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Published byJimena Fickett Modified over 10 years ago
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Chapter 9: Water Heating To be used with the Guide to Building Energy Efficient Homes in Kentucky
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Hot Water Use 90 gallons per day 50 gallons per day
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Energy Factor Energy Factor (EF) = a measure of the overall efficiency of a water heater Includes: ―Recovery efficiency ―Standby losses ―Cycling losses
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Energy Conservation Water conservation measures =
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Energy Conservation New homes: Keep hot water pipe run as short as possible Use a manifold plumbing system
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Energy Conservation
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Water heater setting Temperature = 120 ° F – Provides plenty of hot water – Decreases risk of scalding – Select dishwasher with booster heaters
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Energy Conservation
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Insulate the first four feet of all pipes Use low-flow showerheads
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Energy Conservation Install heat traps Install low-flow aerators on sink and lavatory faucets
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Energy Conservation 1 quart Every 3 months, drain ~ 1 quart
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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
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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
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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
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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
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Electric Water Heaters Higher efficiency – EF > 0.97 – Extra cost is low compared to the savings
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Electric Water Heaters
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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
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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
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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
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Solar Water Heaters Images Courtesy: http://www.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12770
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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
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On Demand Water Heaters On Demand Tankless Water Heater (gas)
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On Demand Water Heaters Save energy: No storage tank Gas-fired units usually heat water more efficiently than gas tank type water heaters
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Summary
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