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Replacing Original 100 yr old Galvanized with Pex-Al-Pex

ajgould124 Member Posts: 2
The title says it all, i'll be replacing Original 100 yr old Galvanized with Pex-Al-Pex on a hot water boiler (pump feed).  I was going to use 1 in copper but i'm opting for the Pex for the cost savings and installation. 

I'll be replacing all the exposed galvanized lines in the basement and connecting the 1" Pex to the exising lines in the walls. 


A couple pointed questions:

1. Does this sounds ok?  After reading a lot it seems like an accepted application

2. Is 1" ok or would 3/4" be better?  There are a few areas where the previous homeowners replaced with 1" copper and our house heats just fine right now.  (Ballpark here, not exact)

3. What tools do I need to accomplish this job using the Pex-Al-Pex?  Reamer, chamfering, manual press, bending tool

Thanks experts!

4. Should I be installing a manifold in the system or could that throw things off with the flow?  I'd like to avoid it but if the benefits are worth it I'll take the time to put it in.


  • jumper
    jumper Member Posts: 1,988
    why ?

    Why replace only some? Put another way, if you're leaving the old pipes behind the wall, what will change after you replace the exposed pipes ?
  • ajgould124
    ajgould124 Member Posts: 2
    Finishing basment

    Finishing the basement...need the old pipes out of the way.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    PEX AL PEX is fine...

    You have to size the pies to the connected loads. You need to buy Dans book EDR so you will know the size of the emitters. You can do a manifold if you want. Or you can do a long running main with individual branches to the radiators. I'd also recommend you do non electric TRV's at the same time to optimize efficient operation.

    If you use Watts PAP, you won't need many special tools, other than cutters and chamfering tools.

    You have some homework to do before you grab the sawzall.


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