[shnichols]

I have a 2 1/2 ton Rheem heat pump and I need to know if the Thermal expansion valve can be disassembled or do you have to unsolder and replace the whole unit? The model # on the A coil is RCOB-C0305 serial number is M3292. It appears to me that the round portion that the bulb sensor goes into will unscrew from the hex portion. Please advise.

Thanks,

Shannon

[hvac1000]

If you replace the expansion valve you replace the whole item. The power head you are talking about in your post could be part of the problem but Rheem usually does not sell it alone. YOU will need a EPA certified repair person to do the work no matter what you replace. The refrigerant will have to be removed then the old valve remover then the new valve installed, leak checked and the system vac down. Then the system will have to be recharged to spec. Note a new dryer should be installed and any old dryer removed during the valve replacement.

There is a lot more to this than meets the eye.

[JackT]

What condition is the evaporator coil in? As hvac1000 stated it can be a lengthly process to PROPERLY change out the TXV. When you compare the price of the valve and what it will cost for labor and material, you may want to consider replacing the complete coil, it might not cost much more.

[shnichols]

I am certified. I was wanting to know if I could disassemble the txv and buy a whole new valve and just replace the power head without all the desoldering and soldering. The unit is my personal unit and is 15 years old so I did not want to put a lot of money into it.

Thanks,

[hvac1000]

I am certified. I was wanting to know if I could disassemble the txv and buy a whole new valve and just replace the power head without all the desoldering and soldering. The unit is my personal unit and is 15 years old so I did not want to put alot of money into it.

Thanks,

If you are certified you would never ask that question to start with. Give us a break.

[JackT]

Unfortunately, certified and qualified are completely different. A four hour class compared to years of training and experience..

[hvacservicetech_07]

I agree w/ jack, I suggest contacting a pro.

[shnichols]

Unfortunately, certified and qualified are completely different. A four hour class compared to years of training and experience..

Well mr smart man, I replaced the power head on a Carrier 4 years ago on a 10 year old unit and it is working great with no complaints. Do not judge someone's ability I simply asked if the head could be replaced. In the future keep your judgement comments to yourself and simply answer the question or just leave it to the people who want to help. Its cocky no it alls like you that give me the most business, fixing your mistakes.

[hvacservicetech_07]

Well mr smart man, I replaced the power head on a Carrier 4 years ago on a 10 year old unit and it is working great with no complaints. Do not judge someones ability I simply asked if the head could be replaced. In the future keep your judgement comments to your self and simply answer the question or just leave it to the people who want to help. Its cocky no it alls like you that give me the most business, fixing your mistakes.

I'm confused... if you do heating and a/c for a living then how much trouble would it be to reclaim the system, replace the TXV and put the same freon back in it? 2hours labor MAX how much money would you be out besides the cost of the TXV?

[JackT]

Maybe your posting should have started, I'm a certified technician and I have a question... then we all would have know who we are dealing with, not assuming it's someone who's not qualified. We all learn as we go along in life and we're here to help everyone we can. Just provide all the information you can so we know where to start.

[shnichols]

I'm confused......if you do heating and a/c for a living then how much trouble would it be to reclaim the system, replace the TXV and put the same freon back in it?? 2hours labor MAX how much money would you be out besides the cost of the TXV?

I do not do it for a living. I only help out friends and family. You are right it does not take long to remove the valve but my torches are shot. (bought used ones and got ripped off) I already work 50 to 60 hours a week on my other job and I do not have money to pay a service man. I do not claim and am very far from an expert. I am more qualified to do electrician work. I am not 100 percent sure that the txv valve is the problem. So I did not want to ruin the valve. I was trying to get information from guys like you that know more about problems like this. The other guy got smart with me and acted like I was stupid. I can rent torches but like I said I am pushed for time and money and like I said in the other comment, I once replaced the powerhead on a Carrier TXV. That's when I later bought the dudd torches.

[hvacservicetech_07]

All right, well let's start here... What is the system doing that makes you think the TXV is bad? Give me a little more info, and I'll try to help.

[JackT]

What's your system doing? Usually if your TXV is bad your suction line pressure will drop down real low. Depending on the manufacture of the TXV you may be able to change just the power element itself. Most AC manufactures use many different brands each year, depending on who can deliver for a low price. Your TXV could be sporlan, alco, danfoss, parker, emerson and many others. I would say if the power element has a place for a wrench on the bottom of it, it most likely can be replaced. Let us know if you need more help.

[shnichols]

Alright, well let's start here.......What is the system doing that makes you think the TXV is bad?? Give me a little more info, and i'll try to help.

