Make up air for boiler shed

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goosegunner

Minister of Fire
Oct 15, 2009
1,469
WI
I am working towards automating my system with the addition of storage. I need to find out a way to bring additional air into my 12' X 16' boiler shed.

Last year I kept the fire going all the time so it was plenty warm enough to keep the window open a little bit to bring in additional air.

This year I will be doing burns hopefully once but probably twice a day. Their will be long stretches where the boiler will be off so I don't want to leave the window open.

What are your methods to bring in additional air?

gg
 
One method I read about last year was a duct in the outside wall. The inlet is near ground level outside, the outlet into the room is near the ceiling. This is supposed to make a heat trap that keeps cold air from freely entering the room when the boiler is not running. My boiler shed is far from air tight so I have a thermo cube that turns on at 40F and runs a quartz floodlight (or maybe a chicken brooder lamp ;-) ) on my critical piping near the floor. That is the only area I have had a problem with freezing initially. Of course, I am not in the frozen north like you.
 
Yes I remember reading about the heat trap. I will have to place it carefully, I get some pretty strong winds. It's not very cold here yet but it's coming soon.

My boiler room is fairly tight, r19 and drywalled. A double door and one window. It is connected to my larger building but there is no common entrance or air.

gg
 
Hi goose,

Could you hook up a small draft blower, piped from outside, that turns on when the blower on the stove is on and turns off when it shuts down? Only need a 2" or 3" column of air at the most I would think. Probably could use a valve similar to the one in my grinder pump, when the pump kicks on it pushes waste past a ball type valve in the pipe, and when it shuts off the "ball' falls back down and closes the pipe so it doesn't drain back down. Theory should work the same, with suction from the blower pulling ball up and when blower turns off ball falls down stopping air from coming through. Just a thought.

Brandon
 
Good idea, it would cut down on the size of opening needed.

Econoburn recommends 200 sq inches of air vents. That is a lot on a 40 mph wind -10 degree night.

gg
 
When I threw out my Wood Gun in 1989 I just dragged everything into a pile and called the junk man. The one thing I wish I had kept was the combustion air actuator motor. I have thought of 100 uses for it since that day.
 
I run 24/7 (no storage) so this is a new thought for me. I left the gable ends open, so there is always plenty of air. :bug:

I don't completly understand your setup . . . what water is going to freeze if your room actually got down below freezing?

Seems like we want the warmest air possible going into the primary CC . . . what about a small W2A HX near the peak, with ducting and an in-line induction fan to bring that pre-heated air down to your inlets? Then install a couple of automatic gable vents - installed backwards - to allow air in. Wire the induction fan to only run when your boiler blower is on??

Probably not the best idea you'll get, but maybe spark some other ideas??

Jimbo
 
ISeeDeadBTUs said:
I run 24/7 (no storage) so this is a new thought for me. I left the gable ends open, so there is always plenty of air. :bug:

I don't completly understand your setup . . . what water is going to freeze if your room actually got down below freezing?

Seems like we want the warmest air possible going into the primary CC . . . what about a small W2A HX near the peak, with ducting and an in-line induction fan to bring that pre-heated air down to your inlets? Then install a couple of automatic gable vents - installed backwards - to allow air in. Wire the induction fan to only run when your boiler blower is on??

Probably not the best idea you'll get, but maybe spark some other ideas??

Jimbo

I am not worried about freeze up because the water is still moving in the pipes for load and the boiler holds heat for quite a while. My main concern is keeping it as warm as possible. The window is near the boiler so it the boiler will cool down much faster with the window open. Restarts are a lot easier if the boiler is hot.


Your idea about the bringing in air only when fan is running is good I just need to figure out how to get it done.

gg
 
I had a leftover exterior dryer vent from building my house. I mounted that in the top of my wall separating my boiler room from wood storage in my out building. when the draft really starts pulling it opens a bit, keeps my boiler room from going negative pressure and dosnt lose warm air when the boiler fan is off, cheap, simple, effective. Not nearly the size opening recomended, but the room isnt otherwise airtight either. you can get largewr ones for venmar ect if the room is really airtight.


EDIT:
If a person needed to duct this to the exterior instead of a wood storage area (like i did) you would need to put another vent (non louvered) on the exterior wall to keep gusts of wind from blowing snow in.

http://www.pexsupply.com/Fantech-COM5P-COM5P-Plastic-Supply-Exhaust-Hood-Combination-Pair-5-Duct
 
Fred61 said:
http://www.grainger.com/Grainger/wwg/search.shtml?op=search&N=11697&in_dim_search=1

Thanks, Those look like they would work. What would you do to tie it to your fan operation?


gg
 
goosegunner said:
Fred61 said:
http://www.grainger.com/Grainger/wwg/search.shtml?op=search&N=11697&in_dim_search=1

Thanks, Those look like they would work. What would you do to tie it to your fan operation?


gg
Just tie it in to the circuit that causes your combustion fan to spin. I used one several years ago in a spray coating application. They're nothing but a small gearmotor so I don't think they draw much current. You can check that out. If it has low current draw and doesn't need a relay, anyone who is able to wire a single pole switch can wire it in.
 
I just wanted to add here that a standard 4" dryer vent opening is not enough make-up air if your space is tight. My shop is R23, new construction and sealed tight. I put in a 4" make-up air vent with heat trap and it works but does not supply enough air for the EKO 25. I have one of the windows open all winter as well. I have been looking for better solutions, so I appreciate all the ideas given here.
 
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