Harman SF-260 Question

[AndrewPEI]

Hello there,

I have a Harman SF-260, first year burning with it, overall I'm fairly happy with it. I'm just experimenting with it trying to get longer burn times and have a few questions after reading a thread from about a year ago.

This boiler has grates primarily used for burning coal, I'm burning exclusively wood in this boiler, in another thread I have read that someone with this unit experimented with putting fire bricks over the grates and used the manual turn knobs to control the air to the firebox, just wondering how this would work out? Essentially running it as a wood stove.

Currently using the automatic draft to regulate the fire the boiler seems to get up to temperature very quickly almost over-firing the unit, then shuts down and smolders wasting wood. So I'm wondering if a slower burn using the manual turn knobs would produce a longer burn, keeping the temperature between 150F-180F.

Thanks for your time.

Andrew.

 

[flyingcow]

Buddy of mine has a boiler, he builds a good fire when he comes home at night. 3 or 4 hours later, when he goes to bed, he throws a shovel full of pea coal on top of it. Works wonders. Wakes up 8 hours later with a boiler at 180ish.

 

[AndrewPEI]

If I had access to coal I would try some for sure, however it would be about a 6 hour drive to get some, not worth it.

Also does anybody know if their is an aqua-stat that will turn the circulator off/on at 140F. Each night when the boiler runs out of wood it keeps circulating the water, so I wake up to water that is 60-80F, which takes much longer to recover from.

 

[JrCRXHF]

I have the SF-260 i am on my second year of burning with it. I use it to preheat the water before my triangle tube natural gas boiler that way if i run out of wood i don't wake up to a cold house.

I have the pump running the whole time the boiler is running so the heat exchanger is always warm.

I do not use the manual valves besides once in a while during start up. I use the set screw on the bottom door to control the over burn on the boiler and crack the slide on the auto control to keep the fire going if the house is not calling for heat. But with a 3800sqft house most of the winter i do not have a issue with it going into idle mode.

As for longer burn times the way i run mine i don't get a very long run time because i turn down the heat to 60F when i go to work then when i get home i build a fire and heat the house back up this takes about 3-4 hours before i go back into the maintain cycle again. This keeps the build up down in the fire box. I try and keep the exhaust temp around 500-600F checking it with a IR on the outside of a single wall elbow on the back of the boiler.

I would have like to do storage and a gasifier but for how cheap i got the SF-260 i can burn a lot of wood to make up for the difference.

As for coal i would love to burn coal but in Michigan it is not cheap and is hard to get.

 

[AndrewPEI]

Thanks for the response. The Harman is the only source of heat in the house, so I cannot let it go out too often, especially with the weather we have been having recently. I do like to let it burn down to 130-140F before reloading to get a nice hot clean burn, with idling at the end of the burn. My thought was to have it in a continous burn mode using the manual valves, adjusting the air intake based on the outside temperature, the dump zone would be energized in the event that the temperature did roll over 190-200F. Therefore giving a longer burn with no idling.

Do you have your set screw turned all the way out to allow the damper to open all of the way? And is the idel air adjustment open all of the way?

 

[longboarder2]

i have a harman sf-160 and have had all the same questions you have. i'm no expert for certain, but following a chimney/attic fire last feb., i've learned a lot and have been forced to work on fine-tuning my wood burning. i can tell you what has worked for me. lately, i have been burning in the afternoon to night and morning like you----finding it difficult to have embers in the morning. i laid three 4"x6" pieces of 3/16" steel plate in the back of my boiler (just three days ago. like some others here i throw a split, a small round log, and a coffee can full of coal on the fire before going to bed---tossing the coal toward the back where the steel now resides. last three days i have awoke to 2-3" of coals on the steel "shelf", rake em, and throw on a couple small splits, and she's rollin.

cant stress enough-----BURN DRY WOOD. ask me how i know----you dont want to have an education like i got on creosote. try not to idle. ever.---run on the edge of not keeping up and hit the dump zone once in a while to keep up the demand. if your harman is anything like mine; you will rip through some wood. but, the project had to make financial sense, so with our short heating season, a gasser (which i would love) was too expensive. especially with the abundance of wood around here. so you will trade efficiency for wood volume.

ask questions here---theres a great bunch of guys on here with a wealth of knowledge and practical experience---they have helped me immensely. another great resource for wood boiler tech is jeff from maine wood furnaces dot com. great guy--always willing to help.

i would recommend using the harman as an add-on to either an oil boiler or a knight 90+ gas boiler (propane fired if youre too far from the gas line) this will take a lot of pressure off of you with the wood boiler---it's nice to be independent, but also nice to worry less. i only burn when the temps are below 40 and some days not at all. i heat about 3200 sq. ft of house, domestic hot water for a family of five, and 1000 sq. ft. finished basement---since october, i have been averaging 1.5-2 gallons of oil per day. i used to burn 8 gallons a day to heat this dinosaur. my goal was to minimize my oil consumption; so far, so good.

using an indirect water heater (megastore) will also help you out. you will heat more water less often, using less energy---try to use your hot water the most when youre burning the most; we run the dishwasher, do laundry, and get showers in the evening when the harman is kickin'.

harman builds a nice unit---a little low-tech, but a great stove for the money. do yourself a favor and ask your questions here---the weakest link at harman is their customer/tech service. THEY SUCK! the guy who answers the tech line sounds about as pleasant as an enima and they always puke up the same answer, "we build them, we don't operate them" if they had just one guy with some hvac/boiler knowledge, they would be a great company. or atleast someone who has used the product giving honest experienced answers

you should be able to set your aquastat up to trigger anything---it's just a switch like any other, but works off a heat signal.

