OAK change draft?

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Kevin*

Kevin*

Burning Hunk
Nov 29, 2011
189
SNOHOMISH, WA
I just plumbed in the OAK today and started a fire. In the past I left the door cracked and the smoke would go right up the flue no problems. Now with the OAK installed smoke started leaking out the door so I had to close it. The fire didn't get going as fast as with the OAK not hooked up.

I've got the Lennox Performer 210 with 4 ft of double wall stove pipe then 2 45 deg's back to back and then 8 ft of chimney. The mfg say's 12-15 ft of draft but the shop i got it from said the stove will draft just fine with what I have.

I do not understand how the OAK makes the differences; I know there is one though. Do I need a few more feet of chimney?

Thanks,
 
You changed the temperature of the air that the stove has to work with so that will affect how the draft works.

If the stove worked fine before, I'd say play around with it a bit more to see if there are any other effects before you make any changes to the chimney.

You may just need to make changes to your starting procedure.

pen
 
8 feet of flue is usually not enough for many stoves and conditions. If the stove install manual is calling for 15', then you should follow the manual, or expect problems.
 
i've got a total of 12 ft, right at the min.
 
Hm, never thought about that, the OAK bringing cold air in means at rest (no fire) the chimney interior may get colder than the interior of the house... with the chimney at the minimum specified height it could be possible the house becomes a better chimney. No OAK means the interior of the chimney could never get colder than the interior at the house (assuming it's all insulated, sounds like this one is).

I guess at a bare minimum if the OAK is necessary for code, make sure your ceilings are well sealed (i.e. no leaks past light fixtures, etc through the attic) and consider adding more chimney height.
 
Kevin* said:
i've got a total of 12 ft, right at the min.
Click to expand...

But that is not straight up. Are the two 45's creating an offset to a ceiling support box or is the "chimney" a thimble, then 8 ft up? Also, it's not helping that our temps are not all that cold. I suspect that slapping another 3 ft of pipe on the top would help it behave a lot better.
 
Yeah, might have too, just reloaded and it smell's smoky in here, didn't see any smoke but... Also, i'm not getting the stove temps i used too. I will add some more wood as i have only been running it for 1 burn so far.

Saddly i installed it because city code says so, otherwise i would have saved the $100 or so.
 
Short-term, before you light a fire, maybe open a nearby window/door (not sure how much that would help with the OAK but it might help satisfy the natural draft of the house itself) and get a lot of newspaper burning inside the stove (produce quick, prolific flames) to preheat the flue. See if that improves things when you go to light the real fire/kindling load, and close the windows/doors when you do.
 
Kevin* said:
Yeah, might have too, just reloaded and it smell's smoky in here, didn't see any smoke but... Also, i'm not getting the stove temps i used too. I will add some more wood as i have only been running it for 1 burn so far.

Saddly i installed it because city code says so, otherwise i would have saved the $100 or so.
Click to expand...

Can you post a picture of the flue setup or describe it in more detail?
 
BeGreen said:
Kevin* said:
Yeah, might have too, just reloaded and it smell's smoky in here, didn't see any smoke but... Also, i'm not getting the stove temps i used too. I will add some more wood as i have only been running it for 1 burn so far.

Saddly i installed it because city code says so, otherwise i would have saved the $100 or so.
Click to expand...

Can you post a picture of the flue setup or describe it in more detail?
Click to expand...

001.jpg


just over 4 ft from stove to 45 deg then 8 ft of chimney above that.
 
Seems like an in-line shut-off for the OAK would be a suitable solution for the cons against it. I wonder what kind of downdraft it would take to reverse flow? Seems like it could happen under "perfect storm" conditions or in other words seems to me it would take more than just a strong wind or a storm.
 
Great, that helps a lot. That offset shouldn't be a major issue. It looks like the stove is burning pretty good at the moment. Even 2 ft. added on top might make a very nice difference. But the class A will need to be braced. There should already be one at the 5 ft level. Another will be required at 10 ft.
 
0012.jpg


Yeah, that excel pipe isn't cheap but it might be the fix. The stove is much more controllable now but i don't want to make a change till i get some "real" wood. I should be able to just adjust the roof brace up to the 5 foot mark then add 2-3 feet on top. sucks cause i really don't like that roof slop when it's wet.
 
I am for OAKs but I've always said, it is not a cure for a pressure deficit problem that is not caused entirely by the stove. If the neutral pressure plane is above the stove, the OAK can and will push smoke into the house. This is because the OAK is trying to be a make-up air source for the house. You need to fix the house and lower the NPP.

I had a perplexing pressure deficit problem one year when the make-up air vent for my HRV clogged and unbalanced the HRV causing it to not replace the air it sucked out.
 
Redbear86 said:
Seems like an in-line shut-off for the OAK would be a suitable solution for the cons against it. I wonder what kind of downdraft it would take to reverse flow? Seems like it could happen under "perfect storm" conditions or in other words seems to me it would take more than just a strong wind or a storm.
Click to expand...

I used 4" PVC and have a cap for the outside of the house when not in use.....that is my shut off. ;-)
 
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