PVC or CPVC for a low (below the waterline) return?

bruce_21

My client's steel low return is clogged and rotted, likely because its partly buried in the dirt floor of the basement. Will PVC or CPVC pipe work here?

ChrisJ

bruce_21 said:

My client's steel low return is clogged and rotted, likely because its partly buried in the dirt floor of the basement. Will PVC or CPVC pipe work here?

Probably, for a while.
But I wouldn't do it. PVC's glass transition temperature is around 176F. Meaning, it becomes soft.

Jamie Hall

Use copper

Mad Dog_2

No way..Copper is the way to go but make sure you have atleast 3/4"  boiler drains on either end.  I like gate valves just above them so you can always power-flush them in the future...Mad Dog 🐕 

Mad Dog_2

Mad Dog_2

This is the Mad Dog 🐕 Method. I PREFER gate valves because they are full port AND The Teflon Ring in a Ball Valve does not hold up well over time with 210 plus Temps, but I have used them in a pinch...Mad Dog 🐕 

ChrisJ

Mad Dog_2 said:

This is the Mad Dog 🐕 Method. I PREFER gate valves because they are full port AND The Teflon Ring in a Ball Valve does not hold up well over time with 210 plus Temps, but I have used them in a pinch...Mad Dog 🐕 

The issue I've seen with the PTFE ring isn't from heat but seemed to be from debris chewing it up. I had a beautiful 1.5" ball valve on the skim port that even the nice plating on the ball was destroyed.

My original boiler drains were also ball valves. All of them, or almost all have been replaced. For boiler drains I went back to good old washer type valves and the skim port I just used a brass plug.

bruce_21

Thanks for your help Mad Dog! Gate valves and copper pipe! She won't like the price but I certainly don't want to have to this twice.

Waher

bruce_21 said:

My client's steel low return is clogged and rotted, likely because its partly buried in the dirt floor of the basement. Will PVC or CPVC pipe work here?

Plastic pipe won't be able to handle the 180f+ heat of steam condensate. Copper ($) or brass pipes ($$$) below the water line is fine. If you use copper, there must be appropriate galvanic isolation of copper from cast iron (use brass/bronze valves or fittings to avoid connecting copper directly to iron)