I doubt many aluminum fin evaporators would stand up to high side pressures well.. and you cannot simply reverse the cap tube, it acts as a metering device restricting the flow of the high pressure liquid refrigerant allowing it to come out as low pressure gas in the evaporator... if you simply reversed the flow through it then you wouldn't have a metering device to perform the same function in the condenser....
if you look up how a heat pump works then you should be able to get a bit better understanding of this... heat pumps usually have 2 different metering devices that have one way bypasses around them so that only one is in use at a time..
I will have to check this, thanks for the input. I thought a heat pump generally use expansion valves that are directional, so it needs two, but a cap tube is not directional.
As for the heat, I am under the impression that the temperatures on the "hot" side of a heat pump are much lower than the glass of an incandescent bulb, that wikipedia says is "between 200 and 260 °C (392 and 500 °F)".
why do you want to heat the inside? and what temperature are you looking for?
Sorry, I missed to explain that.
The reason I want to do this is to build a levitation/fermentation chamber. This, is, something I can control (with a computer) to vary the internal temperature of the chamber between 4C (39F) and 40C (104F) according to a profile, to allow the ideal conditions for several stages of fermentation/levitation/maturation process, all of this independently of the outside weather conditions.
For example, I might want to keep my dough at 25C for 24 hours: during the night the T outside might go down to 13C, and during the day it might go up to 34C: this system will have to "warm up" during the night to keep the dough at 25C and cool down during the day.
It is easy to control the compressor motor with a relay, and start the "cool down" mode when needed. Some people use electric heat generators to warm up, but I was really curious to see if, by using a 4-way reversing valve, I could obtain the "heat up" cycle without having to install a heater inside the refrigerator.