Harman Magnum Not Getting Hotter Than 70

A Coal stoker furnace or stove controls most operations including automatically feeding the coal. They are quite similar to any conventional oil and gas units and easily operated for extended periods of time. They commonly use rice coal but may use larger sizes like buckwheat. They can be used as primary heat, supplementary heat or have a dual set up with your existing oil/gas furnace.
Kramer1782
New Member
Posts: 13
Joined: Tue. Jan. 24, 2017 9:14 pm
Hot Air Coal Stoker Stove: Harman Magnum
Coal Size/Type: Rice
Other Heating: Electric baseboards (Utilized as backup)
Location: Trout Run PA

Post Tue. Jan. 24, 2017 10:22 pm

Hello my name is Rob and we recently purchased a home in northern PA. The house has a coal stove installed as its primary source of heat with electric baseboards as backup. The stove is a Harman though I do not see a specific model on the name plate. Reviewing some other posts with pictures I would say it's a magnum. I fired it up in early November with no issues and burned through the first ton of coal without incident. Even had to have a few restarts as I forgot to fill the hopper on occasion. The stove puts out a great deal of heat and has been wonderful. Much more economical than our previous oil heat system in an old drafty house with poor insulation.

Additionally, I have to say this forum has been a huge insight into the world of coal stoves. I am currently experiencing difficulties with my stove, which I will post in the correct forum, but thus far this forum has helped tremendously. Thank you for maintaining such a collaborative and helpful resource.

THE PROBLEM:

Came home and from work and found the fire had burned out. Earlier in the day the wife had called saying it wasn't real hot like usual. The stone was still warm and when it cooled I disassembled the feeder mechanism. I found the pusher block seized and its movement restricted. I cleaned the block and chute that it travels through and vacuumed the entire unit. When I removed the grates I did not find any clogged holes. With the unit back together I fired it back up. Now the bead of coals is not as intense as before and with the thermostat set at 70 it never shuts off the unit. I have a second thermostat (digital) in the room and it also only registers below 70. I am not sure if the problem is with my coal, as in dirty or wet or of the control and or failing/weak combustion fan is the issue. This is our second ton of coal. We had no issues with the first ton and just started the second in early Jan. The pile is kept outside both on and under a tarp which is how the previous owner stored it without issue. (Future plans to build an outside hopper on the to do list). I fill five gallon buckets every other week from the pile which I then fill the hopper with on the stove. There has always been some wet coal in the bottoms of the bucket when emptied, even with the first load or ton. This load (same vendor) does seem to have more powder or dust. Again based on previous answers in the other thread I have manipulated the restricter plate with no luck. Tonight I opened a window to see if additional air flow will assist and give me a complete burn. I have also adjusted the feed rate which does have an effect on the amount of coal coming in but still does not give me an intense fire like before. The stove will stay lite through the night and if I manually stoke the fire and hand feed it the intensity will increase as well as the temp though still not high enough to switch the thermostat off.

I was reading through another thread on the same issue with a newly installed magnum. Based on that thread I will be buying a draft manometer tomorrow to examine my flue draft.

I realize this may be a lot of information right out of the gate but I wanted to be as informative as possible in an attempt to diagnose the issue as soon as possible. Thank you in advance for your assistance with this matter.
Attachments
image.jpeg
Weak fire
image.jpeg
My stove
Last edited by Kramer1782 on Tue. Jan. 24, 2017 10:48 pm, edited 1 time in total.


User avatar
McGiever
Member
Posts: 5997
Joined: Sun. May. 02, 2010 11:26 pm
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Coal Size/Type: PEA / ANTHRACITE
Other Heating: Ground Source Heat Pump
Stove/Furnace Make: Hydro Heat /Mega Tek
Location: Junction of PA-OH-WV

Post Tue. Jan. 24, 2017 10:46 pm

Seized pusher = forks spread open...need to set forks back to 1-3/4" spread. :)
Magnum_Coal Fork.pdf
(5.84 KiB) Downloaded 21 times
SLOW AND STEADY WINS THE RACE

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titleist1
Member
Posts: 4404
Joined: Wed. Nov. 14, 2007 4:06 pm
Hot Air Coal Stoker Stove: Harman Mag Stoker (old style) one in basement, one in workshop
Hand Fed Coal Stove: Harman Mark III on standby for long power outages
Coal Size/Type: Rice/Anthracite; Nut/Anthracite
Location: Cecil County, MD

Post Wed. Jan. 25, 2017 7:27 am

Welcome to the forum. Good job on the post....pictures and everything!! Do you have a couple CO monitors?

