An AC unit is a heat pump. When used to cool a home in summer, heat is pumped out of the house to the exterior unit, whether this is a window or a split-unit design. A simple heat exchanger/circulator, (a
desuperheater) can be inserted in the AC refrigerant lines to remove some of this heat and transfer it to a water storage tank at 60C / 140F. The heat extracted is essentially 'free', the running costs are simply those involved in capital, fluid circulation and control.
Actually, fitting such a device will reduce the cost of running the AC unit and prolong its life. There are some reservations:
1. The Heat Exchanger has to address the danger of refigerant gasses getting into the potable water supply, and must be sized correctly.
2. The device will be non-operational when the AC is off or reversed, (ie winter), so an alternative hot water heater is needed.
3. Cutting into the refrigerant lines might pose warranty problems and also requires a HVAC engineer to re-gas the AC unit.
http://www.doucetteindustries.com shows a typical unit and a savings chart. Go to: products: desuperheaters.
I'm still looking; I want a stand-alone air-water unit at a reasonable cost, which I can park in the boiler-room to extract heat lost by the boiler in winter or gained by solar effects in summer.
Alan
[This message has been edited by Alan Belson (edited 09-04-2005).]
