Harmon DVC-500 Feed Problem

I have a Harman DVC 500 which is now only 3 years old. It started having issues with the blower making loud noises, then the combustion blower would not work unless you first turned the dial up to 4 or 5, wait for it to turn on, then lower it back down to 1 or 2. Now, I am running into a feed problem. The past two fires, as soon as the coal on the grate is burned, the fire begins to die out. I emptied the hopper and watched the pusher block as it cycled back and forth several times. I then put a small amount of coal in it and watched as it SLOWLY made its way out to the grate. I then filled the hopper back up and lit the fire but now the fire is going out as there is insufficient coal being applied to it. I have no idea where to start with this issue. I could see if the block was frozen but I watched it moving back and forth. Any suggestions as how to proceed with troubleshooting?

First, Did you clean it out good from last year? If the grate holes are blocked, the combustion air won't get thru to burn the coal good and the fire can go out. Did you clean out the fines under the grate or the fines tray is not in the correct position.

If its not feeding, make sure the pusher rod didn't come loose or something in the gearing has not stripped.

Did you make any adjustments to the blower/feeder control module, etc.. settings, maybe change them one way or the other on the timer box. maybe the blower is not on enough to keep the fire going.

All the fan cords plugged in correctly to the correct outlet? Thermostat wires attached correctly and working.

is this the same problem you were having here? or is this a different problem.
DVC 500 Feed Issue

Same problem; good investigative work. Yes, it was cleaned thoroughly and everything appears to be working. I can see the pusher block working, so I'm really confused as to why its not feeding properly. The distribution blower gives me trouble but not the combustion blower. I've cleaned everything, checked seals, etc.. When I run it in test mode, all seems fine. I've been manually feeding it tonight but am ready to call the professionals to come take a look; I'm at a loss!

I seem to remember a few forum members had to remove the pusher block and clean out the pusher slot or channel. There were hardened accumulatons of fines that blocked the coal being pushed onto the grate.

Also, there is a 'fork' that the pusher motor's wheel rides inside of, this fork gets widened out from the stress of pushing/pulling the pusher block, and soon there is too much of a gap or slop in the pusher mechanism, and the block can't push enough coal. The cure is to put the fork in a vise and carefully bend it closed back to original width.

Hope this helps..

Greg L

I agree w/ Greg;

Sounds like Fines got damp and then hardened making a dam of sorts...if so, you'll have to remove pusher block and chisel the dam away to clear the path.

I have seen where some have drilled a couple small holes, one on each end of the motors, to be able to add a few drops of 20 wgt. oil every so often.

Good Luck and let us know how you make out.

I'm not familiar with the mechanics of this stoker but...

then the combustion blower would not work unless you first turned the dial up to 4 or 5, wait for it to turn on, then lower it back down to 1 or 2.

That's usually a sign that the bushings in the motor need oil. Does the fan spin freely?

Wood'nCoal wrote:

then the combustion blower would not work unless you first turned the dial up to 4 or 5, wait for it to turn on, then lower it back down to 1 or 2.

That's usually a sign that the bushings in the motor need oil. Does the fan spin freely?

Yes, time to oil all motors.

Thanks for the suggestions. The hardened fines seems very possible as they have been hardening in the fines tray as well. The only coal I have been able to get this year is still very wet. I'm having a tech come in and go over everything, oil as you've suggested, and check the issue with the blower. My previous post was resolved as stated but I've had a lingering issue with getting the blowers to turn on. The problem seems to be with the dial. If I turn it way up, the blowers start, then I can turn it back down. If I move the dial from, "Ash Out" to "2" for example, they never turn on.

I'll update once it has been checked. Thanks again.

Mcgiever is right, when I had a load of wet coal the fines turned to slurry and formed a speed bump at the end of the pusher block stroke. This blocked the coal from flowing properly. It wasn't real noticeable, I missed it the first time around. It was so hard I had to pound it out with a chisel. I have had the "tuning fork" spread as well. I just used a big pair of channel locks and squeezed it together.

The other problem that you can have is if the stovepipe has an ash accumulation at the bottom elbow (it drops from the vertical section and fills up quicker than you might think in that spot) it restricts the smoke flow and the "smoke" will back-feed up through your hopper. Not only will this possibly kill you if the boiler is in the house but the heat and moisture back-feeding will wet the coal and clog the feeder process

How far apart should the gap in the tuner fork be?

I don't know if your's is like my Super Mag but there is a set screw that holds the feed motor shaft locked in. Check to see that isn't loose.
Also I had issues with caked up coal not letting it feed or push the caked ash out into the ash pan. Weird as it only happened once this season. Bad coal? Wet coal? not sure.

Well after 3 hours last night, and several different calls to tech still no solution. For the smoke in the box the Harman tech and the resident expert at my shop blame it on "wet coal" or wet in the box. I get the coal in bulk, store it outside and bring it in in 5 gallon buckets. I typically have enough buckets in my basement for at least a week and a half worth of fill ups. None the less a little bit of moisture was in the box so the thought was that moisture was causing the "sulfuring". At the end of the day that does not explain the problem that the stove lights great and then slowly fizzles to almost no fire at all.

Today I dried a different coal to see if it was a combination of my coal and it being wet. Due to the fact the techs seem to think its something in my coal. Ultimately different coal, dry, same problem, small amount of sulfuring, and fire lights great and then slowly dies down. Stove is in stove temp, on 4, and temp around 85. I normally run in stove temp, on 3, and temp around 75.

Thinking further about all the solutions offered on here I began to think this may be a feed issue. Being that my feeder was just disassembled and cleaned I checked the pusher block to be sure it was installed correctly, and it was, rounded edges to the bottom. So I still had the stove lit and decided to place a shim in the tuner fork, taking the opening from just shy of 2 inches to just shy of 1 3/4. We'll see how this goes.

The tech tested everything he could think of and all the fans, pressures, etc. tested well. Only solution they could generate was let the stove sit open and empty for a few days to dry out. Also let some coal sit in a place that it can dry out, and go from there. I told them I didn't think I'd have the patience but they said try that and they will be back in touch next week.

I'm on my last hope with the shim in the tuner fork, so we shall see. Thank you all for the input and ideas.