Thread: Attic heating unit

I cannot find anywhere (nfpa 211 or flue gas code) that a 80% heating unit vent pipe is permitted to breach a chimney liner in an attic. This home also has a water heater and heating unit in the basement. Need help on this one.
Rich

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I don't know the answer but I believe it should be metal flue through the chimney because of corrosion it can cause to the ceramic.

I do see water staining in the roof sheathing around the chimney. Roof Leak?

Rich, the IRC does allow common venting in multistories. There are many rules and calculations involved in section 504 and appendix B. There are numerous illustrations and the IFGC commentary.

BTW, you should refer to those furnaces as "draft assisted"--not "mechanical draft", which sounds like a positive vent pressure unit.

You can route B-vent as a vent connector into a masonry chimney breeching as long as the B-vent mfr. allows it and it is removable for inspection. That means it cannot be permanently cemented in. The end of the connector however must be cemented flush to the face of the flue lining. There also must be a cleanout below the breeching, The connector must be properly supported. When in an attic, you must use B-vent as a connector per the code so no single walled pipe.


HTH,
Bob

For those new to home inspecting should you ever need to locate visual evidence of roof leakage when you get into the attic area head for the fireplace chimney penetration. It's almost a sure bet, especially if the chimney is masonry.

So Bob are you saying you can vent a B-Vent into a masonry chimney.
The gases doesn't effect the mortar?
The gases doesn't effect the clay liner? No spalting?
Can it be vented in a chimney with no liner?

This is good info to know and thank you for your time.

Looks like a silly installation to me. Why not just run the vent straight up and out the roof? Why connect to the masonry chimney at all?

Most likely it was installed there because it was a easiest termination point compared to cutting through the roof.
Also one less place for a leak. But I know that wasn't there intent.

You can vent into any chimney only if it meets the class of service. A level II inspection will determine this. Even if the chimney is lined with terra cotta with perfect joints, it may still warranty a liner just for sizing. Yes, the condensate will attack any masonry chimney. Yes, there should be a listed liner installed that this B-vent attaches to.

All chimneys must be lined--period. Whether the original clay tile liner suffices or if it needs to be relined is determined by the Level II.

HTH,
Bob

Richard

No one has addressed the units in the basement, are they sharing the same flue??
Also second concern is how tall is the chimney once it has penetrated the home??

Kevin T Stewart
F.I.R.E. Inspector #020

Yes, they are sharing the same flue as the units in the basement. I just received an e-mail from another F.I.R.E certified inspector that stated this is an improper installation. I really need a definitive answer.
Rich

Rich,

Section 503 of the International Fuel Gas Code - Venting of Appliances

“503.6.10 Gas vents serving appliances on more than one
floor. A common gas vent shall be permitted in multistory
installations to vent Category I appliances located on more
than one floor level, provided that the venting system is
designed and installed in accordance with approved engineering
methods. For the purpose of this section, crawl
spaces, basements and attics shall be considered as floor
levels.”

I believe the remainder of Section 503, 504 and appendix B contains the information you asked for. As you can see from those sections there are multiple considerations and requirements to meet before giving a definitive answer and I believe your post did not contain sufficient information for anyone here to make a fully informed judgment.

Bob Harper did recommend a Level II to determine if this installation meets proper requirements, and that appears to be the best (and expert) advice given.


Jim

Thanks Jim,

However these are the codes I was looking for.

M1801.11 Multiple-appliance venting systems. Two or more listed and labeled appliances connected to a common natural draft venting system shall comply with the following requirements:

1. Appliances that are connected to common venting systems shall be located on the same floor of the dwelling.

Exception: Engineered systems as provided for in Section G2426.

G2426.10.4 Two or more appliances connected to a single vent. Where two or more vent connectors enter a common gas vent, chimney flue or single-wall metal pipe, the smaller connector shall enter at the highest level consistent with available headroom or clearance to combustible materials.

Rich