# Tarm 502



## cokehead (Mar 2, 2008)

Does anyone have experience burning anthracite in a Tarm 502?  It is said fools rush in where angles fear to tread.  Yesterday I just bought a used Tarm and plan on replacing my oil burner with it but there is way too much I don't know about it.  I am going to contact Tarm's customer service in New Hampshire Monday but I'd value  advice from anyone who uses a Tarm.  Stay Warm,   Jonathan  Mystic, CT


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## Eric Johnson (Mar 2, 2008)

Welcome to the Boiler Room, cokehead. Our Webmaster, Craig Issod, used to own Tarm USA, so I bet he can give you some pretty specifc advice on that boiler. Is it multi-fuel? Why tear out the oil boiler? I'd keep it in place for a reliable backup, if you can get the chimney situation figured out (i.e., a separate chimney for each boiler).


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## cokehead (Mar 2, 2008)

Hi Eric,  Wow!.....I came to the right place.  I have a friend who has boiler knowledge but not specifically about Tarms.  He is going to be the brains of this operation.  I was taking the oil burner out because I don't have room or an extra flue for both, and the Tarm has an oil burner built in.  I have heated primary with wood stoves for 15 years.  I switched over to coal stove about a year ago but my wife complains the heat is not even throught the house.  She is right.  I'm to cheap to run the oil burner for heat.  It would cost me a bundle in this drafty house.  The Tarm is a step up in that I have 3 fuel options depending on the season and availabilty and I can tie it into my radiators.  I perfer coal in that it has longer burn times but wood is good to if its free.  Oil ,....well sometimes you just have to use it.  Example  summertime hot water.

My friend (Ian) says it is missing a control on the oil gun and he thinks the hydrostate is missing.  I read somewhare that it is a multi setting hydrostate so the oil burner only kicks in if temps really start dropping in the boiler.  Getting the controls right with parts missing will be the biggest challenge.

The unit seems to have round shaker grates but I'm puzzled by the ash pit.  Half way in there is a barrier and the space is shallow.  There is no room for an ash tray.  I saw on Tarm's web site that they recommend putting the boiler on concrete blocks so you can "scrape" the ashes out into a pan.  Sounds dusty to me!!  I don't want to put that fine dust into my home for every one to breath.  Coal makes a lot more ash than wood which would mean a clean out I estimate every other day.

Also there is a mixing valve that blends hot water from the boiler with cold return water from the radiators.  I guess it is what it is...just leave it alone to do it's thing?

I'm not sure how to get the accumulated ash out of the "heat exchanger" in the boiler.

Wood and bituminous needs preheater secondary air.  Anthracite does better with all the air coming up through the coal bed.  I'm going to have to figure out how to make the necesary adjustments going from one fuel to the other.  

So I'm thinking I might be over my head.  Just moving 1440 lbs is going to be a challange.

I'm sure there will be more questions I don't know enough to know I don't know.  That's life.

Stay Warm,    Jonathan


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## mikeyny (Mar 3, 2008)

Jonathan,
             I have a 502 built in 82. I have used it for 4 or so yrs now. I removed it from a house where I installed a new oil fired boiler because the tarm used way too much oil. Wood was of no interest to them. The oil burning side is not very efficient. I think they were designed to burn wood primarily and use oil as a backup.  The grates i have are shaker grates, they are flat on top. apparently there are optional coal grates and a baffle. All can still be purchased from tarm. I attempted to fabricate a baffle similar to the one in the tarm manual and installed it in the boiler. I had a difficult time learning to burn coal in it. there are many challenges involved with coal burning. I gave up after a while, since wood is more available to me for fee. From what I understand coal can be burned very well in this boiler, but it takes a bit of learning.  When you get the manual from tarm you will see the wiring options and aquastat types to use. There are several different ways to wire and operate these according to your needs. My tarm is in my detached garage. That keeps all the dirt soot and ash out of the house. SMOKE. You forgot to mention SMOKE. Since the tarm is an underburn, ( the smoke exits the bottom). There is a sequence of things you must do before opening the loading door in order to minimize the amount of smoke that come out the door and into the room you are in. My boiler has very good draft and still belches smoke out the door when you open it to load more wood in. This wood boiler works GREAT. It heats a very big house for me. My house is actually much too big for my boiler but it still does a great job. With any wood boiler you should ALWAYS have an over heat zone. The boiler can make too much hot water and may occasionally need a place to dump the excess heat. Redundant pressure relief valves should also ALWAYS  be installed as well a a low water cutoff device to close the damper in the event of a major water leak and sudden draining of the boiler.  Since it is nearing the end of this heating season you will have time to educate yourself here and other places about heating with wood. This is the best way to save a bunch of money. Read though some of the threads here about wood and seasoned wood. this particular tarm boiler requires very well seasoned wood to operate efficiently and safely without too much creoste problems.


