Author Topic: Sidewall vent termination argument  (Read 5354 times)

Offline hottubbrad

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Sidewall vent termination argument
« on: November 28, 2013, 03:01:57 PM »
We are having a disagreement as to the distance from a condensing boiler sidewall vent (110k BTU) from a ventilated soffit verandah open on 3 sides..  One of my guys says 1' and the other says 3'.  Can you confirm what the TSSA wants....?  I thought 12" from a non-vented soffit and 24" to a vented soffit......

Thanks

Offline Admin

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Re: Sidewall vent termination argument
« Reply #1 on: November 28, 2013, 03:51:43 PM »
What is the make and model of the boiler? 

Clause 8.14.8(h) applies to appliance vents installed underneath the floor of veranda's, porches or decks.  Are you venting the boiler above the veranda floor?

If the installation manual specifies clearances to soffit than the manual would be more stringent than the gas code and would have to be followed, as per Clause 4.1.4.

The installation manual would list the vent termination clearances to things like inside and outside corners, soffit, above and below veranda's etc...  The picture below is from a furnace manual that actually requires 12" from the appliance vent to a permanently closed window!  You never know what you'll find in the installation instructions.

I was told that Enbridge is concerned with wood rot and now considers ventilated soffit to be a building opening and does not want appliance vents installed near the ventilated soffit.  I don't think Enbridge should be worrying about wood rot, as a vent can terminate 1' from the bottom of a wooden deck, which has never been a problem in the past.

Quote
Clause 8.14.8 - A vent shall not terminate

(g) within the following distances of a window or door that can be opened in any building, of any nonmechanical air-supply inlet to any building, or of the combustion air inlet of any other appliance:
(i) 6 in (150 mm) for inputs up to and including 10 000 Btuh (3 kW);
(ii) 12 in (300 mm) for inputs from 10 000 Btuh (3 kW) up to and including 100 000 Btuh (30 kW); and
(iii) 3 ft (900 mm) for inputs exceeding 100 000 Btuh (30 kW); and

(h) underneath a veranda, porch, or deck unless
(i) the veranda, porch, or deck is fully open on a minimum of two sides beneath the floor; and
(ii) the distance between the top of the vent termination and the underside of the veranda, porch, or deck is greater than 1 ft (300 mm). 

According to Enbridge if the appliance exceeds 100,000 BTU's you would need 36" clearance from the appliance vent to ventilated soffit, or 12" if the appliance was 100,000 BTU's or less.

I agree with Enbridge that ventilated soffit, by definition, could be considered a building opening but I don't really agree with this interpretation because technically Clause 8.14.8 doesn't mention clearances from appliance vents to building openings.  Clause 8.14.8 mentions clearances to windows or doors that can be opened and air-supplies etc...  In my opinion any air that might enter the vented soffit would not communicate with the appliance or the livable portion of the house so the soffit could not be considered an air-supply.  The word air-supply, found in Clause 8.14.8(g) is bolded, and it's definition clearly says with respect to the installation of an appliance.  Vented soffit would have no bearing on our appliance.  Only Clauses 8.14.10, 9.3.3 and Table 5.2 mention clearances to building openings and they apply to pool heater vents, cylinders and relief devices.  If you were installing a pool heater, then Clause 8.14.10 specifically refers to a building opening, so you would need to keep the pool heater exhaust 10' from the vented soffit.

Quote
Air supply (with respect to the installation of an appliance) — combustion air, excess air, flue gas dilution air, primary air, secondary air, and ventilation air.

Building opening — a planned aperture that is intended to permit air infiltration but does not include an exhaust vent or a non-openable window.

You can call Enbridge's Technical Desk - 1-800-924-5534 or TSSA's Technical Department - 1-416-803-3391.  They might be able to clarify things for you.

Offline hottubbrad

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Re: Sidewall vent termination argument
« Reply #2 on: December 02, 2013, 06:31:06 PM »
It is a Vitodens WB1B 118k BTU max.

Their manual basically quotes the same thing you said.  (attached)

This is an LPG install so thankfully Enbridge will not be adding their 2 cents.....

Looks like 12" minimum is the right answer.
Thanks.  Much appreciated.

Offline Admin

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Re: Sidewall vent termination argument
« Reply #3 on: November 02, 2016, 03:18:35 PM »
If you look at the B139 Oil Code the Clause 8.14.8 equivalent is Clause 4.3.2.2.

Quote
Clause 4.3.2.2 A vent shall not terminate,
(c) within 1.8 m (6 ft) of an openable window, door, or mechanical air supply inlet, including soffit openings, to any building;
Note: When not in operation, exhaust equipment can inadvertently provide a passage that allows fumes or products of combustion to leak into a building.
(j) such that the flue gases are directed at combustible material or any openings of surrounding buildings that are within 1.8 m (6 ft);

It's very strange that out of all the gas exhaust vents only a pool heater, mentioned in Clause 8.14.10, has a specified clearance to a building opening.  I believe all gas exhaust vents should have minimum clearances to building openings, and Clause 8.14.8 should be amended to include the word building opening.

Offline Porcupinepuffer

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Re: Sidewall vent termination argument
« Reply #4 on: November 02, 2016, 05:49:49 PM »
When we had a similar issue in the past, we had placed a piece of white aluminum flashing within the required distance to make the ventilated soffit unventilated just within the required footage to be code. It works out perfectly on the standard white ventilated soffits and you can hardly notice anything has been done. You can cut the piece to overlap under each lip and you only have two barely visible joints on the sides.
You still end up with enough ventilation that there's no issue for the roof.