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Thread: Lineset size

  1. #1

    Lineset size

    I presently have a 12 year old heat pump Rheem 2 1/2 ton compressor outside with Rheem 3 ton air handler inside. When running it had insufficient capacity. The existing lineset is 3/4 and 3/8. It has been recommended that I replace the outside unit with a 3 1/2 ton R22 Amana SEER 13 unit using the existing lineset and later upgrade the inside unit when necessary. Will this work ?

  2. #2
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    How long is the lineset? Lineset size depends on length and size of unit. As long as it's not over 24 feet your good.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  3. #3
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    Need all model #'s for airhandler, coil and lineset length.
    Doesn't sound like any of it will be correct.
    Do you have enough ductwork for the size increase? Possible your issues are in the ductwork for the orig. equip. Throwing more condenser at the problem is likely not a cure.

  4. #4
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    sounds like another home being guessed at for the right size of equipment. airhandlers are pretty cheap compared to the outside unit, i would suggest replacing both at the same time. i am also not a big fan of crossbreeding equipment. the brand of equipment i use, not any of the above mentioned, will not honor any warrenties if i do use different brands toogether.

  5. #5
    Quote Originally Posted by captube View Post
    Need all model #'s for airhandler, coil and lineset length.
    Doesn't sound like any of it will be correct.
    Do you have enough ductwork for the size increase? Possible your issues are in the ductwork for the orig. equip. Throwing more condenser at the problem is likely not a cure.
    Lineset length is close to 50 feet. Ductwork is part of the issue. The house was built in 1962 and is typical cement block bungalow with low roof. No available crawl space in attic. Existing airhandler is Rheem RCHA-36A1AS17 - Replacement condenser would be Amana ASC13-0421A. I realize house will never be ideal but looking for compromise. The 2/12 ton unit was liveable but not able to pull house temperature down enough in Florida summers. Trying to get a quick fix.

  6. #6
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    IF you have 3 tons of supply and return duct, matching 3-ton equip. is likely as quick fix as you will get and have warranty on equip.
    3/4 X 3/8 @ 50' will work on 3 ton with slight capacity loss.
    Do not go 3 1/2 with existing set up, you will have more problems and less money.

  7. #7
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    Quote Originally Posted by salty7c View Post
    Lineset length is close to 50 feet. Ductwork is part of the issue. The house was built in 1962 and is typical cement block bungalow with low roof. No available crawl space in attic. Existing airhandler is Rheem RCHA-36A1AS17 - Replacement condenser would be Amana ASC13-0421A. I realize house will never be ideal but looking for compromise. The 2/12 ton unit was liveable but not able to pull house temperature down enough in Florida summers. Trying to get a quick fix.
    install a whole house dehumifier.
    12yearsold id upgrade inside/outside
    have your local co. due load calc.
    john m
    Last edited by jrbenny; 04-06-2008 at 08:34 PM. Reason: removed email address
    JLM

  8. #8
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    Exactly how many btuh's do you expect to get installing a 3 ton Amana unit on a 2.5 ton Rheem coil???? Yes, that's a 3 ton air handler with a 2.5 ton coil in it (a proper matched system). Does Amana tout the performance you'll get with a Rheem 10 seer coil?

    You may end up with less capacity than you have now.

  9. #9
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    Quote Originally Posted by captube View Post
    IF you have 3 tons of supply and return duct, matching 3-ton equip. is likely as quick fix as you will get and have warranty on equip.
    3/4 X 3/8 @ 50' will work on 3 ton with slight capacity loss.
    Do not go 3 1/2 with existing set up, you will have more problems and less money.
    According to amana(goodman)'s linset spec sheet (via book from unit I installed a week ago), 50 ft lineset on 3 ton+ must have 1 1/8th suction.

    Sounds like the whole deal is screwy. Tell um you want an amana ASH13036 outside with an AEPF364216AA air handler. Thats a 3 ton heat pump with 3 ton air handler. Forget saving the old rheem. I agree with doc, mismatching coils sucks.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  10. #10
    Join Date
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    Lancaster PA
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    68,064
    Your asking for trouble mis matching like that.
    If you want it to work right. Then it has to be installed right.
    Have a load calc done, and then a duct work evaluation done.
    Then find out what it will cost.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  11. #11
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    Quote Originally Posted by hvacvegas View Post
    According to amana(goodman)'s linset spec sheet (via book from unit I installed a week ago), 50 ft lineset on 3 ton+ must have 1 1/8th suction.

    Sounds like the whole deal is screwy. Tell um you want an amana ASH13036 outside with an AEPF364216AA air handler. Thats a 3 ton heat pump with 3 ton air handler. Forget saving the old rheem. I agree with doc, mismatching coils sucks.
    If you'll notice in that long line set guideline they give a capacity multiplier @ 50 ft the multiplier is .98 for 3/4" line and a 3 ton system and R-22 refrigerant.



    Quote Originally Posted by salty7c View Post
    I presently have a 12 year old heat pump Rheem 2 1/2 ton compressor outside with Rheem 3 ton air handler inside. When running it had insufficient capacity. The existing lineset is 3/4 and 3/8. It has been recommended that I replace the outside unit with a 3 1/2 ton R22 Amana SEER 13 unit using the existing lineset and later upgrade the inside unit when necessary. Will this work ?


    By the way to the OP don't mis-match listen to the others....plenty of documentation to prove it's more of a waste then a help.

  12. #12
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    Quote Originally Posted by salty7c View Post
    I presently have a 12 year old heat pump Rheem 2 1/2 ton compressor outside with Rheem 3 ton air handler inside. When running it had insufficient capacity. The existing lineset is 3/4 and 3/8. It has been recommended that I replace the outside unit with a 3 1/2 ton R22 Amana SEER 13 unit using the existing lineset and later upgrade the inside unit when necessary. Will this work ?
    I think that you might be pushing your luck with 3/4 3/8 lineset on a 3 1/2 unit unless the lineset is short. 7/8 3/8 would work alot better especially if you are going to replace the indoor unit at a later date, one less thing to worry about.

  13. #13
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    The capacity multiplier for 3/4" line on a 3 1/2 ton unit is .93 for 50 feet of line set and R-22 refrigerant. 42,000 btu system = 39060 btu's with a 3/4" line 50 foot and R-22 refrigerant. 7/8" line has a .97 multiplication factor for 50 foot line set and R-22 refrigerant or 40,740 btu's.

    1 1/8" lineset has a 1.00 multiplier for everything up to 75 feet and drops to .99 @ 100 ft.







    Still don't mis-match.

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