Venting smoke from boiler room

[700renegade]

Looking for some ingight here. I have a 60x60x18' man cave under construction and am going to partition off a 13x13x8' tall room for an EKO 40. I'll put in a 7' wide OH door to the inside of the shed so I can shove dry wood in there in empty totes w/ the skid steer. OH and man door to inside of shed are to keep smoke and dust contained in boiler room.

I'd like to power vent the room somehow so smoke and dust doesn't end up in the main shop when I refill and clean the boiler. I was thinking of a 16" or so fan ( maybe 2000+ cfm ) near the ceiling with gravity shutters thru the exterior sidewall, but the thought of that uninsulated aluminum shutter clanking away every time the wind is blowing isn't the best. Got them on a number of barn fans and they drive you nuts. I do have an exterior window I plan to open so the room doesn't go too negative while the fan runs.

With the cavern of an attic that I have - 120' of propper vents and ridge vent - do you think I could get away with simply ducting the air up into the attic and letting it dissipate up there? The attic volume is 10X the volume of my boiler room, and I hope the amount of smoke is modest. There may be some moisture effects or something I'm not thinking of now though.

How is everyone tackling this - ideas appreciated......

 

[taxidermist]

NOOOOO on the ducting it into your attic!! one spark and you will have to build a new house. That is advise from a firefighter. If you can run vent all the way to the attic you could do like i did and add a attic fan to the roof top and duct your pipe right to it. Mine works great.
https://www.hearth.com/talk/threads/my-smoke-hood.59029/#post-736920

Rob

 

[woodsmaster]

NOOOOO on the ducting it into your attic!! one spark and you will have to build a new house. That is advise from a firefighter. If you can run vent all the way to the attic you could do like i did and add a attic fan to the roof top and duct your pipe right to it. Mine works great.
https://www.hearth.com/talk/threads/my-smoke-hood.59029/#post-736920

Rob

I'll second not venting it to the attick. It could cause other problems besides the fire issue. condinsation for one.

 

[slim]

Simple experiment would be to pressurize the room from the window with a fan blowing in so to force smoke up the chimney. If not, a fan pressurizing from the shopside & an open window may do the trick.

 

[maple1]

I don't think you'd need a fan near that big.

I'd consider a smaller fan, built into the window opening. Duct it to a hood above the furnace door. Run the fan only when the furnace door is open, or maybe also for a little while after it's closed if some smoke spills. If you keep the window closed & the room tight, the air will draw under the garage door if you keep it open a crack. That will create an airflow from under the garage door to the exhaust fan (or the garage door to the funace air inlet then up the chimney when the fan is off), and should keep the dirt moving the same way too.

Thinking out loud...

 

[Medman]

I am using a 250 cfm fan above the eko and it is not enough to capture all the smoke/ash/dust that is generated when loading or cleaning the boiler. I am upgrading to 1600 cfm this summer. I have it vented up through the attic to the outside through the roof, and I have a make-up air duct that runs inside. I often leave a window open a crack as well, just to keep the temp. managable inside the room.

 

[taxidermist]

I have a 1600 cfm and it dosent keep all the smoke from entering the room sooo if you want to vent it up and out go big and make the hood go out over the door a little more than mine does.

Rob

 

[goosegunner]

Has anyone tried to create a Venturi effect in the stack with a fan?

Hobbyheater's jet stream boiler uses that principle I believe.

I really want to try and reduce the smoke during loading with my Econoburn.

gg

 

[heaterman]

Off topic here but you are probably going to need a combustion air supply in a room that small as well as something to vent the smoke. Figure a direct opening to outside of 1 square inch per 1000 btu of capacity. So if you have a 150K boiler you should have an opening of 150 sq inches. Adequate combustion air and a good stack will go a long way toward eliminating the issue you are concerned with.

PS: ...........I know it's hard but don't open the feed door when the thing is burning....

 

[700renegade]

Thanks for the replies so far. Just to be clear, the fan I was (originally) contemplating was going to be at the ceiling 8+ feet away from the boiler. Arranged as a whole house fan would be. Hopefully no sparks or embers would be that far away to get blown into the attic, but I agree it is still a poor idea.

For those of you with hoods and suction over the EKO door, are you satisfied with that approach or would you simply vent the entire room if you had to do it over. It sounds like you still need decent CFM even with a hood. If 1600 isn't enough on a hood, I'd assume 5000 CFM (24" barn fan) on the whole room wouldn't be overkill. An advantage with venting the whole room is that I can get rid of ash dust when cleaning it out.

Since I don't have the exterior steel on that corner of the shed yet ( trying to obtain decent aluminum louvers for wall ) I may throw in a cold air intake louver near the floor and and keep the window closed. I'll have to research how best to duct it to form a cold trap.

 

[taxidermist]

Thanks for the replies so far. Just to be clear, the fan I was (originally) contemplating was going to be at the ceiling 8+ feet away from the boiler. Arranged as a whole house fan would be. Hopefully no sparks or embers would be that far away to get blown into the attic, but I agree it is still a poor idea.

For those of you with hoods and suction over the EKO door, are you satisfied with that approach or would you simply vent the entire room if you had to do it over. It sounds like you still need decent CFM even with a hood. If 1600 isn't enough on a hood, I'd assume 5000 CFM (24" barn fan) on the whole room wouldn't be overkill. An advantage with venting the whole room is that I can get rid of ash dust when cleaning it out.

Since I don't have the exterior steel on that corner of the shed yet ( trying to obtain decent aluminum louvers for wall ) I may throw in a cold air intake louver near the floor and and keep the window closed. I'll have to research how best to duct it to form a cold trap.

if you vent the entire room you will pull smoke across the whole room. Where if you duct over the top of the boiler then vent out you will pull all the smoke close to the boiler.
Rob

 

[maple1]

I've got a hood, and it's only hooked up to a small fan - I think less than 300cfm. There are times when it isn't enough, but those are infrequent. With a good hood design, you don't need a lot of CFM's - especially if you're careful about when you open the door.

 

[woodsmaster]

Off topic here but you are probably going to need a combustion air supply in a room that small as well as something to vent the smoke. Figure a direct opening to outside of 1 square inch per 1000 btu of capacity. So if you have a 150K boiler you should have an opening of 150 sq inches. Adequate combustion air and a good stack will go a long way toward eliminating the issue you are concerned with.

PS: ...........I know it's hard but don't open the feed door when the thing is burning....

150 square inches seems like an awfull big hole. You may need that for a natural draft But with my biomass I crack a window open an 1 1/2" that is 18" wide so 24 square inches is what I use in a fairly tight building and it works great. I don't see any improvement in operation with the window opened further. I wouldnt want that huge hole opened to the elements in the winter. As far as a smoke hood goes I've learned not to open the door unless it's down to coals so I don't need a hood.