Hello, I have a hot water furnace that heats my tap water and house, and I replaced my heater covers with heavy duty polypropylene soffit, now I did some research, the furnace water never goes above 160F, the water registers never go above 100F, and the soffit is rated not to distort until a temp above 160-200F. Ever since I installed them, the home made soffit covers only get warm,never hot no matter how long the furnace is running, My question is, would this pass for a safe cover until I can afford store bought ones? Thank you..

Depending on where you live, 100 degrees could be an outside temperature. I see no problem with that temperature. Depending on the molecular weight and whether it is a monopolymer or copolymer, the melting points vary from 250-350 degrees F

I live in Pennsylvania, what do you mean 100 degrees could be an outside temp? Right now it's 40F outside. Also are you saying the melting points for the soffit are 250-350F. Thanks for the info also.

i live in Pennsylvania, what do you mean 100 degrees could be an outside temp? right now it's 40F outside. also are you saying the melting points for the soffit are 250-350F. thanks for the info also.

In Atlanta, in the summer, 100 degrees is not uncommon. And having lived in Philadelphia for my first 35 years, 100 is not that uncommon.
Melting points vary based on molecular weight and whether the polymer is a long chain or crosslinked. What I gave you were typical melting point ranges of Polypropylene. 10 years, Rohm and Haas Chemical Company, plastics research.

Last question, so there will be no hazardous fumes or chemicals emulating from the soffit covers, I just want to make shure since I am talking to experts, thank you for your time, very helpful...

last question, so there will be no hazardous fumes or chemicals emulating from the soffit covers, i just want to make shure since i am talking to experts,, thank you for your time, very helpful...

At the temperatures you are talking about, there are no hazardous chemicals emitted. Sleep in peace.