Harmon SF mod

Harmon SF mod

PostBy: NOPEC On: Thu Jan 22, 2009 1:48 pm

Hi, I wanted to share a modification I made to my Harman SF-260 last night. Those with the Harmons know the bricks are arranged horizontally around the grate with four, inch-wide, L shaped brackets to hold the bricks in place on the sides. Unless I carefully and obsessively mound the coal, I have to load more often than I'd like. Plus there's always the issue of burn through should live coal lay against the steel. My firebricks were done after 14 months. I confess to leaving the bottom door open a couple of times to get the fire going and then forgetting to close it. The long continuous burn over the past weekend was the last straw. Since I was replacing the bricks anyhow, I decided to experiment by placing the bricks along the sides and rear of the firebox vertically. Using a masonry blade on my circular saw I notched 8 of the bricks to slide around the retaining brackets. Two quick cuts, then pop out the center part (x8). I can now load 60# easily for a worry free 12+ hour burn time. i don't have to mound or pick nuggets off the top of the brick anymore. Just shovel and go.
NOPEC
 
Stove/Furnace Make: Harmon SF-260 Boiler
Stove/Furnace Model: no-name Lowes woodburner

Re: Harmon SF mod

PostBy: spotcatbug On: Thu Jan 22, 2009 4:02 pm

Wow, I really want to do this to my SF-260. I guess I'll wait until the season is over though - I kinda need the heat right now. :D

My question is, why isn't it made like this to begin with? (Serious question I would like to know the answer to)

Also, I'm currently mounding my coal, and some pieces do end up on top of the bricks, touching the steel. How bad is this? Do I need to make absolutely sure that there aren't any bits of coal sitting on top of the bricks at all? These errant coal pieces don't seem to actually burn. I wasn't concerned about them because I figured they wouldn't burn since they aren't nestled-in with their buddies. When I shake-down, I pull those loose bits off the bricks back into the middle and they don't appear to have burned, but maybe they did a little. They're not shiny, clean black anymore, which makes it hard to say for certain that they didn't burn a little bit, but they're definitely not ash.
spotcatbug
 
Stove/Furnace Make: Harman
Stove/Furnace Model: SF-260 Boiler

Re: Harmon SF mod

PostBy: Joe in NH On: Thu Jan 22, 2009 8:52 pm

I also modified my Harman SF 260. I didn’t tip the firebricks up vertically but laid another layer of bricks on top of the horizontal bricks. Actually, placing them vertically makes a lot of sense and looks like a project for the summer. I was very surprised when my boiler showed up with only one layer of horizontal bricks. This made the depth of the firebox only four and half inches that in my opinion was too little depth for burning coal. If you go to the Harman web site and look under the “specifications” for the SF 260, it looks like the bricks in the illustration are in the vertical position. Could this be a company modification made to reduce the number of bricks used in the stove? I am also using the firebox reducer that gives me a 16 x 15 inch firebox. I keep asking myself if anyone at Harman has ever tried to deal with the ash pan verses grate size differential? Sure gives new meaning to hoeing out the ashes. I would not worry about the coal being on top of the firebricks. The way you describe it, there should not be enough heat to harm anything. Joe
Joe in NH
 
Stove/Furnace Make: Harman
Stove/Furnace Model: Trident SF 260 Boiler

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Re: Harmon SF mod

PostBy: PC 12-47E On: Thu Jan 22, 2009 9:26 pm

The Harman SF250, SF260 Boiler, SF2500 furnace all use the same ash pan and shaker grate. Over 20% of the ash falls next to and not in the ash pan (lots of dust removing excess ash ).

The SF250 Stove has the fire brick in the vertical position (from the factory). The fire box depth is 9" deep to the top of he brick. A 12 hour burn time is very easy with 200*F magnetic stack temp.

RS
PC 12-47E
 
Hand Fed Coal Stove: Estate Heatrola, Jotul 507

Re: Harmon SF mod

PostBy: spotcatbug On: Fri Jan 23, 2009 11:44 am

Joe in NH wrote:I also modified my Harman SF 260. I didn’t tip the firebricks up vertically but laid another layer of bricks on top of the horizontal bricks.


Joe, how do you keep the second layer of bricks held against the sides of the firebox? I assume you had to at least notch the new bricks to fit around the brick holders that are welded to the sides of the firebox. Can you give more details on how you added that second layer of bricks?

Thanks.
spotcatbug
 
Stove/Furnace Make: Harman
Stove/Furnace Model: SF-260 Boiler

Re: Harmon SF mod

PostBy: NOPEC On: Fri Jan 23, 2009 2:01 pm

I considered mortaring a second horizontal row on top of the first. but decided the notched vertical bricks would stay in place better. it was easy to cut them with the circular saw and masonry blade. It becomes a bit of an Amish puzzle to get them all to fit but better too tight than too loose. :D it is certainly nice getting up in the morning to a strong fire. the next project will be hinged wings on the ash pan to catch the excess that we have to shovel out. i already have the hinges and pop rivets. just need to source some free sheet metal.
NOPEC
 
Stove/Furnace Make: Harmon SF-260 Boiler
Stove/Furnace Model: no-name Lowes woodburner

Re: Harmon SF mod

PostBy: Rob R. On: Sat Jan 24, 2009 5:50 am

Do you have any pictures of your modified firebox? I know someone with one of these boilers who commented that it doesn't hold enough coal, sounds like this may help.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Harmon SF mod

PostBy: JB Sparks On: Sat Jan 24, 2009 6:45 am

NOPEC wrote:just need to source some free sheet metal.