Wet coal will cause feed and burn problems don't put the bottom of the bucket stuff into the hopper until it has dried. I use to have the same issue and would go to the top half of the next bucket which was dry while the bottom of the first dried out for another day or two.

As McGiever said, check the forks. Also a couple other things.... check to make sure the combustion fan flange is seated all the way in its bracket so all its air is getting into the stove and the cleanout lever under the stoker housing is closed all the way.

Have you cleaned out the flue pipe? It would be a good time to check for fly ash blocking the exhaust after about a ton of coal to see what your cleaning schedule should be. Some of us use a 'T' instead of a 90* for easy access to the horizontal pipe heading to the thimble.
I drive a VW TDI, heat my home & workshop with two coal stokers and have two vintage JD diesel tractors....
The EPA just loves me!!

User avatar
McGiever
Member
Posts: 5997
Joined: Sun. May. 02, 2010 11:26 pm
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Coal Size/Type: PEA / ANTHRACITE
Other Heating: Ground Source Heat Pump
Stove/Furnace Make: Hydro Heat /Mega Tek
Location: Junction of PA-OH-WV

Post Wed. Jan. 25, 2017 11:03 am

Another stand out in problem reported is 2nd ton having more 'powder' and/or fines.
Damp coal dust will fill gaps around the aluminum pusher block and make a paste that will become near cement as it dries.
You may of noticed signs of this at your past clean out.
It is this drag on pusher block which will allow the motor arm w/ bearings to strech or force open the forks spacing.
With widened foks coal feed rate is reduced and that can equally reduce heat output.
The manual makes reference often to not using wet coal, and boy has it been wet these past couple months. :x
SLOW AND STEADY WINS THE RACE

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WNY
Member
Posts: 5849
Joined: Mon. Nov. 14, 2005 8:40 am
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon
Location: Cuba, NY
Contact:

Post Wed. Jan. 25, 2017 4:39 pm

Sounds like a good cleaning and try to eliminate the fines if possible.

Do those stoves have the FINES tray under the Grate? make sure it's closed and sealed properly, you will loose combustion air and won't burn properly.
- Dave
Hyfire I & Keystoker 90K heating an 1890 Victorian
- Amsoil Authorized T1 Certified Dealer

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captcaper
Member
Posts: 574
Joined: Thu. May. 29, 2008 11:55 am
Stove/Furnace Make: Harman Super Magnum
Stove/Furnace Model: Super Magnum Stoker
Location: Northern N.H.

Post Wed. Jan. 25, 2017 7:28 pm

My Super Mag has a cleaning door you pull with a poker towards the room and any ash,etc will drop down to the ash pan. The fines tray is in the back... don't know about the old Mag like he has.
But that fire doesn't look good...towards the back it seems piled up too high.. and the fire is off center and the front of the grates the ash seems too large..
A good cleaning from the motors which collect dust like crazy to filters etc. check fork... I would think the motors run or they don't.
Titleist is the man for these stoves..
Current Stove Harman Super Magnum
Owned before
Harman Mark III Wood Parlor stove Scandia Wood Stove 2 Chubby Coal Stoves Small Pot Belly Cast Iron

User avatar
titleist1
Member
Posts: 4404
Joined: Wed. Nov. 14, 2007 4:06 pm
Hot Air Coal Stoker Stove: Harman Mag Stoker (old style) one in basement, one in workshop
Hand Fed Coal Stove: Harman Mark III on standby for long power outages
Coal Size/Type: Rice/Anthracite; Nut/Anthracite
Location: Cecil County, MD

Post Wed. Jan. 25, 2017 8:42 pm

captcaper wrote:My Super Mag has a cleaning door you pull with a poker towards the room and any ash,etc will drop down to the ash pan. The fines tray is in the back... don't know about the old Mag like he has.
Same set up on the old mag stokers. You can barely see the end of the plate with the hole for the poker in the pic on the left front of grate.

