Looking to Buy a Harmon SF-260

Good morning Joe, OK here's the situation this morning at 5:AM. Loaded last night at about 5:PM and right now When I checked the boiler temp. The flapper just closed ( meaning there was a call for heat and water temp. got down to below 160* so flapper opened to recover) Flapper closed when water temp. got up to 170*. It's now 5:30 and the temp over shot to 190* and the dump relay kicked in, only runs for about 2or3 minutes and turns off, pulled the water temp down to about 175*. Stack temp. only went up to 200*, which tells me that the boiler is not over-firing. So maybe your right and I should cut back on the flapper being opened too much. I'm going to reajust it to half open and see what that does. I would think that it will take a day or so to see if there is any difference. BTW loaded the box to top of bricks and mounded in the middle.

Noted your comment about your SF260 being too big, How big is your house? I'm heating 3floors (including finished basement approx. 1800 sqft. If I leave the boiler room door open sometimes, the radient heat off the boiler pretty much heats my basement office/man-cave. The biggest load on the boiler is the hot water, that pulls the temp down about 20* to 30*. Freddy gave a solution for that, I'll fix it when the weather warms up a bit.

OK the flapper is set at 3/4" open, down from an 1 1/4". Idle ports are closed half way which seems to work pretty well when nothing is calling the temp. will settle out at about 175* to 180* and hold.

Look at my post Titled Firebox Reducer I posted yesterday, it shows the reducer i'd like to make. Tell me what you think. Sorry I don't how to put in a link.

You can call me J.B. or you can call Jeff, Just don't call me late for supper

Jeff – Sorry I was not able to get back to you sooner but things have been real crazy over the last day. I am having one of those “light dawns over marblehead” experiences. I have been operating my SF 260 as though it were a coal stove and not a central heating boiler. My goal over the many years of having a coal stove in the living room was to keep the fire at a moderate level and temperature fluctuation to a minimum. Once I had established a position for the draft control, I pretty much left it alone. I was operating the Harman with the draft flap set at 3/8 inch with the fire burning at a moderate rate. My water temp is set at 180 degrees. With this arrangement (especially during the recent cold weather), the water temp would rarely get to 180 degrees without a call for heat or hot water. The draft flap would remain open and the fire would burn along at a constant, moderate level probably averaging in the 160 degree range. This was OK until there was a simultaneous call for heat from two zones. The water temperature would drop, which caused each zone to take longer to bring that loop up to the thermostat setting. Then a third or even a forth zone would activate and the moderate fire would struggle catch up to the multiple zone heat requirement. The solution, as I am learning, is to burn the fire hotter (I am now experimenting with the draft flap set at ¾ inch) and with a higher average water temp there is less chance of running into the multiple zone issue. Also, the hotter fire has a much better chance of catching up should the multiple zones occur.

I shook down and loaded the Harman at about 6:00 PM last evening. I moved the flap adjustment screw a full turn to a ¾ inch opening. Where my previous 3/8 inch opening would cause a fire with flames of about 5 to 6 inches, the ¾ inch opening had the blue dancers licking the top of the firebox. The water temperature increased to 180 degrees and the draft flap shut. The temp continued to increase and stopped at about 190 degrees (an overshoot of 10 degrees) which is still 10 degrees less than dump zone activation. I added a little more coal on top at about 9:00 PM and went upstairs thinking that things were working well, but with the hotter fire and an outside temp of 0, would there be any coals in the morning? To my surprise, there was more of an active fire at 5:30 AM than I usually find. I will again deal with the Harman at about 6:00 PM tonight and the real test will be the twelve hour time period. I am optimistic that running the Harman hotter is the answer. I will let you know how it goes. Joe

Joe,
Thats good news, This coal burning thing just keeps getting easier don't it.
Just to let you know, the other day when I reset the flapper damper to 3/4", I have not noticed any difference in boiler temps. from when it was fully open. I Have the aquastat set at 160*. The flapper closes at 170*. Been wondering about that, why would it not shut when temp reaches 160* instead of overshooting 10*. But because it does I adjusted the differential to 1*. So flapper opens at 159*, closes at 170*, and drifts to 180*.

Was out today to check on a different coal supplier. Need to get another ton to make it through the winter, So far I've burnt 2 tons from mid Oct to now. Got enough left for about two weeks.

