Another Kodiak Insert to free standing stove story...

[Coolerman]

Hello folks! I rarely post here, I mostly mine the wealth of knowledge that is available. However I have a story to relate and need some advice/help. First the story... Here is a link to pics of the stove :http://www.globalsoftware-inc.com/coolerman/1335/Shop_Stove.htm

I just bought a Kodiak Stove insert for $150 for use out in my garage/shop. Guy said it was removed from his parents house in 1986 and he thought it was a 1976 year stove.

It was all rusty and pitted from being left in a barn for many years, but the metal was sound. It is really heavy and I had to use a cherry picker to move it around! I sand blasted it, broke off the air vent bolts trying to unscrew them, replaced those with new ones, replaced the gaskets, and gave it three coats of BBQ Black paint. It came out pretty good. I then placed it on some 16" chimney blocks to get it up off the floor for easier loading and to prevent any gasoline fumes from reaching it. ( I do not store gas or other flammables in my garage but I do park in it. Gas tank leaks do occur.)
Now I could measure for the chimney pipe. The stove requires 8" diameter pipe. Ordered one 60" section of galvanized Class A pipe which I painted BBQ Black, one stainless cap, 2 four foot sections of single wall, one 11"slip fit single wall, one stove top adapter and one damper assembly. I already had the roof support left over from the fireplace install. All I had to do was fabricate the Uni-Strut support for the roof support bracket.Total height of chimney from stove top to top of Class A pipe = just about 15'. I have the top of the Class A section (Height does NOT include cap) 2 foot above the roof peak and a bit over 3 feet above the metal roof. I completed the install this weekend.

The problem: Stove set as follows: Pipe damper closed, door open. I build a small fire, (3 splits on top of kindling and paper). Light it with the door open to get it going. Now if I shut the door and open both vents wide open to get the fire going quick it does the following: First it starts going pffft, pfftt, pfffttt, sort of pulsing. If left in this state for long at all the pffttting turns to loud huffing and smoke and flames shoot out the vents and around the supposedly air tight door gaskets. A couple of times before I could get to it, there was a very loud whooooof! and smoke only would shoot out a couple of feet. This was followed by a strange quiet then WHOOOOFFFF! again, this time with flames. I'm assuming that the stove is blowing itself out then re-ignitiing? The only way to stop this is too either open the door or to choke it down to where it's barely getting air. Once choked down it will settle down and burn but really low. I cannot get a high burn withouit opening the doors. Any suggestions? It fills my shop with smoke which is not what I had in mind! I will post the rest of the pics of the install to that link tomorrow.

 

[pen]

Pipe damper closed

Why the heck is the pipe damper closed when starting a fire????

 

[BrotherBart]

Pipe damper closed, door open.

Say what???

 

[coaly]

Your draft is stopping, dropping back down chimney giving smoke the oxygen it needs to ignite. Open damper, open air intakes, light, and as larger pieces are added start to close air intakes to control fire. You have to get the chimney hot first before closing the damper. Don't close it fully with a lot of single wall pipe. Put a thermometer on the pipe as high as you can so you have an idea of what temp your flue gasses enter chimney pipe are. Try to keep temp above 250* all the way up. You don't want it lower than that while smoking. When down to coal stage, you can close it more, but open again when reloading and keep open while new wood load gassifies (smokes) until fully engulfed.
That's the long version of what pen and BB said.

 

[Coolerman]

Thanks for the replies...Glad I provided some of you some entertainment for the evening! This is the first time I have had a stove setup like this with the short chimney and a damper in the pipe. (I do have a modern Lennox stove in my home now. Chimney is 24' of Class A all the way. Absolutely no issues with huffing...)

Last night I tried this whole thing again. Opened the damper fully, small fire to start, with door open. Let it get going good, open the door vents fully, then shut the door. Within 3-5 minutes I had a good fire going. I started shutting the door vents and reached a point where it started this bad behavior again. Opening the door revealed that the fire had "smothered" and become smoky. I left the door open so the wood would burn again, and let the wood burn down to coals. I then added three more splits, let them catch good, then shut the door and adjusted the vents to just barely cracked. The stove then worked perfectly! However, every time I tried to open the vents fully to get a bigger fire, it started this behavior again. Is this a consequence of the shorter 8" diameter chimney with 9 feet of single wall?

I have a Hollis Engineering thermocouple type meter and placed the probe on top of the stove near the pipe. Once it got to burning correctly, I had temps that started at 350 and eventually after about an hour were at 600 degrees. During all this I left the damper open.