I agree the coal bed in the pic looks like it is all burned up with no new stuff getting pushed forward which leads toward McGievers fork suggestion. (or the coal is too wet....or both).
I drive a VW TDI, heat my home & workshop with two coal stokers and have two vintage JD diesel tractors....
The EPA just loves me!!

User avatar
captcaper
Member
Posts: 574
Joined: Thu. May. 29, 2008 11:55 am
Stove/Furnace Make: Harman Super Magnum
Stove/Furnace Model: Super Magnum Stoker
Location: Northern N.H.

Post Thu. Jan. 26, 2017 3:11 am

That's good to know about the fork... I had blockage from large chunks a couple of times but never jammed the feed bar.. I wondered what would happen if a piece got down in there and jammed it good.
Also the set screw in the feeder motor shaft should be checked for slippage..
Current Stove Harman Super Magnum
Owned before
Harman Mark III Wood Parlor stove Scandia Wood Stove 2 Chubby Coal Stoves Small Pot Belly Cast Iron


User avatar
McGiever
Member
Posts: 5997
Joined: Sun. May. 02, 2010 11:26 pm
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Coal Size/Type: PEA / ANTHRACITE
Other Heating: Ground Source Heat Pump
Stove/Furnace Make: Hydro Heat /Mega Tek
Location: Junction of PA-OH-WV

Post Thu. Jan. 26, 2017 8:25 am

The earliest Mag Stokers were originally with a 'oval loop' as compared to the change to the 'open fork'.
Harman found that the oval loop when pusher jammed or somehow became restricted would tend to stall feed motor and cause it to overheat the motor and potentially burn it up. This is when they changed from that oval loop design to the present open fork design.

What can happen is it is possible to 'spread open' just a small amount and not be noticed the small difference in output...but if later there again is cause to have additional jamming and additional spreading it will, at some point become cause for concern due to very noticable reduced stove performace/output.
This gear reduced speed motor has plenty of power to cause the fork to become deformed...it is by design the 'weak link' in the feeder drive. 8-)
SLOW AND STEADY WINS THE RACE

Kramer1782
New Member
Posts: 13
Joined: Tue. Jan. 24, 2017 9:14 pm
Hot Air Coal Stoker Stove: Harman Magnum
Coal Size/Type: Rice
Other Heating: Electric baseboards (Utilized as backup)
Location: Trout Run PA

Post Thu. Jan. 26, 2017 4:57 pm

All,

Thanks for the direction. I will try to capture all questions with a response here. Yes I did have a lot of fines in that last clean out and the initial issue was a feed problem due to the pusher block being seized as it was caked with the dust in a cemet like form. The combustion fan is fully seated and yes I have the fines collection under the grates. I had cleaned that out well during that initial tear down and have since cycled the cleaning lever but always return it to the closed position. I had opened a window which did not seem to influence it much. I feel as though the combustion fan is pushing sufficient air as when I manually stoke the fire it kicks up the heat. I have continued to dry the coal out on top of the stove until before putting into the hopper. This has seemed to make the most impact. Both yesterday and today the stove was able to get the room up to above 80 and remain operational during pilot mode. I also feel that the initial clean out last week resolved the feeding issue. Prior to restarting the stove I ran the unit with no coal pre loaded on the grate and let the pusher block fill the grates with new coal. Also once I started the stove the feed rate does influence the size of the coal bed. However until my issue is completely resolved I will keep in mind and likely clean the block again. I have not cleaned the flue pipe and planned on doing so when I got a draft meter. I was not able to locate one locally and will just have to order the Dwyer 25 online. Just checked it when I got home from work today and the stove seems to be operating as it should. The house is warm and the stove/room reaches temperature and cycles off the thermostat as well as remains operational during pilot mode. At this point I feel the issue was wet coal which led to the initial feed complication. I have since brought all buckets into the house and dumped them all into a kiddie pool in front of the stove. Now with the drier coal the stove is returning to normal operation. However just to be thorough I will measure flue draft and clean the pipe. With all my buckets now empty I will re fill tonight and move them all inside versus kept in the garage. Hopefully this will aid in keeping the coal dry. Also I will take up the advice of recycling the bottom bucket coal into the top of the next bucket. I would suggest the lesson learned for me as a newbie is to remain vigilant ensuring that my coal is kept dry. My coal bin project will assist nicely next year. Thanks again for the timely support and I will keep the situation up to date.
Last edited by Kramer1782 on Thu. Jan. 26, 2017 8:15 pm, edited 1 time in total.

