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  1. #1
    Join Date
    Sep 2007
    Posts
    23

    Questions about systems

    Greetings,

    New to the forum and full of questions.

    I have a 10 year old system in a 2000 SFT dbl wide home, well insulated, 2x6 walls, good windows. Etc.

    The outside unit is a Goodman 4 ton unit with a Copeland Compressor, the indor unit is an Intertherm heat strip unit with a 4 ton coil exposed in no case.

    6 years ago the compressor actually exploded, the side of the compressor where the wiring enters popped and the compressor was toast. I hired a trusted HVAC installer I have know for years to come out and replace the compressor which was under warranty. He said the compressor suffered from a defect as they normally do not fail in that manner.

    All has been pretty much well since then, I do regular maint on the unit, purchasing good filters, keeping the coild clean etc.

    Yesterday the condensor fan "GE 1/4hp" siezed and had to be replaced, I removed the cover and the motor and had the unit ready for the repair tech when he got here. He mounted the new motor and fan, and his knee I guess smashed the side of the condensor coils bending some of the fins. When he started the unit up, inside I could here the unit surging, sounded like water being forced through a tube. The high side was too hot to touch the suction side was cold.

    I called the tech back from his truck and notified him the high side was red hot, he grabbed his gauges and hooked em up after shutting off the outside unit. Once he turned the unit back on I watched the guages and the outermost ring read 300psi on the high side and about 90 on the low side. He started releasing some freon and asked for a water hose to wash the coil ouside. The pressure went down to about 250-275 once the water was applied. The inside coil stopped making the surging noise.

    He claimed at that point that the outside coil was dirty and that it needed to be replaced, cleaning it was not an option. When you hold your hand above the fan outside it feels like it is not moving enough air, and I commeneted on this to him, he disasembled the top and moved the position of the fan blades. Then he added freon back to the system "R22" and the last time I looked at the gauges it was around 300 on the high side and 90 on the low.

    The outside air temp was 90 with 70% humidity. The inside temp was 88 with a humidity of 55%. The unit ran from 5:00pm until 4:00am and brought the temp down to 76. Which is where I keep it.

    We live in South Texas so summers are usually brutal, not this year, we havent had a single day over 95.

    My question is, the surging at the orrifice tube, is this normal, are the pressure normal. And would I be wise to install a TSV? Hope that is the correct name, in place of the orrifice tube. Also, cant this coil be cleaned? I can see through it, and water flows unrestricted through the unit.

    Also could there be an issue with moisture and or air in the refridg lines?

    Your help and opinions are greatl appreciated.

  2. #2
    Join Date
    Aug 2007
    Posts
    49
    OK, one step at a time. TXVs are nice but your unit should work fine without one. (coil exposed? as in: you can touch it? No ductwork?

    Anyway, I've never heard of a coil so dirty it couldn't be cleaned. If he smashed a fist-sized area with his that shouldn't make that big a differance. If a whole lot of those fins are smashed and restricting airflow, that different. But not because of dirt.

  3. #3
    Join Date
    Sep 2007
    Posts
    23
    Yes the coil is exposed, the air handler is an intertherm unit with heat strips - cheap I know.

    The coil was plunked down on top of it exposed, no case, filters strap on to the ouside of the coil, the coil is triangular shaped. It is on top of a plastic drain pan and sealed all around.

    The owner of the AC company I use is coming out today to see the installation and look at the condensor unit to see what he thinks.

    Like I said, I have had the unit regularly serviced, winter-summer, problem is the techs sent out usually dont want to do the work required to service these older units and recommend replacement. I am of the opinion fix it. Unless the compressor goes out.

    I am planning on purchasing a Goodman 4 ton 14 seer heat pump system next year, I personally like the brand. But I just want to share my experiences to make sure I am not getting led on.

    Thanks

  4. #4
    Join Date
    Feb 2007
    Location
    Las Vegas,NV
    Posts
    744
    Back in the 80's, My grandparents had an intertherm split system in their doublewide. I hate mobile home systems beacause they are so noisy. We ended up taking it out and installed a Heil gas pack out on a slab and then cut a nice big floor return in. We were also able to turn the area where the furnace came out into a pantry. I would hope that you wouldnt just add a new c/u to that mess that you have.

  5. #5
    what size motor did he replace it with?did he use the same fan blades?did he take a supper heat calc,or take a temperature drop across the coil? the coils must be in very bad shape to replace.but even if so it would show in the gages.if it is as bad as he said.the high side would be a lot higher then 300psi
    if the temp out side is 90 then the high side should be around 250psi.first use a digital thermometer and check the return air. then check the supply air at a regester.your looking for 20 deg between the coil. good luck!!!

