TXV Repacement $1100???

[wa3kf]

Thanks for the help. I have a Lennox HP25-411-1P that is paired with a Lennox CB19-31-2P inside unit. I have been having problems with the compressor shutting off with a thermal shutdown. It is extremely erratic. Sometimes it will shutdown and sometimes it will not. When the tech was here it did shutdown. The tech who looked at it said compressor current draw is normal. However, he said the charge looked low. Said that when R22 was added, head pressure went up, but suction did not. He said that he found that there was only a 10 degree temp differential across the evaporator coil. Said the temp on suction was

64 degrees and that the TXV is bad and is not allowing enough coolant back to the compressor to help cool it. Price to fix $1100. This seems really expensive to me since the part is only about $160. They are charging $36 a pound for R22 and since the system takes 10.5 pounds that adds up quick. The unit is 12 years old and naturally since they sell units they say best course is a full replacement of the heat pump. Should I be looking at another service tech for their opinion? Is this price high to replace a TXV (drier also by the way)? I'd like to go with a geothermal when I replace this, but could not swing it today, so if the TXV replacement was only going to be about half of the quote, I'd go for it. It would be nice to get a few more years out of this heat pump.

Comments?

Ken

[Bubba]

Ken, Price is relative to where you live and what company you get. That price may be high in one area and low in another. Refrigerant is going up by the month. Nothing is cheap including labor. Look at the price of gasoline. I dont like that one bit but thats the way it is. Anyways, if you are concerned with the price, get another estimate or two. Your conversation on the phone to another prospect company might include your current system problems, the course of action your current company has chosen and maybe asking for one of their more experienced service techs. Armed with that info, you might be suprised at what you find out. By the way, 10 lbs aint diddly. I have a 2.5 ton 14 SEER heat pump that holds about 20 lbs!! Remember A/C is a luxury, not a necessity. Bubba

[udarrell]

First, the R-22 can be pumped down into the condenser & sealed off using the service valves; there is no reason to get rid of the R-22 unless it is contaminated. He may possibly be charging you for R-22 when there may be little or no need for it Additionally, there may be NO legitimate reason to replace the TXV, proper troubleshooting is required to establish if it is bad. Can he show you the tests 'that prove' the TXV is bad?

Second, many TXVs are adjustable as to how low you want the Superheat to be. Also, he sensor bulb should be removed and emery paper used to make better contact & heat transfer to the bulb; the bulb also needs to be mounted in the proper location on the line.

Third, the TXV keeps the refrigerant flow rate constant to maintain a specific Superheat setting, adding refrigerant is not likely to change the suction; a change in the heatload through the evaporator will change the R-22 flow rate toward maintaining that Superheat setting.

Fourth, the TXV may not be the sole cause of the overheated compressor. Is the condenser coils & fins clean & the motor delivering its full RPM, if it's a PSC motor check its run capacitor!

- udarrell

If you allow them to replace the TXV that may not solve the problem. Check the temperature of the air leaving the condenser as compared to the outdoor temp & post those temps & the split in degrees-F. Perhaps the 10-F split across the evaporator is due to a non conditioned source of hot air being drawn into the E-Coil just before the air enters the blower. Are you located in a high humid climate? If the compressor is getting hot I would quit running the AC until the cause(s) of the problem are located & fixed!

- udarrell

[wa3kf]

capacitor!

- udarrell

So how does one go about finding a reputable HVAC person to tell me what is wrong? I gave you all the information that the tech gave me. With that is how he said the TXV was bad. So I guess you are saying he did not know what he was doing? I live northwest of Philadephia. Know any good HVAC techs here? Today it is humid and about 75 degrees outside. The temperature of the air leaving the evaporator is 52 degrees. So that is a 23 degree split. The compressor will run an hour today before it shuts down. Yesterday, at the peak of the heat (95 degrees) it would run about 10 minutes. To be honest, it does keep the house at a constant temperature. I only noticed this because I turn the temp up in the morning and lower it at night. I was noticing that sometimes it took too long for the outside unit to start. This copeland compressor has a replaceable temp limit on it. I thought the sensor could be bad but since it supposedly triggers at 280 degrees have no way to test it. Tech said that was not bad (he did not do any testing to it - just said that). He did put a thermometer on the compressor by the sensor but it never went above 150 degrees (note that the sensor goes into the case though).

So my guess is I need a good tech and do not know how to find one. Naturally everyone will charge me a couple hundred dollars to tell me what is wrong. I do not have a problem with that, but want it to be right.....

Ken

[Bob Pietrangelo]

Price seems a little high but not outrageous.

Philly Area

[<kjpro]

Goes up by the week here!

A/C is a necessity when the temps are 100+ :-)

[Tony]

I am Refrigeration Tech. and not AC person however unless unit is running with low back pressure 9-1 there is nothing wrong with TXV must likely low on charge (gas) or perhaps compressor loosing compression (not pumping) get some one ales to look at your unit because one that you had seems to be big scammer. Tony

[lp13-30]

FWIW- I think I have only changed one of those temp sensors on Copeland scrolls. It goes down into a well that is definitely more than an inch. As I recall it is somewhere around 4 inches. Years ago our local Rheem distributor did not stock them-- said they were not needed and to bypass them. I have no idea if that came directly from Rheem, or just the dist. I never bypassed one though. Actually the one I replaced was on a Lennox, but I got the part from the Ruud dist. One thing is for sure-- they are right proud of them-- $$$$$. With the sensor going down into that well, I would guess that it is sensing winding temp as well as discharge. I would make sure the run cap is at its rating, and that all the electrical connections as well as the contactor are good so the compressor is not running hotter due to low voltage.

[wa3kf]

The Lennox service manual does specifically say discharge temperature is what is being sensed.I can feel that top of the sensor, so it can&#39;t that far down there. I think reading discharge temperature is a reasonable method. If it shuts down and the discharge temperature on the pipe is up in the 200&#39;s, I&#39;d be suspicious. I got an online quote for $120, so yes it is not cheap. The contacter does look a little charred on the contacts so that is interesting. I can check to see if there is a voltage drop across it. How does one check the run cap?