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## webbie (Mar 3, 2008)

The 502 is designed to burn both wood and oil and can be tuned up pretty high on the oil end. It uses a completely separate combustion chamber and a separate set of firetubes, so the wood has little or no effect on the oil combustion.

The unit is designed to use ONE flue, a 6" flue - and can burn both fuels into this one flue. You should be able to get the owners manual from the current Tarm people in Lyme, NH (1-800-782-9927)

The controls are set up as follows:

1. A triple aquastat, Honeywell 8124 (M), the M designation being one that was slightly modified for solid fuel burning - I think it had a big more of lag built in (did not always try to make high limit on call for heat) - but even a stock 8124 should be able to do the job.
This control works the circ, the thermostat and the oil burner to maintain a set temp.

2. An overheat control - this was a single acting aquastat which would "jump" one zone of the system if the boiler got too hot.

3. A non-electric samson or ammark control (c-20) which opens and closes the wood draft flap.

By setting the oil temperature down to 160 or so and having the wood try to be 180, the wood should have a little wiggle room to attempt to make temp before the oil turns on.

The boiler weight about 1100 when you strip the doors, jackets, burner and everything else off. There is a lifting hook on top which can handle the whole boiler. It can be moved using iron pipes, crow bars, sheet metal sheets, boards, etc.

good luck


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## webbie (Mar 3, 2008)

You must have the coal grate set in order to burn coal. Does it have the grates in it? Also, there is a part called a coal baffle which can also make it easier, but that is not 100% needed.


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## cokehead (Mar 3, 2008)

Hi Mike and Craig,  I definitly need an ouners manual.  I was told the Tarm had an 87% efficency on the oil side. That almost sounds too good to be true.  I'm planning on using the oil side for domestic hot water off season and use mostly coal for the heating season.  I only have one zone in my house so I better learn how to regulate it so we don't have to open the windows when we have a 50 degree day.  It appears to have a set of 6 or so round (tube like) grates.  There are two bars behind the ash door which you can hook into and rotate (shake) half the grates at a time.  They look like coal grates to me.  I've paid for the boiler but won't have possession of it til next weekend if everything goes well.  I'm still a little puzzled about how you get the ash out on the back side of the baffle.  The tool I saw looks like a hoe with a rectangular head at an angle back or forward depending on which way is up.  I'm surmizing you use it angle back, push it in and the ash would go over the top on the in stroke.  When you pull back out you would drag some ash out of the door.  I'm assuming the baffle will push up out of the way.  As far as the unit smoking when the loading door is opened could a hinged flap that pushes in be installed at the top of the opening?  I have seen that on some wood stoves.  Thanks for the input.  Stay warm,   Jonathan


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## coaledsweat (Mar 3, 2008)

Webmaster said:
			
		

> You must have the coal grate set in order to burn coal. Does it have the grates in it? Also, there is a part called a coal baffle which can also make it easier, but that is not 100% needed.



It appears to have about 6-7 small squarish rocking grates and a double flap curtain that is hinged below the grates hanging down in its belly. The grates rock front to rear if you push and pull on the two levers hanging in the ash pit. One lever shakes the odd grates and one the evens. The info plate shows a coal rating of 120,000 BTUs.

Don't these things burn in a downdraft? If so, that is going to make burning anthracite an educational experience, yes/no?
At 1440#, it will be a real treat to move. It's on concrete blocks now, so I figured I would grab a pallet jack and just pick it up and roll it out the sliding door. Getting it on a truck or trailer will be fun however.

I did find a TARM dealer that is local, Preston Trading Post. They may be helpful.

Anyone have any idea what this beast cost new? It appears to be the same thing as their Excel 2000 that they still sell except the new ones don't burn coal.

Tanks guys,
Ian


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## kevin85 (Mar 3, 2008)

We had fun moving my Tarm when we brought it in our house...  what we did was we got 4-5 small PVC pipes and rolled it on the concrete floor.  when one pipe would come out the back, we would replace it in the front.  I would never have thought the pipes would support that furnace but it did with ease.  Now getting it up on the concrete blocks was another thing all together!!  But I am glad it is on blocks...much easier to clean out.