When I turn on the AC on this is a heat pump, the suction pressure ranges from 64 to 68 and does not fall but the head pressure continually increases until the high head pressure kicks out at 450. It does this in a matter of 4 to 5 minutes. I have cleaned the condenser coil until low pressure from a water hose will flow through the fins on the coil. I have two Heat Pump units for my house. The fan on the unit that is tripping out is producing more air flow than the unit that is working properly. The heating cycle on the unit appears to be working properly but I have not had the gages on it during the heating cycle and my power bill was good in the winter and I have not noticed the aux heat coming on except during defrost. I have a laser temperature gun that I took readings on the txv valve while it was running. The suction side of the txv was 43 to 45 degrees but the other side or high side of the txv was 70 degrees. The supply line were it goes into the Evaportor coil is only 75 degrees. The inside temp of the house was 72 degrees. There is no filter dryer on the unit only an accumulator and during operation only one line going to the accumulator begins to sweat.

[hvac1000]

Did you add refrigerant to this system lately? It could very well be a overcharge that would show up in the air cond mode and not the HP mode. Many people charge Heat pumps in the colder weather and over charge the unit. Usually to high a pressure on the high side is a indication of a problem with heat rejection in the A/C mode. Your suction pressure is about correct for a 72 degree inside temperature. Do you have a wet bulb reading?

If I were a betting man I would say it is a overcharge condition unless the outside fan motor is running in reverse or the blade is on up side down.

You can check the expansion valve if you want by using a small pail of warm water. Detach the sensing bulb and place into the pail. Then go out and read the pressures. Next step is to use a small pail of ice water and do the same procedure. Make sure you put the sensor bulb back in the same 3 or 6 o'clock position and make sure it is firmly attached for proper contact. Replace any insulation that was surrounding the sensor.

Report back and findings.

[shnichols]

Did you add refrigerant to this system lately? It could very well be a overcharge that would show up in the air cond mode and not the HP mode. Many people charge Heat pumps in the colder weather and over charge the unit. Usually to high a pressure on the high side is a indication of a problem with heat rejection in the A/C mode. Your suction pressure is about correct for a 72 degree inside temperature. Do you have a wet bulb reading?

If I were a betting man I would say it is a overcharge condition unless the outside fan motor is running in reverse or the blade is on up side down.

You can check the expansion valve if you want by using a small pail of warm water. Detach the sensing bulb and place into the pail. Then go out and read the pressures. Next step is to use a small pail of ice water and do the same procedure. Make sure you put the sensor bulb back in the same 3 or 6 o'clock position and make sure it is firmly attached for proper contact. Replace any insulation that was surrounding the sensor.

Report back and findings.

Thanks. I will try this. I have not added freon and the fan direction and air movement are OK but I will try the warm and cold water with the bulb.

[JackT]

Shannon,
I don't believe you have a problem with your TXV. If the TXV failed your suction pressure will drop and your head pressure will remain the same or start dropping after it runs for a few minutes. ( just like a pump down solenoid does on a refrigeration system) Your problem is most likely overcharge, not enough air flow through the condenser or contaminates in your refrigerant. If a unit developed a leak in the low side and the suction went into a vacuum it will suck in air. If the service technician just adds more refrigerant, the air will remain trapped in the system causing high head pressure. You also could be having reversing valve problems, but this doesn't sound like that's the issue here.

[shnichols]

Shannon,
I don't believe you have a problem with your TXV. If the TXV failed your suction pressure will drop and your head pressure will remain the same or start dropping after it runs for a few minutes. ( just like a pump down solenoid does on a refrigeration system) Your problem is most likely overcharge, not enough air flow thru the condenser or contaminates in your refrigerant. If a unit developed a leak in the low side and the suction went into a vacuum it will suck in air. If the service technician just adds more refrigerant, the air will remain trapped in the system causing high head pressure. You also could be having reversing valve problems, but this doesn't sound like thats the issue here.

Well Jack, you guys got me wondering about the charge. I proceeded to pull the system down and then I slowly recharged the unit as it should be and guess what. It is working great. I could not for the life of me figure out how this might have been overcharged. Well 3 weeks ago before I started the unit in AC for the first time, I hooked up the gages and my freon cylinder because the unit does have a slow leak and I figured that I may have to add a touch. I then proceeded to go back into the house, check and replace filters and I even opened the Air handler while it was running to check everything out as I usually do at the beginning of every change over from heating season to cooling. After running all this through my head I realized that my curious and now red butted 13 year old son who was outside.thought that he would play with the gages while I was inside. When he heard the unit stop because of what he was doing, he proceeded to leave the scene of the crime and never speak of it. With enough threats I got it out of him. Next time I will state my problem first and save myself and you guys some time. Thanks so much for all of you guys help.
PS I told my son that it would take a lot of allowance to pay for a new compressor if it goes out on me.

[hvac1000]

((Did you add refrigerant to this system lately?))

Well my question got answered. I hope your son learned a lesson but we are all curious at times. Glad you got it going.

[JackT]

Glad we could help. That's what were here for.