Water Heater vent pipe connection...Need advice

Is this connection safe/ok? Or do I have to recommend a qualified/licensed
contractor to correct?

It seems like there should be a fitting to connect the two pieces together.


So the bottom portion is the water heater exhaust pipe? This is in the HVAC system thread… I’m confused.

The lower pipe is ducting coming from a water heater. ( not shown in the picture ). its connected to ducting coming from the roof. The connection
of the two ducts are open…a little one inside a bigger one.

Yes it appears to be different sized vents connected without a reducing coupler. One is single wall and other is class B but they appear to be a 3" and 4" or such. Typically the same size single walled vent and class B vent will connect together with just an appropriate transition piece.

I was split between right and wrong so I sent the picture to the head of an HVAC company in Houston that I own a part of. He said that technically it’s wrong, that it does need a connection but that he wouldn’t put great emphasis on it as a “need correction now” event because the slope of the exhaust vent should be more than sufficient to allow the heated air to rise and exit properly. However, if he were at the home doing the annual inspection, he would explain to the owners that they should have a connection there and hope to install it. More important, though – and this is something I always explain to my Clients – the installation is technically wrong. If there is a problem with the water heater that results in a claim, the insurance company quite often will deny any claim related to a system that is installed improperly. Since this is a home inspection, it would be best to ensure that the system is installed properly at close of escrow so that there will be no possible case of a problem that the insurance company denies.

According to here it would need a proper designed vent connector also so I agree with you Ray. Insurance companies will pick apart that install for sure.

Screw the insurance companies, what about backdrafting and CO poisoning to the tenants?! It may well be the attic, but it is still a hazard.

H eating V entilation A ir C onditioning

In my world ventilation includes all flue pipes, dryer vents, bathroom exhausts vents kitchen exhaust vents and anything else that might transport air flow from point A to point B

What about the air gap at the top of the WH same principle if it backdrafts its going to do it at the top of the water heater also.

BUT I agree the fitting is improper and I would place it on the repair list reguardless of the location. Is it going to kill someone not likely, less likely in the attic than backdrafting at the top of the water heater

I agree that it doesn’t seem like it would be any more of a CO risk than the draft hood on the WH. There is a possibility that it could help draft due to the warm attic air that is going to be going out. Just like how a furnace when on helps a WH draft. Still I would mention it since it is not really correct and let the owner decide.

Thanks Russell…You cleared it up for me.

Thanks everybody for the feedback…

I am always amazed by the wealth of information on this site. Thanks for asking the questions and thanks everyone for the knowledge.