challenging pvc problem

scrappy57February 5, 2013

I'm going to build a 1000 gallon spa outside my slab-on-grade house. My original intent was to heat the spa with the 130,000 Btu/hr output high efficiency hot water heater augmented with solar panels on the roof. The "boiler room" is in the back corner of the house and my heating contractor/spa specialist POSER who didn't have a clue what he was doing placed a 4" pvc chase under the slab to the spa location 80' away with only a pair of Rehau Pex (only 13/16" inside diameter) to heat the spa. The slab is poured, the house is built. The spa is the last step before I'm finished. Once I excavate for the spa I'll yank the undersized Pex pair out and replace it with schedule 40.

But the largest suction/returns schedule 40 pipe I can fit inside the 4" chase is two 1/5" diameter pipes ' and they only fit if I use "repair couplings" aka "flush inside slip couplings" (they're the same outside diameter as the 1/5" schedule 40 pipes and made so they have 2 street ends or spigot ends [2 ways to say the same thing]. They reduce the ID of the pipe at the connection, so I'll lose some flow there, but as I'll only need 3 pairs of them to get to the boiler room and back, it shouldn't be too bad.
My big problem is this: I can't find any made as elbows. They're all straight. I've tried plastic oddities, spears, nibco, and midland and nobody knows where I might find 45 degree elbows made that way. It'll take 2 pairs of 1.5" 45 degree elbows to get thru the pair of 4" 45's that I created the sweeping elbow with that gets me from under the slab to above it in the boiler room.

The only solutions I've come up with are heat bending some sections to try creating the shape I need, then reaching them into the 4" pvc from above the slab and gluing them to some repair couplings that I'll have prepped on the ends of the 1.5" pipes that I've stuck thru from 65' away outside. It's either that, or I have to take out a section of 4.5" slab, cut off the 4" sweeping turn, poke the pair of 1/5" pipes thru, use conventional fittings to get back above the slab, then sleeve and bush them to protect them from being solidly poured in the slab. Does anybody have a better idea?

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PVC for hot water is not good. Not permitted by any code. Not good choice even if there was no code.

    Bookmark   February 6, 2013 at 6:21AM
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hey bus, pvc is ALWAYS used is spas and heated pools. Water temps into the lines are limited to about 110 degrees and pvc at low pressure is rated to 140. It's the industry standard.

    Bookmark   February 6, 2013 at 9:13AM
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Heated pools & Spas are supplied from the house potable water distribution system and code prohibits using PVC in the potable water distribution system.

The permissible options for this application are continuos roll copper pipe, (types K,L or M) PEX & PEX-AL-PEX

    Bookmark   February 6, 2013 at 10:18AM
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Okay now THAT's a new one for my so-called "knowledge base"! I completely admit inexperience here. If this is the case, why do all the systems I'm seeing in all the forums show pvc?
There's an argument about the issue here that i intend to study:

    Bookmark   February 6, 2013 at 11:32AM
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The tub and it's circulating pipes are not, by definition, part of the premises supply system. Neither is the the piping from the meter to the building. But inside the building, PVC is not permissible for the supply. Piping bringing water to the tub is supply. Most codes start with a section of definitions which may differ from Webster's.

    Bookmark   February 6, 2013 at 3:37PM
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Hmm, you've led me to some interesting reading here:
Thanks for the head's up; I'd hate to violate the code and have to go back and change something. Before I got into all this, I'd assumed PVC couldn't be used because it's not "hot water pipe" like CPVC. Then I started seeing all the PVC in the pool and spa forums. Big expensive heaters all piped with PVC (but OUTSIDE). I'd better be careful what assumptions I make!
After the fiasco with the crooked contractor and lawsuit, the local building inspector told me to leave him out of future contact and continue working on my original building permit. I think he's afraid that since he approved the installation that I eventually identified 102 code violations in, he might get into trouble here. So I've left him out of the loop and at this point don't want any local input. We're so rural, we have one inspector for the whole house. No plumbing, electrical, framing, etc. and there's just no way they can know everything. And they really don't want to. As far as you know, do you think CPVC would meet code to connect to my heat exchanger for the spa outside?

    Bookmark   February 6, 2013 at 4:30PM
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CPVC has the same problem as PVC in that it expands and contracts with changes in temperature-- more than any other piping materials that come to mind at the moment. If the stuff is constrained in any way- like wedged between elbows in a larger pipe-- it may be noisy as it moves and may eventually break due to the stress. Hot water supply piping undergoes the greatest range of temperatures of any piping in the house. Go back and look at the suggestions of lazypup.
If you use CPVC-- not my first choice for your job--get the Flowgard Gold-- much better than the no-name pipe.

    Bookmark   February 6, 2013 at 5:04PM
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Thanks guys, this is sure a humbling experience cuz I sure thot I knew what I was talking about. I intend doing a salt water chlorine generator, so I figured copper was out (but now I'm getting search results for copper pipe and saltwater spas). I phoned a PEX rep last month and he said he thought it was probably ok to use PEX for my application, but that he'd never heard of anyone doing it. PEX-AL-PEX is a new word for me so I'd better go study up. I'm seeing search results about that not expanding much, so you guy are really straightening me out. It sure pays to ask some experts! Thanks for your patience with me!
Man, I always WANTED to be smart!
scrappy out

    Bookmark   February 6, 2013 at 5:15PM
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okay gang, here's what has come up. Copper can't be used in a salt water spa (I didn't mention the salt before, so suggesting copper was a valid suggestion) and PVC is BANNED for use in pool because chlorine levels normal for pools eat it up. PVC piped thru a HE is not part of the distribution piping of a house, so is legal and is the industry standard - at least in the Southeast US. At the 12 to 15 psi normal to spa piping and the limit of 110 degree water, PVC is the norm, tho I don't see why I wouldn't use CPVC for my own system just to make it stronger.
So if I can't make my inside slip coupling idea work, I'm going to cut thru the slab and use standard fittings in order to size up to 1.5" PVC or CPVC.
thank you all for your input.
scrappy out

    Bookmark   February 8, 2013 at 3:04PM
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If you could twin or triple the pex, perhaps that would be better? It's pretty tough.

    Bookmark   February 8, 2013 at 11:29PM
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I totally blew it in my last post. It's PEX that is BANNED because pool and spa chlorine levels eat it up, not PVC!!!
PVC is the industry standard! Sorry, my bad

    Bookmark   February 9, 2013 at 10:05AM
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