Heat recovery

Greg Swob

Anyone have experience - good or bad or can make recommendations on waste heat recovery devices attached to a heat pump for domestic hot water heating or pre-heating?
Do I assume correctly that these devices only produce heated water during air conditioning? Which would make sense not wanting to draw heat intended for general heating purposes from it's intended use. Thanks - Greg

Jerry Boulanger_2

These units recover heat

by desuperheating the refrigerant, so they work anytime the compressor in the heat pump is running.

Wayne_12

Heat recovery using heat pumps

Heat recovery from a heat pump using a desuperheater on the discharge line will maintain a constant source of hot water for family use without any trouble. The desuperheater is part of the heat pump and water piping is installed from the water heater to the heat pump.

You are right in the concern of having enough heat for the water system and heat into the house. Your post doesn't say if the heat pump will heat air or water.

Like all systems the heat pump is sized for the coldest design temperature expected and or the warmest heat gain expected. Any temperature less the than the maximum will have additional capacity to heat domestic water. I do not know if you are looking at a air source heat pump or a ground water source, either way a COP (coefficient of performance) of 2 or greater becomes a economical way to recover heat and reduce our requirements of gas or electric use.

To answer the question of running short of heat during the coldest days or cooling on the hottest days installing some sort of switch to turn the circulator pump off when the demand is highest will assure the owners of addaquate heat or cooling.

WD

Greg Swob

Thanks-

I failed to include enough information- this is an air source HP used as primary heat with a NG fueled furnace as secondary heating for colder days. An acquaintance of mine has a ground source system which used to have a water heating heat recovery device. He claimed it would only operate in the summer- perhaps a controlling device would not allow water heating while in the space heating mode? He claimed it did not work effectively, was a plumbing nightmare; therefore he disconnected and disposed of it.
I will do some research through our suppliers. Thanks again. Greg

Tony_8

there's also

air source heat pumps just for HW. All assembled, just pipe it and wire it.