Water Heater Clearances

**Rick Hurst** · 11-09-2007, 05:55 PM

What is the clearance recommended above a water heater?

I don't think the installer of this water heater had ever heard of the word "clearance".

And how about the covers over the sewer vent pipes? Strange!

rick

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**John Arnold** · 11-09-2007, 06:31 PM

For starters, don't you need 6 inches from the draft hood?

**Billy Stephens** · 11-09-2007, 06:43 PM

Originally Posted by Rick Hurst

What is the clearance recommended above a water heater?
rick

Rick,

AO Smith says 12". Your Model may be different.

**Jerry Peck** · 11-09-2007, 07:35 PM

As I recall, the minimum total rise is required to be 5 feet - and you ain't got it there.

Those caps are not Type B Gas Vent Caps ... and those flashings, they look like 'rubber' ones, which is neither approved nor good next to the B vent ... unless those are plumbing vents ... in which case they should still not have those caps on them.

I see a Type B Gas Vent at the extreme right of the photo - if this is that water heater, maybe you do have 5 feet and maybe it does meet the other requirements for a Type B Gas Vent.

**Jim Luttrall** · 11-09-2007, 07:57 PM

http://waterheating.rheem.com/conten...dianSystem.pdf
Check out the clearance to combustibles listed in the manual above.
This is for Rheemglas Fury models, which was the best I could make out from the label in your photo. 12 inches on top. I don't know about the drywall that they used to try and cover the combustibles...

**Billy Stephens** · 11-09-2007, 08:03 PM

Originally Posted by Jim Luttrall

http://waterheating.rheem.com/conten...dianSystem.pdf
I don't know about the drywall that they used to try and cover the combustibles...

Jim L.

That's what I'm thinking( Fire Rated Sheet Rock? ) I was just going threw the book,

Richard Moore · 11-09-2007, 08:17 PM

Here's another HO install beauty. Brand new water heater, but I guess the seller didn't want to pay the extra bucks for another direct vent model.

It's not like there wasn't a very clear message on the vent itself!

**Jim Luttrall** · 11-09-2007, 08:19 PM

According to their definition

Noncombustible Definition excerpted from the ICBO Uniform Building
Code:
1. Material of which no part will ignite and burn when subjected to fire.
2. Material having a structural base of noncombustible materials as
defined, with a surface not over 1/8 thick that has a flame spread rating
of 50 or less.
The term does not apply to surface finish materials.

Then maybe drywall would qualify, but the combustibles under the drywall are still in the zone and simply covering them with a non-combustible product would not totally eliminate that intrusion into the zone, right?
I am sure Jerry P. or Bob H. would be able to provide a little more insight into this.

**Jerry Peck** · 11-09-2007, 08:33 PM

Originally Posted by Jim Luttrall

Then maybe drywall would qualify, but the combustibles under the drywall are still in the zone and simply covering them with a non-combustible product would not totally eliminate that intrusion into the zone, right?

Right.
G2409.2 (308.2) Reduction table.

The allowable clearance reduction shall be based on one of the methods specified in Table G2409.2 or shall utilize an assembly listed for such application. Where required clearances are not listed in Table G2409.2, the reduced clearances shall be determined by linear interpolation between the distances listed in the table. Reduced clearances shall not be derived by extrapolation below the range of the table. The reduction of the required clearances to combustibles for listed and labeled appliances and equipment shall be in accordance with the requirements of this section except that such clearances shall not be reduced where reduction is specifically prohibited by the terms of the appliance or equipment listing [see Figures G2409.2(1), G2409.2(2) and G2409.2(3)].

To understand what is being said you would need to go to the table and figures. Basically, with the right material, spaced 1" out from the wall, sizing that material so the clearance is maintained such that at the reduced clearance the protection material extends out to meet the regular clearance.

However, you will notice two things in that table: 1) gypsum board is not one of the materials; 2) the table and figures are regarding horizontal clearance from walls, not vertical clearance.

I don't know that there is a reduction for vertical clearance - where would the heat go, but up anyway?