Air Intake on tank-less boiler

Inspected this Tank-Less boiler yesterday. I don’t see many of them but the ones I do alway have the air intake on the outside.
This one had it on the inside of the basement. The basement was only 25x25 and the only fresh air source is from the basement entry steps. There are no windows in the basement and also has the Evaporator/blower for the A/C.

My concern is the oxygen depletion in the basement. Without doing the math for ACH, i feel that this should be noted in my report.

Anyone else experience this?



50 cubic feet/1,000BTUH unless the listed device specifies otherwise.

So for yuks let’s assume the BTUH rating is 199,900 (round up to 200K) that’s 200*50=10,000 cubic feet. The basement is 25x25 or 625 square feet. If the basement ceiling is 16 feet or higher you’re GTG!

Me. I would pull the installation manual off the web and see what it has to say.

Thanks Chuck,

16’ Ceiling, LOL, no 7 at best.

I’ll call Tech Support.

I use as a quick general rule of thumb for any gas tankless water heater that uses internal combustion air, you need at least 10,000 cu. ft. of space around the unit.(basically what Chuck said)
Of course the installation manual should detail this, but the few I have inspected never come close to the requirement. I still verify using the instruction manual before I write up the deficiency.