Unit Heater Concentric Vent Sealing

[dsl_mech]

I recently had a Reznor UDZ unit heater installed. From the beginning the venting was a headache and I honestly regret going with a seperate combustion unit heater. The stainless special gas vent was hard to find and very expensive. Despite numerous local HVAC companies telling me to use B-Vent I ended up using the stainless. Issue now is a gap around he flue vent where it enters the concentric vent box. I know now that Reznor sizes the concentric vent box for B-Vent which would have filled the hole and required a simple bead of high temp sealant. I doubt I am going to find any type of sealant that can fill that gap and last. I am wondering if my best option is to find some galvanized tin and cut/make a plate to fill the gap. I would then seal the plate around the stainless pipe and to the concentric vent box. Does anybody have any other ideas? Not that it matters now but was I correct going with the stainless or could I have used B-Vent? Thanks.

 

[thammel]

What about high temperature RTV?

 

[BillK]

Not that it matters now but was I correct going with the stainless or could I have used B-Vent? Thanks.

What do the furnace directions say ???

A good sheet metal guy should be able to make you a split collar to cover the gap.

Storm Collar And Flashing | Tough 28 Gauge Galvanized Steel

The FAMCO SC Storm Collar is used w/ FAMCO metal pipe flashings. This product is used to divert water from running down the pipe. Adjustable.

www.famcomfg.com

 

[TurnipTruck]

This is a different brand heater, but my coax adapter doesn’t have a gap like yours. This is all double wall exhaust. I had to special special order the flex for the exhaust but the intake is just single wall.

 

[The Cobbler]

cut a disc out of galvanized sheet metal. seal it with RTV high temp

 

[PoorUB]

The manufacturer of the stainless venting should have a "storm Collar" available. In your case you will need a split storm collar.

I commend you on using stainless, I have used B-vent with Rezonr's concentric and it rots out in no time at all. Lucky to get a couple years out of it.

 

[Jackfre]

The issue for you was choice of vent material, AL or SS. PoorUB‘s experience should make you feel pretty good about not going with B-vent. The condensate from a gas appliance lands at about a 3.2pH. That is pretty hot and AL will go away in a hurry. Good choice on the SS. I’d get a couple sets of tin snip and cur a two piece collar with fins on the inside. Those you can bend against the pipe and they will give more of a bite for the RTV.