Missing check valve in Heat Pump?

[sdilley]

I purchased the units for my split Heat Pump system, set them in place, then I had a professional replace the valve on the air handler with a TXV, silver solder the tubing, vacuum down everything, and charge the system. It has worked well though-out the summer on AC, but when I turned it to heat, no heat and the compressor overload (or overpressure) turned off the compressor.

I shut-down the unit and looked it over. I did not find a check valve on the air-handler. I suspect that this is my problem, but I am not a certified HVAC technician.

The system is composed of:

American Standard Outdoor Unit Model 2A6H2036A1000AA

HealthySolutions Indoor Coil Model HA54243A170A000490

Emerson TXV Model VAL07467

30 feet of 7/8 Suction and 3/8 liquid tubing

I placed a call to a highly recommended HVAC service. A technition came out looked over the unit and stated that the check valve may be incorporated with the TXV, he would check and call the next day. He never called.

Should there be a check valve parallel to the the TXV or does the TXV incorporate the check valve?

Assuming that a check valve needs to be added, what should I expect to pay?

Is there someone in my area you could recommend for this job?

Stan Dilley
Raleigh, NC 27612

[HayZee518]

thermal expansion valves do not have check valves. there's no reason to restrict flow in a cooling line. when an ac system goes into heat mode there is a reversing valve that reroutes the refrigerant so that heat is given off at the evaporator not cooling. the purpose of the txv is to distribute the refrigerant to the evaporator. if it stopped the flow the compressor would unload and just run on idle.for expansion valves look into the SPORLAN manufacturer type - most dependable.

[sdilley]

Thank you for your quick response!
The American Standard schematic shows a check valve in parallel with the TXV that would allow freon to bypass the TXV in the heat cycle. This valve would be closed during the cooling cycle, forcing the freon through the TXV.
It sounds like this check valve is missing. Can one be added? Or do I need to have the air handler coil replaced with a unit with both valves?
Who in the Raleigh, NC area could handle this work?

[HayZee518]

ok, this makes sense - I have no idea who is dependable - I live in new york state. the check valve would need to be brazed into the line which will require the entire system to be evacuated of freon, then vacuum purged and refilled with freon.

[dosser]

Sorry but some TXV's DO have check valves built in. If you need one it can be added. The TXV's are in the liquid line on the inside and outside units on heat pumps. My own unit has a built-in check valve. Is your system R-22 or 410A?

[hvacwiz]

Sorry but some TXV's DO have check valves built in. If you need one it can be added. The TXV's are in the liquid line on the inside and outside units on heat pumps. My own unit has a built-in check valve. Is your system R-22 or 410A?

since when do txv's get installed on the outdoor unit.

[sdilley]

TXV's with Check Valve

DOSSER you are correct, some TXV's do have check valves. I called the factory and have the part number for the correct TXV (with check valve). I received a quote to replace the TXV of $1250.00. I realize that this procedure requires capturing the Freon (R-22), removing and re-silver soldering in the new valve, vacuuming and presurizing with nitrogen, before recarging. In any case, $1250.00 seems extreme.

[hvacwiz]

seems very high to me also, I would get other quotes.

[dosser]

All high seer (14 and up) use TXV's on both inside and outside units. Whoever installed the wrong TXV should replace it with the correct one at no labor cost and if he supplied the valve he should be replacing it with the correct one at no cost. Sounds like you were charged for the wrong TXV. Your outside unit has sevice valves, and a good tech can pump the refrigerant into the outside unit with the system compressor. Hook up gauge set, close the liquid line service valve (the smaller line), turn system to cooling, watch the suction pressure and close the suction line service valve (the larger insulated line)when you read 5in vaccuum. Turn off unit, connect gauge set to suction service valve, add a little nitrogen (to break vac), remove liquid line service valve schrader, use low flow nitrogen while replacing TXV, blow out a little nitrogen after soldering, install schrader, put 200lb nitrogen, test for leaks, dump nitrogen, vaccuum system, open service valves, check run pressures, and enjoy heat and cool. Merry Christmas