[Rav]

I wasn't sure whether to put this thread in plumbing or insulation, so I picked plumbing.

I have a gas water heater. As you can see I have insulated the hot water pipe with 1" thick polyethylene foam, up to the recommended 6 inches away from the flue pipe. (Please ignore the foil tape below that; that's temporary.) I would like to insulate all the way to the top of the WH because there's a lot of wasted heat emanating from the uninsulated section of pipe. The recommendation I have seen states "single wall metal venting must have 6" clearance to combustible materials." But would it be OK to use UNfaced fiberglass pipe insulation all the way to the WH top, since that isn't combustible? Or perhaps up to but not beyond the edge of the draft hood? The pipe insulation I'm looking at is also 1" thick and is rated up to 1000 degrees. I would secure it with wire. Thanks for your thoughts.

 

[jmon]

Imo, it's not needed. it won't make that much more of a difference in your heating bill. Plus most wh have heat traps that do a good job keeping heat in.

It looks like you had a little downdraft/overheating issue at one time by the melting of the plastic hot and cold markers on the top tank inlet/outlet by the flue. Another reason you don't want anything combustible near there.

Again just my opinion and thoughts. others may disagree, and you are free to do what you like if you think it will make a difference.

 

[Rav]

<Snip>
It looks like you had a little downdraft/overheating issue at one time by the melting of the plastic hot and cold markers on the top tank inlet/outlet by the flue. Another reason you don't want anything combustible near there.
<Snip>

You're correct about the downdraft issue. A few years ago I noticed an odor at the WH, and had someone come in to check it. They said it was backdrafting a little and thought the exhaust pipe was too narrow, so they put in a larger diameter section, and that seemed to solve the problem. Anyway, thanks for your thoughts on this.

 

[Bondo]

Ayuh,..... I can't see where yer loosin' that much heat there, not worth insulatin' anyways,.....

 

[huesmann]

No clue if this would be code-compliant, but if you must insulate that section of pipe, you could get a silicone sheet (like a making mat) and wrap it around the pipe, securing it in place with wire ties.