# Burning coal in my HS Tarm wood boiler.



## Rick Watson (Dec 18, 2012)

Hi, I think I can burn coal in my Tarm but want to find out for certain. I have used it for the past 10 years for wood, but last year I put in 2 Harman pellet stoves. They work great and I have saved a lot of money by not using oil. I used oil originally and then put in the Tarm for back up. When oil spiked I went to mostly wood but got kind of sick of it, the mess, the smoke, the work involved. It's in my cellar and I have a bulkhead, but still a hassle. Anyway I miss my big cast iron radiators (1800's Georgian Revival) getting hot and staying hot. The pellet stoves just blow hot air and I'd like to try burning coal. I KNOW ABSOLUTELY NOTHING ABOUT COAL. I assume I can buy it bagged and would like to try it out. How do I light it? Build a wood fire and add coal? How long will it burn? etc. etc. etc. Thanks and if these questions are answered somewhere please point me in that direction. I am fully capable of learning something new, but better to ask first I figure. Thanks, Rick in Maine.


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## BoilerMan (Dec 18, 2012)

Where is Maine Rick? 

I kave several friends who burn coal up here in Mapleton.  Several of them hand feed as you speak of.  You need to get "stove coal" as this is the biggest size and will burn well in a hand fed situation.  The smaller nut, pea, and rice are generaly for stoaker setups.  You light a good hot wood fire and let it get to a hot coal bed and add the coal on top to get it going.  It burns for a LONG time, you can pile it up as high as the Tarm will hold and it will just burn nice and slow, the burn rate has alot to do with draft, and how often you shake it down.  I assume your Tarm has shaker grates, shaking it means letting the built up ash fall into the ashpan and lets more air to it making it burn hotter and faster.  The biggest drawback to coal IMO, is the ash........ about 30% in volume as I understand it.  Where wood is somewhere like 2% or less depending on species.  Others will chime in.

TS


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## cmperry (Dec 20, 2012)

Rick Watson said:


> Hi, I think I can burn coal in my Tarm but want to find out for certain. I have used it for the past 10 years for wood, but last year I put in 2 Harman pellet stoves. They work great and I have saved a lot of money by not using oil. I used oil originally and then put in the Tarm for back up. When oil spiked I went to mostly wood but got kind of sick of it, the mess, the smoke, the work involved. It's in my cellar and I have a bulkhead, but still a hassle. Anyway I miss my big cast iron radiators (1800's Georgian Revival) getting hot and staying hot. The pellet stoves just blow hot air and I'd like to try burning coal. I KNOW ABSOLUTELY NOTHING ABOUT COAL. I assume I can buy it bagged and would like to try it out. How do I light it? Build a wood fire and add coal? How long will it burn? etc. etc. etc. Thanks and if these questions are answered somewhere please point me in that direction. I am fully capable of learning something new, but better to ask first I figure. Thanks, Rick in Maine.


Best way I found to start coal is with Matchlight charcoal. Put a half bag on grates..light it..let it burn down..spread it out and begin to add thin layers of coal until the firebox is full. I use my coal stove during really cold spells and I use nut. Stove size burns hotter and faster because more air space between the coal for air to come through. During warmer spells use pea..less air space burns slower and longer with less heat..Real cold days shake the grates twice a day topping off after every shake, warmer days once a day. Get a barometric damper installed if you don't have one to limit your draft. Check manufacturer specs for draft numbers. I use bagged coal. Be careful of leaving ash drawer open coal gets VERY hot quick if draft goes unchecked.


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## mikeyny (Dec 20, 2012)

I have a tarm 502. You need the coal baffles in order to really burn coal. I fabricated some myself out of steel plate. I have burned a bit of coal but I cant seem to get the hang of it. Your door gaskets need to be perfect in order to control the burn rate. You get a lot more btu's from coal. Its best to use in coler weather, less likely to overheat.


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## MaineMike100 (Dec 21, 2012)

I have an OT-35 which is the older model very similar to your 502.  Burning coal produces much more heat than wood as a rule, and as stated above door gaskets must be maintained in order to control the fire.  I use Pea coal this time of year since it burns a little slower (packs tighter so less air flow).  In the extreme cold I switch to nut coal for a faster burn and more heat.  I always start a wood fire, then just dump the coal on top.  It is important to have an even bed, no space around the coal to allow air flow, this forces the combustion air to pass through the coal bed itself.  

I get 24 hour burn times with pea coal, little less with nut. 

Good luck.


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## SmokeEater (Dec 23, 2012)

All of the suggestions on burning coal listed above are good.  I burned coal for several years in a combo PowrMatic coal, wood, oil furnace with shaker grates.  Be very careful about leaving your draft or ash door open and unattended while coal is on the bed.  It does get VERY hot very quickly with unlimited draft.  I had to replace one of my thick cast grate sections because of my inattention to the draft and the hot fire warped to grate.  Also I found that you must always have some draft opened to keep your fire going.  No draft and the coal fire will go out and be cold in an hour.


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