Should I to use outside air and purchase an OAK?

[vermonty]

We're awaiting the install of our Hearthstone Green Mountain 40 along with an interior chimney later next month. I'm trying to decide if I should install an outside air kit as our 9 year old home is fairly tight. This stove has a 3" OAK available.
Unfortunately, our stove will be installed at an angle near a wall (but not in a corner). The back of the stove may be ~1-2 feet from the outside wall.
I just found an Energy Standards test that was performed on our house when it was built. Here are some 'air sealing' numbers from this document that may help in answering my question:

1. ACH50: 2
2. CFM50: 413

I can wait until the stove is installed to decide, but if you folks think it's a 'no brainer', I'll start planning for the OAK install now. If I do get one, I'd want to incorporate some type of shut-off of the outside air vent when the stove is not in use.

With thanks.

 

[begreen]

An OAK may be beneficial due to the tight house sealing. One thing to consider, is the proposes outside location for the OAK intake on the windward side of the house?

 

[NickW]

Yes, and there are damper mechanisms available.

Make sure it's insulated, to stay below stove level at the oak intake, and have a 'P' trap in the duct.

 

[EbS-P]

We're awaiting the install of our Hearthstone Green Mountain 40 along with an interior chimney later next month. I'm trying to decide if I should install an outside air kit as our 9 year old home is fairly tight. This stove has a 3" OAK available.
Unfortunately, our stove will be installed at an angle near a wall (but not in a corner). The back of the stove may be ~1-2 feet from the outside wall.
I just found an Energy Standards test that was performed on our house when it was built. Here are some 'air sealing' numbers from this document that may help in answering my question:

1. ACH50: 2
2. CFM50: 413

I can wait until the stove is installed to decide, but if you folks think it's a 'no brainer', I'll start planning for the OAK install now. If I do get one, I'd want to incorporate some type of shut-off of the outside air vent when the stove is not in use.

With thanks.

AHC50 of 2 is tight. Do you have any other fresh air vents/hrv?
I would install it.

 

[vermonty]

The vent would be located on the eastern side which is not the windward side.
We do have an ERV.
Can you explain why the recommendation for a P Trap?
Re: damper, I was looking at a dust collection blast gate. I'm open to other idea's.
Thanks!

 

[NickW]

Potentially a draft reversal in the chimney could result in the oak becoming a chimney. When I installed mine it was very clear in the instructions to have a 'P' trap and the intake below the stove.

Note that an oak is more restrictive on letting air into the stove and often will require air settings a little more open than the same setup without an oak. However, in a tight home it will definitely help with negative air pressure.

 

[begreen]

A p-trap is not normally specified for wood stoves that I have seen. It's more common for larger fireplace air intakes. In that case I think the P-trap is to trap incoming air so that the fireplace doesn't leak cold air when not burning. It may also act as a buffer to wind gusts?

 

[NickW]

I mentioned it because my Stratford 2 called for it, and a zc fireplace is basically just a stove enclosed in a metal case.

OP - On the fireplace the air intake is on the right side. The duct attaches, goes up, then down through the floor, attaches to the damper mechanism that's controlled by the wall mount, then out. The damper mechanism is above the 2x6 in the last photo.

 

[vermonty]

Attached are all the info re: OAK and Green Mountain 40 Stove

 

[Highbeam]

I would always install an OAK if it's reasonably possible. There are no drawbacks, only benefits.

I had one on my last Hearthstone stove and on that stove, a noncat heritage, every bit of combustion air came through the OAK nipple.

I see no reason to install a shutoff valve in the OAK duct. No reason to install a P trap either.

 

[GG Woody]

I like the idea of a blast gate type damper. Full open port to full closed, keep some insects and such out? Keep it close to the wall to limit ingress?
I made my own hoods for our stoves and left a void in the face of them to stuff a piece of filter media to filter dust and bugs.

 

[Highbeam]

I like the idea of a blast gate type damper. Full open port to full closed, keep some insects and such out? Keep it close to the wall to limit ingress?
I made my own hoods for our stoves and left a void in the face of them to stuff a piece of filter media to filter dust and bugs.

The bugs would just climb into your stove right? This oak is tight lined into the stove.

 

[stoveliker]

I like the (idea of the) capability to close the OAK.
I don't have an OAK myself (stove below ground level), but why have air flowing through OAK and flue (either direction) when the stove is not in use? Either it's adding warm air in summer or colder than the room-air in winter when the stove is not on.
Blocking that flow will only have good consequences, I think.
Though I do wonder about the effect of stagnant humid air in the stove in summer.

 

[GG Woody]

The bugs would just climb into your stove right? This oak is tight lined into the stove.

Theoretically yes, not mine as hopefully I've stopped them at the outside envelope with filter media. My upstairs insert F/A is piped into the old open fireplace clean out, so technically not attached right to the firebox. Basement stove is air gapped and I don't need additional dust, debris or bugs using that ingress point either. House is very likely more than leaky enough but I do like to have more than enough combustion air.
I work in a sheet metal fabrication shop, sometimes my ideas get out of hand...
I live in the forest, there's mice, and bugs, lots of dirt, dust and debris...
In the OP's regard, If I had a choice to have a cleaner combustion air pipe, I'd likely do it. I believe you can get a blast gate for under $5.

 

[Highbeam]

I like the (idea of the) capability to close the OAK.
I don't have an OAK myself (stove below ground level), but why have air flowing through OAK and flue (either direction) when the stove is not in use? Either it's adding warm air in summer or colder than the room-air in winter when the stove is not on.
Blocking that flow will only have good consequences, I think.
Though I do wonder about the effect of stagnant humid air in the stove in summer.

In the event of a chimney fire, you could cut the air off too. Not all stoves get all of their air from the OAK nipple but some do.

Air flowing through all summer or stagnant. I suspect the climate conditions matter a lot. A cold stove (AC in the home) passing hot humid outside air through if you live in Mississippi might create a huge rust problem but in milder climates like mine there is very low risk of any condensation.

I might agree with you about adding that valve. At least it's a neutral decision. If it's open all the time then there is no difference.