  6. #6
    Join Date
    Sep 2007
    Posts
    23
    Craig, he replaced with a 1/3hp not a 1/4 which is what it calls for, and he suspicions that this could be the reason for the higher pressure, he is going to order a 1/4 hp and measure where the fan goes with the old unit.

    He stated he is not flooding the evaporator, this is why it is not cold all the way to the top, when he does the high side pressure goes to high he thinks due to limited air flow on the condensor.

    Does that sound right?

    So we shall see. He is also a Trane fan, and is going to quote me a new system inside and out along with some needed duct work.

    Sammy, the air handler is in its own room, about 24x24 with a downflow air handler, thin sheet metal non insulated ducts, these are all going to be replaced with insulated ducts next year.

    20degree drop across the indoor coil over outside air temp.

    Comments and suggestions are welcomed

  7. #7
    Join Date
    Sep 2007
    Posts
    23
    P.S. Found a problem with the ductwork today as well, two sheet metal ducts run the length of the house with a flexible crossover.

    Two ducts in the Dining room have had the bottoms corroded out of them so they are leaking air into the crawlspace under the house 1 small hole was sealed, the other one is much larger but we sealed it the best we could.

    My choice would be to run new lines in the ceiling using felxible ductwork, and then cut off the floor vents and patch with 3/4 inch plywood.

    Anyone ever retrofit a mobile with ducts in the celing?>

    Thanks in advance.

  8. #8
    Join Date
    Sep 2007
    Location
    North Carolina
    Posts
    48
    If your supply is leaking and blowing air out side of the house then the home is under a negative pressure as compared to the outside. This will cause outside air to be pulled in from the path of least resistance (the biggist hole it can find) like leaking seals around windows or doors. Some mobile homes have a 4" or 5" duct in the furnace closet which lead directly up to a vent in the roof. With a leak on the supply side this would cause the system to pull very hot air down the duct an dump it right in on top of the evap coil. This would cause your pressures to be abnormally high.

    How are you planning to put duct in the cieling of a mobile home?
    I have changed out the duct in mobil homes before, but always under the home.

    I would not do anything else on the refrigeration side until you fix the air side.

    Then you would evaluate the performance of the system only after it has pulled down to 78 to 82 inside. A return temp of 88 is pretty high and would cause high pressures if outside temp was above 90.

    The pressures should come back into the proper range when the inside temp drops to around 78 to 80.

    Dont worry about the TEV. Your system has worked 10 years with out one.
    I hope you get a couple of more years out of it but most systems like this dont last more than about 10 or 12.

    It will hurt for a couple of days after they cash your check but you will not regret getting a new system if it is properly installed.

    The new Goodman units are not to bad but Trane is better.

    Fix your air leaks and look at it again.

  9. #9
    Join Date
    Sep 2007
    Posts
    23
    Krazy, thanks for the info, we sealed the holes, the return air tube above the evap was capped off when the A/C guys installed the coil 10 years ago, so that part is good.

    The unit is cooling and dropping the temp across the coil by about 20 degrees, it will just take some time to get the heat out.

    As far as the ducting goes, I was hoping to utilize the small tubes 2" diam with the high pressure evap unit, but running those ducts will be fun if not impossible for the installer.

    I guess that section of floor duct will just have to be replaced.

    Many Thanks

  10. #10
    Join Date
    Aug 2007
    Location
    MN
    Posts
    2,677
    1st make sure the cond fan rotation is proper and blade is same distance up the shaft as before, either situation would mess up airflow.
    I doubt you can even crawl up into the attic space of a doublewide. I cut an access in a buddies closet(dead center of the ceiling) there was no way in hell I was getting in there. we needed to mount a 2x8 to install a ceiling fan in his living room, ended up cutting a slot in the sheetrock and patching the ceiling there was about 15" max for me to try to squeeze into.
    You can't fix stupid

  11. #11
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,541
    I would make sure the fan is spinning in the right direction first. Then make sure the shroud is on and not knocked off if your unit came with one. Then make sure the blade isn't below the shroud. We put a Carrier air handler in place of an Intertherm a few years ago. We put it under the trailer, used the old closet bottom as the return ducted into the new air handler, the homeowner turned the top of the old furnace closet into a place to store towels, etc... It worked out pretty well. We had lots of room under the trailer to work.

  12. #12
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    WHOA WHOA! You said, " He started releasing some freon and asked for a water hose to wash the coil ouside". FIRE HIM!
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

  13. #13
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    Quote Originally Posted by yorkdude View Post
    You said, " He started releasing some freon and asked for a water hose to wash the coil ouside"
    and then he added freon back in, possible semihackish



    .

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