Indoor Air loss after burn complete

[OldHickory]

Directed at those of you who have overnight fires but do not continue burning in the morning.

In the morning my stove might be 100F with an ember or two...but the fire will have been out for 2-3hrs. The air supply on the stove is still open & I've been thinking that a semi-warm stove & masonry flue is probably capable of drafting a fair amount of heated room air out of the house during my daytime absence. Therefore, if the fire is sufficiently finished & not smoldering, I've been shutting the damper on the stove in the mornings if I can remember to do it. However, I know that there is also some self-regulating secondary air intake that I cannot shut off.

This brings up the question whether an outside air intake could avoid this heat loss for intermittent fires? Wouldn't the air intake then only suck OUTSIDE air up into the warm (but cooling) masonry flue which would avoid heat loss? It seems like when your stove is not up to temperature at startup and cool-down, an air intake from somewhere other than room air would improve the overtall efficiency of having a fire.

Any thoughts and comments? Does anyone else damper the stove after the fire is out to avoid heat loss?

 

[fossil]

..It seems like when your stove is not up to temperature at startup and cool-down, an air intake from somewhere other than room air would improve the overtall efficiency of having a fire.

An outside air kit (OAK) will improve the overall heating efficiency of the stove/room system regardless of the stage of burning. Rick

 

[Highbeam]

Yes. You are right. An ourtside air intake has the benefit of not exhausting the room air 365/24/7 with or without a fire. I'll give you another point: if you have a crawlspace and you take combustion air from that crawspace through an OAK then you are adding a powerful ventilation system to actually exhaust that stagnant air.

We work so hard to get our chimneys to draft well. Construct them very tall, straight up with positive slope, so that they have a natural draft. That's why the smoke immediately runs up the chimney when you start a fire. Well that 6"+ flue pipe is moving air ALL the time and you can't stop it from pulling through the secondary system of your stove.

Realize that in the summer, the outside air is less dense than the cold air in your home so your chimney's draft will be weaker. An inline stovepipe damper (is that what you mean when you say damper?) would be one of the only ways to slow this loss of inside air.

Good thinking. Go get an OAK.

 

[burntime]

Get up a half an hour earlier and stoke the fire and forgetaboutit Or turn your air intake all the way down before bed.

 

[Todd]

I hooked up OAK to both my fireplace and stove last year and found it made a big difference in heating efficiency. House stays warmer longer after fire dies out. I highly recommend them not only for a tight house, but a leaky one as well.

 

[CantAfford$5Oil]

Hi, Newbie here -

Is it possible to install an outside air kit on an insert that will be put into an existing masonry fireplace that is caddy corner up against two poured concrete foundation walls without drilling through the foundation, the firebox walls, or the chimney? I am thinking about if the insert ever is taken out would there then be a hole to fill from where the outside air kit had been installed?

Thanks!

And thank you very much to all who responded to my other much longer post about models to choose from! I'll be back there later.

 

[savageactor7]

OldHickory has got me thinking, even though I burn 24/7 in the winter now I'm rethinking an OAK...I use to think they were bogus...now the jury out again.

 

[fossil]

...Is it possible to install an outside air kit on an insert that will be put into an existing masonry fireplace that is caddy corner up against two poured concrete foundation walls without drilling through the foundation, the firebox walls, or the chimney?

There's gotta be a hole someplace, because you need to run a continuous duct from outside the living/heating space to the insert/stove. And the woodburning appliance you choose has to be one which allows for this option. Boring a 3" hole through masonry isn't all that big a deal, just beyond the capabilities of most DIY'ers. Your stove intaller can advise, it's possible they can even do it for you, or they'll direct you toward someone who can. But, yes, you need a hole. Unless...your existing fireplace happens to have an ash clean-out door in the floor that dumps into a space accessible from outside, then that could possibly be adapted to serve. Rick

 

[fossil]

OldHickory has got me thinking, even though I burn 24/7 in the winter now I'm rethinking an OAK...I use to think they were bogus...now the jury out again.

