Re:Re-using the heat in bathwater in Britain
by SECProto on Sunday October 30, 2022 @11:58PM
(#33401886)
> I'm not convinced of SEC's 2-3x estimated increase
It's a simple calculation, but very location specific. In my particular case, if the water heater is set to 50C, and tap water is 22C in Summer, it has to impart a ΔT of 28C. If your tap water is 4C in winter, the ΔT is 46C. Not quite double, but close to it. If your water heater is in a poorly conditioned space, then it would lose considerably more heat to the surrounding space when outside temperatures are -15C than when outside temps are 35C. All told, hot water energy usage for my particular situation is between 2x and 3x. Other situations would vary, but still significant.
It's a simple calculation, but very location specific. In my particular case, if the water heater is set to 50C, and tap water is 22C in Summer, it has to impart a ΔT of 28C. If your tap water is 4C in winter, the ΔT is 46C. Not quite double, but close to it. If your water heater is in a poorly conditioned space, then it would lose considerably more heat to the surrounding space when outside temperatures are -15C than when outside temps are 35C. All told, hot water energy usage for my particular situation is between 2x and 3x. Other situations would vary, but still significant.