Thread: Boiler vent through foundation wall

At an inspection today I came across an oil fired boiler with a single walled vent pipe that penetrates a concrete foundation wall to another section of the house, which then terminates into a masonry chimney.

I know that the aluminum foil has to go, but is there anything wrong with a vent pipe terminating into a chimney that is located in another room?

Is a vent thimble or sleeve with annular spacing required for a concrete wall penetration?

Is single walled vent pipe OK in this application? (both sides of the foundation)

Anything else that is a problem?

Looking for your input for my report.
Thanks

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It's vented, sealed, properly sloped and not touching combustibles...I don't see the issue.

Answer, to some degree, depends on code in force at time of installation:
NFPA would allow passage through the non-combustible wall provided it is not a required fire partition. Sometime back in the nineties it was modified to required the "unexposed" portion within the wall to be stainless steel (or eq).
IRC says the chimney connector must be within the space the appliance is located, but then lists approved methods to pass through a wall. Those methods vary depending on the listing of the appliance.
Also note the reducer installed in the connector and be sure to verify proper sizing. I would suggest a complete inspection of the chimney and connector by a certified chimney sweep.

No issues, WTH ?!?

First off if that is indeed single wall, and an oil-fired appliance, that would not be vent or vent connector, but a CHIMNEY CONNECTOR.

Stated SW, oil burner?!? galvy for Oil?!? Uknwn stack temps, zinc burnoff, not to be used for chimney connector for oil fired, if SW galvy, unkwn listing, therefore no, without contrary info..

Not buying in. Multi-family, hmmm.

Tape doesn't belong on the vent above the boiler.
The aluminum foil obstructing the thimble is not allowed.
Snaking unprotected on the floor, crimp. Unsupported to long, flex.
Big Orange Tag, someone removed big red one?

Where's the draft control?

Unknown elevation re: grade, height, overall length, etc. Unknwn if block chimney is i/s or o/s, Unkwn Lined or shared status of "chimney", questionable breaching. Note ash/c.o. door and deterioration/rust streaking, hard to scale looks more than 12" below breaching.

Boiler codes, fuel codes, mechanical codes, chimney.

Analysis and corrections by a qualified party Level II, likely III. Definately not right, definately "issues" requiring attention.

Mass. is pretty highly regulated, and doesn't allow DIY fitters, etc. Obviously some unqualified work and safety concerns.

The issues I see:

The chimney connector (the single wall pipe between the boiler and the flue/vent) needs to connect to the flue in the space where the boiler is located (2009 IRC M1803.3). As installed, the chimney connector connects to the vent outside of the room the boiler is installed in. The chimney connector also needs to be fastened together with screws.

24ga single wall galvanized pipe is acceptable for use as a chimney connector (Table M1803.2).

However, single wall metal pipe is not approved for use as a vent. In your photos, the piping between the chimney and the foundation wall has to be approved as vent pipe. Type L is acceptable for use as an oil-fired vent, provided the boiler is listed and labeled for venting with Type L (Table M1804.1).

Never seen an expansion tank on the return side of the boiler. Check manufacturer's instructions.

M1803.3.1 Floor, ceiling and wall penetrations. A chimney connector or vent connector shall not pass through any floor or ceiling. A chimney connector or vent connector shall not pass through a wall or partition unless the connector is listed and labeled for wall pass-through, or is routed through a device listed and labeled for wall pass-through and is installed in accordance with the conditions of its listing and label. Connectors for oil-fired appliances listed and labeled for Type L vents, passing through walls or partitions shall be in accordance with the following:

1. Type L vent material for oil appliances shall be installed with not less than listed and labeled clearances to combustible material.

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

See also 1806 clearances unlisted SW @ 18" and 9" if used with appliance listed for L vent, and reduction of clearance provisions in chapter 13.

Originally Posted by H.G. Watson, Sr.

M1803.3.1 Floor, ceiling and wall penetrations.
<snip colorful reply>

I stand somewhat corrected. Either way, single wall not approved outside the wall as it is not listed nor labeled, nor through a listed and labeled sleeve. So the vent must extend into the room or you have option B.

I guess we are agreed that there is no problem using single walled galvanized pipe (edit: as a chimney connector) with oil-fired boilers?

First of all, single walled G-90 galvanized steel pipe is THE standard chimney connector for oil burning appliances is the US. Now, NFPA 211 states the acceptable gauge metal based upon diameter. Up to 6" diameter, you can use 26 ga., which btw is the most common ga. found across the country. From 6-10, it must be 24 ga., which is actually hard to find these days and a little harder to work with.

This appears to by a typical Weil-McLain Gold boiler, which usually has a 7" appliance collar meaning the connector must be 7". It appears to downsize right at the chimney. You can downsize the liner ONLY if permitted by the mfr. Functionally, I will share with you that downsizing WM Gold series boilers, esp. oil burners, is asking for trouble. Even though the boiler may be firing at say 0.85 GPH, which normally might call for a 5" liner, that size would probably cause blowback and spillage with this series boiler. Not to single this one make and model out for demonization but to illustrate my point that different boilers behave differently.

As for the pass-through issue, let me just add my thoughts on the functional side:
First of all, why pass through a wall when the chimney backs up to the Combustion Appliance Zone? Why didn't the installer punch through the wall into the chimney in the CAZ?

As Jim noted, connectors buried in masonry should be stainless steel. From my daily experience, 100% of all galvanized steel connectors cemented into masonry walls rust and rot out where you cannot observe this decay. Inevitably, homeowners jaws drop when I reline a chimney and pull the rusted out connector from the foundation wall breaching. Whether passing through a wall or into a wall/ breaching, it should be stainless steel. Note that with connectors, you can drop one gauge size for stainless steel so 26ga. ss is good up to 10".

There should not be any joints buried in the masonry. How are you going to disconnect pipe when the screws are mortared into the wall? The answer is, you can't, therefore that section goes uninspected or serviced. In the case with a typical chimney breaching, the portion entering the masonry should be one piece back into the flue where it must be flush with the inner wall face and fullly grouted with refractory mortar, which it NEVER is. I repeat--NEVER! I do see a lot where the galv. connector protrudes well into the flue or even all the way across until it touches the far wall. Often, you'll see a 3" connector for a gas WH above the boiler/ furnace connector where it protruded too far so the gases from the heater accelerate the rotting of the WH connector, which begins to crumble and block the WH's exhausting and also the furnace's discharge into the flue.

These connector defects can best be revolved by the installation of a listed liner. Very, very few masonry chimneys can pass a Level II inspection without a listed liner so you should be looking for this closely on all inspections or recommending the level IIs.

The boiler was probably set too close to the wall to allow for a proper offset and return of elbows. You need some room for service, inspection and combustion analysis.

HTH,