#11  
Old 01-05-2010, 09:22 AM
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Default Re: Indoor Kitchen and WFO

You may get some information from these builders
STOVEMASTER - Custom Design and Construction of Masonry Heaters

Rod
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  #12  
Old 01-05-2010, 11:49 AM
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Default Re: Indoor Kitchen and WFO

Masonry heaters have a very clever closed loop system, with both the outside air input and flue tightly closed off after the wood is burned off to conserve the heat in the masonry unit. I'm not sure how that would work in a WFO.
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Old 01-05-2010, 02:53 PM
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Default Re: Indoor Kitchen and WFO

As far as your options for incorporating an air intake, google "outside air kit" and you'll find lots of good info and options for units that could probably be repurposed or retrofit for a WFO application...
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Old 01-05-2010, 03:35 PM
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Default Re: Indoor Kitchen and WFO

Here's a very interesting article from woodheat.org It's about masonry fireplaces, but remember, from a building code perspective, a WFO is a masonry fireplace.

The money quote:

Quote:
Makeup Air
While improper design and location is a major cause of poor fireplace performance, tighter house construction and powerful exhaust fans must share some of the blame. By installing vapor barriers and using doors and windows that have sealing gaskets, builders commonly reduce air leakage by more than 75% compared with the standard construction of 20 years ago. And homes are now commonly equipped with high-volume exhaust fans, such as those in downdraft kitchen ranges, which can move air out of the house at a rate of 600 cubic feet per minute (cfm) or more. Because tightly sealed house walls will not allow this much air back into the house through leakage, these powerful fans create negative pressure that can cause a chimney to backdraft and fill a house with smoke (Figure 4).
One standard fix for smoky fireplaces has been to install a supply of outdoor air in the belief that air starvation is the root cause. While lack of combustion air may be a problem in some cases, supplying outdoor air to the fireplace through a duct is certainly not the cure. Two research studies, one conducted in Canada on a series of factory-built fireplaces and one done in the U.S. on a masonry fireplace, looked into the behavior of outdoor combustion air supplies. In both studies, the fireplaces were installed within chambers that could be depressurized continuously after a fire was lit. As the fires died down to charcoal, technicians monitored carbon monoxide readings in the chamber to see when exhaust began to spill from the fireplaces. Tests were done with and without combustion air supplied from outside the depressurized chamber. No consistent difference in spillage timing or amount could be found whether or not outdoor air was supplied.
Here's the link to the Rumford.com article I referred to earlier in the thread.
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Old 01-06-2010, 07:57 AM
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Default Re: Indoor Kitchen and WFO

Thanks DMUN. Interestingly enough I had contacted John Gulland (author of that WOODHEAT.ORG). He got back to me and advised against putting an oven in the house. My situation of running the oven in my basement kitchen would have 2 x 90 degree elbows (top of oven back to wall to exterior chimney and then up) and he suggests with the amount of smoke oven's create on start up, that it would likely fail. He suggested a power exhaust fan on the chimney might make it work (additional $1500). The Chimney and exhaust fan will likely be around $6,000 alone (I arrived at this figure using the online Sentinal Chimney configurator and added the $1500). He speaks form experience as he too has an outdoor oven but would not consider one indoors. He also suggested that a WETT certified professional would not be able to pass judgement on the design because an oven is beyond that of a fireplace and chimney and there are no relevant code provisions and suggested I contact the building dept and get more guidance before proceeding.

All in all, his advice is very useful. I expected to have some hurdles to get over on this one since ovens are not typical and people may not know how to deal with them (i.e Building Dept). I did contact several WETT certified professionals and not one got back to me. Not sure if they are too busy or just do not want to get involved because of what I am trying to do.

At this point the whole idea is somewhat of a turn off for me. Given the cost of the chimney alone and hurdles I need to rethink this and see whether or not I want to pursue. It was a challenging project for me which I was looking forward to.

I will keep any additional feedback or progress (if any) posted on this site. Many thanks to DMUN and others for feedback and comments.

Regards
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Old 01-06-2010, 08:44 AM
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Default Re: Indoor Kitchen and WFO

So is the implication that the smoke-on-start up issue is unacceptable with a WFO (vs. other woodburning fireplaces) because of the design of the WFO or because of your chimney requirements?

Chimney issues aside, it seems like smoke on start up is in no way exclusive to a WFO and has as much to do with the method of firestarting and state of the wood used as it does design. Not much different from many current-era fireplaces in that regard.
If this is the primary stumbling block, I believe one could devise means of mitigating the problem by 1. mimicking to the curved throat and flue design ala Rumford (which many WFO builders have done anyway) and/or 2. devising some kind of a door for the outside arch to keep the smoke contained until draw has been established.

There are, after all, MANY people who already have successful WFO's indoors.

I completely hear you on the cost thing, however. I have the advantage of being able to go straight up inside, but it's still ~25' feet straight up.
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Old 01-06-2010, 09:21 AM
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Default Re: Indoor Kitchen and WFO

As an FYI, 30 degrees is the accepted maximum deviation from plumb for a chimney. You can surely fire a WFO without smoke spillover using the same techniques as used for balky fireplaces and rumfords. The key is to get heat into the flue without generating smoke by using a small fire from dry wood.
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Old 01-10-2010, 08:16 PM
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Default Re: Indoor Kitchen and WFO

a smoking oven at only the begining of a fire (and not periodicly durring the fire)tells me that your flue to opening ratio is proably out or the throat is not built correctly in a unit that is allready installed not a lot you can do. try starting your fire as safly as possable to the front of your oven then after it gets going push it to the back of the oven
you want your out side air vent as close and as un ubstructed as possable to the opening of the oven as possable try submiting one that can be manualy opened and closed upon demand
what the inspectors/planning dept. will proably be wanting to see is that you did your homework . try looking up the specs for a fireplace that are the same(or close to it) to where it sits in the building as your oven. look for clearances to combustables, air gaps,reinforcement,ties to building, outside air vent ect.
good luck!
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Old 01-15-2010, 01:55 PM
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Default Re: Indoor Kitchen and WFO

Greetings,
A little experience to share from Indiana if I may.

I have built an indoor WFO with the door opening in the laundry room of our old brick farm house. I would have liked to use the shutoff damper such as the ones used on some masonry heaters but I couldn't wait. I decided on installing a chimney top damper which I assumed would work best if the 8 x 12 flue ran directly above the landing area. This assumption was correct but I discovered that the 2 story chimney can hold, and release, MUCH black soot. This soot of course falls directly on the handles of the oven door. And on the landing area. If the chimney had a small amount of offset the soot would still be there but it would not fall on our work area.

I believe that the moisture of the laundry room may have some bearing on the problem. Last winter during a windy -20 degree power outage the damper stuck which meant a trip up a ladder at 5 am!!

I have second door which I call the landing door. It slides up into the facade and may help keep some of the moisture from going up the chimney but I am not sure how much it helps.

On the combustion air.
Off to the side of the landing area I have an ash drop which dumps into a chamber on one side. (there is still room for wood storage underneath) This chamber has an 8x8 clean out door which can let in some air if we find it to be necessary.

Keith
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Old 01-20-2010, 01:36 PM
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Default Re: Indoor Kitchen and WFO

Hi Keith
re: your comments about the chimney soot
Based on what I've read on fireplace chimney design, the smoke shelf that is common element in WB fireplaces seems to have a somewhat vague purpose/function (suggestions have been that it gives a chimney sweep someplace to stand...), and it seems like your experience with soot falling on your door and landing defines its usefulness to some extent...
excellent info. thanks for posting!
would LOVE to see pictures of your indoor WFO.
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