Can I replace an air exchanger with a heat pump?
I'm not sure if there are versions of heat pumps that have the compressor and evaporator both outside, but mine has the compressor outside and the evaporator/air handler inside, which is about the same size as the air exchanger you have in the picture. So if you install a system similar to mine, you won't have any space savings.

On another note, heat pumps are only really usefull in areas that don't have harsh winters. Their optimal range for heating is 40°-55°F, and they don't perform efficiently in colder climates.

I'd talk to a local HVAC installer to see what type of system is best suited for your climate if you're dead set on changing the type of system you have installed.

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