3-1/8" vent in 4-5/8" hole

[Ashful]

Hi folks,

The 14k BTU direct vent LP wall heater in my garage was in need of replacement, but unfortunately I have been unable to find anything using the 4-1/2" or 4-5/8" diameter coaxial flue used by the old heater. If there are still heaters that take this flue size, I'd appreciate someone pointing me in the right direction.

What I did find were Ashley's (and the like) that require the cutting of a large rectangular pass-thru, and then Rinnai’s (and the like) which all use a smaller 3-1/8" coaxial flue.

Figuring it would be relatively easy to put a 3-1/8" pipe in an existing 4-5/8" hole, and not wanting to cut a large square hole in my stucco wall, I went with the Rinnai. Unfortunately, I found the interior and exterior flanges on the included 3-1/8" vent are not large enough to cover the existing holes thru the wall. I suppose I could fabricate some custom stainless trim rings, but figured I'd check in for some experienced advice, before inventing my own wheel. I'm guessing I can't be the first one to run into this scenario.

Thanks!

 

[Ashful]

The stove calls for a 3-1/8 hole thru drywall and siding, for the coaxial vent. Existing hole is 4-5/8, larger than weather flange or interior flange of new vent. Thinking a 3” b-vent thimble (Selkirk 187703) might be the proper solution. It has 3-5/8” bore, to accommodate new vent, and 7” flange to cover old hole. Safe? Legal?

 

[bholler]

I would probably just make a trim ring to cover

 

[Ashful]

Hole saw and aluminum or stainless sheet? That could be done!

 

[bholler]

Hole saw and aluminum or stainless sheet? That could be done!

I would use stainless because that's what I have but aluminum would work fine

 

[Ashful]

Yeah, stainless would have been best, but I didn't have any, and didn't find any stainless sheets at the hardware store. So, I milled it out of some .093" aluminum that has a chemical conversion coating, which should be good enough for outdoor exposure. Applied a complete ring of solvent-based (Big Stretch) caulk to the back, screwed it to the wall, and then caulked the fillet all the way around, leaving a 1/2" gap at the bottom. It covered the un-painted portion of stucco left by the old vent, which was a bonus in our current weather, which wouldn't allow me to repaint.

New flue fit thru it perfectly. Drilled and tapped mounting holes on the indoor side of the ring. Had to build a strong shelf onto which to place the new heater, as it's designed to be floor-standing at the wall, rather than hung on a wall. I could have placed it on the floor and used a remote flue kit, but decided it would just be a mess with dust and debris, being in a garage. Also, since I have the floors epoxy-coated with drains, I often scrub and hose the whole garage floor down to get rid of road salt, dirt and debris. Wouldn't want the heater getting wet, when I do.

Sound good? Can post a photo, after I get the shelf painted and cured well enough to put it all back in place.