Venting a high-efficiency boiler
We’ve installed a mod/con boiler. The specs say it can be vented directly through the back wall, and in fact this is the preferred method over venting through chimney. But neighbor objects to the “smoke” (water vapor) blowing into her yard — it’s at least 15 feet from her windows and door. This seems to…
We’ve installed a mod/con boiler. The specs say it can be vented directly through the back wall, and in fact this is the preferred method over venting through chimney. But neighbor objects to the “smoke” (water vapor) blowing into her yard — it’s at least 15 feet from her windows and door. This seems to be a gray area in the code. Have others run into problem with back-wall venting of mod-con boiler? Must the boiler be vented through the chimney (which would mean lining 4 stories with PVC pipe)?
Silvermax,
What boiler do you have?
Check your equipment spec’s, in that much direct vent equipment is unable to be routed up a chimney, unless you only mean to utilize the current chimney as the path for the correct pipe. The exhuast is not hot enough to draft itself up a flue.
JMiles: good info re intake and exhaust — they are currently proximate, but if we vent out the chimney, they won’t be.
123go: We most certainly have a permit, and approved plans. It’s not venting out a side wall, but the back wall of an addition, at a considerable distance from my neighbor’s windows and door. We are acutely aware of having drawn the DOB’s attention — given my neighbor’s response to this reno, it has been unavoidable. Ultimately, we want to arrive at a solution that satisfies all parties without breaking the bank. Judging from other people’s experiences, I’m concluding that venting through the chimney may be the only solution. JMiles’s info regarding air intake adds a further complication to the situation, however.
Thanks for your support, SteamMan. I keep reminding myself that renovation is just a temporary lifestyle, not a forever thing, and this too shall pass.
It would appear you didn’t get a permit, so why mention the DOB code? Also, that boiler’s burning gas – the exhaust is not just water vapor. Its very difficult to get approval to vent out a side wall on any building other than detached 1 and 2 families. Since you mention 4 stories, that doesn’t seem to be your situation (though I could be wrong). Either way, you have now drawn the DOB’s attention. Might be something you’d want to straighten out asap.
We just finished installing a Weil-McLane Ultra 3 condensing boiler, and I had one (another company) in our last house, as well. The most critical issue for these is having the exhaust and intake in the same (proximate) place, such that pressure differences don’t influence the boiler (ours is 299k BTU, and uses 4 inch PVC for both inlet and outlet, and they go to the roof, through the entry and the corners of the upper floors. Check your manufacturers installation directions very carefully, because in our old house, having the inlet and outlet in separate places led to etching the glass in a bathroom window 10 feet from the chimney.
Second thing to pay attention to is the need for a drain for the condensation in the chimney (did I mention that this contains sulfuric acid?).
Jeff Miles
Few points here:
1- You are dealing with world class pains in the A&$es (your neighbor and the DOB)
2- I can’t imagine it would be THAT expensive to get down the chimney with 4 lengths of PVC. Support it at the top and at the bottom and you should be fine.
3- Please remember there are no better smoke blowers than DOB inspectors. They don’t care if your boiler is a coal burner converted to oil, a wood pellet stove, a methane burner at a DEP plant or a mod/con gas burner. It’s all the same to them. They come out, blow smoke and get back in their little white cars and leave.
What gets me some bent is the ignorance factor. Wow, this isn’t even my job and I’m upset! Look, now I’m venting. I hope your jackass neighbor doesn’t call DOB on me.
-SteamMan
Thanks, SteamMan. I’m hoping others will weigh in as well.
The boiler is vented exactly according to manufacturer’s specifications. My neighbor has been informed that it is water vapor, but she continues to call it “smoke” or “fumes,” and so did the first DOB woman, repeatedly. It will still blow into neighbor’s yard since we can’t control which way the wind blows in. The second DOB woman — two days later — said she would see what her colleague had said.
My feeling is that DOB inspectors are not that familiar with these new boilers, and I’m wondering what other people’s experiences have been. Or do we just bite the bullet and vent it up the chimney, same as old-style boilers? But of course, to do that, you have to first line the entire chimney — four stories — with PVC pipe, which is very expensive. And, according to the mfr, totally unnecessary…
Silvermax,
15′ is more than sufficient. Sounds like a situation that might be dealt with through educating your neighbor as to what is coming out of the vent and perhaps the code requirements. Other than that it is a question of how far to push one’s neighbors.
Also: NYC Fuel Code 501.2.2 gives some indication as to the spirit of the law.
See also 502.5 and 503
-SteamMan