Well, savage, just think about it for a moment. You already know that the fire needs lots of air for combustion to take place. And you spend a good deal of time and effort trying to warm the air in your living space. Without an OAK, all the air for combustion is coming from the living space, so it's air you've put a lot of energy into (so to speak) in more ways than one. Then it's through the firebox and up the stack and gone. Your stove isn't going to pull a significant vacuum on your house, so all the air that the stove consumes has to be made up somehow to keep the pressure inside your house pretty much the same as outside...so you're pulling outside air into your house from wherever it can find a way (and air is pretty darned small!) to replace all the air the stove's using and sending up the stovepipe. More accurately, the atmoshphere is pushing air into your house through every single little crack and crevice it can find to keep your house at atmospheric pressure, even as your stove's doing everything it can to evacuate the space, thanks to the good draft of a properly installed and operated stove. An OAK is by no means a bogus idea or some sort of gimmick. That said, I don't currently run one on either of my stoves, though I'm considering retrofitting the Lopi with one later this year. Rick

 

[Girl]

Get up a half an hour earlier and stoke the fire and forgetaboutit Or turn your air intake all the way down before bed.

Thats what I do!

 

[CantAfford$5Oil]

That's kind of what I thought you'd say - no such luck on the outside clean out box as the chimney is internal to the house - only the very top that goes through the roof can be seen from outside the house, maybe four or so feet of chimney up on the roof. Where would the best place be to drill through - the firebox and foundation, or higher up into the chimney so they only have to drill through the shingles, chimney and flue liner (not the actual house foundation)? That they could drill from outside, though it would make me nervous they'd really damage the clay flue liner. Is it even possible to do either scenario? Thanks!

 

[fossil]

...Where would the best place be to drill through...

I can't even venture a guess at an answer to that question, for a host of reasons. It'll depend on the exact configuration of the existing structure, and the configuration of the insert/stove you choose. The professionals on-site will advise, I'm sure. Good luck! Rick

 

[burntime]

You are stressing out too much. I am in Wisconsin in a 1957 brick ranch. If the fireplace has the 6 inch liner and you are burning right the air control is usually choked down... My home stays warm to 20 below last winter. Now when you start a fire at first there is minimal gain but once it is going ok and you choke it down you gain heat.

 

[OldHickory]

Well, it sounds like we have some proponents for an OAK, which is something of a surprise to me. I've read some strong arguments against it (maybe on heat.org?) because the air-tight stoves are supposedly drawing limited amounts of air. These arguments don't consider loss of air during periods when your stove isn't fired that I recall. Glad to see that my point was considered... the stove is drawing air up the flue ALL the time and especially after the flue has been really hot and the fire has died.

>Highbeam wrote:
>"An inline stovepipe damper (is that what you mean when you say damper?) would be one of >the only ways to slow this loss of inside air."

No, Highbeam just my main air intake all the way down when my fire is out in order to stop a draft into the semi-warm stove & up the flue. Last season when cleaning, I contemplated adding an in-line damper, but the ones I've seen are NOT totally occlusive. They have holes so that you can't accidently block your stovepipe/flue completely. My conclusion was that it would not justify me adding it.

Despite the arguments I've seen against an OAK, I think it seems more sensible to have. My natural gas furnance has it! It also seems that if I heat the air inside the house with additional outside sourced air then the heated indoor air would expand and create positive pressure and actually PUSH air out of the house instead of drawing it in. I'm not too sure if the OAK would provide ALL the air (primary and secondary intakes) needed for the stove. If it did, then it certainly should eliminate my concerns for heat loss after an intermittent fire. If it did not, then I'd be back in the same situation. Hearing that some of you have had a noticeable improvement in efficiency would probably justify the trouble to get one installed though.

I'm likely relocating before burn season & my stove & hopefully my seasoned wood is coming with me. When I get there, I anticipate trying to get an OAK installed!

Anybody out there have an OAK installed on a Jotul F600 (non-catalytic)? (if so, does the OAK provide air to the main intake AND the self regulating, non-adjustable secondary intake as well?)

Also, I didn't hear anybody saying whether they also close the damper on their stove when not firing to avoid heat loss with a warm flue?

 

[burntime]

If you can do one then it will help. If you can't I would not lose sleep over it. The oak is more for the airtight new homes so it does not create a negative presure. Negative preasure will do odd things. Water heaters will not exhaust right, vent fans will not work well... Oak also introduce COLD air into the fire, its gotta cool it somewhat. If the oak is easy, heck give it a try, if not, forgetaboutit!