Boiler in utility closet, hole to outside

amin1992

Hi guys hoping someone can help me out. We bought a bilevel home with the lower level finished. Inside the office is the utility closet with the boiler. It's probably about 12' x 5'.

It is pretty warm in there when the boiler is running. I see an opening to the outside on the exterior wall, about 6" diameter, that is currently shut off with a mesh and insulation.

Should I open this up? The utility closet door is usually shut, but there is a small vent cut into the wall of the closet (6" x 12" about). Not sure if that is enough for combustion air though and we keep office door shut because of the noisy boiler.

My worry is if I open this vent up to the outside, I will get bugs inside and also be letting freezing cold air in during the winter into a finished basement.

Is there anything I can do to the vent to only allow air in sometimes? So new to all this. Boiler tech who did the annual tune up said to just keep the office and utility doors open but that isn't an option. Thanks for the advice

amin1992

Wanted to add, the boiler is 115k BTU and the closet is approximately 390 square feet. The adjoining office is approximately 900 square feet.

My calculations show I would need 5750 square feet which seems impossible as that would equate to over half of the first floor! The door to the office is not airtight and has a inch gap below (hardwood floors) - would that help?

STEVEusaPA

No you do not have enough combustion air and risk either sooting up your boiler, sooting up your house, or pulling combustion air down the chimney and possible exposing you to Carbon Monoxide.

What type of burner/boiler? If you have a Beckett, they do make a combustion air kit for it and you can utilize the existing hole to the exterior.
https://www.supplyhouse.com/Field-Controls-CAS-2B-Beckett-Oil-Burner-AirBoot-Kit-2-0-GPH?gclid=EAIaIQobChMIhsLb772u5QIVGI7ICh1jYAotEAQYASABEgJ6p_D_BwE

They also make combustion air systems (CAS) that can be installed to provide combustion air to the burner.
https://www.fieldcontrols.com/fan-in-a-can-cas-3-oil-and-cas-4-gas/

amin1992

STEVEusaPA said:

No you do not have enough combustion air and risk either sooting up your boiler, sooting up your house, or pulling combustion air down the chimney and possible exposing you to Carbon Monoxide.

What type of burner/boiler? If you have a Beckett, they do make a combustion air kit for it and you can utilize the existing hole to the exterior.
https://www.supplyhouse.com/Field-Controls-CAS-2B-Beckett-Oil-Burner-AirBoot-Kit-2-0-GPH?gclid=EAIaIQobChMIhsLb772u5QIVGI7ICh1jYAotEAQYASABEgJ6p_D_BwE

They also make combustion air systems (CAS) that can be installed to provide combustion air to the burner.
https://www.fieldcontrols.com/fan-in-a-can-cas-3-oil-and-cas-4-gas/

Thanks for the response. I will look into the kit. However I looked at the "closed up" vent to the exterior. All that is over it is a piece of filter paper and some netting (to keep animals out?). I guess I didn't notice a draft as it isn't too cold yet. Here are two photos, one from inside and one from outside.

https://imgur.com/gallery/OioiI7t

When the boiler is on, I can feel cool air from outside being pulled inside. I suppose this is how the boiler is getting it's combustion air. What do you think?

STEVEusaPA

You can post the pictures right into your posts.
I think it's a band aid. Better to hook that right into the burner so the room doesn't have to feel a cold draft.
There should be an insect screen on the outside, and that intake should be above the expected snow line.
Inside you'll have a vacuum breaker on the pipe (looks like a small barometric damper) in the event the outside opening gets plugged, the damper will open to allow some combustion air, and to let you know there is a problem.
Carlin's new primary control can also be used to take advantage of their blocked vent contacts to additionally warn you of a problem.
For fresh air intake into the burner you generally want as long a pipe as possible to warm the combustion air, even if it means running it up to the ceiling, then back down to the burner.