We had a friend with a small crane truck that helped get it in and out of the truck.


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## webbie (Mar 3, 2008)

Sold for about $5,000 new when I sold them, would be higher today
Coal grates were extra

Yes, that boiler has coal grates in it! 

And, yes, it can be a learning experience to burn coal in a 500 series (or 400 series, which is an add-on identical), BUT it does burn and burn well. It has to do with the way you bank the coal, more toward the front in this case. In the rear it should not be piled as high as the opening where the gases exist. There is a optional piece called a coal baffle, which is an upright piece installed in the read (two grates are removed) - this makes it even easier to burn coal, but it may not be available any longer. Check with tarm.

The little swing piece under the grate is designed to deflect air up through the coal bed so it does not all bypass the coal.

The Excel is a completely different boiler. A 502 is a natural draft system, while an Excel is a forced draft unit with higher wood efficiency due to the ceramics and design. Yes, Gabe over at Preston probably has a manual. He is away on vacation now, but will return in about 10 days.


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## webbie (Mar 3, 2008)

cokehead said:
			
		

> Hi Mike and Craig,  I definitly need an ouners manual.  I was told the Tarm had an 87% efficency on the oil side. That almost sounds too good to be true.



Probably close to correct - at least 84% - steady state. Of course the AFUE is not going to be that high. You have to carefully check the oil chamber before using as there were cast iron baffles between the oil and wood chamber that tended to burn out early. Replacements can be ordered and there is also a kit to shield them with ceramic bricks.


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## coaledsweat (Mar 3, 2008)

Webmaster said:
			
		

> You have to carefully check the oil chamber before using as there were cast iron baffles between the oil and wood chamber that tended to burn out early. Replacements can be ordered and there is also a kit to shield them with ceramic bricks.



They have an oil boiler there and the Tarm oil gun was stripped of its primary control, it may not have been used that much. Do you think a wet patch kit could help or the refractory bricks would be the best bet in the oil chamber? 

Is the baffle burn out caused from running the oil only or just happens on either fuel?

The plumbing with the temp loop looks like something from a nuke missle boat. :bug:


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## mikeyny (Mar 3, 2008)

I know they claim that the oil burning side is very efficient but, like everything else out there, it seems to be a bit over rated. When I replaced that boiler with a new boiler the oil consumption almost went in half. The efficiency claims of the the new boiler were similar. A wet pak would definitely make it easier to protect or repair the separation between the to sides of the boiler. The oil combustion chamber appears to use a fire brick target. Be sure to use the proper nozzle when firing it. One this is for sure, that chamber is not designed to atomize the fuel very well.  First of all the chamber is a bit too short. A good boiler guy could probably re-configure the chamber to burn better. When I moved mine we use a come along to get it up the cellar stairs on some wood planks lined with aluminum. We removed all of the metal shroud, doors grates, oil burner and anything that could come off to lighten it up and make it safer to handle. We got it into the truck the same way. Rollers work great on flat ground. Be  carefull, it is definitely top heavy and unstable when in the up-right position.

                                                                                         Mike


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## coaledsweat (Mar 3, 2008)

Could the Thermovar controls be used to modulate heat in the home?

What I mean by that is run the circulator continuously and modulate the water temp fed to radiators to produce a more even continuous heat. It seems like an ideal way to heat in a drafty, uninsulated home with single pane windows. Is something like this worth doing?

Just looking at all the options here, any ideas? A heat storage system is probably not an option with this install.


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## cokehead (Mar 8, 2008)

