Question regarding type b vent flex connector by Mitchell Metal

Any advice or input is much appreciated…

See pics. I am confused by the flex vent connector between 2, Type B metal vent pieces for a gas heater in an attic. I have pulled the installation instructions by Mitchell Metal Products and in bold caps it states the following;

“MITCHELL METAL PRODUCTS, INC. MITCH FLEX-VENT IS NOT TO BE
ENCLOSED OR USED AS A TYPE B GAS VENT. IT IS ONLY A GAS CONNECTOR
AND IT IS NOT TO BE USED TO PASS THROUGH WALLS, FLOORS, OR CEILINGS.
IT IS NOT TO BE USED IN ATTICS OR CRAWL SPACES.”

Obvious strike 1 is that it states the flex vent is not to be used in an attic and this is indeed in an attic. Obvious strike 2 is that the vent termination is floating inside the roof jack. The confusing part is that the labeling sticker states it is for use with Type B gas vents but not to be used AS a type B gas vent. Can someone explain what this flex vent is meant for if not to be used as it is in this case? What is meant by gas “connector.” Also, what is meant by “enclosed” in the installation instructions? Enclosed in what specifically?

My comment in the report read as follows;

“Improperly installed heater exhaust vent. Non-approved material for gas exhaust vent used as connecting piece. Vent not securely attached to roof penetration. These conditions may allow for hazardous gasses to escape into the attic. Evaluation and repairs are recommended by a licensed HVAC technician and roofing contractor.”

Upon re-inspection, where the buyer, agent and seller were present, the only improvement that was made was a new vent cap was installed onto an old rusty roof jack where no cap was present at initial inspection. The seller’s “guy” added the vent cap and it was an odd scene where my explanation was being met with trepidation.

I guess my ultimate question is, does my report comment sufficiently explain the condition and should I not worry about the buyer choosing to allow the seller to have his handy man do the repair? Should I reiterate my concern to the buyer and agent at this point? Should i require seller’s not be present at re-inspections?

Thank you in advance for your constructive advice.



I believe they mean that it can be used from the appliance to the class B vent pipe and THAT class B vent pipe can be run up through the attic, etc.

That is how I would interpret also. Kudos to the OP for doing his research.

I would cite the manufacturer’s installation specifications as an authoritative source and document that the vent is still deficient. I would have a verbal discussion withe the client and their agent that the person who affected the “repair” was obviously not competent to do that work so that they can consider alternative approaches.

Got it thank you sir.

Thank you for the advice.