Home depot has 16 gauge sheet metal for cheap money. I like your idea.

I've been thinking about the ash pan issue myself, i have an SF160. I am thinking about a way to reduce the fire box by rounding the corners with bricks and running another layer of bricks along the sides so all the ash makes it into the pan. am thinking the rounded corners would help stop the dead fire in the corners. Haven't figured out just how i'll do it yet, but it will probably involve some ss plates made to order to set the bricks on and drill and tap the existing hold downs to extend the brackets. Obviously a spring time job.

As far as the depth of the coal, i've learn from Greg L that in the boilers it's ok if the coal is against the steel as there is water on the other side so the steel will not get too hot. I mound the the coal to a depth of about 6" to 7" deep and have no problem getting 12 to 14 hours burn times. I keep the water temp. at 180* and am heating 1800 sqft., 3 floors.

Just my 2 cents.
JB Sparks
 
Stove/Furnace Make: Harman - Chubby
Stove/Furnace Model: Harman: SF160 - Chubby Sr.

Re: Harmon SF mod

PostBy: Joe in NH On: Sat Jan 24, 2009 10:02 am

Spotcatbug – The second layer of horizontal firebrick is currently balancing on the first layer. I had originally planned to put a dab of furnace cement behind each top layer brick but found that if I brushed the dust and any small pieces of coal off the top of the first layer the second balanced well and I really did not need the cement. I had a bit of a problem once when some coal got caught under one of the grate supports and the bottom firebrick started jumping around while shaking the grate. This caused the top brick to move out of position but once the obstruction cleared all was normal. I do like the idea of the vertical set up and will probably go that route when the season is over.

I also notched the bricks with a masonry blade that I use in an old radial arm saw. I broke off the blade guard several years ago so I no longer use it with a saw blade but it sure works well for cutting and notching firebrick. I had considered throwing the saw away several times but am now glad that I kept it. Firebrick is soft and really easy to work with. I have become quite a firebrick sculptor.

I really like nopec’s idea about the hinged wings on the ash pan. Have you thought about selling the idea to Harman? Let us know how it works. J.B. - When are you coming to NH? I have my firebox reduced on my SF 260 but would be concerned that reducing your firebox to the size of the ash pan on your SF 160 would not allow for a large enough area to provide the heat you would need. Joe
Joe in NH
 
Stove/Furnace Make: Harman
Stove/Furnace Model: Trident SF 260 Boiler

Re: Harmon SF mod

PostBy: JB Sparks On: Sat Jan 24, 2009 10:37 am

Joe in NH wrote: When are you coming to NH? I have my firebox reduced on my SF 260 but would be concerned that reducing your firebox to the size of the ash pan on your SF 160 would not allow for a large enough area to provide the heat you would need. Joe


HI Joe, Don't know when i'm coming up, been busy getting my media-care all set up to take affect Feb.1.
Wish me happy birthday, never thought i'd make it this far or i would have set myself up better.

Putting another layer of firebrick on the sides would only reduce the box by 2-1/2" side to side and would help hold the 45* angled bricks in the corners. I will have set up the radial arm saw to cut the bricks. What kind of blade did you use?
JB Sparks
 
Stove/Furnace Make: Harman - Chubby
Stove/Furnace Model: Harman: SF160 - Chubby Sr.

Re: Harmon SF mod

PostBy: spotcatbug On: Mon Apr 20, 2009 4:07 pm

This past weekend I finally made this modification. Now I can't wait until next Winter to load the boiler with coal. I don't plan to fill it more than I have been. The burn time I was getting with my mounded loads was just fine. I just don't want to do the mounding.

I ended up with vertical bricks the whole way around the inside of the firebox, except for at the front. Of course where the load door is, but also the first two bricks at the front on each side. It turns out that, on a SF-260 at least, the sides are not exactly 5 half-bricks wide, as they appear to be. If you put 5 bricks vertically against the side wall, there's still about a quarter inch gap to fill (those two half-bricks that come with the boiler are about a quarter inch longer than half a brick). Strangely though, the half bricks weren't quite wide enough (beats me how that worked out), so I had to cut two, new, a-little-more-than-half bricks.

The notching and cutting of the fire brick was not easy (at least for me). I used a 4.5 inch grinder with a masonry wheel. The eight notches and two cuts I had to make ended up wearing-out two wheels ($6, total). Four of the notches end up being pretty deep - nearly the entire width of one of those L-brackets. I would suggest getting a grinder that is more than 4.5 inches. Maybe 5 or 5.5. The other four notches are pretty shallow. I hope I won't have to replace those notched bricks too often.
spotcatbug
 
Stove/Furnace Make: Harman
Stove/Furnace Model: SF-260 Boiler

Re: Harmon SF mod

PostBy: Razzler On: Mon Apr 20, 2009 8:32 pm

This will cut the brick like butter. I cut 4 brick in 3 minutes! I've bin useing the same blade for 10 years now. http://www.amazon.com/dp/B00004RH8Y/ref ... nkCode=asn :P
Razzler
 
Hand Fed Coal Stove: Harman SF 250

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