CO2 - AirThings Monitor & Atmospheric Boiler

DJDrew

We have an atmospheric boiler in a utility room within our finished basement, recently we installed an AirThing monitor in the finished part of the basement, everything is looking mostly fine, however this past week the temperatures dipped and the boiler started running we noticed a coincidental spike in the CO2 level.

Whenever the boiler runs, the CO2 on the AirThings monitor goes up significantly. Normally the CO2 is 450-500ppm, but when the boiler runs, it consistently jumps to 600-675ppm. The basement is on it's own heating zone that is not normally on, so the temperature of the space is not changing much when the boiler runs. (I can verify this by looking at the graphs of temperature overlayed on CO2.) We have two CO monitors, both in the boiler utility room and those have never gone off.

Is this something I should be concerned about? The CO2 levels themselves don't look to be of a huge concern, but it seems strange there is a noticeable spike. The boiler was checked with a probe in the stack last fall and came back as normal according to the technician. The service tech will be back doing the annual boiler service in the next week or so, anything I should ask them about to specifically check?

Just an odd observation, any thoughts? Is it normal?

Jamie Hall

Assuming that that really is CO2 -- people do get it mixed up with CO -- what I would be interested in is what is the CO2 level elsewhere outside the utility room? What I'm thinking is that it may be higher in the rest of the space, and what you may be seeing is the running boiler pulling air into that space.

DJDrew

@Jamie Hall I updated the photo, this really is CO2, not CO. The AirThings monitor is in the finished part of the room.

Are you suggesting that perhaps it is because air from other parts of the house is being pulled downstairs and thus increasing the CO2 while the boiler is running? I hadn't thought of that.

Jamie Hall

DJDrew said:

@Jamie Hall I updated the photo, this really is CO2, not CO. The AirThings monitor is in the finished part of the room.

Are you suggesting that perhaps it is because air from other parts of the house is being pulled downstairs and thus increasing the CO2 while the boiler is running? I hadn't thought of that.

Exactly.

neilc

or is the boiler scary to look at?
mechanical room?
is there adequate make up combustion air piped in ?

Teemok

Check the boiler, yes. Small leaks can be hard to prove. Every breath you take, all humans take, adds co2 to the air. Vent the house well, close it all up, with all humans gone, fire boiler and see if you still get a co2 spike.