Capped roof penetration?

[Jon Hodgkins]

I would appreciate any insight to why the pvc roof penetration, in the middle, appears to be capped. I was only able to perform an exterior inspection from the ground. The homeowner was not aware of any issues but indicated that they had problems with the contractor. The home owner also indicated that they had gas forced air heating units. My thoughts were that it might be for combustion air for the hot air furnace. Could this be anything other than a cap? I would doubt that it is a coupling. My other thought was maybe it is some type of check valve fitting that only allows air in, but I would be concerned that it would not work properly in the winter. This is new 2016 construction in Needham, MA.

Thanks

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[Jim Baird]

...a great excuse to get a drone camera.

[kurt]

My WAG.... It's the combustion air intake for the furnace, but the installer decided to pull combustion air from interior instead of the exterior (which is allowed), and they capped the pipe.

What's a drone going to show that's not already apparent? Seems like the answer is to be found on the interior, not exterior.

[Jon Hodgkins]

Thanks for the answer, that makes sense to me.

For future inspections - if this was for combustion air, assuming it was not capped, or had a "rain head" (upside down trap) - would there be concerns that moisture from rain would enter through the pipe and could cause the hot air furnace to shut off?

[Jerry Simon]

Could be a rough-in for a radon mitigation system; many jurisdictions around here want such for new construction.

[kurt]

Thanks for the answer, that makes sense to me.

For future inspections - if this was for combustion air, assuming it was not capped, or had a "rain head" (upside down trap) - would there be concerns that moisture from rain would enter through the pipe and could cause the hot air furnace to shut off?

Yes, sort of, maybe in a few very specific and highly unlikely conditions, but no. There's already a lot of moisture in the pipe from condensation.

[Brandon Whitmore]

The combustion air intake for the condensing furnace should be the one facing downwards. Water shouldn't be able to enter that pipe. The "vent" should be the one with the coupling/ cap piece on it. If the vent is capped, then the pressure switch should prevent the furnace from operating, so it's highly unlikely that it is in fact capped, assuming you operated the furnace. Usually, you can see which pipe the exhaust is coming out of when it's in operation.

[kurt]

I misread on my previous answer. Brandon's right; no water should get into the intake; that's a problem. Water getting into the exhaust...not really, but the amount of moisture that might actually get in is probably less than that being produced by the furnace.

I need to retire.....

[John Kogel]

I'll bet that 'cap' is a screen on the exhaust, but that's my guess from 4000 miles away.

Make yourself a pole camera. Mine is a paint pole, paint roller handle, mini camera tripod, all done up professionally with black tape. []

[Jon Hodgkins]

Thanks for the responses - the screen makes sense.

My inspections are for insurance. With the added information from the home owner, that they had issues with the HVAC contractor, I included a requirement to verify what the "cap" is, and to make sure the system is in proper working order.

There is most likely a sensible explanation, but maybe the contractor has had issues with payment and would cut the "cap" off after receiving final payment? I use to work for a masonry contractor and would hear stories about masons installing a pane of glass between a couple of the clay flue tiles, and would drop a brick down the chimney to break the glass after they received their final payment.

I will let you know what the answer is as soon as I hear back from the home owner.

[Marc]

...

I use to work for a masonry contractor and would hear stories about masons installing a pane of glass between a couple of the clay flue tiles, and would drop a brick down the chimney to break the glass after they received their final payment.

That would boil my blood.

Marc

[plummen]

My WAG.... It's the combustion air intake for the furnace, but the installer decided to pull combustion air from interior instead of the exterior (which is allowed), and they capped the pipe.

What's a drone going to show that's not already apparent? Seems like the answer is to be found on the interior, not exterior.

I agree with that. Id look at the furnace and follow the pipe feeding it combustion air to see where it goes now.

[Jim Katen]

I would appreciate any insight to why the pvc roof penetration, in the middle, appears to be capped. I was only able to perform an exterior inspection from the ground. The homeowner was not aware of any issues but indicated that they had problems with the contractor. The home owner also indicated that they had gas forced air heating units. My thoughts were that it might be for combustion air for the hot air furnace. Could this be anything other than a cap? I would doubt that it is a coupling. My other thought was maybe it is some type of check valve fitting that only allows air in, but I would be concerned that it would not work properly in the winter. This is new 2016 construction in Needham, MA.

Thanks

Click to Enlarge

27.43 KB

I saw one just like it today, but was distracted and didn't take a picture.

When I looked at it from the ground, it looked like a cap, but from the roof, I could see that it was a small coupler. The installer had put it there to make a small recessed space, which accommodated a metal screen.

Of course, the furnace instructions said, "Don't place a screen there. . ."