I've been able to get my manual from NH. A lot of my answers are there. I have pulled the grates out (5) and the baffle plates that separate the oil and wood/coal side. I have the top off and the oil gun removed. All my electrical components are disconnected. One of the separation baffles was all warped and had a hole burned through it up high where it can't be seen unless you look up through the oil gun opening. The separation baffles had slide forward and interfered with the grate operation. There seems to be two "clips" on the boilers body down near the bottom of the baffles. I'm not sure if they where to retain the baffles or hold a flat bar to form a barrier to stop the baffles from contacting the grates. The diagrams don't show the "clips" or a bar so manual doesn't help to unravel the mystery. The grates and separation baffles where easy to remove. The separation baffles are still available. I didn't check about the coal baffle systems availability. Looks like ash removal should be easier because the hanging baffle under the grates could be removed along with the two rear grates. That hanging baffle looked like it would make ash removal difficult. Letting the coal ash build up under the rear grates could make them overheat. When I have it all figured out I'll make on hopefully complete parts order. It did have a smoke flap on the loading door frame as part of the original design. I didn't remember it when I made my earlier post. I can't go look at it anytime I want at it's present location. Ian and I should be able to make the final separation of the domestic and circulating hot water pipes Sunday. He is making up a special 4 wheeled dolly to move it. Sounds like work to me but he thinks it will be easier and safer to move that way instead of rolling it on pipes. The diagrams in the manual show an external lever to shake the grates. Mine doesn't appear to have that feature. Also mine has some sort of control that is missing that went on the top left side toward the front. This control had about 3 sets of wires running to it and was in addition to the master hot water control and the overheat control pictured on page 14 of the manual. It appears to have a well for a thermal probe. I'm not a professional boiler man so I apologise if I use terms which are non-standard. I've purchased a wood stove "Lopi Patriot" new from Preston Trading Post and I think they are a good bunch but the more I can do for myself the better. If I call them in it will be a last resort. Money and independence is the issue not them. Along with the manual came a lot of info about Tarm USA's current products.  I wish I had the space for the heat storage system. It makes sense especially meeting domestic hot water demand in the off heating season. The plan it to use the oil burner for hot water in the summer. I'll likely install a .85 gph nozzle to try and hold oil consumption down.   Stay Warm    Jonathan


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## mikeyny (Mar 9, 2008)

great update Jonathan. there should be a tag on the top of the water jacket in the front above the loading door. That will tell you exactly what model you have. mine is a 502 made in 82. I do have the lever to shake the grates on the right side of the boiler. My seperation baffle also has suffered some damage from the oil burner. I patched mine temporarily with some steel plate and furnace cement.  Good luck with moving it. Just remember it is very top heavy. Put some plugs or caps on any fittings coming out of the boiler to prevent any "stuff" from getting into it during transit. One dump in the dirt and you could have junk in the boiler that will eventually find its way to a circ or valve in the future. 
                                                                                                            Mike


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## cokehead (Mar 10, 2008)

I sent an e-mail to Tarm USA asking about the availability of the coal baffles. I should have an answer soon. My boiler never had the external shake lever. My grates have the arm in the middle of each grate. The grates shown in the manual with the external lever have their arm cast in on the far right side. Looks like if I want an external shaker lever at the very least I would need new grates. I'm going to leave that alone. Maybe it will be obvious when I install my new separation baffles but does anyone know what keeps them in position? Would the .85 GPH nozzle reduce potential damage to the separation baffle plates? I'll look at that plate on top of the boiler tomorrow. I'm going there to do clean up and check for leaks in the pipes we capped off. Ian and I got the boiler on the dolly he made today and moved it in the basement. Because of Ian's help things went well. For a second I thought he made the dolly too narrow but it just fit. The boiler base is actually bolted to the dolly so there is no danger of it sliding off. Next Sunday I hope to borrow a low trailer and move it to my basement. I have a lot of preparation to do, mostly cleaning out my basement to make room for my new toy. Years of procrastinating and saving anything that might be useful SOMEDAY is biting me in the backside. I have to decide if I save or get rid of my old oil burner. That is a tough decision for a pack rat like me. My basement is small and I need the space. After I have my Tarm up and running for a while I should let it go. But if i move I want to take the Tarm with me. If I get rid of the oil burner then I'll be needing to buy another one....but I may never move...it's a disease.


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## coaledsweat (Mar 10, 2008)

mikeyny said:
			
		

> Good luck with moving it. Just remember it is very top heavy.



That was my biggest concern. Where it is going has a few whoopdedoos to get there. I found 4, 3" by 10" with polyurethane tread dryer wheels at work to borrow and make the move easier, it should roll like gangbusters on them. They had a tapered WOODS style bore so I made some bushings out of 2" PVC couplings to fit the taper and bored them for the 2" pipe axles. I used the bolts holes that secure the split hub with bolts and washers to hold the tapered bushing in place. The 2" angle iron tray I made is bolted to the base of the TARM and I have two sets of 2" pipe axles for it. A narrow set about 26" wide for getting it out of her doorway and a wide set 48" wide for once it is outside. I called TARM and they said everything is welded to the base so it should amount to a 4' X 4' block at 1400#, I would think that would be stable enough. I did not want to have to strap or bind anything to the sheet metal covers. I'll post a few pics tonight when I get home.


