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Anyone installing this unit domestic how water preheat
Anyone installing the following drain water heat recovery unit. Gets installed on the main waist water stack and you pipe potable water into it and then into the water heater in the house. They say it warms up the cold incoming water temp and thus the water heater can produce more hot water and can use less energy.
Does this work? How much does it raise the incoming water temp?
Anyone using anything else to raise water temp?