Plastic Vent Connector 80 percent Efficient Furnace

[greyboy39]

Anybody ever seen this before, and if so how can this be allowed when plastic is considered a combustible material? Plastic vent connector connecting single walled flue and exhaust blower. 

Edited August 25, 2017 by greyboy39
Punctuation error

[Bill Kibbel]

I've seen hundreds if not a thousand without any failures.  There are heat resistant plastics/polymers that can easily handle the heat from a furnace and more.  

I have a car with a turbo that has plastic parts.  How many vehicles have water pumps with plastic impellers and housings?  there's even plastic valve covers now.   Gonna see all plastic combustion engines in some cars soon so makers can meet the 2020 CAFE standard.

[John Kogel]

It is probably a heat-resistant PVC. " PVC starts to decompose when the temperature reaches 140 °C (284 °F), with melting temperature starting around 160 °C (320 °F). The linear expansion coefficient of rigid PVC is small and has good flame retardancy, "

It can be modified with additives to withstand even higher temps.

We saw ABS used for furnace exhaust on high-E for a little while, but the standard now is ABS may be used for air intake but not the exhaust. That's got to be PVC.

 

Edited August 25, 2017 by John Kogel

[Jim Katen]

Very common. 

Heck, Rheem/Ruud made the entire draft inducer assembly out of plastic throughout the '90s. . . oops. Bad example. . .