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Must I use copper?

josephny
josephny Member Posts: 270
in THE MAIN WALL

I suspect this is a very (very) basic question, but I'm a complete newbie.

Must we use any copper in a closed radiant system?

Why not pipe exclusively in pex (3/4" or 1") from the boiler through the controls/pumps/valves/manifold/etc.?

Thanks!

Comments

  • PC7060
    PC7060 Member Posts: 1,158
    edited January 2021
    Pex is commonly used in hydronic systems; it MUST have integrated oxygen barrier. For example, Pex-Al-Pex.   There are others as well. 
  • Zman
    Zman Member Posts: 7,569
    Any pex with an O2 barrier is acceptable and widely used.
    Many still prefer copper for the near boiler piping. It is easier to support and looks more professional. It can also handle the hot temps sometimes seen near the boiler better than pex will.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    HomerJSmith
  • josephny
    josephny Member Posts: 270

    Thanks guys!

    So, as long as I'm using hePex (for example), and not physically/mechanically supporting the components with the piping, and don't object to the aethestics of it, it's totally fine using 100% pex?
  • Zman
    Zman Member Posts: 7,569
    I sure don't know of a reason you cannot. What type of boiler is it? What temp are you planning on running. You should be aware that the inside diameter of the pex is quite a bit smaller than copper. You may have to upsize it to get proper flows.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Keep in mind that pex will expand/grow when its heated. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    mattmia2fenkel
  • pecmsg
    pecmsg Member Posts: 4,843
    If you want it neat and clean then all piping near the heater needs to be copper. The supply's and returns are then pex
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    The reason copper is used at the boiler is because of the higher temperatures developed within 5 ft. of the appliance. It's fine to connect pex after 5-6 ft. (barrier pex)
  • mattmia2
    mattmia2 Member Posts: 9,630
    Also clearance to the vent of conventional appliances and cost of the fittings to make a manifold and getting things heading in the right direction near the boiler.
  • josephny
    josephny Member Posts: 270
    Thank you all so very much! I'm learning so much, so quickly from all you very generous and experienced people.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,828
    edited January 2021
    I have suggested this to others with similar ideas. If you don't like to solder, rent a ProPress tool. If none are available for rent then go to eBay or craigslist and get a used one. After the project is done, then sell it on craigslist or eBay. Pro press fittings cost a little more but with good planning, you can use a combination of black iron and copper to support your attachments like; air separator, circulator, expansion tank, zone valves, and the like.

    Once you are far enough away from the boiler, and can neatly attach the PEX to a manifold, or support it on a wall or framing, then you will have a good working system that looks good too.

    After you are unable to work on it yourself, some professionals will need to make repairs and if you are not around to assist/instruct the guy, your loved ones will not be happy with the recommendations of the Pro.

    If I walked into something like this I would recommend an expensive repipe or a complete new system.



    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    BillyOjosephny
  • JUGHNE
    JUGHNE Member Posts: 11,060
    If the boiler allows it, I use a lot of black pipe fittings and nipples.
    I use threaded components and a lot of unions.
    Black fittings and especially unions are less than copper fittings.
    josephny
  • hot_rod
    hot_rod Member Posts: 22,120
    With larger bore pex, 1-1/4" for example the fittings get expensive and the crimp tool is quite large. Look at the flow rates 1-1/4 pex may be needed to substitute for 1" copper.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2
  • josephny
    josephny Member Posts: 270
    EdtheHeaterMan: I went with a manual press (2, actually: Hydraulic on Amazon for $100 and manual on Supplyhouse for $180). Interestingly, both only go up to 1" copper and my new system needs 1-1/4" piping, so I'll be sweating some fittings (but not many). That's a great point about neatness -- saves immeasurable amounts of time later. Thank you!

    hot_rod: I looked around and noticed that the Uponor EP manifold uses 1-1/4" connections while the Uponor Stainless manifold uses 1", so I asked my supplier (who is also designing my system). He explained that the heating capacity (BTU carrying capability?) is around twice the amount for the 1-1/4" pipe and because I have plans to add zones later, he recommends staying with the 1-1/4" and sweating the handful of connections. Thank you!

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