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  1. #1
    Join Date
    Sep 2011
    Location
    Central Florida
    Posts
    3

    Adding HRU to R-22 system. All new refrigerant is required?

    I am adding an HRU to my 3.5 ton R-22 Trane system. It involves adding about 5 feet of additional line to the superheat line coming out of the compressor.

    An HVAC guy I kind of know (friend of a friend) told me that the only way to do it is to vacuum down the system, then replace all of the R-22 with new refrigerant, which will add about $ to the cost of the service. But he works out of his own small truck and I got the feeling that it's not the kind of work he usually does.

    So, do I have to replace all of the R-22 refrigerant? The system is only about 6 years old and runs like a champ. I just need a second opinion before spending more
    Last edited by beenthere; 09-14-2011 at 11:35 PM. Reason: price

  2. #2
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
    Posts
    1,781
    Find a professional who knows what their doing, and has worked with HRU's before to do the work.

  3. #3
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,670
    First off, please remove pricing from your post, that is not permitted here.

    He is partly right.

    If I'm understanding you correctly, you are adding a device to recover some of the heat removed by your AC unit. A water heater, perhaps?

    If this is the case, the refrigerant will need to be removed from the system, temporarily stored in a cylinder and then reinstalled into the system.

    Additional refrigerant will be required as you are adding volume to the piping system.

  4. #4
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,060
    Would that be a clean, evacuated recovery tank?

  5. #5
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,535

    Warranty?

    Aside from letting your "buddy" put this HRU unit on your system, you might consider any warranty problems this addition could cause you. Done improperly, it could and very well might cause some severe damage and then the dealer may not warranty your system. Crazi is right, better safe than sorry.....have an insured, and licensed pro install it!!!

  6. #6
    Join Date
    Sep 2011
    Location
    Central Florida
    Posts
    3
    I see no way to edit the post and I took the "no pricing" rule to mean no absolute pricing. It just part of the explanation for why I am looking for a second opinion. He mentioned off hand that it's probably about 8 lbs of R-22.

    Yes, it's an HRU for making hot water. The docs for the HRU calculate about 3-5 ounces of additional R22 will be needed for my line length.

    I am assuming that if you are going to vacuum the system down, there would be a tank to store the R22 in, even if it's not going to go back into my system. As you would have to pump it to a pretty hard vacuum to start, and it would only be used for R22, just how clean is "clean"?

    I'm only semi-knowledgeable about automotive AC and in those systems removing all of the refrigerant, opening the system, repairing it, pumping a vacuum and returning the same refrigerant, plus some if needed for top-up, is pretty standard fare. That's why it threw me for a loop when he mentioned that he couldn't do the same for my home system.

    Is the pricing roughly equivalent either way: recovering about 8 lbs of R22 or just putting in new R22? I guess that's what I really wanted to know.

  7. #7
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,670
    Quote Originally Posted by Chubber View Post

    I'm only semi-knowledgeable about automotive AC and in those systems removing all of the refrigerant, opening the system, repairing it, pumping a vacuum and returning the same refrigerant, plus some if needed for top-up, is pretty standard fare. That's why it threw me for a loop when he mentioned that he couldn't do the same for my home system.
    Ask him to explain to you WHY he cannot use the R-22 and come back and tell us.

    I could use a good laugh.

  8. #8
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    6,048
    If it was mine I would use the new freon also.

    You are gambling with introducing contaminates any other way.

    But- If you specifically asked me to re-use.

    Yes its possible.

  9. #9
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
    Posts
    1,781
    Quote Originally Posted by SBKold View Post
    If it was mine I would use the new freon also.

    You are gambling with introducing contaminates any other way.

    But- If you specifically asked me to re-use.

    Yes its possible.
    Not if you do it right.

  10. #10
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    6,048
    Quote Originally Posted by CraziFuzzy View Post
    Not if you do it right.
    Im guessing you mean by starting with a clean, vacuumed cylinder and purge machine well.

  11. #11
    Join Date
    Sep 2011
    Location
    Central Florida
    Posts
    3
    Thanks everyone, I will go back and find out more from him. I will probably also get a second opinion from another company that I was referred.

    What's sad is that I DID call two other local larger companies (franchises) from my chamber of commerce and both of them had never heard of HRUs and flatly denied to do anything at all to the outside unit that wasn't factory original. Maybe it's a liability issue for them or maybe they are just not used to doing anything differently, but it surprised me. But I like to use local guys whenever I can anyway, as I am also a small business owner.

    It's 6 or 7 years old now, so there aren't any warranty issues. But if I have to have the system apart, are there any other parts I may want to consider replacing at the same time?

  12. #12
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,670
    Quote Originally Posted by SBKold View Post
    Im guessing you mean by starting with a clean, vacuumed cylinder and purge machine well.
    Not all that hard to do.

    I find the reluctance of many residential contractors to re-use refrigerant confusing. I have re-used refrigerant many, many times without a problem.

  13. #13
    Join Date
    Jun 2008
    Location
    NW Florida
    Posts
    707
    I used to install them years ago. But the higher efficiency units 16 seer and higher would cause problems until water heated up. I have not installed any in probably 10 years or so. The quality of the hru's went down. The newer ones would not produce enough heat to even be worth while. Then good luck finding parts for them. Usually the company that made them where either out of business or moved to China.

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