I have a wall mounted high efficiency boiler. It is direct vented with 3 inch PVC outside the house. I am going to be adding a sink and need to vent it quickly, can I tie into this, or will it cause my boiler to run less efficient?
If I cannot tie into this I am wonder if anyone knows if an AAV is legal in Minneapolis, Minnesota? I would prefer to not have to redo this in the future
Got to be the best post of the year
That would not be the best idea you have had this year, nor the smartest one. I can just imagine someone doing that, and then using AAV's on all the other drains and wondering why NOTHING drains properly while the boiler is operating.
I know you wouldn't have posted this if you understood the implications of doing it. Quick answer is for a quick vent use an AAV if only for the one sink. May not be code so you might want to check it out with the city first. They are not quiet btw.
Problems with connecting the vent to the boiler vent=
When the boiler fires, it will have positive pressure running in the vent. This could/would cause the exhaust along with the CO and combustion by products to push its way through the sink's p-trap and cause deadly gas to be released inside your home.
The vent from the sink will be connected to the main sewer line which has methane gas and odors. When the blower is in between cycles, the methane could be vented back inside your boiler. When ignition occurs- bang! There is no p-trap on the exhaust vent so it could also fill the room with methane along with the sewer odor.
Last edited by Daltex; 01-05-2010 at 03:04 PM.
Not only that all boilers that are electronically ignited have a prepurge time of the fan to clear the combustion chamber of any gases.
And on top of that you need the proper mixture of air to methane to combust it. So is it possible that you could ignite methane from the sewer inside the combustion chamber and have it explode all the way back into the city sewer..... absolutely not.
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All the other articles (glanced over them quickly) were caused from someone actually down inside the main sewer with an open flame or another source of ignition like a short in some underground wiring. Again they were all basically from 80+ years ago too.
So I don't think any of those articles prove what I said is wrong. I'm not saying sewer gas can't be explosive but the chances of a HE boiler with a positive vent pressure lighting up your neighbourhood's sewer is 0%.