Kramer1782
New Member
Posts: 13
Joined: Tue. Jan. 24, 2017 9:14 pm
Hot Air Coal Stoker Stove: Harman Magnum
Coal Size/Type: Rice
Other Heating: Electric baseboards (Utilized as backup)
Location: Trout Run PA

Post Thu. Jan. 26, 2017 5:03 pm

Forgot to mention, the house came with one CO monitor but the battery was dead and with out its battery backup the unit would not operate. After reading the other thread I went and replaced the battery. I have moved it around the house to ensure the house was clear and it is now on the main floor with the stove in the basement. Our readings have been 0. I will also be getting additional units so as to not have to move the one around and also to create a redundant safety blanket.

User avatar
McGiever
Member
Posts: 5997
Joined: Sun. May. 02, 2010 11:26 pm
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Coal Size/Type: PEA / ANTHRACITE
Other Heating: Ground Source Heat Pump
Stove/Furnace Make: Hydro Heat /Mega Tek
Location: Junction of PA-OH-WV

Post Thu. Jan. 26, 2017 9:56 pm

Sounds good K, Keep up the good work. It can get better after the learning curve. :)
SLOW AND STEADY WINS THE RACE

Kramer1782
New Member
Posts: 13
Joined: Tue. Jan. 24, 2017 9:14 pm
Hot Air Coal Stoker Stove: Harman Magnum
Coal Size/Type: Rice
Other Heating: Electric baseboards (Utilized as backup)
Location: Trout Run PA

Post Thu. Jan. 26, 2017 10:11 pm

Thanks. This family has definitely helped with that curve.

User avatar
Hambden Bob
Member
Posts: 6469
Joined: Mon. Jan. 04, 2010 10:54 am
Hot Air Coal Stoker Stove: Harman 1998 Magnum Stoker
Hand Fed Coal Stove: Blower Model Coal Chubby 1982-Serial#0097
Coal Size/Type: Rice-A-Roni ! / Nut
Other Heating: Pro-Pain Forced Air
Location: Hambden Twp. Geauga County,Ohio

Post Thu. Jan. 26, 2017 10:34 pm

These Poor Devils have thrown You some extremely solid advice. Excersize it one step at a time and find the answer. Get back to Us with Your results. Always remember,these Stokers Love 'Da dry coal,and keep an eye out for debris..... :up:
Remember,There's No Sight Like Anthracite !......Hambden Bob

User avatar
titleist1
Member
Posts: 4404
Joined: Wed. Nov. 14, 2007 4:06 pm
Hot Air Coal Stoker Stove: Harman Mag Stoker (old style) one in basement, one in workshop
Hand Fed Coal Stove: Harman Mark III on standby for long power outages
Coal Size/Type: Rice/Anthracite; Nut/Anthracite
Location: Cecil County, MD

Post Fri. Jan. 27, 2017 6:53 am

Sounds like you made some progress!

I have a First Alert CO monitor on the first floor, it has an LCD display you have to hit a button to see the number. I like the Kidde nighthawk CO monitor better that I have in the workshop and at ceiling level in the basement because it has an easy to see LED display without having to hit any buttons. Its nice to have a couple/few and to stagger their replacement by a year or two that way they aren't all at end of life at the same time.

Even though things seem back to normal I would measure the fork spread as McGiever suggested earlier for the 1.75". You don't have to shut down to do this, just remove the cover over the stoker motor and either catch a quick measurement as it rotates or wait for it to stop.

How many 'dots' is your pusher block moving?
I drive a VW TDI, heat my home & workshop with two coal stokers and have two vintage JD diesel tractors....
The EPA just loves me!!


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