Koker 160 With Direct Vent Hopper Fire

So far I have been more than happy with the performance of the new Koker 160 that was installed in May and fired up in October. It had been working great until Monday morning (New Years eve of coarse) In the morning when I checked it it was burning fine, I filled the hopper and was on my way. A few hours later I was going to take the dogs out for a walk and when I went downstairs some thing didn't sound right and I could smell plastic burning. I checked the stoker and could see the direct vent fan was working but the combustion fan was not and I could hear the coal crackling in the hopper, I immediately unplugged the unit and called Ken from Weller's chimney sweeps, they did the initial installation. I explained to Ken what happened, he was very helpful and checked to make sure the parts were available and was at my house within a few hours. With the expert there we did confirm that the fume switch did trip which caused the combustion motor to stop but did not stop the direct vent fan which caused a draft in the hopper. He did rewire it so that if it trips it will shut down the entire system. He replaced the nylon cam and motor and the stoker is running again. In discussions on how this could have happened he mentioned that the draft is critical on the direct vent stokers, I have a gauge and had been checking it occasionally and was consistently at -0.02, which is correct. He thinks maybe there was a gust of wind coming back into the direct vent which caused the fume switch to trip. He did mention that the factory did have some issues in upstate New York and were working on a barometric damper to help with this issue. I am thinking of asking him to install a barometric damped so this doesn't happen again. And in closing I would like to say that I was very happy with the service from Weller's Chimney sweeps. Thanks again Ken!

Hopefully you caught it soon enough that the stoker gasket is still in good shape. Might be worth some time next spring to just pull the hopper and then the stoker out just to inspect the gaskets. Mine had a hopper fire before I bought it and it had burned quite a while...the stoker gasket mount surface was warped.

Thanks for your advice. I think I did catch it pretty quickly, within an hour or two, but you never know. The hopper was full and the fire was just at the very bottom. As soon as I realized this I removed all the coal from the hopper. It has been running well since the repair on New Years eve so I am hoping it is OK. I plan on shutting down in the spring and cleaning it out, I will be checking the gasket.

Bill were you aware of any high winds that day?
I have been considering this type of stove,
but I am in a very windy area and this exact problem was
a concern of mine.

Hi Dutch, yes it was windy that day but the wind was much worse during hurricane sandy and I did not have a problem. I am not an expert but maybe the wind direction also has something to do with it. The direct vent is vented to the side of my house with a street going north and south. So far what I have found is that if you are going to use the direct vent, especially in windy areas, you should look into a barometric damper. I should have done more research prior to installing the stoker but I have been told that the barometric damper can still be installed on my stove.

Just need to jump in here with my 2 cents worth when you start talk of adding a barometric damper to a direct vent furnace. Hopefully I just don't understand what you're saying.
A barometric damper SHOULD NOT be added to the 4" Koker vent pipe inside the house. The pipe is under pressure with exhaust gas. That's why all joints need to be sealed.
Here's what I suggest you consider doing. Vacuum out the direct vent housing if you haven't already done so. Also, vacuum out the two exhaust pipes inside the furnace that run from the bottom rear corners up to the direct vent motor housing. If these pipes become clogged with ash you will lose your draft and the fume switch will shut down the furnace.
I occasionally have "wind tunnel" conditions at my place with open fields all around us, and have never experienced a problem with the draft because of them. I do have a tee and "china hat" on my vent pipe to shield the vent pipe from wind (see illustration below).
Your service guy is correct about the wiring problem you had. The fume switch is supposed to shut down the furnace completely. Sounds like Keystoker made a mistake with the wiring.
I hope this is some help to you.
Good luck,
-Len

Hi Len, thanks for your two cents. As I mentioned in my previous post I am no expert on coal stokers, just tired of paying the oil man all my $$. When the service guy was at my place he discussed the barometric damper on the Koker and did not mention that you could not use it on a 4" stack. He did say that threre were issue in upstate New York with this same issue and the fix was the barometric damper. On the wiring, he was on the phone with Keystoker. They knew how it was wired and my service guy told them it was not good to do that due to the hopper fires. They told him how to modify the wiring to shut the whole system down if it trips again. Believe it or not I heard the conversation. My koker has the direct vent coming out of the top of the stove with a 4" connection for the stove pipe. I have a few photos of this posted. There is no tee on the inside but on the outside the piping is the same as yours with the "china hat" and tee. I do vacuum out the inside of the stoker and use a brush to clean out the tubes that run up through the sides of the stoker. When it was down I cleaned out the direct vent, through the opening in the stack, there is a removable panel to access the direct vent , which had some dust in it but in no way was it blocked up, the stove has only been running since the middle of October. I would like to know what caused this but at least if it happens again the stoker will shut down instead of starting the hopper fire. Thanks again for your input.

I'm with you on not paying the oilman (in my case the propane man)!
It sounds like you've got things handled well.
Stay warm and coaled!
-Len

Bill, this may sound dumb, but you are burning rice?
I am in NYS and have been dealing with this situation in several locations. I would say the majority of the problems was from homeowners burning buck or buck/rice mix.
Also, make sure the hopper is sealed well to the burner. I use gaskets and/or silicone.

Oilman, have you had the hopper fire problem or just the sensor shutting down the stove?
I'm at 1500 ft here in Madison County.... it howls here!

Hi Oilman, I am burning just rice coal and I keep the hopper full. Like dutch we are at about 1550ft and it does get windy up here.

dutch wrote:Oilman, have you had the hopper fire problem or just the sensor shutting down the stove?
I'm at 1500 ft here in Madison County.... it howls here!

Hopper fires. Went on one last night on a Hitzer 710 which is basically a Koker clone. Homeowner wasn't educated enough on maintenance and installation procedures.
Although there is a small sliver of coal users here on this forum,(as compared to the total overall number of coal burners in the N.E.)who have done wonderful installations and really know their stuff, there is a huge percentage of DIY installs done terribly with gear sold by dealers who don't know much more than the homeowner, which result in things like hopper fires which result in all the used stoves you see advertised for sale.
Sorry, I'm venting a little
I just get frustrated sometimes.......

Had the exact thing happen to me last week(hopper fire). Fume switch tripped and direct vent motor stayed on. Cam and nylon screws all melted. Keystone gave me instructions on rewiring the unit which will be done this weekend. I can't believe they sent these units out wired like this. I understand they wanted the direct vent to remove fumes from the house however they are causing hopper fires now.

shanedoe,
Would you please post the rewiring instructions Keystoker gave you?
I was assuming they simply made a mistake on the wiring the first time I heard of this but if they intentionally wired it so the vent motor keeps running, mine may be the same way.
I agree with you, the vent motor should shut down along with the other motors.
-Len

According to my installer my koker was wired it like that from the factory to remove the fumes. I was not given the new wiring diagram as my installation guy was on the phone with Keystoker while making the wiring changes. The wiring change was to shut down the stoker entirely if the fume switch trips. My main concern now is why did the fume switch trip in the first place?