performing and substantially more efficient sealed combustion

water heating units than what is currently available in the market. These units have the added benefit of

significantly reduced space requirements with dimensions of 21” diameter and 47” height. The

specification of crossover units will hasten the realization of the many benefits including cost reduction,

greenhouse gas reduction and occupant safety.

Crossover Sealed Combustion Units Comparison to Currently Available Storage Units

The specification of this product type provides substantial energy savings in comparison to the base case

unit, in addition to the other non-energy benefits discussed above. This table provides a summary of the

energy savings percentage realized by specifying the RGH75 in place of the code base case unit in two

example projects.

First Hour Ratings

The RGH75 crossover units combine the benefits of instantaneous and storage water heater designs

without sacrificing performance. These units utilize .5” inch diameter gas supply lines and provide

superior First Hour Ratings. The table below provides a comparison to standard storage units base on the

AHRI Certification results1.

1 Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Directory of Certified Product Performance; https://www.ahridirectory.org/ahridirectory/pages/home.aspx ; August 2, 2016

City and

Climate Zone

Retrofit

(DHW and Hydronic

Heating)

New Construction

(DHW only)

San Francisco CZ 3 36% 24%

San Diego CZ 7 37% 26%

Escondido CZ 10 37% 25%

Sacramento CZ 12 36% 24%

Palm Springs CZ 15 39% 27%

RGH-75 Estimated Energy Savings

Over Code Basecase Unit (EF=.60)

Crossover

20 gal

Natural Gas

HTP RGH-75 104.5 gallons

AO Smith 70-92 gallons

RHEEM 59-93 gallons

Whirlpool 67-70 gallons

Bradford White 55-112 gallons

AHRI certified

products:

40 & 50 gal

Natural Gas

AHRI Certified First Hour Rating

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Presentation of model results

The opportunities represented by the inclusion of high efficiency sealed combustion water heater units

have been quantified using two actual completed projects and their associated energy models. The

projects are described below. The savings are presented for five typically encountered climate zones.

Example 1 – Retrofit Project: combined domestic hot water (DHW) and Hydronic Heating

Multifamily project: 6 buildings, 68 units (2, 3 and 4 bedrooms) water heaters providing domestic

hot water and hydronic space heating with hot water fan coils.

o 72,593 sq.ft. of conditioned floor area

o Two, three and four bedroom apartments

o One 50 gallon water heater per apartment

Water heater used: AO Smith-50 gal with Energy Factor = .62

Funding Program: CTCAC; Target savings 10%

RGH75 high efficiency sealed combustion alternative measure

o Energy Factor = .83

o Project energy savings = 11.3%

Project energy savings = 22% over unit specified for this example project (CZ3 results)

Note: TDV =Time Dependent Valuation of Energy2

2 TDV: Time Dependent Valuation of Energy for Developing Building Efficiency Standards, E3/CA Energy Commission, Feb. 2011

City and

Climate Zone Model EF

Project Percent

Improvement

TDV2

Project

Therms/year

(used)

RGH 75 Percent

Project Therms

Saved

Basecase 0.60 0.0% 25,109 24%

AO Smith Low Efficiency 0.62 1.0% 24,605 22%

AO Smith Cyclone 0.72 6.9% 21,730 12%

RGH75 0.83 12.3% 19,093 NA

Basecase 0.60 0.0% 16,894 26%

AO Smith Low Efficiency 0.62 1.0% 16,394 24%

AO Smith Cyclone 0.72 5.4% 14,192 12%

RGH75 0.83 8.8% 12,530 NA

Basecase 0.60 0.0% 19,267 25%

AO Smith Low Efficiency 0.62 0.7% 18,768 23%

AO Smith Cyclone 0.72 4.2% 16,366 12%

RGH75 0.83 7.1% 14,406 NA

BaseCase 0.60 0.0% 29,027 24%

AO Smith Low Efficiency 0.62 0.7% 28,525 22%

AO Smith Cyclone 0.72 4.9% 25,318 12%

RGH75 0.83 9.2% 22,187 NA

BaseCase 0.60 0.0% 15,365 27%

AO Smith Low Efficiency 0.62 0.4% 14,869 24%

AO Smith Cyclone 0.72 2.2% 12,764 12%

RGH75 0.83 3.4% 11,282 NA

Palm Springs

CZ 15

San Francisco

CZ 3

San Diego

CZ 7

Escondido

CZ 10

Sacramento

CZ 12

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Example 2 – New Project: DHW only

