Thread: CSST and return air

This is similar to a question to one posted the other day. I found CSST running under the furnace which was on a plenum platform. I can't image this is allowable. Any thoughts.

Thanks
Mat

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Originally Posted by mathew stouffer

I found CSST running under the furnace which was on a plenum platform. I can't image this is allowable. Any thoughts.

Mat,

Most likely your "I can't image this is allowable" is correct in it not being allowable, but first ...

The stand the furnace was on, was it: a) an open stand with return air coming in through the open stand, or, b) an enclosed stand with a return duct to the plenum enclosed within the stand?

If a), then that is considered "environmental air", such as would be flowing through your conditioned space, and in which case that is allowed.

If b), then that plenum is a "duct" and no gas piping is allowed through any duct, much less return air.

Originally Posted by mathew stouffer

This is similar to a question to one posted the other day. I found CSST running under the furnace which was on a plenum platform. I can't image this is allowable. Any thoughts.

Thanks
Mat

.
IRC. G2415.1 = Prohibited locations. Piping shall not be installed in or through a circulating air duct, clothes chute, chimney or gas vent, ventilating duct, dumbwaiter,or elevator shaft.

Here are the pics.

What's going on with the flexible flue pipe for the furnace in the first pic? Is that flex line even allowable for gas furnaces? They're common on oil-fired systems but only inside the chimney as a liner, not right above the unit itself. It doesn't look right and there appears to be tape where the top of the flex pipe attaches to the solid flue pipe. Is it even the steel type rated for use in a heating system or is it the cheap aluminum flex you see on clothes dryer ducts? No overflow pan either beneath the funace for the AC system and it's hard to see if there is a combustion air makeup provision installed on that utility closet. As for the return air vent, I never like seeing a return air vent that close to a utility closet housing a furnace and water heater when the units have open combustion chambers. Code may or may not allow it but it seems like a poor set-up regardless.

Maybe the pic isn't showing it clearly enough but it looks like iron pipe spliced in between separate runs of the CSST flex gas lines.

Originally Posted by Nick Ostrowski

What's going on with the flexible flue pipe for the furnace in the first pic? Is that flex line even allowable for gas furnaces? They're common on oil-fired systems but only inside the chimney as a liner, not right above the unit itself. It doesn't look right and there appears to be tape where the top of the flex pipe attaches to the solid flue pipe. Is it even the steel type rated for use in a heating system or is it the cheap aluminum flex you see on clothes dryer ducts? No overflow pan either beneath the funace for the AC system and it's hard to see if there is a combustion air makeup provision installed on that utility closet.

Maybe the pic isn't showing it clearly enough but it looks like iron pipe spliced in between separate runs of the CSST flex gas lines.

Nick - Here is a url for flex pipes like the one in the photo. AmeriFlex® by AMP
Also - I don't see any sediment traps.

Thanks for the link John. I'm adding that to the favorites file.

Plumbing vent also not allowed in that space.
.

Neither is most electrical (adding to Billy's 'not allowed in there either).

Also, the return air plenum is required to be lined with an air barrier (basically gypsum board or equivalent).

The looks of that plenum is that it is sucking air from the stud cavities, possible all the way to the attic.

No trap in the condensate line either - neither primary or secondary.

And the secondary condensate connects back to the primary? What good is that going to do when the primary clogs and backs up?

What looks like flexible conduit is also not properly supported, nor that low voltage cable either.

I don't see any support for that filter either, no cross wires or anything. Those filter types will just be sucked back from the return air grille, allowing unfiltered air to bypass the filter and enter the unit.

Thanks for the info. What about the gas line, just for furture reference.

Originally Posted by mathew stouffer

Thanks for the info. What about the gas line, just for furture reference.

Originally Posted by Jerry Peck

If b), then that plenum is a "duct" and no gas piping is allowed through any duct, much less return air.

It was b) above. Also see Billy's response below.

Originally Posted by Billy Stephens

IRC. G2415.1 = Prohibited locations. Piping shall not be installed in or through a circulating air duct, clothes chute, chimney or gas vent, ventilating duct, dumbwaiter,or elevator shaft.