Unburned Gases/Heat/PVC Pipe

It depends primarily on the surface temperature attained by the PVC. If a propane flame impinges directly on the PVC, the PVC may melt, char, or oxidize (burn). If it is a properly adjusted condensing furnace, the exhaust temperature should be mild enough to avoid problems.

a 250,000 BTU gas salamander construction heater was installed (at 6,000' on propane gas) for the sub-contractors during construction. The crawl space was air tight with no vents. After two days it was found ( by the plumbers who went back in to clean up) that all the pvc piping had distorted from the high temps, and the pipes turned a dark grey with no soot on the pipe. This grey color was completely through the pipe, ( i cut a piece off) and the insides were also grey. The water piping (aqua pex) was a brownish colour. My question is this, could the heated pvc pipe which was very distorted) outgassed it's chlorine, and then absorbed the unburned gas and particulates, from the burner to change it's color? and then it cooled rapidly when the heat went out (it"s been below 0 at night) I think that the pipe changed states.What do you think?

Plausible.

Probable.

So, direct the output of the heater away from these plastics.

Just curious...

Are you trying to form the heated pliant pipe? If not, can you just move the heater?

I don't know, but it is hard to imagine that the pipe color would be changed completely through like that. I almost wonder if it was Schedule 80 PVC, which would have been grey already, but would still have drooped in the hot air.

i also could not imagine that the pvc pipe could change color all the way through, but it was. Incredible. The polymer had changed from one thing to another. I think that if it had been electric heat instead of gas, that the pipes would have deformed, but not changed color. It is almost like the cell core dhw pvc pipe had in fact changed to sked. 80 pipe. The general contractors sphincter is smaller than small.

Sounds like highly accelerated thermal aging. Eventually it would have turned black and fallen apart into charred ash.