So it seems that a cold stove with a fairly short chimney can't be rushed into putting out heat. I just need to let the stove and pipe get up to a good temp to maintain the draft. I will continue to learn this beast!

Now someone give me the low down on proper use of the pipe damper...

 

[Coolerman]

Oh and I will pick up one of those magnetic pipe thermometers today and see what my pipe temps run in comparison to the stove top. It was so nice to be able to work out in the shop last night with it freezing rain outside...

 

[pen]

Sounds like when you have it shut right down, the fire is smouldering and there is a lot of smoke, if you open the draft caps and let oxygen in that smoke is bursting into flame and giving you the whoofing action.

How do things burn if you leave the air drafts open a bit more instead of closing all the way.

Is this cord wood that you are burning? Hard / soft wood? Construction scraps / pallet cut-offs?

So long as you aren't turning to burn a bunch of really small wood in there, I'm thinking you are leaving the door open too long and getting things way over engulfed, then turning the air down too soon after that causing a hot raging fire to get choked down.


pen

 

[coaly]

Dampers may or may not be required on different chimneys. Mostly used to slow draft when there is too much. They are handy when starting a fire and it gets roaring up the stack so much you don't have the heat in the stove to get the larger pieces hot.
Originally they were not used on single door stoves from that time period. The first stoves when yours was built were connected to existing fireplace chimneys that were too large, so chimneys the correct size for stove came after the development of the stove. Double doors required them since they were designed to view the fire and burn in "fireplace" mode with a screen in place with doors open. You then have no air adjustment and the only control is the damper. Close slowly until smoke at top wants to roll in. Then open slightly to slow exhaust holding heat in stove, but enough to vent.
No one can tell you how much to close it due to variations in chimney draft and atmospheric conditions. Older dampers have a larger hole in the middle and can be ran closed overnight for longer burn, newer dampers have smaller holes along the shaft that plug easily and need to be ran partially open. Trial and error and check creosote accumulation regularly until you know how much you create.
Most operating and baffle tips can be used from the Fisher Forum since that is basically what you have. Fisher was the first steel plate stove (with single door) that was copied by many. One of the licensed builders in Oregon had a customer that wanted to view the fire and came up with the idea of double doors with a screen. He and Bob Fisher agreed to cancel his license to build Fishers and became Frontier. Most builders that copied Fisher then offered double door stoves as well. The idea started in 1975 and production started in '76. Yours in between 76 and 80, but it's an early one due to the older style draft caps.

 

[coaly]

Similar problem here that was corrected by baffle in stove with the correct "smoke space" for the fuel he burns;
https://www.hearth.com/talk/threads/grandma-fisher.120270/

Here's a video of the same stove in another thread. Post #28;
https://www.hearth.com/talk/threads/cant-seem-to-figure-out.119184/page-2

 

[Coolerman]

Pen: Seasoned Red Oak splits for the fire last night but I'm pretty sure the first fire with all the drama was seasoned pine splits. (Took a pine tree out of a friends yard this past fall and took the wood home. Normally use it as kindling wood to start the Lennox stove, but figured the garage stove could burn it... Duh! that may explain all the smoke and smell...) Me thinks your right about turning down the air too quick. Last night right before I shut down for the evening I opened it up a bit and did not get the huffing. I think I just did not have the stove hot enough for a good draft.

Coaly: The damper does have a large cutout in the center which allowed me to start a fire with it closed. I will play around with the damper tonight after I get the stove up to temp and see what closing it down does. I have been spoiled by the "modern" stove. Single lever air control: Light it, lever wide open, get a good fire going, close it about a third. burn till bed of coals, add some splits let get burning then throttle it all the way down and watch the light show!
I will check out the Fisher Forum and start reading there. Thanks!

 

[Coolerman]

OK, bit of an update : I had a fire out in the shop every evening this week so I could learn how to adjust it for the best burn with no huffing. I was surprised at how little I have to open the door vents to get a good burn. 1/16" to 1/8" is all it takes! I can get the stove top to 550 degrees every time now. The pine I have burns hot, but boy does it create a lot of smoke and smell. The red oak is better but I need to burn up the pine to get rid of it. I was not able to find a pipe thermometer but the local Ace Hardware said they will have one in on Monday. Then I can monitor flue temps. I can heat the 40 x 24 x 12 insulated metal shop from 36 to 52 degrees in about 3 hours. Today I plan to see if I can get it to 60 by the end of the day. 55-60 is the temp I like to work in.