Multifamily project: Four stories, 60 units

o 42,531 sqft of conditioned floor area

o One, two and four bedroom apartments

o One 50 gallon water heater per apartment

Water heater used: AO Smith-50 gal with Energy Factor = .62

Funding Program: CTCAC; Target savings 30%

RGH high efficiency sealed combustion alternative measure

o Energy Factor = .83

o Project energy savings 6.5% (CZ 3)

Project energy savings = 29% over unit specified for this example project (CZ3 results)

City and

Climate Zone Model EF

Project Percent

Improvement

TDV

Project Therms/

year (used)

RGH 75 Percent

Project Therms

Saved

Code Standard 0.0% 10,513 36%

AO Smith Low Efficiency 0.62 2.3% 9,550 29%

AO Smith Cyclone 0.72 6.2% 7,872 14%

RGH75 0.83 8.8% 6,759 NA

Code Standard 0.0% 10,127 37%

AO Smith Low Efficiency 0.62 2.4% 9,159 30%

AO Smith Cyclone 0.72 6.5% 7,505 14%

RGH75 0.83 9.2% 6,421 NA

Code Standard 0.0% 10,037 37%

AO Smith Low Efficiency 0.62 2.0% 9,066 30%

AO Smith Cyclone 0.72 5.4% 7,417 15%

RGH75 0.83 7.6% 6,340 NA

Code Standard 0.0% 10,358 36%

AO Smith Low Efficiency 0.62 1.9% 9,391 29%

AO Smith Cyclone 0.72 5.2% 7,723 14%

RGH75 0.83 7.3% 6,622 NA

Code Standard 0.0% 9,279 39%

AO Smith Low Efficiency 0.62 2.0% 9,066 38%

AO Smith Cyclone 0.72 3.8% 6,666 15%

RGH75 0.83 5.5% 5,647 NA

San Francisco

CZ 3

San Diego

CZ 7

Escondido

CZ 10

Sacramento

CZ 12

Palm Springs

CZ 15

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Conclusion

There are considerable costs and energy savings available to California multifamily projects if new

crossover water heating products which combine the benefits of instantaneous and storage strategies are

allowed to be specified for the multifamily housing market. The allowance of these units in the multifamily

programs by accepting the 20 gal units where the programs specify 40 or 50 gallon units will benefit

residents, multi-family housing operators and project developers through better indoor air quality, lower

capital and operating expenses, and reduced construction testing requirements.

The enhanced performance of these units would benefit residents, multi-family housing operators and

project developers through better indoor air quality, lower capital and operating expenses, and reduced

construction testing requirements.

Appendices

Appendix A: Energy Model Details

Appendix B: RGH 75 Product Specifications

Appendix A: Energy Model Details

Following pages

Example 1: Multiple buildings-Existing building built in 1972

6 buildings, 68 units (2, 3 and 4 bedrooms)

72,593 sqft of conditioned floor area

Domestic hot water and hydronic space heating with hot water fan coils

Target Compliance margin:

10%

Modeling software:

EnergyPro 5.1.9.12

Envelope:

R-6 walls wood framed 16”OC

R-11 wood framed roof 16”OC

Slab on grade floors

Double metal tinted windows U= .79, SHGC=.59

Hollow metal exterior door

Mechanical:

Existing Ducts located in conditioned space

Example 2: Single building Multi-Family- New construction

1 building, four stories, 60 units (1, 2 and 4 bedrooms)

Domestic hot water only (no hydronic space heating)

Target Compliance margin:

30%

Modeling software:

EnergyPro 5.1.9.12

Envelope:

R-15 walls 2x4 wood framed 16” OC

R-38 Cathedral roof wood framed 16”OC

Cool roof with Aged solar=.68, Thermal Emmitance= .84

Uninsulated raised slab floor

NRFR tested windows U value=.34, SHGC .31

Mechanical:

Ducted split heat pumps, HSPF=10, SEER=15, EER=12

Ducts located in conditioned space

Hydronic space heating provided by domestic hot water with forced air

cooling, 10 SEER, 9.2 EER

Energy Model Details

Appendix B: RGH-75 Product Specifications

Following pages

Fighting the High Cost of

Water Heating!

Fully Condensing Achieves up to

95% Efficiency

Half the Storage & Twice the Btuh Result

in a Recovery Rate that is 4 Times Faster

than Traditional Storage Units!

