Burning wood in a Harmon SF260 boiler

We think we have settled on getting a Harmon SF 260 and wanted to know if anyone has burnt wood only in this model and if so what burn times were you getting? We have approx. 1800 square feet (that we will heat) and will probably use coal, but if the coal is too $$$ then we could burn wood. We like to keep the house at 72 and do not use the boiler for the hot water tank.

Thanks
Dan

I have a SF360. Burn wood and coal. I burn Pine, and have no problem getting 8 or more hour burns, BUT, smouldering (is that spelled right) fire tends to produce lots of creosote.The creosote stays in the boiler, does not get in chimney. Harman recognize this in manual, you can download it. When I burn coal it tends to dry up the creosote and slowly burn it. now I have added water storage and much,MUCH more efficient on both fuels. My coal is bit. With storage the draft is set where I get maximum transfer of heat to water and at lowest chimney temp. I used laser thermometer on pipe in/out and chimney.

Robby

I realize this is a bit late but here's my experience. I have a SF-260 boiler. I have lots of "free" wood. The trees are mine. I only pay gas, oil, time and back pain. Bagged nut is $275 per ton. A ton of coal lasts about the same as a cord of wood in my 2500 sq ft house. I do have the hot water coil. It saves me about $60 per month in winter in reduced electric bills. Even the driest standing dead wood will make a surprising amount of creosote when you get into transitional weather: days too warm to call for heat and nights too cold to go without. In the deep of winter, if your damper is set correctly, you'll get minimal creosote. Anthracite makes no creosote, but lots of fine ash. I pulled my pipes once last winter to check buildup of ash. It took 10 minutes after letting it cool down to pull the pipe and vac out the ash.

I like having the wood option. But this year I will go 90% coal versus the 50/50 split I did last year (5 tons & 5 cords). FWIW, the last time I was splitting wood. I calculated that at $275 per ton for nut, and using ~5 gallons of gas (saw, splitter, quad) to cut and split a cord of wood, and given that it takes me three six hour days to produce a cord of cut, split and stacked wood, my weekend time is worth $14.58 per hour. And I'll lose 15 to 24 weekend days to build my stack. My "free time" is worth more to me that that, at least it is as long as I have a job and it STILL costs less than half of what I paid to keep the house at 65 degrees using heating oil and now it's a very comfy 72. Your mileage may vary.

NOPEC wrote: A ton of coal lasts about the same as a cord of wood in my 2500 sq ft house.

One cord is slightly less, about 1.25 cords to eqaul one ton: Anthracite Compared to Other Fuels

I burned a Harman SF260 through the last heating season using only coal. I had used a little wood for testing the boiler last fall and was surprised at the amount of creosote I was able to produce. The weather was warm and I was a little nervous about getting the Harman too hot so the wood fire was pretty much smothered down. It is good to learn that creosote is not a problem when burning wood during cold weather. I have no plans to burn wood but it is a nice option to have when living in northern New Hampshire. Thanks for the info. Joe

A friend of mine bought a new sf-260 and burned coal until the end of the season. He tried wood for 2 days and went back to coal. He could not get through the night with the fire box stuffed with wood.

We have a Harmon SF 360 boiler and burn wood (pine, spruce, ash, elm, birch, maple) as well as anthracite. I like to use the soft wood during the "shoulder seasons", the hardwood during the colder months and the anthracite for Jan-Feb. 6 cords of wood and 2.5 tons of anthracite this past season. Fuel oil for back up. The anthracite burns through the night otherwise I must load it at 2100 and refill at 0300 during the coldest of nights. I am pleased with the Harmon. The creosote build up is burned off during the coal burning months. I am thinking of adding a 500 gallons indirect pressurized water storage tank that I have available. Anyone have experience with using a indirect water storage tank with combination wood and coal boilers? I realize that they are recommended for the wood gasifier boilers. Thanks for any thoughts.

What is indirect storags?

I have 1400 gal of storage. Water from bottom of tank to bottom of boiler, top boiler to top of tank. Water for heating ( both house and DHW) out from top and returns to mid tank. Whole system at 15 PSI.

The difference in efficiency is amazing. I cannot tell exactly how much better with storage, but at least 50%, yes 50%. Creosote is much reduced. The draft door is turned in 7 turns, those of you who have SF360 know that is not very much draft. Fire burns steady, if not loaded too full, wood burns with very little smoke and because there is almost no idling, stays very clean. On both coal and wood chimney virtually does not need cleaning. i know nothing about anthracite, never seen it, but on BIT storage allows long steady burn, with absolutly NO smoke at all, none, nada. Only heat waves are visible above chimney. Throw in 1/2 a 40lb. bucket, come back in 45 min, throw in the other 1/2, wait 45 min, anither 1/2 etcc for a total of 2 buckets. If it is real cold sometimes 2 1/2 buckets. Come back in 10 to 12 hours and repeat. Really that simple.

Before I had storage it was easy if it was cold, but very difficult if there was low or no immediate demand (on coal). On wood I ran draft 4 turns in to increase draft to come up to temp fast. Idling 100% loss, then smoke when draft door opens, all leading to creosote.

I guess you've gathered that I am sold on storage. It,s so easy now mt daughter runs it if we are away.

Robby

Robby,
thanks for the response. My storage would be a pressurized 500 gals. propane tank with fixtures welded on for running the system in parallel or series. I am thinking that since hot temperature rises to have the hot water from the boiler plumbed in to the bottom of the tank and then the hot from the top of the tank to the DHW and radiant and baseboard systems we have in place in the house. I was also wondering if I should add more storage capacity than the 500 gals. Sounds like you are sold on your volume.

I don't know what is the optimum storage amount. I have 1400 gal because I found the right tank at the right price. I would imagine that house insulation,size,windows etc. and your climate would dictate the right amount. There must be folks on this site with a bunch more knowledge than me.

I would comment that in low heating demand you can fill with fuel (coal, BIT, not as pronounced), idle all day, use none or little of the heat, and burn up all the fuel. 100%, or close, loss.

I try to have no idling at all. After a bit of experience you get to know how much fuel to burn to bring temperatures back up. One of the gasification wood boilers, Garn, has storage temperatures up to 200F. I so far have increased mine to 190F . Temperature overrun is no longer a concern with storage. Also a preasurized system has a higher boiling point. It appears that the higher the water temp it allows flame or fire temp to be higher. Creosote appears to be reduced.

I only have bitumen coal available, so no comments on anthracite. This boiler burns BIT real well. I use about 6 tons in colder months.

Good Luck

i'm starting to like this thread. i too have wondered about storage. the internal tank seems too small. mine overshoots all the time in "shoulder season" and then the house is in the 90s and we're opening windows. my theory was to pick up a couple of scratch-n-dent hot water heaters and plumb them into the system for my storage. I figured that these are ready to handle the pressure, are already insulated, and are manageable sizes. the general opinion seems to be that coal systems don't need storage, but i have a hard time getting 8 hours out of my sf-260 if the temps are below freezing regardless of how much I mound up the anthracite. on those sub-zero to single digit days, it runs continuously.

I think the attractive idea of the storage tank is during the shoulder seasons when the boiler can easily meet the energy demands and the excess is stored for later use. I think the water heater idea sounds reasonable as long as you have the floor space to spare. I hope to use an old propane tank 500 gals. as my storage the down side is getting it into the basement.