Domestic Hot Water Supply Efficiency
A significant portion of the average home’s energy consumption is dedicated to the generation and supply of domestic hot water. Taking shorter showers and washing our clothes in cold water can help, but there’s something else that needs addressing: the hot water tank.
Think of your hot water tank as a big kettle, except that it never stops heating the water inside it. Heat is constantly escaping from the water in the tank through the tank itself, as well as the piping connected to it. Need proof? Try touching your hot water tank with your hand; warm, isn’t it? If you’re still not convinced, open a hot water tap in the kitchen or bathroom and time how long it takes until hot water makes it to the sink.
The Green Homes Program now requires that all electrically-powered hot water tanks must be wrapped in insulation (minimum RSI 1.76) to help limit heat losses at the tank. Gas-powered hot water heaters are exempted from this requirement for fire safety reasons.
The Program also requires that the last 1 m of piping leading to any domestic hot water tank and the first 3 m leading from any domestic hot water tank be wrapped in insulation that has a minimum RSI of 0.35. There’s an exception, however, for constantly-recirculating domestic hot water systems; for this type of domestic hot water distribution system, all of the hot water piping must be insulated to the same RSI 0.35 level.
By-law Language:
12.2.2.3. Hot Water Tanks
1) Electrically powered hot water tanks shall have insulation that provides a minimum RSI value of 1.76.
12.2.2.4. Hot Water Tank Piping
1) The first 3 m of non-recirculating hot water piping leading from both electrically powered and gas powered hot water tanks, and the last 1 m of piping prior to connecting to the hot water tank, shall have insulation that provides a minimum RSI value of 0.35.
2) Despite Sentence 12.2.2.4.(1), the entire hot water piping system, if it is of constant recirculation design, shall have insulation that provides a minimum RSI value of 0.35.
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