OAK Damper/Shutoff

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wjohn

Member
Jul 27, 2021
211
KS
As I come close to completing the installation of my VC Aspen C3, someone had previously mentioned that a shutoff on the OAK might not be a bad idea. I tend to agree since there is no manual air control on the stove - it is all adjusted automatically by a bimetallic spring that pulls on a chain that in turn opens the internal damper more or less depending on temperature. In the event of something bad happening it would be nice to be able to completely put the brakes on the air.

I did some digging around and found that folks on here have used everything from all metal duct dampers to PVC gate valves. I like the idea of the better seal I would get with something PVC, and I think that would hold up okay if I basically mounted it at the wall, well away from the stove. Alternatively I could go with an all metal one like this: 4" Damper

I haven't worked with those before, ever, and am unsure if they would seal well enough for the close to 100% air shutoff I am looking for. I'm open to everyone's thoughts and suggestions.
 

EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
I don’t think complete sealing is very important. You are at most working with 0.2” of water column pressures. Really If it’s an overfire you are wanting to stop just stepping on a crushing a short piece of flex duct probably will do the trick. If you are looking for burn rate control the C3 wasn’t a great choice. I really don’t see a need to have any input control on the OAK except for an over fire. A damper is the better choice for draft regulation.

One of those sliding metal gates for 3 or 4” is all I’d be looking for.
 

begreen

Mooderator
Staff member
Nov 18, 2005
93,149
South Puget Sound, WA
Leave the stove alone. Work with it and learn how it works in all winter conditions. The stove may be fine. The operator still controls the amount of wood the stove is fed and the size of the splits. If more control is needed after learning how the stove burns, then add a key damper to the flue.
 

wjohn

Member
Jul 27, 2021
211
KS
Sorry if I wasn't more clear. I am only looking for something to put the brakes on the air in the case of an overfire, or perhaps a rare night with very strong east winds (right into my intake). I am not looking for something I would be fiddling with during normal use.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
28,441
central pa
Did not know those existed - blast/guillotine gates. I'll look into those as well, thanks.
Usually used for dust collection in woodworking
 
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wjohn

Member
Jul 27, 2021
211
KS
I don’t think complete sealing is very important. You are at most working with 0.2” of water column pressures. Really If it’s an overfire you are wanting to stop just stepping on a crushing a short piece of flex duct probably will do the trick. If you are looking for burn rate control the C3 wasn’t a great choice. I really don’t see a need to have any input control on the OAK except for an over fire. A damper is the better choice for draft regulation.
Actually, it was you who suggested thinking about this in my thread ;)

OAK Air Control
 
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EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
I’m not sure everyone understands Kansas wind. Never needed a compass all the tree pointed north. ( if you could find one;)
 
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wjohn

Member
Jul 27, 2021
211
KS
I’m not sure everyone understands Kansas wind. Never needed a compass all the tree pointed north. ( if you could find one;)
Sometimes it blows out of the north in the winter, for a few days, haha.
 

wjohn

Member
Jul 27, 2021
211
KS
I found this - cheap and I can pick it up locally. It is not metal but I am thinking I can mount it on the wall and at that point it is only ~4" away from the intake hood which is also plastic anyways. This will also hopefully address the very unfinished hole in my drywall around the duct. There was no need to finish it previously since it was hidden behind the framing/structure for the old prefab fireplace.

Menards 4" Blast Gate
 
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Sailrmike

Feeling the Heat
Sep 20, 2017
295
06371
I found this - cheap and I can pick it up locally. It is not metal but I am thinking I can mount it on the wall and at that point it is only ~4" away from the intake hood which is also plastic anyways. This will also hopefully address the very unfinished hole in my drywall around the duct. There was no need to finish it previously since it was hidden behind the framing/structure for the old prefab fireplace.

Menards 4" Blast Gate
This is what I would recommend, too bad it's not in stock right now Screenshot_20211021-113307_Chrome.jpg
 

semipro

Minister of Fire
Jan 12, 2009
4,156
SW Virginia
I have an outside air source on our stove and experienced an over-fire once.
I was able to go outside and stuff a rag into our outside air intake to slow the burn.
Just mentioning this in case you want to see how things go before installing a gate valve.
 
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NewGuy132

Member
Jan 22, 2021
92
Central MA
Shouldn't the auto temp sensor shut down the intake or at least slow it down in case of an over-fire?
 

wjohn

Member
Jul 27, 2021
211
KS
Shouldn't the auto temp sensor shut down the intake or at least slow it down in case of an over-fire?
That I am not sure of. I have a hard time thinking they could've designed it to completely shut off after reaching a certain temp. Yes, it does decrease how much the intake is open as temperature rises, and conversely opens up as it cools (I presume starting a fire from dead cold would be the maximum opening situation). I suspect there is probably some minimum amount of air allowed through once it reaches X temperature, but I'm really not sure what that temp is or if it would continue to be fully shut after an even higher temp, to be fair.
 

NewGuy132

Member
Jan 22, 2021
92
Central MA
That I am not sure of. I have a hard time thinking they could've designed it to completely shut off after reaching a certain temp. Yes, it does decrease how much the intake is open as temperature rises, and conversely opens up as it cools (I presume starting a fire from dead cold would be the maximum opening situation). I suspect there is probably some minimum amount of air allowed through once it reaches X temperature, but I'm really not sure what that temp is or if it would continue to be fully shut after an even higher temp, to be fair.
That was just an assumption by me. I honestly have no idea if it would close it down enough. I bet you are right and it would still be open a little. You’d have to ask someone at VC to be sure.
 

begreen

Mooderator
Staff member
Nov 18, 2005
93,149
South Puget Sound, WA
I think it is safe to assume the stove is designed to not smolder which snuffing out the fire could easily do. If air was introduced at that point the risk of a puffback increases greatly. Most likely there is always a small amount of air at the fire for this and to keep the glass clean.
 
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wjohn

Member
Jul 27, 2021
211
KS
I took a look tonight while getting things in place. Unfortunately my pics ended up being terrible, but you can just barely tell there is a round hole and another hole from the punchout that gets bent over for the chain retainer in the damper plate. These would still allow air through when the damper is fully closed.

The air intake hookup is kind of weird - the manual says to use 3" diameter ducting, which fits inside of the cylinder. There isn't a great seal there so I'm sure a small amount of room air will be sucked in at that interface between the duct and the face on the intake that it seats against.

The OD is a bit too small to get 4" duct to clamp down around it.

I did buy the black plastic blast duct from Menards and got it mounted on the wall tonight. I think it will do what I intend, provided not too much air is leaking past the duct/intake interface.

20211022_181746.jpg
20211022_182005.jpg
 

EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
I took a look tonight while getting things in place. Unfortunately my pics ended up being terrible, but you can just barely tell there is a round hole and another hole from the punchout that gets bent over for the chain retainer in the damper plate. These would still allow air through when the damper is fully closed.

The air intake hookup is kind of weird - the manual says to use 3" diameter ducting, which fits inside of the cylinder. There isn't a great seal there so I'm sure a small amount of room air will be sucked in at that interface between the duct and the face on the intake that it seats against.

The OD is a bit too small to get 4" duct to clamp down around it.

I did buy the black plastic blast duct from Menards and got it mounted on the wall tonight. I think it will do what I intend, provided not too much air is leaking past the duct/intake interface.

View attachment 283785 View attachment 283786
I bet you can seal that up if you feel the need. The air intake area when fully closed isn’t very big. from what I am seeing, the two holes, I’m guessing are the primary and secondary air. It’s nice to see it controlling the secondary air. In principle I really like this system. Kept us posted how it burns.
 
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