Aquario, any update on the defrost control now that it's gotten a little colder, at least here in Wisconsin? My biggest need right now for my Hot Tub Heat Pump(HTHP) is a reliable defrost setup. I'm currently testing a Dehumidifier control board for my defrost. It's got a thermistor that gets mounted on the vapor suction line just before the compressor and will shut it off when it gets too cold for too long.
I tested it today on the line just after the cap tube where it frosts up first and it did indeed shut down the compressor after a few minutes, but than it stayed off for a half hour until I hit the switch that determined if the bucket was in place to simulate taking it out and putting it back in. I think it's getting cold enough to shut the compressor off, but in 33* weather, maybe not getting warm enough again to bring it back on. After all this was designed for a basement in the 50 or 60* range.
I'm going to try it with the sensor closer to the compressor like intended and see if that makes a difference. I have a hunch if I insulate the line from the compressor to past the thermistor, the heat of the compressor will warm the line enough during the defrost to let it come back on. My A/C doesn't have a reversing valve btw so it's just compressor off, fan on, defrost.
What do you all think? Will it work or should I pursue a new direction? I'm thinking if I can't get the thermistor to bring it on reliably I may build a simple timer that essentialls simulates the bucket being removed and put back, bringing the compressor back on, after a set amount of time, maybe 5-10 minutes. The other option is to use a FischerTechnik interface, thermistors, and relay, design my own demand defrost system, and make a program for it in RoboPro. That would be a fun challenge.
Adam
Adam
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