Boiler question

[nate379]

Burnham SVG 85% boiler. Right now exhaust and intake come out back wall of garage which is near my bedroom. It is annoying to hear it come on.

I am looking at running the pipe through the roof instead. Last year I had an HVAC guy come out and said it would be expensive because the intake would need to be on the roof too. Said because it would be different pressures.

I have the book for the boiler and not mention about that, in fact can pull intake from inside and of course vent outside.

I tried to contact burnham thru referred me to several approved installers, well the list was ****, out of service numbers or places that shut down years ago.

What do you all think? Exhaust is 3" z pipe.

 

[Jackfre]

You may likely be able to vertically vent the boiler, but it is common and best practice to have the intake/exhaust in thw same pressure zone. It is a "balanced flue" concept. You are far better off with outside air for combustion. Can you install some sound baffling on the basement ceiling to minimize the noise. Z-vent is excellent pipe, but pricey.

 

[nate379]

Boiler is in the garage. It is quiet, just it's a power vent and the exhaust us loud. My neighbor has same boiler and u can here his running from my backyard 300-400 ft away.

Also gas company expressed concern that exhaust could enter attic through soffit vent.

Exhaust to roof would be about 8th higher than intake which I'd leave on the wall.

 

[Boiler]

A nice thick hedge do the trick?

 

[nate379]

Not sure how?

The garage is attached to the house and off the garage is a patio.

The house is about 15ft longer than the garage and that extra length is the master bedroom. Would put a photo but I'm not sure how to load them on here with my phone.

The exhaust is about head level, roughly 5ft from the wall of the master bedroom. Have been hit right in the face with hot exhaust before while BBQing on the patio and boiler kicked on.

 

[Jackfre]

While deciding how to proceed, if the gas company has made any statement of their concern, I would ask if you have good CO detection in the house?

 

[nate379]

Yup, required by code, 120v fire and CO detectors with battery backup.

 

[raspy]

The 85% power vented boilers have a lot of leeway on the venting system.

It's the condensing boilers that vent through PVC that are more touchy about intake and exhaust locations. And in those cases they will state in the manual if they require the intake and exhaust to be outside together or not. Some specifically say it is not needed and advertise that it's OK to use inside combustion air and outside exhaust termination.

Years ago I installed a power vented Burnham and used inside combustion air and outside termination. Never a problem with it. In fact, if the manual does not specifically prohibit it, the manufacturer thinks it's fine. Power venting gives about 1% better efficiency and it allows installations where the vent must go horizontal to get out of the building, or where there is some other problem that a conventional vent can't handle. But it doesn't mean you have to go out the side.

Just make sure you have a combustion air source that will never be blocked and of the right size for this burner. The normal is one high and one low. They can also come in through the roof as one pipe and tee near the ceiling and terminate near the floor. That counts as two. Drawing from under the house is fine too, provided they are upsized according to code and the crawl space vents are adequate.

 

[IGOTWUD]

Did you consider extending the existing pipe by adding a 90* elbow and run the pipe up the outside of the house above the roofline, and terminate away from the window? I have a 94+ gas furnace, and I wood move both. My furnace came with a termination kit.

 

[nate379]

Yes I did consider as a temp fix, but where it's located it would be very visable and also in the way. I have 18" overhangs plus a 4" wide gutter so it would be not close to the wall at all.

 

[raspy]

danski,

You say that combustion air setup will never work?

If you have a closed mechanical room in the middle of a house with no available air source, it certainly does work. That's why it's in the code as an available method. It supplies combustion and ventilation air (high and low fresh air). The exhaust gasses are much hotter, or are fan forced, and vent through a different pipe to the outside. Works fine.

 

[nate379]

Yes for sure that is allowable. That is the setup the contractor wanted to do, but again $2000 price tag.

I made contact with a Burnham installer and he is coming tonight to check it out. Said I should be able to do double wall 3" through the roof.

 

[nate379]

Huh? The intake is pulled from outside, up on the roof. Same pipe as the exhaust, just a pipe in a pipe and the middle is the exhaust and the outer is the intake.

 

[raspy]

danski,

We're kind of mixing two different systems here. Concentric and room ventilation.

I'm sorry you don't really understand what I'm describing, but your theories don't hold much water. Yes, codes do matter and they are based on reality. Broad generalizations about temperature and wind affecting attic pressure and "chimney" theory are fine, but sometimes broad generalizations based on limited knowledge miss the actual physics involved. Or miss the fact of what actually works. This arrangement is commonly done and works fine. I've used it for years and so have many others. It's not really valuable to tell someone it will "never" work.

How could it be that all those installations actually do work just fine?