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## cokehead (Mar 17, 2008)

Ian helped me move the Tarm today.  His dolly worked well.  We used pry bars to steer it and a cable come alone to get it in a U-Haul trailer.  It is in my basement next to the oil burner waiting to get hooked up.  I bought the triple aquastat and some other oil burner parts yesterday.  Now that my Tarm is home I'll order up another $500 worth of parts fron Tarm tomorrow.  Maybe in a few weeks I'll be operational!


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## mikeyny (Mar 18, 2008)

I set mine up on 6 pieces of flat 4 by 16 inch solid cap blocks. It keeps it up off the floor a bit. Makes ash removal a little better. Also keeps it up away from any water on the floor.  Great job so far. I know it feels like a big accomplishment when that big ole thing gets into the basement. Now you can read some to  the info here about all of the various ways to pipe it into your system. There are several different ways to do it. If you have a plumber friend he may already know how, but , be sure to check out all of the options before going forward, and take your time, the season is almost over.    I   remember rushing thru my install and having to "back up " a few times and re-do what I did'nt spend enough time thinking about before. It will all come together with some patience. Also be prepared to drain down a few times, you may have an occasional leak here and there. I actually had a pin hole in a brand new copper el near the boiler. Have fun.

                                                                                                                        Mike


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## coaledsweat (Mar 18, 2008)

We left it on the cart I made. It is off the floor about 3", it should work out well as it has room under the front for an ashtray to slide up under it a few inches. If he wants to move it when he sells the house he can just slide the axles back in and it's "TARM to go".


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## cokehead (Apr 7, 2008)

I finally had some time this weekend for my Tarm. I got the new shielding block for the oil side of the separation baffles in. I did it without removing the large plate the oil burner bolts to. My arm just fit through to opening for the oil gun. I had to remove and trim the side shielding bock to get it to fit. Also there was a piece of steel melted into the rails that the separation baffles rest on up high. I used a 8 lb sledge and a 4 foot crow bar to persuade it leave. There is a bar welded into the boiler that gives the top of the separation baffles something to rest against. That appeared to be cast iron judging by the way it was swelling and granulating on the right side. It's not good but it will still work. I think it warped about a eighth to a quarter inch toward the front of the boiler so the separation baffle doesn't lay in perfect. I can't let it get worst so I think the .85 gph nozzle should lower the intensity a bit. I'll have to do a little experimenting when I get to that point. Also to protect that bar I slid the shielding block a few inches higher than it was designed to go and slipped some fire brick under the low end to hold it there. Because the shielding is at a shallower angle I think the fire box volume shouldn't be affected and the flow into the fire tubes shouldn't be adversley affected either. I figured out the coal separation baffles and got them installed, put 4 grates in with the connecting bar, and the smoke flap in the loading door opening. I left out the hanging baffle under the grates. I think they would make ash removal a pain and with the coal baffles in place I doubt air distribution under the fire would be such a problem. I made a simple tool out of a tire iron to shake the grates. I heated it up orangy red in my Warm Morning 617-A and beat it into submission with the 8 lb sledge on the anvil. It feels good in the hand. I got all the fire tubes clean (gave everything a good scaping and vac) and installed a new gasket on the fire tube access panel. I put Never Seize on all the bolts and where the gasket contacts the top of the boiler. The old gasket was stuck to the boiler. I had to scrape it off. Then I filed the sharp edges left from manufacture. The gaskets are too expensive to keep ruining. The loading door and ash door gaskets are ok. I'll replace them eventually but not a priority. On previous weekends I got a 20 amp outlet wire where it is handy and put up two permanent pull chain lights in the ceiling over the Tarm. No more extension cords. Next step will be to re-install the oil burner and figure out the wiring! I'm a little befuddled by the wiring. I need to lock myself in the basement (with a Dogfish Head 90 Minute IPA) and make myself a diagram. All in all I'm happy with what I got done considering I've had a killer back ache all weekend. Stay Warm, Jonathan


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## kart42 (Dec 21, 2008)

