Proposed Design
The water heating system is defined by the tank type, heater element type, distribution type, multi-family central water heating distribution, efficiency (either energy factor or recovery efficiency with the standby loss), tank volume, exterior insulation R-value (only for indirect) and rated input.
Tank types include:
Small storage: <= 75,000 Btu gas/propane, <=105,000 Btu/hr oil, <= 12 kW electric, or <= 24 amps heat pump.
•Small tankless: gas or propane with an input of 200,000 Btu per hour or less, oil with an input of 210,000 Btu per hour or less, or electric with an input of 12 kW or less. Tankless water heater is a water heater with an input rating of >= 4,000 Btu per hour per gallon of stored water. Rated with an energy factor.
•Large storage: > 75,000 Btu gas/propane, >105,000 Btu/hr oil, or > 12 kW electric. Rated with thermal efficiency and standby loss.
•Large tankless: gas or propane with an input of >200,000 Btu per hour, oil with an input of >210,000 Btu per hour, or electric with an input of >12 kW. Tankless water heater is a water heater with an input rating of >= 4,000 Btu per hour per gallon of stored water. Rated with thermal efficiency.
•Mini tank: a temperature buffering electric heater sometimes used with gas tankless to mitigate fluctuations between draws (units not listed in the appliance database use a standby loss (in Watts) of 100).
•Indirect: a tank with no heating element or combustion device used in combination with a boiler or other device serving as the heating element.
•Boiler: a water boiler that supplies hot water. Rated with Thermal Efficiency or AFUE.
Heater element type includes:
•Electric resistance
•Natural gas/oil
•Propane, or
•Heat pump.
Distribution system types for systems serving an individual dwelling unit include:
•Standard (the full length of the line from the water heater to the kitchen fixtures and all piping of nominal ¾” or larger diameter insulated with 1 inch of insulation
•Pipe Insulation, All Lines
•Insulated and Protected Pipe Below Grade
•Parallel Piping
•Recirculation, Non-Demand Control
•Recirculation, Demand Control Push Button
•Recirculation, Demand Control Occupancy/Motion
•HERS Required Pipe Insulation, All Lines
•HERS Required Insulated and Protected Pipe Below Grade
•HERS Required Parallel Piping
•HERS Required Recirculation, Demand Control Push Button
•HERS Required Recirculation, Demand Control Occupancy/Motion
•HERS Required Point of Use
•HERS Required Compact Distribution System
Distribution types for multi-family central hot water heating include:
•No Control
•Recirculating Demand Control
•Recirculating Temperature Modulation Control
•Recirculating Temperature Modulation and Monitoring (standard design for new construction)
•Dual loop design for buildings with 8 or more dwelling units w/HERS Verification (can be combined with any of the recirculating conditions)
•Increased pipe insulation w/HERS verification (can be combined with any of the recirculating conditions).
Some distribution systems have an option to increase the amount of credit received if the option for HERS verification is selected. See Appendix E for the amount of credit and Reference Appendices, Residential Appendix Table RA2-1 for a summary of inspection requirements.
Standard Design
Individual dwelling units: The standard design is based on §150.1(c)8. For single-family dwellings or dwelling units served by a dedicated water heating system, each dwelling unit has one small storage (< 75000 Btu), 50-gallon gas storage water heater, meeting minimum federal Energy Factor standard (0.575 in 2014, 0.60 in 2015). If natural gas is not available, the fuel type is the same as the proposed fuel type, meeting the minimum federal Energy Factor standard for propane (0.575 in 2014, 0.60 in 2015) or electric (0.904 in 2014, 0.945 in 2015). When the proposed fuel type is electric resistance, a solar water heating system with a minimum solar savings fraction of 0.50 is included. The distribution type for gas or propane is either standard or, if a recirculating system is shown in the proposed design, a recirculating system with manual controls. The distribution type for electric resistance is no recirculating system.
Multiple dwelling units: If the proposed design is a central water heating system the standard design is the same type of water heater equipment (natural gas, if available or electric meeting minimum appliance efficiency standard) as the proposed design meeting the minimum appliance efficiency requirements. The system includes a recirculation system with controls that regulate pump operation based on measurement of hot water demand and hot water return temperature, is capable of turning off the system (§110.3(c)2), has two recirculation loops (if serving more than eight dwelling units) with efficiency based on Nonresidential Appendix NA6, and incorporates provisions of §110.3(c)5:
1) Air release valve or vertical pump installation,
2) Recirculation loop backflow prevention,
3) Equipment for pump priming,
4) Pump isolation valves,
5) Cold water supply and recirculation loop connection to hot water storage tank, and
6) Cold water supply backflow prevention.
A central water heating system standard design also includes a solar fraction of 0.20 in climate zones 1 through 9, and 0.35 in climate zones 10 through 16.
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Does the proposed water heating system have a storage tank? |
Yes |
Is the input rating of each water heater in the proposed design less than or equal to 75,000 Btu/h or if electric, less than or equal to 12 kW? |
Yes |
Standard design is one or more NAECA gas or propane water heater. If natural gas is available at the site, the standard design is a gas water heater, otherwise it is electric. If the total storage volume of the proposed design is less than 100 gallons, then the standard design is single water heater with a storage volume equal to the total storage volume of the proposed design. If the total storage volume of the proposed design is larger than 100 gallons, then the standard design shall have multiple water heaters. The number of water heaters is equal to the total storage capacity of the proposed design divided by 100 and rounded up. The EF of each 100 gallon water heater shall be based on the compliance year as: 2014 Gas-fired EF = 0.67 –
(0.0019*Vol) 2015 Gas-fired > 20 -
< 55 gal EF = 0.675 – (0.0015*Vol) See specification of distribution system below. |
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No |
Standard design is composed of the same number of large storage gas or propane water heaters as in the proposed design with a storage volumes the same as the storage volumes of the proposed design. If natural gas is available at the site, the standard design is a gas water heater, otherwise it is electric. The thermal efficiency is 0.80 and stand-by losses are as specified in the Appliance Efficiency Regulations See specification of distribution system below. |
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No |
Standard design is the same number of natural gas or propane instantaneous water heaters as in the proposed design with input ratings equal to those in the proposed design. If natural gas is available at the site, the standard design is a gas water heater, otherwise it is electric. Efficiency of the instantaneous water heaters shall be: 2014 Input < 200000
< 2 gal EF = 0.62 – (0.0019*Vol) See specification of distribution system below. | ||
Verification and Reporting
All modeled features and the number of devices modeled for the water heating system are reported on the CF1R. Where distribution systems specify HERS verification, those features are listed in the HERS Required Verification listings on the CF1R.
When a water heating system has a solar system to provide part of the water heating, the Solar Fraction (SF) is determined using an F-chart program, OG-100 or OG-300 calculation method (see http://www.gosolarcalifornia.org/). The calculation method requires that the user specify the climate zone and conditioned floor area, 'in 'addition to published data for the solar water heating system.