Re: boiler room make up air
IMO all mechanical rooms containing gas fired appliances should have a combustion air supply direct from outside. An intake with an interlocked fan/damper is more efficient but unnecessary unless your code calls for it. I would just use an appropriate sized non-mechanical intake. In your case, a 6” round flexible duct terminating within 1’ of the burner would be sufficient.
You will never expand your mind, if you do not challenge your beliefs.
By the reading of this post, you acknowledge and agree that the poster shall not be responsible or liable, directly or indirectly, for any damage or loss caused or alleged to be caused by or in connection with use of or reliance on any content contained herein.