CPVC in Hydronic System


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Old 04-26-05, 12:05 PM
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CPVC in Hydronic System

Hi folks,

I discovered that CPVC is for hot water (and cold) and PVC is only for cold water. Now, my hot water comes from the tankless coil in the oil furnace (boiler) and is therefore the same temperature as the hot water in the pipes for the baseboard heaters.

Since the hot water in the drinking water lines is the same temp as the hot water in the heating pipes, is it true that I could use CPVC in the heating loop in certain places?

I stand to gain several advantages: #1) It's very, very, very easy to work with and is flexible to a point; #2) It glues together in a few seconds vs. soldering and is foolproof (no leaks); #3) It's cheaper #4) since it's plastic, you'll get a certain ampount of insulation built-in.

I checked the rating of CPVC and it says at 180 degrees it's good for 100 psi and the heating system stays at about 20-25 max. and the system would be set for 180 degrees.

Anyone ever hear of this being done? If not, do you think it's safe to do?

If you have any thoughts, please tell me "why." I need to learn principles, not just memorize yes/no answers to a certain situation.

Thanks!!
 
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Old 04-26-05, 12:45 PM
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CPVC for hydronic

Don't do it. CPVC is rated for 180. That's true but your system can & likely will at some point in time go over 180. CPVC can get very brittle & snap. You don't want to be hit with 180+ water. Trust me, been there, done that & don't want to do it again. CPVC can be used for domestic hot water if you keep it at least 2 feet from the boiler. Some areas require more distance. Personally, I don't like to see CPVC used for domestic from a tankless untill a couple of feet beyond a tempering valve. I've never used it, except for in/under floor radiant, but some PEX pipe can be used for hydronic heat. If you decide to use PEX, make sure you get one with an oxygen barrier. Oxygen is a boiler killer. Hope this answers your question.
 
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Old 04-26-05, 02:35 PM
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OK, thanks.

I have looked up info about PEX and I'm very excited on how flexible it is; I'd love to use it.

However, I cannot find info on connecting it with baseboard water radiant heaters. Everything I find is about in-floor radiant.

So, I need to know: what fittings do I use to go from PEX to copper. Actually, that's all I'd need to know since I'd sweat 90 degree elbows down into the floor then change to PEX under the joists to the next baseboard heater.

Does anyone have suggestions on where I could get that info? Call a PEX supplier perhaps?

Thanks!
 
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Old 04-26-05, 03:16 PM
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PEX to copper

I would think you would use a pipe thread adaptor on the copper & one on the PEX but check some of the manufacturer's web sites. They should tell you. One more thing you have to be careful of with PEX is it expands a good bit when hot. Don't fasten it too tight to the floor joists.
 
 

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