I am replacing my existing faucet plumbing with red / blue PEX all over the house. Everything that goes to the sink, dishwasher, washer, bathroom sink and so on will be color coded and installed correctly.

Although, I was pondering on changing my water heating system with PEX while I was at it. Of course, I would leave my baseboards with a copper pipe so that it gives off more heat. What I would like to do is to have quick-connects from the PEX to the copper, so that if ever I need to remove the baseboards (redoing flooring, walls, etc), I just disconnect the whole thing and pop out the baseboard.

PEX is better at keeping the heat in the pipe compared to copper so I would be losing less heat if I go from the boiler to the baseboard with PEX. Then I'd have copper inside the baseboard which would feed into the other PEX that would go to another baseboard...

Is this recommended in 2014? I feel like copper is old and out dated.

My boiler is powered by bi-energy electrical elements, which then gets pumped through the whole system with approximately 12-15 psi.

Will I eventually regret putting PEX? Should I keep going through this old house and fixing the copper whenever there's a leak?

3 Answers 3


I did this very thing (replaced copper with PEX for baseboard heating). But I did this because my copper had frozen and split in about 200 places.

So, if your copper is shot, I'd replace with PEX. But if the copper is fine, save the hassle!

But if you do decide to do it, some tips:

  • Sharkbite connectors are great and make it super easy to connect copper to PEX (at the baseboards)

  • Be sure to get oxygen barrier PEX. This is designed specifically for heating systems and has a metal liner inside to prevent air from permeating in.

  • pex is a pain for tight corners. You'll either need room for a gradual bend (they make elbow clamps for PEX to handle radiused corners) or you'll need to use elbow fittings for sharp corners (either those designed for the PEX you are using or, again, sharkbites--though sharkbites can get pricey)

  • I see. I've been using elbow fittings for the sharp corners and they work well. I prefer PEX over copper and will take your advice for sure with the Sharkbite connectors (baseboards to PEX).
    – Alex
    Sep 23, 2014 at 18:24
  • @hazardousglitch it doesn’t actually say that. They say it’s only for water, but they’re clearly rated for heating system temperatures. (The FAQ essentially says you can’t use it for gas or oil)
    – DA01
    Jan 2, 2019 at 6:38
  • I don't know about you but I wouldn't called water that's in my hydronic system potable with the various chemicals and oil that can be in it. After reading a product page, it does specificy hydronic systems as a use so it looks to be OK afterall which is good to know. Jan 2, 2019 at 12:46
  • @HazardousGlitch well, I'd be really worried if chemicals and oil were somehow getting into the hydronic heating system. It should only be potable water (unless someone is using gray water or something like that). I've only had experience with a few systems, but they were both hooked up directly to the potable/municipal water system.
    – DA01
    Jan 2, 2019 at 19:19
  • Of course you only add water ( or anti freeze ) but there is already other stuff in the system unless you did a good job of bleeding it out multiple times to get it all out from the start (which I've never seen done and will take who knows how much time and how many flushes). There is a reason the water is never clear when you bleed it out and you wouldn't ever think about drinking it. This is the reason I originally said SharkBite wasn't designed for it and their FAQ reinforced it but turns out it's OK for hydronic systems. Jan 2, 2019 at 20:02

How often does your heating system spring a leak? It's not particularly often in my (long) experience with closed-crcuit hot water heating systems - less than once per 20 years, I'd say, and usually with some outside cause. In general, it is a waste of money to remove/replace a system that's working. To address one of your "benefits" - where do you suppose the heat "lost" from your copper heating pipes goes? Unless the pipes are running on the outside of your house (which would be a bit unusual) it goes to heating your house. Absolutely nothing is gained by "saving" that (small amount of) heat "for the radiators." If the pipes are running outside the building, they should be insulated regardless of their material.

Quick connects are more likely to INCREASE the number of leaks you have over time .vs. leaving the copper pipes alone. Replacing a reliable soldered joint with a complex mechanical seal is not a direction that will benefit your leak statistics. Most people simply work around baseboard heat when redoing walls, floors, etc. and manage to get by just fine without "popping them out."

You need to use an oxygen barrier type PEX if your heating system is (as is typically the case) a closed circuit system. Copper pipes do that by default.

You may, or course, do what you like, but this appears to be a somewhat absurd project. There are good arguments for building a NEW system with PEX "in 2014" but really no good reason to rip out a copper system and replace it with PEX and copper.

  • I agree with most all of this, but one exception: the Sharkbite connectors--at least thus far--seem to be holding their own reliability-wise in the industry. I don't know that there's any evidence that they leak any more than soldered copper joints.
    – DA01
    Sep 23, 2014 at 17:42
  • I've been there for 2 months and already had about 3 leaks. The setup is piss-poor and that's why I want to change it. It's a hackjob and the copper pipes are not supported by anything other than by themselves. The weight of the water is probably what causes the leaks.
    – Alex
    Sep 23, 2014 at 18:22
  • You would also need a valve at each "pop out" location to make such a thing practical, another knock against that idea. Jan 1, 2019 at 23:13

There is one good reason to go to PEX, that is when you have high acidity water from your well -- a common situation in wooded areas. I get pinhole leaks in the copper pipes and have ruined a wall and a ceiling so far. You know you have this problem if you see greenish deposits in your tub, shower and sink.

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