Jonathon,

I have had my Tarm for a long time.   I bought it new in 1983.    I burned wood for 20 years.    I always bought loads of logs and cut and split (by hand) the wood myself.    I estimate I burned 130-140 cords.    It was never much cheaper than using oil, because oil seemed to only go down.   After a couple of years I realized that to control the creosote the fire had to burn hot all the time.   This meant that there had to be some place to store the heat.    I envisioned using water and my calculations indicated that 2000 gallons of water would hold the heat from 24 hours of hard burning.   I then learned that such systems existed and despite a couple rounds with a very bad dealer/installer I had a 2000 gallon Dumont hydronic tank.  That solved the creosote problem.    Five years ago I found I could no longer get loads of logs (my source retired) and so I switched to oil.   With the price of oil this summer I decided to burn coal (wood was wildly expensive).   I knew that decision would force the price of oil down and it surely seems to be working.   The Tarm manual said it would burn coal, even describes how to do it.   It doesn't mention modifications required to properly do it. and I naively assumed it would burn coal.   I am looking for the coal conversion kit, but I am not very optimistic that I will find one, maybe a used one?   The Tarm franchise has apparently been moved around several times since the 80's.   With some digging on the net I am starting to learn about coal burning.    I now know that there are coal baffles that are required to burn coal well.   I can also see that they are on the upper left hand corner of the parts blowup page in my manual, but I have been unable to find one word about them anywhere else in the manual.   So...   I have six tons of bagged coal (price of bagged was same as price of bulk coal where I am in Vermont) and so I am learning how to burn it, without the coal baffles.   

The problem seems to be that the wood set up when used with coal (which generates a lot of ask & clinkers) leaves at lot of ash and clinkers at the back of the firebox on the angled baffles.   This area is not over the grates and it is very difficult to clear the ash /clinkers from this area while the fire is burning.   It works out that with my hydronic tank I can still only burn for about 24 hours before the tank is hot (200F).   So I let the fire go out, and clean it out and then start another fire if needed.   It is messy and dirty and I wind up with unburned coal as coal seems to only burn well as thing.   As it goes out at some point it loses critical mass and really does just stop burning.   If I didn't need to let the fire out anyway, this whole process would be very frustrating.   Trying to continuously burn to heat a house with the wood setup in my Tarm would be a problem.

You are looking for a manual and while poking around on the net I found one yesterday.    I have my manual, but I wanted to find newer ones.   Mostly to see about grates.   By the way, the manual does explicitly say that the grates are good for both wood or coal.    What I found was that newer Tarm 502's have and outside handle for shaking the grates.   I was unhappy to find that the change also changed the grate design.   The "arm" on my grates is in the center.   The new design has the "arm" on the left.    I had a broken grate (the arm broke in such a way that the bolt fell out) and ordered a new grate for the Tarm 502, only to find it won't help without a whole new set.    Themanual is a pdf document.   I now have a copy on my computer and I will try to get a link into this document.   I am not completely sure how to do that but I will give it a try.   If that fails I can always send the file directly to you outside this forum, which has size limitations.

Link  
Tarm500Manual

It doesn't seem to be a live link but you will find the complete manual there.

Somewhere else on this site the worry was about the baffles between the oil and wood combustion chambers.  I replaced them twice before I was told how to fix it by the Tarm folks.   I had to replace them after only 1500 hours of oil burning.   The oil flame against the cast iron baffle just spoils them in a very short time.   They crumble into small pieces and there is a hole.    You must put fireboard inside the oil chamber against the baffle to protect the cast iron.   The board can be obtained from any furnace wholesaler.  There is a piece on the boiler wall across from the oil burner if you want to see what it is.   It is not firebrick, but some quite light stuff that is impervious to the flame.    There is also a solution to the problem of the shortlived  seals on the cleanout door for the firetubes which Tarm sent to me which can be implemented with locally available materials as well.   I can write about that later.   

Happy heating with your Tarm,
Paul


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## glhenry56 (Dec 27, 2008)

Paul & others,

Thanks for the great info (pun intended).  I am burning wood again this year in my mid '80's vintage 502 after about a decade on #2 oil only.  I have experimented with coal in the past (without benefit of the mysterious Tarm baffle), and found that I could sometimes make it 2 - 3 days before a frustrating "flameout" and the pain of shoveling out a bunch of unburned fuel along with the light fluffy ash.  I would also like to locate one of these baffles, or at least a good spec sheet so I could see about making one up.  I'd appreciate any info.

Years ago, I installed a "draft inducer" fan in the outlet flue to help deal with the smoke when loading the unit up, and I find it indispensable.  The fan also makes re-lights much quicker & easier.  However, I would caution that if left running and unattended, it could lead to overheating.  Mine starts on a "countdown timer" switch (same type as some bathroom exhaust fans are).