■ Integrates the benefits of both storage & instantaneous concepts without sacrificing performance

■ Fully condensing unit achieves up to 96% Efficiency

■ Half the storage volume and twice the Btuh result in a recovery rate that is 4 t imes faster than tradit ional storage units

■ Equipped with an ASSE 1017 domestic rated thermostatic valve piped to the outlet to increase first draw capacity and control the outlet temperature for reliable temperature control

■ Stainless steel tank with integrated heat exchanger; extra thick insulation reduces standby loss

■ Ultra low NOx emissions leave almost no carbon footprint

■ Compatible with recirculation■ 6 Year Limited Warranty

Thermal Efficiency (NG) 96% Installation Indoor / Floor StandingGas Input Rate 100,000 BtuhGas Supply Pressure NG: 3.5 " ~ 10.5" WC; LPG: 8" ~ 14" WC Gas 1/2”, 3/4” Female NPT

Connections Water 3/4” Male NPT

Electricity 120VAC, 60Hz Condensate 1/2” PVC Tank Volume, Material 20 Gallon, Stainless Steel

Ignition System Electronic Spark Ignition with Automatic

Flame Sensing, No Pilot First Hour Rating 160 GPH @77°F Rise Factory Preset 120°F Output Temperature Setting Range Built-in Honeywell Tempering Valve from 70°F to145°FStorage Temperature Setting Normal 125°F, Hotter 145°F, High Output 165°FUnit Dimensions (D)20.9” x (H) 46”Unit Weight 120 lbs

RGH100 Speci�cations

20.

9”

20.9”

46”

www.htproducts.com

TM

Advanced Heating& Hot Water Systems

SCAQMD Rule 1146.2

Residential Water HeaterRGH-75F & RGH-100F

LLC

®

TM

Crossoverincorporates the best of both worlds in one unit with its tank and tankless components. The result is one appliance that exceeds all of your hot water needs

We are excited to introduce the new high efficiency Crossover models – RGH-75F and RGH-100F. This revolutionary product was designed to be the most highly efficient affordable residential tank type product in the industry.

High Performance The Crossover Residential Floor model combines the flow capacity of a 50 gallon tank type water heater with the continuous flow feature found in tankless water heaters. It has dual activation by flow or thermostat sensing which guarantees hot water delivery even with low flow fixtures. It’s built in fire tube heat exchanger is surrounded by a stainless steel tank that holds a full 20 gallons of up to 167 degree hot water and then mixes the delivered temperature down through a ASSE 1017 mixing valve and can thus fill a 40 gallon tub at the same rate as a traditional 50 gallon tank type water heater. The RGH 75 and 100 can also produce more first hour delivery than conventional 50 gallon water heaters. These two new models will change the way people view residential water heating and it is only available through HTP and our agent partners.

The

TM

Fantastic FeaturesExtra thick insulation combined with small water volume storage

result in very low standby loss

High altitude compliant – certified up to 10,000 ft. above sea level

All stainless steel tank construction with integrated fire

tube heat exchanger design

Endless hot water - advanced temperature control - compatible

with recirculation systems

Preset for natural gas ships with a liquid propane

conversion kit

Eco-friendly and low NOx combustion system

leave almost no carbon footprint

Air handler application: Combination heating & DHW

Includes an ASSE 1017 domestic rated thermostatic valve (prepiped) increasing 1st draw capacity & temperature control

Crossover Tank Type Tankless

RGH-75 RGH-100 50 Gal. Atmospheric

50 Gal. Power Vent

199K Btuh

199 Btuh (Non Condensing)

FeaturesEfficiency .83 EF

.88UEF 95% TE .60 EF .70 EF .95 EF .82 EF

Ultra Lo NOx Complaint YES YES NO NO Varies by

ModelVaries by

Model

Performance

Btuh 75,000 100,000 40,000 40,000 199,000 199,000First Hour Rating

@ 90°F Rise 107 130 88 90 NO NO

30 Gal. Dump Capabilities YES YES YES YES NO NO

Zero Flow Activation YES YES YES YES NO NOOptional Two-

Temperature Delivery Capability (with kit)

YES YES NO NO NO NO

Savings Annual Operating Energy Cost (NG) $196 N/A - TE

Classification $272 $233 $172 $199

Materials

Tank Stainless Steel

Stainless Steel

Glass Lined Carbon Steel

Glass Lined Carbon Steel

Stainless Steel /

CopperCopper

Heat Exchanger

Stainless Steel

Stainless Steel

Glass Lined Carbon Steel

Glass Lined Carbon

Steel

Stainless Steel /

CopperCopper

Annual HX Anti-Scale Maintenance Required NO NO NO NO YES YES

Installation

Venting PVC PVC B-Vent PVC PVC Stainless Steel Category III

Vent Length 2" at 50' 2" at 50' 3" at 50' 3" at 100' 2" at 50' 3" at 50'Space Saving Low

Profile Vent Capability YES YES NO NO NO NO

Anti-Draft Direct Vent Capable YES YES NO NO YES YES

Field Convertible YES YES NO NO Varies VariesAnti-Scald Mixer

(ASSE 1017) YES YES NO NO NO NO

Display Digital with Error Codes YES YES NO NO Varies by

ModelVaries by

Model

Dimensions

Height 38.6" 38.6" 57" 50 3/4" 23 5/8" 20 1/2"Diameter 21" 21" 22" 24" N/A N/A

Width 21" 21" 22" 24" 17 3/4" 13 3/4"Depth 21" 21" 22" 24" 11 1/4" 10 1/2"Weight 110 lbs. 110 lbs. 165 lbs. 198 lbs. 63 lbs. 51 lbs.

