HVAC question, anyone ??


I have a LENNOX heatpump with a newer replacement RHEEM outside unit, due to a gas leak at the coils of the original LENNOX unit. It works fine in AC mode, but when it switches to heat, the compressor gets VERY hot over time, and the accumulator starts frosting up from the bottom up. It's a dual fuel, and I switched it over to gas, and the icing leared up almost instantly. In heatpump "heat" mode, the air at the registers is only about 75deg. I'll have to switch it back to heatpump mode to see ig that's happening all the time, or just when the compressor is heating up.
I'm thinking the defrost board might be wacky, but not sure .. .. anyone got opinions ??
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Bob, air to air heat pumps only work well to about 50 degrees. They are prone to icing - nature of the beast. It will be more cost efficient to use the heating coils if all electric or other alternate fuel.
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That's just crap, modern heat pumps work fine far lower than that. Certainly more effeciently that electric resistance. Gas back up will be more economical at a higher point.
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50 degrees?
Not buying that one. I had an old clunker that worked fine at 32. Worked good below that as well but being a clunker the efficiency dropped more rapid.
Then there was another old one, not as old, that went into a defrost cycle for a few minutes if icing occured.
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My Lennox automatically switches to gas when the outside temp get s down to a preset level. You can set this level in your thermostat. Recommended level is 45F. This may be setup wrong or doesnt work with the RHEEM unit.
Jimmie
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What's your location?
It's not clear to me exactly what you have. A heat pump is primarily the outside unit. The A coil inside is very similar between a heat pump and a straight ac. Some use the same A coil for both. You said a leak in the coil, do you mean the outside coil or the inside coil? You now have a rheem heat pump outside? Was the A coil inside repaced with a rheem unit as well? When did this happen? Have you had a successful winter season with the combination of equipment you have now? Or did this replacement happen last summer? It's ok to mix the inside air handler or one brand with the ac/heat pump of another brand. Not so good to mix inside A coil of one brand with outside unit of another brand.
It could be low on refrigerant. Slightly low refridgerant sometimes causes a unit to actually be colder initially but have freezing problems.
It might be the defrost cycle first. Have you seen it start the defrost cycle? There are several ways this happens, it can be a simple timer circuit or there is a sensor that triggers the defrost cycle. Most of the boards have a test point that can be used to force a defrost. Look for that. If you can trip it watch to see that the flow reverses and the outside fan stops running. If you can't force it then you have to watch it a while.
Be careful, serious electricity and high pressure gas. If you are not comfortable with these then call the guy.
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