Another OAK Thought..

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Daves said:
I have a Quad Mount Vernon AE and recently had it on high to heat the house quickly. I just happened to walk by my front door, and thought it was left open. It turns out it was closed and the air being sucked through the was ridiculous (no wonder it seems so drafty). Anyone running an oak up through the chimney with a Quad? The manual shows this as an option, but my dealer says I don't need it and besides there is no chimney cap option that supports it.
I have a 3 inch OAK and exhaust running up my 15 foot chimney flue. I also have a blue stone cap on the top of the chimney. By code you have to have a height difference, intake being lower, of at least 12 inches between the intake inlet and exhaust outlet. I had to get creative on this setup. I got a 3 inch 180 degree U bend from the auto parts store and then cut a hole in the stainless steel flue cap where the exhaust exits. I mounted the U bend, sealed the connection to the flue cap and attached the 3 inch flexible aluminum duct to end of the U bend under the flue cap. I now had the separation required by code and the inspector said he never seen nothing like that before. The inlet of the U bend hangs to the outside of the chimney. I had to make a 3 inch adapter to attach to the back of the MT Vernon Insert, flat plate with a straight piece of the 3 inch U bend I cut off welded to the flat plate. The inlet duct and exhaust also run through a sealed plate where the chimney damper was. Even on the coldest days the intake air gets warmed by the heat from the exhaust when they are running in the same flue. When I put my hand on the intake pipe it is not as cold as the outside air. Don't have any pictures but will try to get some up sometime soon.
 
What are you referring to with OAK? What is it and what does it do?
 
BillM2 said:
What are you referring to with OAK? What is it and what does it do?

OAK is Outside Air Kit. It is used to pull outside air and plumb it right into the stoves intake. The biggest gain is it helps keep the stove's draw(suction) from pulling in cold air where there are leaks in the house. Reduces draft's at the leaks.
 
Yes, realized that just as I sent it. Thanks for verifying!
 
To FordMasterTech--

Any pictures you can provide would be greatly appreciated!

Merry Christmas!!!
 
Daves said:
To FordMasterTech--

Any pictures you can provide would be greatly appreciated!

Merry Christmas!!!

I thought I had some pictures of my OAK termination at the chimney but couldn't find them in the computer. I took a few from the deck and a upstairs window today but nothing showing the U bend attachment. I wasn't going up on the roof today with the storm brewing. The bricks you see laying on top of the flue cap are there to support the blue stone, it has a small crack in it and I didn't want it to fall down' I'll get to it in spring. Hope these will do for now.
 

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Just curious - what's been your experience with the OAK compared to pre oak with regard to heating/comfort? Was it worth it? Any problems?
 
Daves said:
Just curious - what's been your experience with the OAK compared to pre oak with regard to heating/comfort? Was it worth it? Any problems?
Dave
I have never run the AE without the OAK. When I installed the stove and chimney liner in 2006 I also did the OAK. I feel the OAK installation is worth it to prevent sucking the heated air, that you payed for, out of the house and to prevent unnecessary drafts from the houses leaky spots. My house is not real old, built in 1974, but it is also not tight like a newer home. I have replaced all the doors, all the larger crazier windows and some of the smaller windows but still have about 17 double hung windows to replace. I don't use the replacement type windows I use new install type windows so it is a lot more work and some what more expensive. As far as OAK problems I don't have any with mine. I have a 1/4 inch hardware cloth type screen in the inlet to keep the critters out and make sure to keep it clean, otherwise there is not much maintenance to it.
 
Hello

The Selkirk Corp Biomass Mult-Fuel venting looks great! The intake air would definitely be warmer and drier.

I would highly recommend it.

Info PDF with hookup parts diagrams
http://www.noutilitybills.com/PDF/Selkirk/DT-M/MF Catalogue.pdf

Overview
http://www.noutilitybills.com/chimney/dt-m/DirectVentMF.html

Web Site
http://www.selkirkcorp.com

Unfortunately my pellet stove flue just dumps right into my chimney but if I used the above venting from the stove up to the chimney and then go outside from there with my existing vent, I bet that might warm the intake air enough too!!!
 

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FordMastertech said:
Daves said:
I have a Quad Mount Vernon AE and recently had it on high to heat the house quickly. I just happened to walk by my front door, and thought it was left open. It turns out it was closed and the air being sucked through the was ridiculous (no wonder it seems so drafty). Anyone running an oak up through the chimney with a Quad? The manual shows this as an option, but my dealer says I don't need it and besides there is no chimney cap option that supports it.
I have a 3 inch OAK and exhaust running up my 15 foot chimney flue. I also have a blue stone cap on the top of the chimney. By code you have to have a height difference, intake being lower, of at least 12 inches between the intake inlet and exhaust outlet. I had to get creative on this setup. I got a 3 inch 180 degree U bend from the auto parts store and then cut a hole in the stainless steel flue cap where the exhaust exits. I mounted the U bend, sealed the connection to the flue cap and attached the 3 inch flexible aluminum duct to end of the U bend under the flue cap. I now had the separation required by code and the inspector said he never seen nothing like that before. The inlet of the U bend hangs to the outside of the chimney. I had to make a 3 inch adapter to attach to the back of the MT Vernon Insert, flat plate with a straight piece of the 3 inch U bend I cut off welded to the flat plate. The inlet duct and exhaust also run through a sealed plate where the chimney damper was. Even on the coldest days the intake air gets warmed by the heat from the exhaust when they are running in the same flue. When I put my hand on the intake pipe it is not as cold as the outside air. Don't have any pictures but will try to get some up sometime soon.