Compare the RGH with the Competition

Super Durable All Stainless Steel Fire Tube

Heat Exchanger

RGH-75F & RGH-100F

40%Less Space Required

than a Standard Tank

Produce More Hot Water than a

Standard Tank with

RGH-75F & RGH-100F

40%Less Space Required

Than a Standard Tank

More Hot WaterThan a Standard Tank

70%and up to

A Closer Look Inside

Water Heater

Tank

Tankless Water Heater

+ =Water

Heater Tank

Tankless Water Heater

+ =Water

Heater Tank

Tankless Water Heater

+ =Water

Heater Tank

Tankless Water Heater

+ =

Model RGH-75F RGH-100F

Efficiency EF .83 (Energy Factor) | UEF .88 (Uniform Energy Factor) TE 95% (Thermal Efficiency)

Installation Indoor / Floor Standing

Vent Run3” PVC or Polypropylene2” PVC or Polypropylene

Up to 100ft, 6 Elbows Max (3” pipe) [3ft Deduction Per 45º Elbow ] [5ft Deduction Per 90 º Elbow ]

Up to 50ft, 6 Elbows Max (2” pipe) [5ft Deduction Per 45º Elbow ] [8ft Deduction Per 90 º Elbow ]

Condensate Discharge 2GPH

Condensate pH Level 4 pH

Gas Type Preset for NG / LP Conversion Kit Included

Unit Connections Gas 1/2” or 3/4” Female NPT (3/4” by 1/2” Bushing Adapter Included )

Water 3/4” Male NPT

Electricity Dedicated 120VAC, 60Hz w/3 Pronged 5 1/2 ft. Power Cord

Condensate 1/2” Male NPT Connection

Gas Input Rate Hourly Max: 75,000 Btuh – Min: 37,500 Btuh Max: 100,000 Btuh – Min: 50,000 Btuh

Gas Supply Pressure NG / LP 3.5” WC to 14” WC / 3.5” WC to 14” WC

Ignition System Spark Ignition, No Pilot

Burner System

Gas Valve System Air Ratio Negative Pressure

First Hour Output @ 77°F / 90°F 125 Gallons / 107 Gallons 160 Gallons / 130 Gallons

Reserve Tank 20 Gallons

Tank Material Stainless Steel

Temperature Sensing Inner Tank and Hot Outlet Discharge Pipe Sensors

Domestic Temperature Control Thermostatic Mixing Valve - ASSE 1017 Rated

Domestic Temperature Settings Range 120°F Factory Preset / Adjust Knob 70°F to 145°F

Tank Storage Temperature Settings Normal 127°F / Hotter 147°F / High Output 165°F

Unit Dimensions (D x H) 21” x 47”

Unit Weight 110 lbs

Safety Devices T&P Valve, Vent Blockage APS, Flame Rod, Fan RPM Check, Eco Burner Plate (305º F ), Eco Water Limit (194º F)

Optional Accessories 3” or 2” Horizontal Terminal, Concentric Venting Kit, Condensate Neutralizer Kit

RGH-75F & RGH-100F are for Indoor residential applications.

FRONT VIEW SIDE VIEW TOP VIEW

A

D

A - Cold Water InletB - Hot Water OutletC - Exhaust (3” PVC Connection)D - Electric ChordE - T&P ValveF - Thermostatic Mixing ValveG - Gas ConnectionH - Drain ValveI - Condensate SystemJ - Tank SensorK - Display Control

EF

I

J

H

GK

B

C

2 7 2 D u c h a i n e B l vd, N e w B e d fo rd, MA 0 2 7 4 5 • M K T L I T-XX - 0 6 / 2 0 1 6 © H T PIn accordance with our company policy of ongoing product improvement, HTP Inc. reserves the right to make changes without prior notice. • All weights are approximate.

Keeps You In Hot Water

GAL

LON

S PE

R H

OU

R @

90º

F

Holds Only 20 GallonsBut Can Produce up to

More Hot WaterThan a Standard Tank

70%50G Tank RGH-75F RGH-100F

RGH-75F & RGH-100F