EcoRenovator - View Single Post - Water-to-water heat pump rebuild?

Bill Sanford · 01-05-13, 09:21 AM

Hey guys,

I have a 20 year old Florida Heat Pump WH50 - 50k BTU water to water, heating only heat pump that needs help.

I had the compressor fail several years ago. I found a Copland scroll compressor online that was listed as a direct replacement sub for the old piston compressor that was in it.

I brought the entire unit with the new compressor to a local HVAC shop and had them change it for me and recharge the unit (R22). That they also changed the TXV because they felt that it may be contaminated by the burnt up compressor. They didn't consult the heat pump manufacturer regarding the type of TXV. The TXV is not an adjustable type.

Since that time, the unit works, but doesn't seem to put out much heat compared to before the original compressor failed. The HVAC shop doesn't have a clue. They don't seem to understand anything other than how to change parts.

The heat source is well water in a pump-and-dump setup with the well water at 50 degrees F.

I think my problem is that the temperature of the R22 coming out of the TXV valve is 43.7 degrees and the well water is only 50 degrees.

The suction pressure is 54psi, which on the R22 chart is 30 degrees F, so my superheat is 13.7 degrees. The source water temp never changes from 50 degrees.

My question is: How can I lower the R22 temp coming out of my TXV? If it was 34 degrees, I'd be able to extract a LOT more heat from the well water through the heat exchanger (evaporator).

If my TXV had adjustable superheat, I assume I could lower it quite a bit and this would lower the R22 temp leaving the TXV, right?

What would more charge do?

My temps and pressures are as follows:

High R22 pressure 240 PSI
Suction R22 pressure 54 PSI
R22 line temp entering the evaporator 43.7 degrees
R22 line temp leaving the evaporator 44 degrees
Source water temp entering the evaporator 49.9 degrees
Source water temp leaving the evaporator 45.5 degrees

Again, how do I get my R22 temp lower leaving the TXV and entering the evaporator? Doing this should solve my efficiency problem.

Bill

01-05-13, 09:21 AM	#1
Bill Sanford Helper EcoRenovator Join Date: Jan 2013 Location: Northern Minnesota Posts: 32 Thanks: 1 Thanked 0 Times in 0 Posts	Water-to-water heat pump rebuild? Hey guys, I have a 20 year old Florida Heat Pump WH50 - 50k BTU water to water, heating only heat pump that needs help. I had the compressor fail several years ago. I found a Copland scroll compressor online that was listed as a direct replacement sub for the old piston compressor that was in it. I brought the entire unit with the new compressor to a local HVAC shop and had them change it for me and recharge the unit (R22). That they also changed the TXV because they felt that it may be contaminated by the burnt up compressor. They didn't consult the heat pump manufacturer regarding the type of TXV. The TXV is not an adjustable type. Since that time, the unit works, but doesn't seem to put out much heat compared to before the original compressor failed. The HVAC shop doesn't have a clue. They don't seem to understand anything other than how to change parts. The heat source is well water in a pump-and-dump setup with the well water at 50 degrees F. I think my problem is that the temperature of the R22 coming out of the TXV valve is 43.7 degrees and the well water is only 50 degrees. The suction pressure is 54psi, which on the R22 chart is 30 degrees F, so my superheat is 13.7 degrees. The source water temp never changes from 50 degrees. My question is: How can I lower the R22 temp coming out of my TXV? If it was 34 degrees, I'd be able to extract a LOT more heat from the well water through the heat exchanger (evaporator). If my TXV had adjustable superheat, I assume I could lower it quite a bit and this would lower the R22 temp leaving the TXV, right? What would more charge do? My temps and pressures are as follows: High R22 pressure 240 PSI Suction R22 pressure 54 PSI R22 line temp entering the evaporator 43.7 degrees R22 line temp leaving the evaporator 44 degrees Source water temp entering the evaporator 49.9 degrees Source water temp leaving the evaporator 45.5 degrees Again, how do I get my R22 temp lower leaving the TXV and entering the evaporator? Doing this should solve my efficiency problem. Bill