Lastly, I note that Craig Issod is the Webmaster for this site, and recalled working with him when I purchased my Tarm.  He also assisted with sending me a "baffle protection conversion kit".  Based on my experience, I'd say this site is in good hands.


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## cokehead (Dec 27, 2008)

If you are looking for coal baffles contact Brian Millette at 1-800-782-9927 durring business hours.


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## kart42 (Jan 1, 2009)

The number Codehead posted is correct and is for Bioheatusa in Lyme, NH.   I called on Dec 22 and ordered and received the baffles on Dec 23.   Really outstanding service.   The cost was $255 plus shipping (to Vt that was about $22).   I found a bulletin from HS Tarm on the coal baffles somewhere on the net and printed it.   I think I have the PDF file on my computer.    The prints are not too clear but if you are interested I can post the PDF (or the link if I can find it).   The baffles have significantly improved coal burning.   However, keeping them in place is a bit challenging.   I think the design could have been better.     I am also worried about the longevity of the cold rolled steel plate that holds the base of the cast iron baffles.   It sits very close to the base of the fire.    Time will tell I guess.


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## glhenry56 (Jan 9, 2009)

Cokehead / Kart42,

Thanks for the coal grate info. I'd like to see the PDF files or a link if you could. Might be a project for next year.

Did my midwinter firetube cleaning tonight - lots of soot on the oil burner side. I have 2 particular issues that have been a thorn in my side when it comes to the oil burner: 1) "blinding over" of the oil burner air inlet with dust, and [I believe] inaccurate O2 readings by burner technicians when servicing my unit. Either or both have resulted in several really messy soot events over the years. The dust buildup issue is something that I can control, but if it isn't regularly vacuumed away or wiped off, it can creep up on me fast. With insufficient air to the oil burner, it starts to smoke, the soot rapidly plugs the firetubes, and soon I'm smelling sulfur in the basement and have a nasty sooty mess to clean up. Ugh! 

My second concern is really a result of the draft inducer - one of those unintended consequences of making an improvement. For the inducer to work properly, it must pull a quantity of room air into the fan (which is located close to the boiler outlet). Thus there is a hole near the flue gas outlet. Unless the burner tech inserts his gas probe all the way into the boiler itself, it is likely that some of the room air is being drawn in to the flue pipe (by natural draft), diluting the sample. O2 reads higher than it should, and the burner tech is likely to restrict air to the burner. Since I'm rarely at home when this is done, I've relied on notes, and as I can tell from trying to describe the situation in writing, the message may not be getting through.

In any case, I'm going to try to attach some photos of the inducer for those who might be interested. It has served me well, and I recommend it as a way to reduce smoke blowback and as an assist in starting a fire. Don't know where or even if these are still available, but I would certainly think so. It is a Fasco brand, Type U63, 1600 RPM, 115V, 1 amp, continuous duty.


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## kart42 (Jan 10, 2009)

I found the pdf file with the coal baffle info.    The pictures are not very clear.   If I had a chance to do it over I would take some pictures before I put the pieces into the furnace.    The part shown in figure 1 (of the pdf file) is made out of cold rolled steel.   It sits on top of the rails that hold the shaker grates in the front of the firebox up against the separation baffles (those that separate the wood and oil combustion chambers.   This piece performs two functions.  1.  Hold the coal baffles themselves  2.  Seal the space behind the coal baffles from air in the ash pit (the air must flow through the coal, burn and then go over the top of the coal baffle, down behind the coal baffle and then up the firetubes.   The base of the cast iron baffles sit on the cold rolled steel plate and go up almost vertically.    They are held away from the upper front of the combustion chamber by a couple of narrow cast projections at the top.    They need to be away from the wall so the hot combustion gasses can flow down behind them and then up the firetubes.  If you have your original Tarm manual the parts explosion page shows the coal baffles and the support plate in the upper left hand corner of the page (item 50, coal baffles) in my copy.

The baffles have had a really positive effect on my Tarms ability to burn coal.   I am still learning, but I can now say for sure that without these baffles keeping a coal fire for a number of days would have been really difficult.

Paul

The pdf file was to large to include here.   Now that I know what they are the picture in the Tarm furnace manual is descriptive.   However, only a few weeks ago I didn't understand and it was not clear.   Perhaps my description above will help with understanding, at least a bit.


