Hello guys. I want to modify a dehumidifier so that it will dehumidify a bathroom and will simultaneously heat the water. As you know heat pumps, air conditioners, refrigerators and dehumidifiers are basically the same thing. What I plan to do is to add a refrigerant/water heat exchanger between the compressor and the condenser. In so doing I will achieve the following: if the water is cold, the refrigerant will condense in the heat exchanger thus heating the water. If the water is already warm, the refrigerant won't condense in the heat exchanger, but will condense after that in the condenser, the way it would have worked in a nonmodified dehumidifier.

So after made all of this clear, you will notice that the whole volume of the system will be increased, so I will need to add refrigerant. What is the engineering method of determining that? Is there any practical method, provided that I can't rely on precalculated tables or stickers on the appliance?