Ask Me Help Desk - PVC vs CPVC Solar Water Heater

I constructed a solar water pre heater for my water heater and after a day the many of the fittings started to leak. The local HD said regular PVC probably would be OK, but apparently it was not. Little did we know the water got up to 140 deg F inside the PVC, which I had painted black. I am wondering if CPVC will work - CPVC is supposed to be rated at 180 deg F and I just have normal household water pressure. Back to the drawing board. Solar Pre Water Heater

Hey.. great idea! Painting was critical to success!

Yeah... PVC pipe is rated to not exceed 140 degrees F so seems you got some bad info... but let me ask.. did you PRIME and cement your fittings and pipe? This can make a HUGE difference in joints holding...

You will definitely be better off with CPVC pipe/fittings as it is rated to not exceed 180 degrees F. Be sure to use the correct primer and cement or you will be back here unhappy again... ok? Just be sure that whatever type of cpvc you choose, you choose the right primer (if needed) and cement.

Check out this link below:

CPVC Products - Frequently Asked Questions

Unfortunately, you will need to paint with a good quality latex paint to reduce harm from UV rays... ;)

Let us know if need more information... good luck with it! Looks like a great setup! Our friend HKSTROUD will love this... :)

MARK

Thanks for the response - I actually looked at the website you suggested today.
I did prime every joint with the purple primer and thought I had glued them well. Let them set for more than 24 hrs AND I plumbed my entire house with PVC and CPVC and never had a leak. Now I make this thing and it had about 15 or more seeps and leaks and I can only attribute it to the use of PVC and it's components. Will do a row in CPVC and see how that goes. I think the temp probably exceeded 140 deg and it just failed in many places. Never saw anything like that. Oh I used brand new glue and primer. Will keep you posted. Thanks for your help.

Glad to help anytime Jack...

Thanks for updating me... good luck, really neat idea here!

PS... what new cement and primer did you use? New stuff on pvc.. or new stuff on cpvc?. just curious?

Thanks... MARK

What I meant was, I used fresh, new primer and Oatley Gold PVC cement. I just think the heat got it. The glue softened and then the joints separated. 140 deg F + did it in. Thanks again - back to the HD for CPVC pipe, primer and glue. Will just do one row and give it a test before investing another $100. Guess I can use the 3/4 for a lawn sprinkler - ha. PS - The PVC and CPVC in my house has held up since installation in 1982 - 26 years! No leaks, no problems. House H20 is about 120 deg F.
Cheers
JackTheBearTexas

Well I took out the PVC and replaced it with CPVC. Let all joints cure overnite and all looks OK. Just used the same box and about 100 ft of CPVC. Of course I did prime and use CPVC cement. Water temp at a trickle - 130 deg. Have placed glass over the top of the enclosure, but sun going down - Was up to 130. Will check tomorrow. If it holds under pressure, will purchase 2 or 3 hundred feet more and give that a try. Oh, I did paint it flat black. I hope it works - the water temp going into the water heater is higher than the normal hot water temp. Should save a little gas if we remember to use hot water appliances during the day time. Thanks for your help - will update if all goes OK. Cheers JackTheBear

Quote:

Originally Posted by JackTheBearTexa

I constructed a solar water pre heater for my water heater and after a day the many of the fittings started to leak. The local HD said regular PVC probably would be ok, but apparently it was not. Little did we know the water got up to 140 deg F inside the PVC, which I had painted black. I am wondering if CPVC will work - CPVC is supposed to be rated at 180 deg F and I just have normal household water pressure. Back to the drawing board. Solar Pre Water Heater

Finally got the solar heater running and it is putting out really hot water - Check out the finished product (well I have to spiff it up some) at Free Hot Water - Really Hot Water!
Thanks for all your help - I have to write on the "blackboard" one hundred time "PVC for cold water, CPVC for hot water"

Too late now but I would have considered ridgid copper or even flexible copper tubing. It convects heat much better/faster than CPVC. You must live in a place where freezing is not going to be an issue, right?

I used PVC for my water heater and so far have had good results. I did a couple things differently. My heater was a thermosyphon under very low pressure. This meant that the water in it was constantly circulating. I also insulted all of the PVC connections so that they would be protected somewhat from the heat. To check out my design just follow this link:
http://solarhotwater.teaters.com

Quote:

Originally Posted by jaketeater

I used PVC for my water heater and so far have had good results. I did a couple things differently. My heater was a thermosyphon under very low pressure. This meant that the water in it was constantly circulating. I also insulted all of the PVC connections so that they would be protected somewhat from the heat. To check out my design just follow this link:
http://solarhotwater.teaters.com

Hello in Brazil. I spent 3 weeks in Brazil last November and loved it there, especially the people. I didn't see that shower head as it is presented in your video but I saw similar thing in Perú.

I like what you've done. But just wonder why you didn't use copper for the coil. You cannot get maximum heat out of PVC. Also, I would suggest to put sheet of galvanized sheet metal on the bottom of the solar box, than manifold painted black and cover it with glass top. It works magic even in winter time...

I built it this way for my pool. I never used heater afterwards.

But overall, I like your attitude. We need people like you ! Not in Brazil - but here in States ! :D

Best regards ! Milo

I priced copper - and its just too expensive here in Brazil. The whole thing cost less than $500 (solar collector, water tank, glass etc). With the price of copper I would have spent more that $500 on just the copper.

The galvanized sheet metal - Yeah, I wish I would have done that. The bottom is plywood, then 1 inch of styrofoam, then black plastic. The styrofoam is already warping and the black plastic is tearing. Oh well, live and learn. That's what this heater was for anyway, we plan to put one on the orphanage I work at, this was solar heater 1.0 beta.