Vent Insulation

smellslike$tome

I installed a tankless water heater outside under a deck. I had my reservations at first but the IFGC allows for this location for the install and the wh rep assured me that it would be fine. Less than one hour after the install the HO calls and the exhaust is a problem above the deck. So now we are talking about extending the vent (it currently has only a vent cap). The shortest route is to run the vent through the deck and mount it to the exterior chimney wall right next to a gutter downspout. I informed HO that this would be highly unusual install of gas vent piping and that I was frankly unsure if code would allow it. I could'nt find anything in the governing code to disallow it and I called the code official for that area see what he had to say. He was unaware of anything written in the code to prevent it. However, I feel like this is one of those things which may not violate the code but does certainly violate common sense. Since the vent pipe would be mounted to the wall above a deck, it could easily be touched by anyone. I am concerned about the possibility of someone getting burned (they have two young boys). Finally I am getting to my question. If I install the vent pipe at this location, what sort of weather resistant insulation, with a minimal wall thickness can be installed around the section of vent pipe above the deck for a distance of about 8' and who (insulation contractor? Have'nt had much luck there) typically would install this type of insulation?

QWIKWHIP

Wow, I would question what that rep is telling you. Here in NY venting under a deck is a big no no. What brand heater is this and were are you located? All your other options you described are against code here in NY as well. So I guess it depends on your local code, but it sounds like you should just cut your loses and relocate the WH so it can vent properly.

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JCW Residential Services
Heating - Cooling - Plumbing

plumber jay

check on the hvac site but you get insulated duct work. i think it is called c vent. that should protect the kids.

JamesNLA

ok, leme see if I can see what you did.

You put a tankless with a vent cap under a deck outdoors?

What is the distance from the vent cap to the deck?

As for your vent insulation, forget that idea it's not happnin.
You can by code put a vent run in an area that is accessable to anyone, but if they touch it while it's operating, your gonna hurt people.
So forget that idea.

Did you properly size the gas for this unit? What unit did you put in?
What are the chances you can relocate the entire heater somewhere else? I assume that will be a lot of work but you dug yourself in on this one. Just because some "rep" said it was OK, doesn't mean it is a good thing to do. Inspectors are still learning all the ins and outs of tankless heaters. I have given a few of them tips on how these should be installed. They often will look at what the manufactures guildlines say, and base proper installation off that.