Water System Help

Modified on Tue, 30 Jan at 11:31 AM

Basic System Information

Water Fixture Type	Either Low Flow or standard. Low Flow means every fixture in the home (showers and faucets) must be equal to or less than 2 gallons per minute (gpm). If a shower has multiple showerheads that operate simultaneously, the sum of all showerheads must be equal to or less than 2 gpm to qualify has low flow.
Use Default Hot Water Pipe Length	If checked, the calculation will be done assuming the hot water pipe length is equal to the HERS Reference Home hot water pipe length. This cannot be checked when completing confirmed HERS Ratings.
Hot Water Pipe Length [ft]	From RESNET/ANSI 301: ...measured length of hot water piping from the hot water heater (or from a shared recirculation loop serving multiple Dwelling Units) to the farthest hot water fixture, measured longitudinally from plans, assuming the hot water piping does not run diagonally, plus 10 feet of piping for each floor level, plus 5 feet of piping for unconditioned basements (if any). Examples: For a 40ft x 40ft home with two floors and an unconditioned basement, if the water heater is in the basement in one corner of the home and the farthest fixture is in the exact opposite corner of the home on the second floor, the hot water pipe length should be 40ft + 40ft + 10ft + 10ft + 5ft = 105ft. For a 40ft x 40ft building with multiple Dwelling Units using a recirculation loop, use the beginning of the branch from the central hot water loop. If the branch for this unit is 10ft x 10ft off the corner in an unconditioned basement, and the furthest fixture is at a far corner on the second floor then the hot water pipe length should be 30ft + 30ft + 10ft + 10ft + 5ft = 85ft. This field is not used in the calculations if a recirculation system is present, unless that system is shared across multiple attached dwelling units (see checkbox below). Anticipated addition to RESNET/ANSI 301 for 2019 found here
At Least R3 Pipe Insulation?	Check this if domestic hot water pipes are insulated to at least R3. IECC 2015 section R403.5.3 exempts pipes smaller than 3/4" diameter within the conditioned space of the home and not in a demand re-circulation system.

Recirculation System

Hot Water Recirculation System?	Check this if the home has any type of hot water recirculation system. This should include systems providing a shared loop across multiple attached dwelling units.
Hot Water Branch Length [ft]	From RESNET/ANSI 301: "The measured length of the branch hot water piping from the recirculation loop to the farthest hot water fixture from the recirculation loop, measured longitudinally from plans, assuming the branch hot water piping does not run diagonally"
Hot Water Pipe Loop Length [ft]	From RESNET/ANSI 301: "The hot water recirculation loop piping length including both supply and return sides of the loop, measured longitudinally from plans, assuming the hot water piping does not run diagonally, plus 20 feet of piping for each floor level greater than one plus 10 feet of piping for unconditioned basements." For the HERS Reference Home, this value is 2x the "Hot Water Pipe Length" minus 20ft.
Recirculation System Control	Choose the recirculation system control type from the dropdown.
Recirculation Pump Power [Watts]	Power of the recirculation system pump.
Shared?	Check this box if the recirculation system serves multiple units. If this box is checked and the system serves more than 1 unit, the hot water pump kWh/y will be calculated according to equation 4.2-15b of RESNET/ANSI 301-2019. Also, if this box is checked in versions 4.0.0 and later, Branch Length and Pipe Loop Length will be ignored because other than the recirculation pump energy, the system will be treated as a non-recirculation system as per ANSI 301-2019 Footnote 42.

Drain Water Heat Recovery

Drain Water Heat Recovery?	Check if the home has a drain water heat recovery system.
Drain Water Heat Recovery Efficiency	Drain Water Heat Recovery Unit efficiency as rated and labeled in accordance with CSA 55.1
Supplies preheated water to:	Indicate using the dropdown menu - To which systems does the DWHR system supplies preheated water?
Fixture Factor of Drain Water Heat Recovery	From RESNET/ANSI 301: Fixture Factor = 1.0 if all of the showers in the home are connected to DWHR units Fixture Factor = 0.5 if there are 2 or more showers in the home and only 1 shower is connected to a DWHR unit.

Fire Sprinkler System

Has Fire Sprinkler System?

Choose Yes, No, or Unspecified. Unspecified is the default. This input will not change the HERS Index, but is required for certain energy codes and utility programs, which sometimes provide added infiltration allowances for homes with fire sprinkler systems.