Cold Air Trap
#1
05-23-09, 08:57 AM
Cold Air Trap
I know there was a thread some time ago that mentioned how to size the vent for a cold air trap. I'm putting a new door and window in the boiler room and am afraid it will be too well sealed up. I'm running a Becket AFG with a 1.0 nozzle @ 150 psi (1.25 gph) and since the boiler is underfired the air settings are not open very far. I'm hoping a dryer-style vent with 4" diam vent line will do the job....
#2
05-27-09, 07:00 AM
Mike, grab an install manual for any of the regular (non-direct vent) oil fired boilers. In the front section they usually have the formula for square inch opening vs. burner BTU's.
A 4" ID pipe is has an area of 12.6 Sq-In. My thought is that the 4" duct in a cold trap is more of a supplemental air supply. But may be all that is required.
Can also get boot system that attaches to the burner. These are then connected to the outside via 4" ducting. The burner pulls all of it's air via the duct. Field Controls makes these.
Al.
A 4" ID pipe is has an area of 12.6 Sq-In. My thought is that the 4" duct in a cold trap is more of a supplemental air supply. But may be all that is required.
Can also get boot system that attaches to the burner. These are then connected to the outside via 4" ducting. The burner pulls all of it's air via the duct. Field Controls makes these.
Al.
#3
05-27-09, 12:12 PM
it is 1 sq in. per 4000 btu's. You need the difference of what is required and how much you have.
The room the appliance is located in is 50 cu ft per 1000 btu's. If the room does not supply enough the balance must be brought in from the outside.
The area of a pipe is pi(r2)
Pi = 3.14
to square a number you multiply the number by itself.
or
sq in = 3.14 x r2
If we are using 4" pipe the radius is 2"
so it would look like this
Sq In = 3.14 x (2 x 2)
or 2 x 2 = 4
4 x 3.14 = 12.5 sq in.
For more info see link
Combustion_Air_Calculation
The room the appliance is located in is 50 cu ft per 1000 btu's. If the room does not supply enough the balance must be brought in from the outside.
The area of a pipe is pi(r2)
Pi = 3.14
to square a number you multiply the number by itself.
or
sq in = 3.14 x r2
If we are using 4" pipe the radius is 2"
so it would look like this
Sq In = 3.14 x (2 x 2)
or 2 x 2 = 4
4 x 3.14 = 12.5 sq in.
For more info see link
Combustion_Air_Calculation
