Thread: Best way to "finish" tankless vent?

Tankless doublewall vent through furnace room ceiling to exterior. Cavity is uninsulated per manufacturer and lined with sheet metal but what is best way to close off penetration? Pipe was mildly warm and graspable after 15 minutes of operation at 125 degrees just above appliance and at ceiling.

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Ross.Type B flues should have minimum one-inch clearance from combustibles.
Should be proper thimble per manufacturers installation instructions. If you have the name of the tankless unit you could do a goggle search and find proper installation vent instructions.

Ross,

That looks to me (flared junction and band clamp at the connection at the ceiling) like "Z-Vent" brand single wall stainless steel (UL 1738) vent pipe, which is required (the listing, not the brand) by manufacturers of many tankless water heaters.

If so, it must be installed per the manufacturer's instructions and when "enclosed" (like that ceiling) requires greater clearance to combustibles that B-Vent. Some other brands require even clearances, in some cases as much as 12". In my area many installers and municipal inspectors are not aware of this, and it is often 1) done wrong and 2) passes inspection.

http://www.novaflex.com/information_centre/zflex/01Z-Vent%20Residential/Z-Vent%20Residential%20Installation%20Guide.pdf

Its actually FasNSeal and follows the same instructions. The only problem is this is my home (before I became licensed). Go figure. I actually left a hot water faucet on in the laundry room for several hours accidentally but when I found it on I immediately went to the basement to feel that vent pipe. After that much time I was impressed with how cool it was--it was pretty warm, don't get me wrong--but I was surprised at the temp. Of course, it doesn't make that installation right. It is something I will need to address sooner rather than later.