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-   -   unequeal heat pump/air handler tonnage (http://www.houserepairtalk.com/f8/unequeal-heat-pump-air-handler-tonnage-3426/)

howie89 01-21-2008 10:11 PM

unequeal heat pump/air handler tonnage
 
Background:
Two years ago under a home warranty call my heat pump a Janitrol CPH36-1FB (3 ton?) was replaced with a Payne PH10JA042000 ( 3 ton?) unit. At that time it was recommended that the indoor air handler, a Janitrol/Goodman A36-10 (3 ton) be replaced because the accumulator had a lot of rust. Since it was actually still working the home warranty company would not allow replacement. Fast forward to a week ago and trying to heat my house the outdoor unit would not work. It would cycle on and off and then eventually it would not even do that. I called in the original company that had put in the new heat pump and they said there was leak and all the Freon was gone and that the air handler needed replaced. I was able to run on emergency heat. Since I no longer have a home warranty service I called around and got quotes based off of the information on the tag on the air handler, a 3 ton unit. Using a new company, I had a new 3 ton Ducane air handler installed. Everything was fine for a few days, then once again the outdoor unit was not running. Called in the new company and they found there was no Freon in the line. They traced it to the reversing valve in the heat pump. The tech said the problem is having a 3 ton heat pump installed with a 3 ton air handler. He said that the original installers of the heat pump should have never have done this and that the heat pump should never be bigger than the air handler, smaller is ok. He also said that if all that I do is fix my heat pump that I will probably have leaks twice a year somewhere in the system. He recommended that I install a new 3 ton system.
My Questions are:
1. Is it true that the heat pump should be equal or less in size than the air handler?
2. If this is such a bad situation how was I able to get along two years with a 20 year old air handler before there was a problem?
3. If I pursue fixing the heat pump as is, can I expect more leaks to occur due to the heat pump size?

A long winded question, but I wanted to make sure I gave all the background information.

New to this site, I appreciate any and all help. Thanks.

CraigFL 01-22-2008 06:15 AM

I'm not a HVAC guy, only an engineer but I find it very difficult to believe that 3-1/2T vs. 3T would be of any significance. Having my own repair business and seeing how others "diagnose" problems, it is more likely that the tech is wrong and you've had poor diagnosis of your problems all along. I don't understand why you needed a new air handler when all you really needed was a new condensor coil. In any case, the tech needed to make sure where the leak was with a sniffer.
There are a lot of "old wives tales" floating around the repair business and the tech may really believe that that was the problem because he was told to believe it. If the reversing valve is the problem, it would be more likely that it was just worn out...

Ok you HVAC techs... prove me wrong.... :)

glennjanie 01-22-2008 10:53 AM

Welcome Howie:
Craig is right, the only thing a smaller air handler would do is make the unit
'short-cycle' occasionally and that is no problem.
As far as the refrigerant goes, there is a leak somewhere but it is not causes by miss-matching. The system should hold 400 psi or more regardless of the size. I think the guy who changed out the heat pump unit after 2 years was pulling your leg (not to mention your wallet). You may need new lines between the 2 units but size is of no consequence.
Service technicians are quick to change out units or to 'add gas' when it is not needed. Its just an easy way for them to make more money. The gas does not consume away, wear out or get too old to work; it only leaks out. So if they are too lazy to find the leak they go to replacing equipment and adding gas. Tell them to go back to vocational school.
Glenn

howie89 01-22-2008 08:07 PM

I agree with you on the tech's troubleshooting skills. So far I am less than impressed. So far it has consisted of feeling for oil and then saying that is the bad part. As far as the condensor coil I was told from one guy he would try to find a replacement and never heard back from him, and from another I was told that due to the age of the air handler, 25+ years, that it would be difficult to find a replacememt and I could have one custom built, but for a couple hundred more dollars I could have a whole new air handler. As far as the reversing valve it is only two years old.

What is 'short cycle'? The air handler is new (now), the heat pump is two years old, but the last tech is trying to get me to buy a new one because of the 'mismatch' in ratings. Is there something that he could have done when installing the new air handler that would have affected the reversing valve or caused a leak in the heat pump?

Is there any troubleshooting procedures that I can do myself to at least start to get an idea of what the problem is? So far leaving it to the "pros" has been dissapointing.

Thanks CraigFL and glennjanie for your help.

glennjanie 01-23-2008 11:08 AM

Hello Howie:
'Short Cycle' means the outdoor unit builds up the required refrigerant too quickly for the indoor coil to use it and causes the outdoor unit to kick off too soon. Whereas, if they were matched the outdoor unit would run longer but you are not all that much off the match. The short cycle you may have is not a real problem, it just uses a little extra electricity.
Yes, the technician could have damaged your unit when he did his work. He probably left a solder joint with a pinhole in it. Reversing valves don't go bad, typically it is the solenoid that operates it that goes bad.
You have a leak or several leaks allowing your refrigerant to escape. I suspect he used 50/50 solder which is easier to use but doesn't hold near as well with the vibrations found in a heat pump. I would use a silver bearing solder on HVAC and Refirgeration. It requires a higher heat but gives a better joint; its more like welding than soldering.
Glenn

howie89 01-23-2008 10:52 PM

Thanks for all the help. I will post to this thread again when I am able to find out more what the problem is.

Thanks,

geo fan 06-19-2008 09:32 AM

techs opionon
 
an over sized condenser to a undersized evap coil can cause slugging this happens when the liquid sent to the evaporator can not be completely evporated due to the smaller coil and lower fan speeds this can cause the luquid to build up in the accumulator and make it to the compressor . you can not compresse a liquid and baboom you need a new system this can be over come by undercharging the mismatched system ,but the possobility exsists .
All refrigeration pipes Shall be brazed never use solder you pump a trickle of nitrogen through the lines use an oxy-accendaline tourch no oxy no big deal and be carefull when r22 is heated above 500 degrees it become phosen gas and you will get sick fell a little better then 2 days later not wake up no antidote and no obvious symptoms so purge the system to 29w.c. for 20 min and purge the lines with nitrogen . the full system replacement is probubly recomended becouse likely the tons are different and the seer rateing this compounds the original statment . Reversing valve can leak cheap condensers and evap coils come with leaks in the welds all the time and some of the blame goes on the install for not catching it .
Sorry for the spelling and gramer but the second tech was right about the right to do it is replace the full system to match tons and eff and he has a responsibility to recomend that to cover himself and the comp whenever he touches a system that was impropperly installed


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