Author Topic: high efficiency furnace - pipe clearances  (Read 4541 times)

woody organic

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high efficiency furnace - pipe clearances
« on: July 21, 2007, 08:59:32 AM »

Is there a certain clearance requirement that the pipes of a high efficency furnace and water tank need from the ground on the outside of a house?

I had one contractor tell me that 6 feet clearance is needed from the ground. Another contractor said 12 inches is all that is needed. This is a big difference. The situation seemed to indicate to me that something was not right for whatever reason.

So, I tried to tactfully bring dew point and condensation into the picture with the 2nd contractor. He insisted indubitably on the 12 inch figure. Also, he wasn't the least bit concerned that the air conditioner would be about a foot to 2 feet away from the pipes.

Is there someone that could please clarify clearances for me?

Thank you in advance for your responses.


Offline TECH X

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Re: high efficiency furnace - pipe clearances
« Reply #1 on: July 22, 2007, 07:22:54 PM »
Typically the manufacturer and gas code require that you have a minimum of 12" clearance from the vent to grade.

There is one Clause that may be of concern depending on where the vent pipe terminates.

Also note your furnace is considered a CONDENSING appliance. The water heater is a NON CONDENSING appliance.

This is from the CAN/CSA-B149.1-05 Natural gas and propane installation code,

Clause 8.14.8 - A vent shall not terminate
(a) directly above a paved sidewalk or paved driveway that is located between two single-family dwellings and serves both dwellings; This does not apply to non-condensing appliances;
(b) less than 7 ft above a paved sidewalk or a paved driveway that is located on public property;

Offline Fitter597

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Re: high efficiency furnace - pipe clearances
« Reply #2 on: August 04, 2007, 09:19:13 PM »
All the installations instruction I get say at least 12" above average snow fall, also you need to consider your venting codes for your city.,
I'm in Chicago, code is weird here, you need 5 ft from any opening in the home, windows doors etc, also can not be an eye sore to the surrounding home owners. Also if you are drawing outside air for combustion intake and exhaust they need to be with in 18" of each other to draw from the same atmospheric pressure.

Offline Ron

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Re: high efficiency furnace - pipe clearances
« Reply #3 on: September 06, 2007, 03:02:18 PM »
The manufacturer provides the installation instructions with the furnace.  These must be followed.

I was born illiterate but after Mom sent me school that changed.  Tough, but we got a handle on it now.