The winter heat in my apartment is supplied by old PTAC (Packaged Terminal Air Conditioner) units, using resistance heat (it's too cold for the heat pump to work). A lot of cold outside air leaks through the insides of these units. I was wondering whether putting insulation on the exterior side of each PTAC unit, so that the whole unit is completely insulated from the outside, is a good idea.

Obviously, I'd remove that rear insulation when the cooling function is needed in the summer.

My goal is to reduce heating bills.

EDIT (additional information):

Manufacturer: Islandaire

I've tried to find the manual online but I couldn't (probably the model is too old), here's the closest I could find: https://islandaire.com/pdf/units/EZSeries42manual.pdf

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  • Hello, and welcome to Home Improvement. What's a PTAC; "something something air conditioner"? Do you have a make and model? And, you should probably take our tour so you'll know how best to participate here. – Daniel Griscom Nov 20 '19 at 16:27
  • "It's too cold for the heat pump to work" is a faulty assumption. Thereafter, the idea crumbles. It's too cold hour by hour and day by day. How will you keep it from running in heat pump mode on a nice day? – Harper - Reinstate Monica Nov 20 '19 at 19:05
  • @DanielGriscom Thank you for the pointer to the tour, I've edited my post to try to follow the recommendations. I've added the maker/model number, and a photo of the specs and the wiring diagram. PTAC is "Packaged Terminal Air Conditioner", and in the case of my unit, it contains an air conditioner/heat pump, and a backup resistance heater. – user1020406 Nov 24 '19 at 1:00
  • @Harper-ReinstateMonica From my observation, the heat pump doesn't seem to turn on. The manual (for a different model though) suggests that the heat pump turns on only if the external temperature is above 40F. The wiring diagram seems to suggest 38F. This is higher than a typical temperature where I live, especially at night (and for bedrooms at least this is when I need heat). As for how to technically prevent the heat pump from even trying to run, the unit has a switch that forces the heat pump off and uses resistance heating only. – user1020406 Nov 24 '19 at 1:09

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