Jeff – The ¾ inch opening on the draft flap and the subsequent hotter fire appears to be working better than I expected. Took care of the fire this morning at about 5:30 AM and found a very active fire tonight at 6:00 PM. Removed the ash pan and dumped the ashes and then proceeded to rake and shovel almost another pan full of ashes out of the ash catch area. What a PITA. If you are finding that the ¾ inch flapper opening on your Harman is no different than the full opening, then perhaps we have found the sweet spot. Are you still getting the overshoots to the point of activating your dump zones? I feel that I can live with an overshoot in the 10 degree range. I will continue to experiment with the ¾ inch flap opening and look forward to hearing how things are going at your end.

I saw your draft reducer and it certainly looks like it will get the job done. I am not sure if I understand exactly why you need such an elaborate and potentially expensive arrangement. If you are trying to reduce the firebox because your boiler is generating too much heat, I happen to know that the local stove store where I bought my Harman has a SF160 firebox reducer with no home. If you are having trouble with ash buildup in the corners of the firebox, I can set you up with an antique coal furnace ash “digger” that will get the ashes out of any boiler. I kind of collect antique coal furnace tools and have one that is about seven feet long. The coal boiler that it went to still exists and now burns oil. Ah yes! It is all about getting the ashes to fall into the ash pan. Priceless. Joe

Joe, So glad things are getting better for you, but your right ashing is a neccessary pita, however that also is getting easier with refining methods. On that point I took my garden hoe and cut the blade in half to fit under the grates easier, I also cut the handle down to about 28" for easier handling. Works good for going to the back of ash pan area and dragging all the ash out that doesn't make it into the ash pan. hopefully the reducer will make that less of a pain.

My idea for the firebox reducer is to solve three things. 1. to get a deeper firebox, 2. to bring the sides in so less ash falls outside the ash pan, 3. to cut out the square corners, which should reduce the dead spots. According to what I've read on this site, a deep round firebox is the best design for coal burning. Thanks to Franco b who told me about castable refactory, I can make my own fire bricks. Did a little measuring and i'll need to cast this design in two pieces to be able to fit it through the load door. I figure it will take about three 1gal buckets of refactory cement at 20.00 ea. so 60.00 isn't to bad a price if it works. Can't count my own labor. How much is Harman's reducer?

The boiler doesn't pull the dump zone at all when the outside temp is low as the first floor zone calls enough to hold it down to 180*. I have the dump zone set to come on at 190*, but when it comes on, it only runs about 2 or 3 minutes and will pull the temp down about 15* and only does it after a new load gets going good.

Have a good day Joe,
Jeff

Jeff - Am very interested in your reducer project. The three reasons you gave are all valid. Of the three, the most important to me would be making the firebox deeper. I am not sure what the SF160 firebox reducer would cost but I paid $75 for my SF260 reducer. Anyway, I am on day three of the wider draft flap opening experiment and wondering why I didn't think of this sooner. Thanks for getting me started in the right direction. The way I am thinking - there is a finite quantity of heat energy in a load of coal in the boiler. You can either burn it constantly at a moderate temperature with little idle time (as I was doing) or you can burn it hotter with longer idle time. The increase in burn time and decrease in circulators running to try to heat with tepid water support the wider draft flap position and hotter fire. Its about 20 degrees and snowing. Joe

Hi Joe,
It's good to hear your having success with the SF260. I have also noticed that everything works better by keeping the water temp higher (180*).

$75 for firebox reducer, well that means I can make my own cheaper and deeper. Guess i'll have to get a move on and get this done. Been looking for a used coal stove to heat the shop. With this cold weather haven't wanted to run the electric modine heater out there, too expensive! If you know of one for sale let me know.

On another note, I found another supplier for coal, going to pick up a ton in a couple of weeks, 275 for bagged nut. Will be interesting to see where his getting it from. Jeff

Jeff - We have this informative (to me) little dialog going at the end of this SF260 thread and I am wondering if we should be PMing or should we continue to use the general forum? Nothing yet from the Moderator who I assume will ask us to go private when he decides that our discussion is not appropriate for the forum.

I at one time owned a total of six hand fired coal stoves. I am now down to one (not including the SF260). My brown enameled Saey Bremen II is just too sweet to sell. The Crane 44 would have been the perfect stove for your garage but I moved it along last fall. Had the round firebox you have come to appreciate.

Bagged Blaschak nut is $318 a ton here, so $275 sounds like a pretty good price. Why are you not getting more Kimmals? I heard that one of our local fuel oil companies had brought in a load of Kimmals and I was going to check out their price based on your and other forum members success with that coal. Watch out for no name coal. Joe