i set my high limit on the wood unit between 175-180---a little low to make sure the dump zone will work on time if called upon. dont get caught up trying to always maintain 180 degrees---thats how i screwed up last year. you will idle a lot.---that's No Bueno for the chinmey. allow it to fluctuate between 140 and 190---its okay if it goes down, you can always heat it back up---let it move like that and you will idle less. when it's low, stoke up a nice hot fire that will burn clean and raise the temps where you want.

i try to do a nice hot burnout once a day or once every two days---open up that door and let her rock up to about 500-550 on the smokepipe. ive burned nearly two cords and the chimney sweep took a coffee can worth of nice gray soot out of my 30' flue pipe.---he said keep burning the way i have.

program your thermostats in the house rather than using the boiler controls to help you make it thru the night with heat---lower when sleeping and out of the house. i actually prop the air intake on my harman open full time. i have my set screw turned in so the damper door opens about half way---on colder days, i open it a little more or open the knobs on the door. if i hit 200 and the dump zone opens, its okay---its my basement so i still benefit from the heat.

make sure you have ample expansion---i was steaming off a lot this year--a few guys on the forum helped me out with the expansion and viola! havent been about 24 lbs. once since adding the additional extrol----with the potential to reach very high temps quickly, its important to have.

sorry for the long-winded reply, but i realize how little info there is out there about real usage of these thing---figure more info was better. hope this helps.

 

[AndrewPEI]

Thank you for this. It has proved difficult to find any useful information about the unit online. I like your idea of creating a shelf in the back, I wonder if this can be done with firebricks, creating a shelf on the back 1/3rd of the boiler over the grates and still allow airflow under the grates to the front 2/3rds? I don't have access to coal to try a shovel full at night unfortunately. I have 2 yr old dry seasoned wood, mostly maple or birch. To get the fire rolling every morning I open the ash pan drawer to give it full air for about 5 minutes to get everything burning nice and hot. I have been burning almost 24/7 since the first week of October, probably put 2.5 cords through the unit, long heating season on PEI Canada, Oct 1-May 15 or so.

 

[longboarder2]

i do the same thing to get mine going---open the bottom door and run some paper, kindling, and 1/3 of a starter brick. i also do that for a burnout of the flue pipe occasionally. now that i can maintain coals, it's a couple pieces of paper, some kindling , and whoof--right to splits. i like the bottom-up air flow so thats why i only blocked off the back third. i thought it would be difficult to effectively control the flame using only the front door knowbs. haven't tried fire-brick yet. let me know how that works for you. in addition to the coal, i have also experimented with pellets for the overnight stretch. they burn hot and clean---i somethimes throw a can full in when i need some extra power. they should be readily available near you. i pickup a 40lb bag at tractor supply yetserday for just under 5 bux.

i've told harman, a sight glass would be helpful on these units to fine-tune burning (ya know, since their tech department isnt very useful). it would be nice if one could replace one of the damper knobs on the front door with a some kind of sight glass for observing the flame. i'm sure we could both use less air and get a nice flame and burn less wood, but after an hour and a half with 5 or 6 spilts, i have some fine ash and a few embers on the grates-----these things are wood hogs. you'll have it way worse than i----we only heat from halloween to st. patty's day---with a fistfull of 42+ degree days where we dont even let it run during the day.

you will definitely get more out of your unit if you use it as an add-on to an existing system, like the gas or oil boiler with an indirect water heater. and you'll never run out of hot water. we have five in the house---after everyone showers i can still fill up a whirlpool tub for a good soak---cools off towards the end, but recoops quickly.---use the electric backup for added insurance.

i think my next experiment will be to move the "shelf" to the front third of the unit---seems like it would allow the air to flow more naturally through the firebox.

you could definitely benefit from storage---a lot of it too. run that baby WFO and rely on the storage overnight and in the early and "leave" hours. for me, storage doesn't make sense considering my lack of space, short heating season, and abundance of wood. a gasser with storage is the deal where u are, for me it would evelate the cost of the system to the point that i would never recoop the cost or benefit significantly from it. there are lots of heat exchangers being removed/exchanged from commercial and govt./military buildings all the time---you might scrounge one from a local demo, hvac, or construction company to use for storage---just a thought.

 

[AndrewPEI]

Thanks for this. I will be picking up some fire brick this weekend, I think it will also add some more thermal mass to the firebox helping with heat retention, they are cheap, so if no efficiency is gained, no big deal I may even put the firebricks in the middle of the firebox so air can come up from the front, back and sides. The pellet idea is neat too, I think I will try that to boost the boiler on these cold mornings. Thankfully I have my boiler running preheated hot water into an electric hot water tank, so I'm not too concerned with always keeping the temperature up for hot water as the electric kicks in when required. I'm only heating roughly 2000 sq feet, climate is a little cooler than South NJ I would assume roughly 1000 miles northeast of you. I will let you know in a few days how I get along.

 

[AndrewG]

Hello there,

I have a Harman SF-260, first year burning with it, overall I'm fairly happy with it. I'm just experimenting with it trying to get longer burn times and have a few questions after reading a thread from about a year ago.

This boiler has grates primarily used for burning coal, I'm burning exclusively wood in this boiler, in another thread I have read that someone with this unit experimented with putting fire bricks over the grates and used the manual turn knobs to control the air to the firebox, just wondering how this would work out? Essentially running it as a wood stove.

Currently using the automatic draft to regulate the fire the boiler seems to get up to temperature very quickly almost over-firing the unit, then shuts down and smolders wasting wood. So I'm wondering if a slower burn using the manual turn knobs would produce a longer burn, keeping the temperature between 150F-180F.

Thanks for your time.

Andrew.

Hi Andrew From another Andrew in PEI. I would like to chat with you about your SF 260. Im getting ready to build a new home and thinking about the sf 260 ,,if u like I can send u a email with my number and chat. Thanks so much.