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Discussion Starter #1
Years ago, I did some remodeling. I subbed out the HVAC, with my usual company.
Today, there was a home inspection for a future sale. The home inspector noted the 4" flue.

Here is the quote: "The single walled flue pipe dose (sic) not have a 6" clearance from combustible objects. Recommend a HVAC technician/plumbing contractor evaluate and repair."

The 4" single wall runs between floor joists, for a short distance, before switching to double wall. 14 1/2" between joists, minus 4" pipe, leaves approximately 5 1/4" air space.
Space between the top of the pipe and the bottom of the floor is similar in distance.

So, my question. Is there code on hot water heater vents? I talked to the HVAC sub. He said no codes.

I'm thinking fire code?

I appreciate your time and input.



Either way, I will do what it takes to correct. I just don't want to waste my time, because some home inspector, fresh from is test, wants to nit pick.
HVAC contractor said they will do anything for me, but not at that house, for that guy. He hired them to repair his air conditioner and didn't pay the bill. He told them he was laid off and couldn't afford to pay the bill. I know he was laid off, 3 years ago, for about 6 months. He has been employed since then. He is lying. I'll still make sure our remodel is good, but I don't blame them. I told them to file a lien.
 

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I tried to look a few things up but couldn't nail down why the clearance ? Not the obvious answer, but a flame spread rating of materials around the 6" clearance ? The info is there somewhere ?

Seems easiest to use a fire retardant paint on the adjacent materials bringing it up to Class A protection or similar designation. Paint can be had for < $100.

What if the materials were Dry-Con, would that abate the 6" requirement ? The paint would do similar ?

Addl - can't fully picture what you have there but covering the existing surrounding materials with a cement board product may be an option. Ask the inspector if so ?
 

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Discussion Starter #3
I think I can adjust the existing and be good.

I was just wondering if anyone knew of any code.

Home inspectors can come up with odd stuff. When people have money on the line, they start to believe anything a home inspector says.


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Discussion Starter #5
I appreciate you educating me.

Truthfully, it’s a little late for me to read it.
I’ll look in the morning

Thank you


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Discussion Starter #7
I read it. Maybe I missed it. The only part I could find, where they talk about 6" clearance is:

M1803.3.1
2. Single wall metal pipe shall be guarded by a ventilated metal thimble not less than 4" (102mm) larger in diameter than the vent connector. A minimum 6" (152mm) of clearance shall be maintained between the thimble and combustibles.

And, this is for penetrations. This pipe is good at the floor penetration. I believe he has to be talking about the single wall pipe extending from the top of the water heater, running between the floor joists, then turning up through the floor, heading up the wall to the roof.

I appreciate you providing this link. I really don't think there is an issue here, but having something to reference makes it better.
 

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I read it. Maybe I missed it. The only part I could find, where they talk about 6" clearance is:

M1803.3.1
2. Single wall metal pipe shall be guarded by a ventilated metal thimble not less than 4" (102mm) larger in diameter than the vent connector. A minimum 6" (152mm) of clearance shall be maintained between the thimble and combustibles.

And, this is for penetrations. This pipe is good at the floor penetration. I believe he has to be talking about the single wall pipe extending from the top of the water heater, running between the floor joists, then turning up through the floor, heading up the wall to the roof.

I appreciate you providing this link. I really don't think there is an issue here, but having something to reference makes it better.

Call the township hvac inspector.
 

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2015 IRC:

G2427.7.8 (503.7.8) Clearances. Minimum clearances from
single-wall metal pipe to combustible material shall be in
accordance with Table G2427.10.5. The clearance from single-
wall metal pipe to combustible material shall be permitted
to be reduced where the combustible material is protected
as specified for vent connectors in Table G2409.2.

For some reason I can't get a good copy/paste of it, but Table G2427.10.5 says 6" minimum to combustibles.
 

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2015 IRC:

G2427.7.8 (503.7.8) Clearances. Minimum clearances from
single-wall metal pipe to combustible material shall be in
accordance with Table G2427.10.5. The clearance from single-
wall metal pipe to combustible material shall be permitted
to be reduced where the combustible material is protected
as specified for vent connectors in Table G2409.2.

For some reason I can't get a good copy/paste of it, but Table G2427.10.5 says 6" minimum to combustibles.
Something like this

https://up.codes/s/clearance-reduction
 

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Discussion Starter #13
2015 IRC:

G2427.7.8 (503.7.8) Clearances. Minimum clearances from
single-wall metal pipe to combustible material shall be in
accordance with Table G2427.10.5. The clearance from single-
wall metal pipe to combustible material shall be permitted
to be reduced where the combustible material is protected
as specified for vent connectors in Table G2409.2.

For some reason I can't get a good copy/paste of it, but Table G2427.10.5 says 6" minimum to combustibles.
Probably can't get a copy and paste because of protection. Alot of those sites have that.

Thanks for the help.

I went and adjusted the pipe, today. Also realized it's 3", so it is now within specs.
 

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Here most of the time the code references the manufacturers spec's but even though many older work fine with 3" we are required to bump them up to 4".

I believe the BTU chart for chimneys and connectors is the reason. I was also told 3" gets too hot
 
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