Question about direct venting height above the ground

Jersey2

Looks like I will be getting a high efficiency boiler with direct venting. My question is, how low to the ground can the vent out the wall be? Is it okay for the bottom of the vent to be 9 or 10" above the ground? I didn't think to ask the contractor/sales guy that question. My house has very little clearance from the ground grade to the floor, just barely 12". I guess the installer will figure it out, and not have to make the vent go through the floor into a bedroom, and through the bedroom wall.

pecmsg

 12 - 24” above the average snow line. 

Venting is listed in the IOM and MUST be followed!

STEVEusaPA

To add, there's also clearances to windows, doors, vents, inside corners and heights above public walkways that need to be followed. As well as specs for combustion air inlet.
Just because it comes out at 9" doesn't mean it can't be elbowed up.

EBEBRATT-Ed

you will get different answers from different people. Originally they used to spec a height above grade. Then a few years later they remembered it snows in much of the country.

Same thing with the condensate. When they first came out with condensing appliances they said it was harmless like you could drink it if you wanted to. Later they decided it ate steel and copper pipes and now we have condensate neutralizers.

So you have to find your average snow line which you can do on line. Then follow the MFG instructions. It can be elbowed up, but I wouldn't go higher than necessary

HomerJSmith

If you don't do concentric venting which I recommend you don't do, then you can come out of the building at any height and go vertical when you exit the building to a height above the snow line. You would have 2 vents out of your building, one intake and one exhaust. Your instructions should explain this.

Jersey2

Thanks guys, I didn't realize they could be elbowed and raised with a 90 degree. I did call the contractor after I posted this, who looked at my system today, and he said yes there is enough room for it.

Jersey2

HomerJSmith said:

If you don't do concentric venting which I recommend you don't do, then you can come out of the building at any height and go vertical when you exit the building to a height above the snow line. You would have 2 vents out of your building, one intake and one exhaust. Your instructions should explain this.

In the proposal it lists a Concentric Vent Termination Kit 3". So it appears it will be concentric venting.

EBEBRATT-Ed

@Jersey2

The reason some don't like concentric venting is under some conditions (wind etc) is many cause flue gas recirculation. Flue gas coming back in through the fresh air intake. Talk with your installer

Jersey2

EBEBRATT-Ed said:

@Jersey2

The reason some don't like concentric venting is under some conditions (wind etc) is many cause flue gas recirculation. Flue gas coming back in through the fresh air intake. Talk with your installer

I will talk to them about that. And it also sounds like a concentric vent has to be straight out the wall, not able to put an elbow on it to raise it upward.

EdTheHeaterMan

Power venting and Direct venting have different rules. (basically the difference between outside combustion air and outdoor combustion air). The manufacturers instructions will have the minimum dimension requirements. Each product follows a standard format and will include a diagram like this in the Venting section of the I/O manual

The standards are also available from the publication NFPA 54.

Jersey2

Thanks Ed

JUGHNE

I had a job that was a house remodel.
Condensing furnace, the sill plate was at outside grade level.
The exhaust and inlet pipes were brought up inside thru the floor at the outside wall.
The pipes then exited the house at about 3' above grade.
The pipes inside were gracefully boxed in with a 2 x 6 stub wall about 3' high in the bathroom. This then was made into a shelf along that outside wall, to look as if it was in the plan.

This kept the vertical risers within the heated house.
If placed outside then the entire height of the piping is subject to freeze up.
That is the main concern with the "periscope" vertical extensions that require insulation and still can have freeze up problems.
(Also look like sh&t on the exterior).

HomerJSmith

Good Job!

rick in Alaska

If it is gas, and I assume it is, then talk to your gas supplier as they have their own rules about what is allowed. They will let you go a certain distance out and up, but it depends on how cold it gets in your area. And when you tell them the book says you can do this, they will probably laugh at you and leave. They are the authority having jurisdiction, unless the main code is more stringent.
Rick

Jersey2

I think I am going to get a conventional cast iron boiler after all. They seem to last longer and there is less maintenance. The only thing is, it is a lot more expensive to install. Had another contractor over who installs slantfin boilers. From reading, slantfins seem to be good. Do any of you have a slantfin? It would be the Sentry model.

Steamhead

We've installed some Sentry boilers. No issues so far, and Slant/Fin is good to deal with.