I like this idea, and had actually planned to do the exact same thing with my outside air. I didn't end up going that route, but find it interesting your inspector had never seen anything like that before. I'm in the automotive industry as well, so I guess our minds think alike : )
 
I'm reminded of the 2nd Law of Thermodynamics, which states something to the effect that energy can't be created or destroyed, just converted from one form into another. I'm thinking that the amount of energy lost to using and exhausting inside air is the same as the amount of energy needed to heat outside air to room temperature, in which case an OAK only serves to supply air that is richer in oxygen and can therefore produce hotter combustion, meaning quicker heating. That would mean that heating the outside air would cause it to expand and thus be less oxygen rich. In winter, air that is very humid is also very cold, and thus very rich in oxygen and that added oxygen would easily help to vaporize moisture in the cold air.
Also, starting with that fact that a perfectly sealed building which has an exhaust fan blowing air outside, that fan will become ineffective at moving air outside at the point at which the vacuum in the building is strong enough to not allow any further air escape. Thus, it would seem that an OAK is far more effective in houses that are very well sealed, while being unnecessary in homes, like mine, that are rife with air leaks. Those who report a significant difference in stove performance after adding an OAK probably have very tightly sealed homes and lack an off-setting air draft to compensate for the exhaust draft. Whether outside air comes in through an OAK or through leaks, it's the same cold air, but with the OAK it doesn't cool the interior, only the interior of the stove's intake pipe.
Also, here's another new thought, the positive pressure from expanded warm air from the convection blower balances the negative pressure from the exhaust fan since the amount of air and heat from both is essentially equal, but the expanded, heated interior air creates a positive interior pressure which resists outside air from so freely being sucked in through leaks. To get good airflow in that situation requires that the amount of house air-leakage has to be great enough to more than match the positive pressure from the stoves heated air. Unfortunately, that describes my house, including the one room I'm using it to heat.

I learned quickly when I first began using my pellet stove, that the amount of heat in the exhaust was about the same as the that from the convection blower. Therefore about half of the price of the pellets was being wasted as exhaust heat. Bad design from an economic stand-point. I dealt with that problem by doing something very unconventional. Instead of using pellet vent pipe, I just used what I had on hand, which was salvaged galvanized gas-water heater pipe and a 4.5' length of heavy 4 inch cast-iron sewer pipe and elbow. I butted the sewer pipe up tight against the 3" stove exhaust pipe insulation and attached the galvanized pipe to it after the 90 degree elbowvia use of an adjustable 90 degree galvanized elbow to angle the pipe at 45 degrees up into an old unused gas water-heater ceiling vent pipe. (about 5 feet of galvanized pipe before the vertical section.) I went 2 steps further in trying to retain exhaust heat. Before connecting the heavy iron sewer pipe, I first cut and inserted 4 4' lengths of heavy old steel plumbing pipe in order to increase the metal mass inside the sewer pipe (to absorb more heat). Since the pipes were pipes, I figured they would let the air pass through fairly unimpeded. Upon finally firing it up, I could see no difference in the strength of the combustion "wind", so it appears that the use of 4 in. pipe inside the house allows adequate air movement, even though the old unused ceiling/roof vent pipe is only 3 inch.
But then I added one last element, I covered much of the inside pipe with wet towels, which dry out in about 1 1/2 hours. When they're baked dry they're barely warm because the heat is being dispersed fairly evenly and no one spot is overly hot. The result of all this seems to match what my curious mind suspected, namely that the amount of heat exiting the exhaust vent above the roof is roughly half what it was when I first tried out my stove using only the galvanized pipe running at a somewhat raised horizontal angle. If that is true, then I'm keeping about half of the lost exhaust heat inside, which would translate to saving about 25% of the cost of a bag of pellets, instead of losing about 50% of the cost to heating the great outdoors.
The whole experimental arrangement is temporary and I'll dismantle it and move the stove outdoors in the Spring since it's not in a convenient location.
It would be wonderful if some one or some company would invent a pellet stove or vent add-on that could retain 95% of the exhaust heat. When that day comes, people will be able to heat their well insulated homes so cheaply that nothing else will be able to compare (unless natural gas becomes as cheap as dirt).
As someone who lives next door to a neighbor who burns wood with half the air his stove needs, and thus badly pollutes the air that I have to breath while outdoors, I am amazed at how the forced-air of pellet stoves results in almost no burn-pot ash residues and clean, almost breathable exhaust air. Now if only they would invent one that's truly high-tech when it comes to heat retention.
 
If you decide to go with outside air look into the Harman Direct Vent Wall Passthrough. It incorporates the outside air into the wall thimble without being complicated. I found it makes a nice clean install without having extra vent on the outside.
 
Checkthisout said:
New here.

Has anybody thought it might be a good idea to heat the the OAK with the exhaust gas? Simple experimentation could be done by simply getting some more tubing and laying it in front of the exhaust and allowing it to heat the tube to see if it makes any difference in the amount of pellets consumed.

I just purchased a new stove and was rather taken aback by how hot the exhaust gas was during test-firing.

I think there is lots of room there for heat recovery for people with some decent fabrication and a little ambition to stay busy during the winter-doldrums. :)

With a forced exhaust it would seem you could suck out as much as you want without any negative impact on stove operation. (VS say a stack robber on a wood stove which tends to kill your draft).

Just some thoughts.

Amaizablaze stove have an interesting exhaust. They have a single wall 3 inch vent that you place a 5 in single wall over. The air is drawn in from outside in between the two.
 
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