[brianosaur]

I need to add a low mount air combustion vent and a high mount air exchange vent, both to the outside, in my enclosed oil fired boiler utility closet.

The spec stickers on the Peerless boiler state the max at 129k btu's.

If I need 1"sq/2000btu's for horizontal duct that would be a 65sq in.
8"x8" or 10" round.

If possible, I would instead like to add a 4" round with an in-line duct fan to save what little space I have.

How would I convert the additional cfu's from the fan into the amount of square inches I need and know what size cfu fan to get?

 

[Plumber101]

If I understand you right you are going to bring combustion air from the outside of the house.

 

[brianosaur]

Yes.

Trying to figure size of 'intake' duct and in-line duct fan needed.

 

[beenthere]

Adding a 4" round with an inline fan would not meet code. Since if the fan failed, the boiler would still run. Unless you have an interlock that prevents the boiler from running unless the fan is running.

What are you calling "a high mount air exchange vent"?

 

[Plumber101]

Adding a 4" round with an inline fan would not meet code. Since if the fan failed, the boiler would still run. Unless you have an interlock that prevents the boiler from running unless the fan is running.

What are you calling "a high mount air exchange vent"?

I think he is saying one horz duct high and one low.

If I were to do this I would have motorized dampers with proving circuits so you can shut off the cold air when not in use.

 

[beenthere]

I think he is saying one horz duct high and one low.

If I were to do this I would have motorized dampers with proving circuits so you can shut off the cold air when not in use.

That would be the better way to do it.

 

[brianosaur]

Okay, than would you recommend a CAS-3 Fan-in-a-Can instead?

 

[beenthere]

Yes, it has an interlocking switch. That must prove the fan is bring in air before it wil allow the burner to operate. Its UL approved.