Chapter 9: Water Heating To be used with the Guide to Building Energy Efficient Homes in Kentucky

Hot Water Use 90 gallons per day 50 gallons per day

Energy Factor Energy Factor (EF) = a measure of the overall efficiency of a water heater Includes: ―Recovery efficiency ―Standby losses ―Cycling losses

Energy Conservation Water conservation measures =

Energy Conservation New homes: Keep hot water pipe run as short as possible Use a manifold plumbing system

Energy Conservation

Water heater setting Temperature = 120 ° F – Provides plenty of hot water – Decreases risk of scalding – Select dishwasher with booster heaters

Energy Conservation

Insulate the first four feet of all pipes Use low-flow showerheads

Energy Conservation Install heat traps Install low-flow aerators on sink and lavatory faucets

Energy Conservation 1 quart Every 3 months, drain ~ 1 quart

Gas Water Heaters Energy Factors (EF) for ENERGY STAR ® Gas Water Heaters TypeEnergy Factor Gas Storage (ending 8/31/2010)≥ 0.62 Gas Storage (beginning 9/1/2010)≥ 0.67 Whole-home Gas Tankless≥ 0.82 Gas Condensing Storage≥ 0.90

Gas Water Heaters Gas water heater efficiency is affected by: Burner design Shape of the flue baffles Amount of surface area between the flue gases and the water Presence of blowers for venting and delivery of combustion air

Gas Water Heaters Fuel-fired water heaters, in conditioned space: Must be in a sealed mechanical room ―Fresh air inlets To avoid the sealed mechanical room ―Use a fuel-fired water heater that includes provisions for outside combustion air Direct-vent unit with a double flue pipe

Gas Water Heaters Higher efficiency units have: Blowers for venting and delivery of combustion air More sophisticated energy features ―Electronic ignition ―Flue dampers ―Condensing heat exchangers EF > 0.90

Electric Water Heaters Higher efficiency – EF > 0.97 – Extra cost is low compared to the savings

Electric Water Heaters

Heat Recovery Units Heat Recovery Unit = Desuperheater Recovers excess heat from air conditioner or heat pump to provide “free” hot water Heat Recovery Unit = Desuperheater Recovers excess heat from air conditioner or heat pump to provide “free” hot water

Heat Recovery Units In summer: – Desuperheater can usually provide 100% of the hot water needs of a family and improve the efficiency of the air conditioner In spring and fall: – Desuperheater is ineffective In winter: – Desuperheater is more effective and saves money

Heat Recovery Units Performance of a desuperheater is affected by: Size and efficiency of the water heater and cooling equipment – Cost $550 to $750 – Annual savings = $50 to $180 – Make sure that it does not void any mechanical equipment warranties – Check the water supply to see if any buildup may occur

Solar Water Heaters Images Courtesy:

Solar Water Heaters Cost effective option because: Current cost of energy Tax incentives at state and federal levels Can be oversized – Used to assist with heating a home

On Demand Water Heaters On Demand Tankless Water Heater (gas)

On Demand Water Heaters Save energy: No storage tank Gas-fired units usually heat water more efficiently than gas tank type water heaters

Summary