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## glhenry56 (Jan 10, 2009)

I spent a few minutes and located the parts diagram in my Tarm manual.  With your description, I now have a good idea of how it works.  I also have a couple of drawings of the separation baffles and protection bricks that Craig Issod sold me back around 1991.  I'll scan and post them sometime soon.


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## TimfromPittsburgh (Jan 29, 2009)

Hi Fellow Tarm 502 Owners,

I just foiund and registered on this forum today. Great information here. 

I have a Tarm 502 that I have been burning wood and coal in for 11 years. My boiler has the coal grates with external shaker handle. I bought the coal baffles when I purchased the boiler. I burn wood except when the temperature is consistently below 20 degrees (the entire month of January this year) I burn coal.

I would like to share some lessons learned from my experience burning coal:

1. The coal baffle is essential for burning coal.

2. Either anthracite or bituminous coal can be burned in the boiler. I prefer anthricite because it is smokeless. For me the "nut" size works best. Main thing is to get good quality coal. If the coal contains a lot of rock you will need to let the fire die and clean the grates frequently. The grates just won't allow big rocks to fall through into the ash pit. Coal that forms clinkers also clogs up the grates and chokes off air flow. With good coal I can run the boiler for 4 or 5 days before the grates clog up.

3. While burning coal I shake the grates often. When shaking the grates I continue shaking until I am getting hot coals falling into the ash pit. Some unburned coal falls into the ash pit but it helps prevent the grates from clogging. When I empty the ash pit I pick out the unburned coal and throw it back into the firebox.

4. When I burn coal, I close the secondary air control.

I just recently installed a draft inducer in the flue pipe. I wish I had done it a long time ago. The draft inducer really helps with smoke control when loading wood into the firebox. When burning coal, I can successfully burn coal at higher outside temperatures.

Hope this helps.

Tim from Pittsburgh


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## kart42 (Jan 30, 2009)

It has taken awhile but I feel I am starting to know how to burn coal in the Tarm 502.   I am two days from having a continuous fire for a month.   I guess I have "good" coal, because I have no problem with jammed grates, although I have developed a technique that is probably helping with that.    A friend had a new coal stove of some kind, and noted that the grates were not moveable.   The ashes were moved through them by moving a poker around in the bottom of the coal bed.   The Tarm came with a long rod with a handle and so I have been poking that through the slots in the front swing gate all the way to the back of the chamber.   Do this a number of times and some ash falls through, but it also helps to break up the "slag" and the shaker grates then work much better.   I "shake and feed" twice a day.   Generate a "hod" full of ashes a day and the oil burner hasn't even thought of turning on in 4 weeks.    The "coal baffle" is , I now know, essential to successful coal burning.   I had a few weeks of frustration while I learned (and unlearned most of my wood burning techniques) but it is going very well now.     Only drawback is that I do need to be in the cellar twice a day, but that is to be expected.   I am also not saving as much money as I had anticipated, since I decided to burn coal this year when oil was $4.50 / gal.   However, I burned wood for 18 years and the price of oil stayed low until I quit.    I still have the satisfaction of knowing the Arabs are not getting even $45/ barrel from me.


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## glhenry56 (Feb 27, 2011)

I guess this topic has gone cold (pun intended), but for anyone searching for info on Tarms and coal burning, I have an update on a "hot" topic (search "Tarm 404 - Question about coal baffles for burning anthracite" to find it).

The "official" Tarm coal baffles are very expensive (still available at Tarm USA in NH), but they have made burning rocks much easier than I previously experienced.


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## cokehead (Mar 1, 2011)

I'm still out here.  I took my oil burner out (It's in the back yard.)  about 6 weeks ago.  I'm heating my hot water with a mini coal boiler hooked up to a 77 gallon Peerless indirect water heater and heating the house with a coal stove upstairs.  When I piped it up ( Montgomery Ward No. 20) I put in tees so I can pipe the Tarm to the same indirect for the heating system and use the tiny coal boiler for the summer.  I have most everything I need to finish but the time.  Don't hold your breath.  I'm a bit slow.  Maybe I'll have my first fire in the Tarm in a year or two.  If I got by but in gear I could have it done in a coupe days.


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## Jersey Devil (Mar 2, 2011)

Jonathan,

I have one. We have burned coal but went back to wood due to cost and ease of disposing of wood ash.  Be sure to replace the DHW coil gasket before you fill it up.  

Mike


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