PEX for Hydronic Head advice (fittings, insulating, route)
We live in a 1 1/2 story house with baseboard heat fed via 3/4″ copper. Our upstairs is one large room with a heating circuit where the copper was run through the outside attic spaces into a baseboard on each end of the house. We’re in MN and have had a cold spell (no surpise) the upstairs circuit froze and in the process of thawing I discovered we had a burst pipe. We brought in a contractor who then found 6 more leaks. I then fired up the system and found yet more leaks. So, at this point, we figure the system is shot. The contractor suggested we switch to PEX as it’s a little more forgiving. In addition, beef up the insulation around the pipes. Given we’re broke, and I’m a sucker for learning something new and buying new tools, I want to tackle the PEX myself. I plan on fishing the pex up from the basement into the 2nd floor attic space, along the outside of the knee wall and then into the first baseboard. From that baseboard, I’ll run it through the other attic space behind the knee wall along the length of the house to the other baseboard, then from the other baseboard back into the first attic space and then back down to the basement (following the current path of the copper.) So…questions… Fittings? Any strong feelings towards one system or the other? Looks like I can go with the copper crimps, stainless crimps, expanded fittings (where the pex is expanded, then inserted), or one of the no-tool systems (looks like Watts’ system or the SharkBites). Any of those particularly suited for hydronic heat or, like the marketing literature says “all are suitable”? As for the number of fittings, I’m trying to get away with just six. Copper to PEX in the basement (2 each for in/out), pex to copper + Copper to PEX (2 each for each baseboard). So the fittings will primarily be PEX to Copper. However, in the transition from crawl space to interior, I’m not positive that I can make the transition purely with PEX so may also end up needing 4-6 90 degree fittings. As for insulation, the old copper was simply run along the outer part of the knee wall where 1-2 batts of fiberglass were layed on top. Where the pipe had to cross access panel openings, it was just wrapped with the cheap black foam pipe insulation. My guess is that the batts shifted and were able to open up enough of an air gap that the cold air just poured in freezing the system up. With the pex, I could do a few things: 1) run it in the same space, but use more heavy duty pipe wrap (the thicker foam or fiberglass tape). 2) Pull down all fiberglass, drill through all the knee wall studs, run pex through that, then wrap, then put the batts back up. 3) Decide that they simply shouldn’t NOT be in the attic space to begin with and begin figuring out clever ways to run the pex through the interior of the space (which would be a lot of work and $$, but if it’s necessary, so be it). Finally, what’s the color coding for on PEX? At the big-box the guy told me that the blue is better as it’s less porous to air/oxygen. True? Reading the specs, it seemed identical to the Red leading me to believe they were just color coded for convenience of labeling hot and cold lines. Is there a particular brand and/or type of PEX I should be looking for that would be best for this particular application?
Replies
I used Uponor PEX products for domestic and hydronic systems in my home, strongly recommend them over other "big box" brands.
Not sure how to best deal with your attic issue, I would assume that the best route would be to keep the piping as close to the conditioned heat source side and add more insulation.
Red - blue - white colors have NOTHING to do with O2 transmission. hePEX is barrier tubing and is NOT POTABLE, standard PEX-a or PEX-b is for domestic water.
Find a "real" plumbing supply store and use whatever professional grade brand they stock and represent. Or pexsupply.com
Looks like pexsupply.com does a lot of brands:
hePEX, ThermaPEX, HydroPEX, ViegaPEX, Mr. PEX-al-PEX, FostaPEX Tubing, Onix
Looks like my local supply house carries ViegaPex as well as SharkBite connectors. The SharkBite connectors are appealing...as I wouldn't have to use the torch on anything.
I'd be careful using
I'd be careful using ViagraPex. It's really stiff. Hard to work with.
(tee hee)
I'm leaning towards FostaPex,
I'm leaning towards FostaPex, which my local plumbing supply house carries. I only need about 100' of it, so might as well go for the good stuff.
Has anyone used FostaPex? If so:
- do you know the smallest corner radius it can support?
- have you used it with SharkBite connectors?
I have Wirsbo (Uponor) supplying fin tube convectors with the expander type connections. No problems what so ever.
I'd try to keep the supply out of any unconditioned space. Sure the PEX is more forgiving but it can still rupture.
Any way of feeding the second radiator from the basement instead of from the first?
If you have to still keep it in the knee wall, maybe just one. Come back from the second radiator along the same path you used to supply it.
Uponor's system looks really
Uponor's system looks really nice. And they're local here in MN.
Alas, they seem to have absolutely no interest in selling to consumers. So, they're not getting a sale from me.
Silly how hard it is to give some companies money.