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  1. #1
    Join Date
    Jun 2006
    Posts
    96

    Replacing R22 System with R410A - New Lines??

    We will be replacing our 4 year old R22 AC system with a new properly sized system (total tonnage is going down). We currently have 2 separate systems (ductwork, outside units and air movers) rated at 3 Ton and variable speed fan units servicing our 3,200 sq. ft house.

    The contractor will be replacing the outside units with R410A units, sized correctly. What else do I need to change? Do I have to change the coil units in the air handlers? Can I keep the same coolant lines or do they have to be replaced as well?

    Thanks for your advice.

  2. #2
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658
    Just curious...Why are you replacing a 4yr old system??? I think you might get a few more years out of it.

    But if you ar egoing to redo it ALL.....all is the key word.....Go ahead and get new line sets.
    You're only as good as your customer will allow you to be.........If they want junk, sell them junk, but make your junk look neat!!!

  3. #3
    Join Date
    May 2011
    Location
    tallahassee,fl
    Posts
    380
    Yes, please elaborate on why 4 year old systems are being replaced. Size reduction, curious. Explain

  4. #4
    Join Date
    Feb 2009
    Location
    Mount Vernon TX (East Texas)
    Posts
    15
    If they are the right side you dont have to change the lineset.

  5. #5
    Join Date
    Jun 2006
    Posts
    96
    We have a 3,200 sq. ft. ranch style home near North Dakota. The house has radiant heat so we elected to install 2 sets of ductwork in the attic (all new). The wholesaler did teh manual J (they say) for the contractor and specified 2 x 3 ton Rheem units. We used variable speed motors in our 2 air movers. All of this is controlled with Tekmar control systems to integrate auto heat/cooling with our Weil McLain modulating boiler.

    The problem is the AC system cycles endlessly (15 minutes off 5 - 10 minutes on) unless it is 85F+ and we have visitors (ie extra bodies) in the house, In the shoulder season and in the evenings it is cold, and clammy in the house and the RH is usually about 60 - 65%.

    The wholesaler has gone over the numbers and finally agreed that they oversized the installation for the contractor and will be making the problem right. They are going to start the calculations from scratch and wil be downsizing the compressor units. I'd like them to go with a 2 stage system unless there is a reason I should stay away from them.

    I'd also like to make sure we have properly matched air handlers as well as evaporator coils and coolant/suction lines. I don't want to change one part of the system if the other parts will cause it to not operate as the manufacturer designed it to.

    So, do I need new stuff (air handler, coil and lines) or will they be able to reuse that stuff after evacuating the R22 coolant?

    Thanks,

    kayjh

    PS, I'd prefer to have everything new, but if they are able to make the argument that some of the stuff is good, I'd like to know they just aren't trying to cut corners again.

  6. #6
    Join Date
    May 2011
    Location
    tallahassee,fl
    Posts
    380
    Get them to provide ari numbers. If they can than its a matched system. If not than its a no go. Line sets are fine if they are the right size. 2 stage units are not bad but over rated in my opinoin due to cost. Go 2 stage if money is not an issue.

  7. #7
    Join Date
    Jun 2006
    Posts
    96
    Quote Originally Posted by nismo1 View Post
    Get them to provide ari numbers. If they can than its a matched system. If not than its a no go. Line sets are fine if they are the right size. 2 stage units are not bad but over rated in my opinoin due to cost. Go 2 stage if money is not an issue.
    Money is always an issue, but after what we've been through over the last 4 years, we have to consider comfort too. If a 2 stage system will keep the humidity down better and will provide longer run times with less "stale" air feel, then we would put in 2 stage.

    Does anyone know what the cost difference is (percentage between 2 stage and 1 stage) with the same tonnage?

  8. #8
    Join Date
    Oct 2002
    Location
    Illinois
    Posts
    132
    You cannot mix R22 and 410A. IF you are going to switch to 410 then you need to replace everything.

  9. #9
    Join Date
    Feb 2010
    Location
    Ohio
    Posts
    562
    R-22 oil is all through the existing lineset! If I remember correctly r-22 uses PAG oil while r-410a uses POE oil. The oils do not mix or work well together. However, if you must, you can flush the lineset to get the old oil out if it is immediately chased with a strong long blast of nitrogen. If the lineset is flushed, the tech needs to use enough that it will get a lot of liquid through there not gas, to properly flush the system. Also, it is crucial that the tech perform a triple evac on the lineset. It would be safer to replace the lineset. If it isn't flushed properly, you may be buying a new compressor a few months or years down the line (no pun intended).

  10. #10
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,615
    if they are the right size blow them out with nitrogen and reuse them no flush needed

  11. #11
    Join Date
    Feb 2010
    Location
    Ohio
    Posts
    562
    Quote Originally Posted by catmanacman View Post
    if they are the right size blow them out with nitrogen and reuse them no flush needed
    What?!? Not true, unless you want to kill your compressor.

  12. #12
    Join Date
    Jun 2006
    Posts
    96
    Thanks for your replies. The HVAC company has come back with an outside consulting firm. They confirmed that we have way too much cooling capacity @ 6 tons and recommend 1.5T for the bedroom unit and 2.5T for the LR/DR/Kitchen/entry/family room area. The original contractor (who will be fixing this mess) says that the wholesale distributor confiirms after the fact that his Manual J showed a 4.2 T requirement for our home. The current 3 T system for our Bedroom has 9 supplies, but 2 service the kitchen as there would have been too few supplies from the bedroom unit without it being set up this way. That will be corrected once the unit is replaced. What a mess! The question is why the wholesaler sold the contractor 2 X - 3T units instead of the right size units? Maybe to get rid of stock, maybe to charge more for more expensive equipment. Who knows.??

    Anyway, things are going to br replaced in the next few weeks with new Rheem equipment. I'll be installing 2 stage equipment and would also like to use matching Rheem air handlers and condenser (evaporator coil, is that the correct term?). The ductwork in our attic is laid horizontally along with the air handlers and the contractor need to check to see if Rheem makes an evaporator unit that will work in this orientation, does anyone know if Rheem does?

    Finally, now that we know the new units will be 1.5T and 2.5T, can we use the same lines or do we need new ones?

    Thanks,

    Kayjh

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,770
    First, no one makes 2 stage in half ton sizes. So you would have to use a 2 ton and a 3 ton(or a 2 ton for teh 2.5 ton area, which could be too small). Yes you can reuse the line sets if they are the right size, best to flush/purge them out with nitrogen. And Rheem does make evap coils for horizontal installation.
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