 

[coaly]

Object is about half the temp of the stove top where the pipe dumps into chimney.

You didn't mention if you're using a blower.................

Don't know if the intake air across the bottom, and the double wall jacket goes up the back to exhaust out the front like a Fisher. I assume it does. You need a blower to really bring your inside temp up. The hottest part is where the exhaust vent pipe exits the firebox and should have air flow around it which blows out the front. Use the search box at top of page to search 'insert blower' in the Fisher forum for different styles. Huge difference that doesn't take much BTU away from the stack. When inserts are set back in masonry, a lot is absorbed and radiated by the hearth, but the negative is how the mass allows a lot of heat to migrate upwards and out of roof. So the object is to heat the air inside the structure, instead of using the mass of the masonry like a fireplace was designed to do. The outer shell surface should stay warm, and not be able to cook on, (without turning fan off) but be uncomfortable putting your hand in the airflow. Then you're heating the building, not the stove.

 

[Coolerman]

Coaly, I do indeed have a blower. It's a re-purposed furnace fan. It sits under the stove and when turned on it pulls air the reverse way it would normally work but it makes all the difference in the world in getting heat across the shop. It's a bit overkill but I have a smaller blower I got off E-bay I plan to mount under the stove to blow the air up and out the front. My next mod will be adding secondary air which will mean removing the OEM smoke shelf and replacing it with one that comes more to the front and has fire brick. I also plan to add an outside air source that I can control. Those mods should allow me to cut down on the amount of wood this thing consumes. Also since my chimney only has about 12" inside the shop, with 9 feet of single wall leading up to it, should I still measure the flu temp where they join? Seems the gases would cool a lot before reaching that point?
I sure do appreciate this advice. It helps make this project worth it.
Mark aka Coolerman

 

[begreen]

What is the flue setup on this stove? Can you describe the pieces from stove top to chimney cap? How tall is it overall?

 

[Coolerman]

Sure, the stove has an 8" opening in top of the stove, an 8" pipe to stove adapter that is 8" tall, damper section sits on top of that it's 5" tall, then two 4' sections of single wall, next is a slip fit 3-11" collapsed down to about 5", then an adapter from single wall to Class A, 3" tall, and finally a 5' section of Class A that extends 4' above the roof and two feet above the roof peak. Total height around 15'. No problem with draft, it pulls STRONG.
I've learned to control the huffing but can make it do it at any time by simply opening up the door vents fully. I believe a resonance sets up in the air flow as there is 8" going out of the stove but only about 5 inch total for the two door vents. Opening the door immediately makes it stop huffing as does closing the vents down to about 1-16 to 1/8". Yesterday I burned all day and got the shop to 61 degrees. Perfect working temp for me. I can improve on that when I get the outside air source hooked up. Not as much cold air being pulled in around the shop. Can probably do a bit of caulking around the door and windows but the main air influx is around the overhead door.

 

[begreen]

Cool, looks like you have plenty nuf flue there for decent draft. That is interesting rigging of the chimney support. Not exactly per instructions, but clever. My only concern is with the rear clearance. It should be 12" and only if there is a ventilated 1" air space behind the cement board. Hard to tell from the picture if this is the case, but I am judging it is not by the size of the blocks that the insert is sitting on.

 

[Coolerman]

Hey begreen,
Like my chimney support huh? It's a factory chimney support mounted to some Uni-Strut that is bolted to the roof purloins. No different than nailing it to a wooden box like it was intended. I do have the top of the chimney pipe strapped to the roof even though it is under 5' above the roof. Just made me feel better as we have very high winds here being on the very top of the hill with no trees to slow down the wind. (Grazing pastures on all sides.)

Local code says there must be 18" clearance to any combustible material. There is actually a full 18" of clearance from any part of the stove to the plastic faced insulation on the metal walls.This is a double wall stove in the back so you can lay your hand on the back at full burn. The stove is sitting on four 16" x 16" x 8" chimney blocks on edge. The cement board was placed there just to make sure it would not melt the plastic and to act as a heat reflector of sorts. I had no idea how much heat this stove would put out, so took the precaution of putting the board in place for the first few firings.

Yesterday I removed the cement board, filled the stove full of red oak and did an all out, wide open burn just to see how hot everything could potentially get (barring a chimney fire). I actually got the upper section of single wall smoking for the first time! (Just burned off the paint volatiles ... ) Turned out that, even wide open, the back of the stove does not get hot enough to make the plastic facing of the insulation more than warm. Since it was not needed, I did not put it back.