Venting issues

See that white thing just above the back object? That is the boiler vent. The object just above that is the water spigot, and if you look up toward the corner along the same wall you can see the woodstove air intake. Still buried is the intake/exhaust for the HRV unit. I was able to stand on the snow and easily touch the roof

Our car. We got a near record amount of snow for a March storm

This morning we were awoke by the not-quite-full-on smoke alarm signaling intermittently. Not smelling smoke we quickly opened the doors and a bunch of windows in case it was a CO alarm, which it actually seems to have been.

We quickly ascertained that the boiler vent had been covered over by the prodigious snowstorm we experienced last night and today. The boiler is able to detect when the vent is blocked and will shut itself down which would prevent an accumulation of CO.

I suited up and went out to shovel the vent out. The amount of snow covering this thing was stunning. What was curious was the fact there seemed to be a bit of a bubble, for lack of a better way to describe it, around the vent. In other words there was a non-snow space that I shoveled into when I got near the vent pipe. What this makes me think is that the heat of the boiler vent gas was kind of creating its own little pocket under the snow and perhaps this was the reason the boiler seems to have not actually shut down, hence the CO alarm.

With the vent cleared and the house thoroughly aired out we shut the doors and windows and felt okay about the situation. It was a bit later that it occurred to me to check the HRV air supply duct as well. Like the boiler vent, it was also burried, and like the boiler vent it seemed to have it's own little air-space pocket in the snow once I reached it. Like the boiler vent it is venting warm-t0-hot air, so it makes sense.

We take this stuff absolutely seriously; I was aware of these potential problems when the installation work was done, but I got a bit of resistance and didn't push further about locating the venting higher up. I wish I had. The task now is to correct it.

To that end I'd already put in a call last week to the plumber about the situation, so we are going to correct it. On the upside, we are grateful for the alarm system and glad it works.

Dedicated Air

Air to supply the woodstove comes in through this duct hood...

...then passes under the first floor and up to the woodstove...

...then into a little add-on air-supply box under the woostove where the stove draws it's air. Once combusted, the fumes travel up the stove pipe...

...into the insulated pipe in the second floor living space and up through the roof...

...and back out to the great outdoors, having never mixed with the interior air

A key element required of a super-tight super-insulated house is insuring a dedicated air supply to all combustion. Likewise all combustion needs to have a dedicated vent route, also isolated from the interior air.

Two examples of this principal are the propane boiler in the basement which has a short in-and-out combustion air supply and the woodstove on the first floor. The woodstove, unlike the boiler, is located in the middle of the house so there is a good measure of ducting running from the outside supply hood to the woodstove and then exhausting from the wood stove up the stovepipe to the insulated stovepipe and through the roof. I've been quite careful to make sure the whole run is tightly sealed so that the woodstove is only pulling air from outside and only venting to the outside. I don't want any leaks.

The not-really-resolved aspect of this equation is the propane-fueled gas stove-top range. The air supply is the ambient household air, and the venting, such as it is, will be a hood mounted over the stove top. This will all work okay, but it isn't ideal. If we run the hood, we'll need to open a window or door to allow air in so as not to create a negative air pressure in the house which could then result in a back draft in the woodstove. We have carbon monoxide detectors on both floors even though they are not required by code since there will be a small amount emitted by the stove.