PVC pipe from Spa Heater melted - why?

[CountyBumkin]

I was out spraying the weeds around my pool pad and I noticed something strange - the PVC pipe from my Spa Heater looks to be melted.
This Heater was just installed (self install) at the beginning of the year and has only been run twice (setup and testing).

I don't see anything in the manual that would indicate my pipes are too close to the heater. I could move the heater to increase the space between pipes and heater but that would mean having gas company out and redo the gas line.

Maybe I need to switch to CPVC from header to where pipes enter ground.

Maybe that deformed pipe is not schedule 40 (I got a couple of pre-cut 2" pieces from the rack at Lowes where it was listed as "Schedule40 pipe". But the pipe is marked "DWV" (Drain-Waste-Vent) which I always thought was thinner than S40 - so I specifically asked the store manger to confirm - and he said it is schedule 40. Or, possibly the deformed pipe is something else that someone just tossed in the bin with the S40 pipe. I don't know.

Any ideas? I can't think of anything else that would cause that deformation besides heat. But there should not be any heat in that location. The exhaust is on the top.

 

[RonsPlc]

Two things I noticed...

1- If you look on the pipe, it says "DWV" on it... this means Drain/Waste/Vent These are a cheaper/thinner pipe than what is usually used for any pressure applications.
2- Anything that is being heated needs to be CPVC, instead of PVC. PVC weakens with heat.

I may be off base, and am sure that I will get corrected if I am, but those are my thoughts.

If I am reading it right, the pipe is also only rated for up to 73.4 degrees F. (If I read the pipe right).

 

[CountyBumkin]

I found some more info on DWV pipe: This. Sch 40 is a SIZE specification. Both pipes have the same O.D. and I.D. The difference is that the DRAINAGE ONLY pipe has a foam core and a thin PVC cover and liner. This lets waste flow smoothly and gives the glue something to "grab". The other (more expensive) pipe is solid PVC and will withstand for pressure as well as outside abuse.

My previous Spa Heater was plumbed with Schedule 40 PVC and had no issues like this. I think you are right, and I need to replace the DVW pipe with "standard" Sch40 PVC. If 2" CVPC is available, I use that, but I really think the problem is that I used DVW pipe.

 

[ps0303]

All heaters are installed with standard sch 40 PVC which is the same PVC that is used on the pool piping. CPVC is sometimes used as nipples but then converts to the sch 40 PVC. Just like in the pics above, CPVC is coming out of the unions and then converts to PVC.

If this is truly DWV pipe, then you have an issue and need to replace it. Just replace it with normal SCH40 PVC pipe. No need to run a bunch of CPVC.

 

[kadavis]

Why is a check valve needed on the discharge line leaving the heater

 

[CountyBumkin]

It is said in the manual to have a check valve there so the heater can't drain when the spa function is shut off.

 

[kadavis]

I'm sorry but I'm confused, your signature says you have a Raypak heat pump and a Jandy heater, which manual are you referring to? Is the pool heater installed above or below spa? Does the heater have a cool down cycle