Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: ambonci on January 16, 2016, 07:28:33 PM
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I have a few questions about setting the temp on the OWB. The first two years I've lived in my current home and used my OWB my temp was always set at 180 using the factory thermos disc. last year after I reinsulated it and hooked up the ranco I ran at 170 with a differential of 7. Burned great all year(80% oak and maple). This year I added some insulation used on nuclear power plants thinking it will be even better. They claim 2000 degrees on one side and u can touch the insulation with your hand and not feel any heat. Anyway, this year I set my aqua stat at 190 with a differential of 5(mix of cherry, beach, soft maple, not really seasoned 100%). I don't really see much a difference running 190. May I add I also swapped from a gundfos 15-58 running on medium to a 26-99 running on medium. This year has been very mild and it seems like I'm during more wood. I don't believe its the insulation because I still using the same insulation as last year just added to it. So my question is, is it because I'm running 190 and the differential is only at 5 or am I circulating water to fast? I am around 50 feet away so a total of 100 feet loop. Sorry for the long winded stuff but you guys are great on here and thought id give as much info as I could. Thanks.
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I always ran at 180 on my old boiler, tried running at 190 a few times and it seemed like it took a lot more wood to keep the water ten degrees warmer than “normal”. But, last time I tried that was before I replaced my old underground line with Logstor.
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If you don't need the higher temp, you could turn it back down and see if you notice any difference. If you have the pump pulling water out of the top port, I wouldn't run it that hot.
Were you having excessive delta t with the 15-58 pump? It should have been big enough if you don't have a lot of fittings and restrictive heat exchangers. The speeds on the 15-58 and 26-99 are spaced fairly even so with the new pump, it is like gaining speed 4,5 and 6. Low speed on the 26-99 will pump more than the 15-58 on high.
It could be a circulation issue. With the lower flow, a good portion of the boiler may have been running at a lower temp which could have resulted in less heat loss in certain parts of the boiler. Normally it is the other way around but could vary depending on heat load and wood quality.
Do you notice if the stove is hotter around the door and bottom?
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The hotter the water, the higher the stack temp losses will be on a conventional unit.
As Marty said, underground heat losses with poor quality pipe could also be an issue, look at it this way, the hotter the boiler water and colder the ground water, the more heat will transfer into the ground water because the differential is higher.
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The reason I went for a bigger pump and higher temps was I have a hard time getting my house above 72 when its near 0 or with a windchill below 0. I was thinking the higher water temps would give me more available btus inside. I have a fairly big plate exchanger(50 plate for heat and a 30 plate for DHW). My thought was the 15-58 couldn't give the plate exchanger enough flow for it to work to its full potential. We have yet to have those days this winter so I can see if it helped my problem. From past experience I don't think its gonna help.
RSI- I switched my pump to feed off the bottom for my house loop and my garage loop is feeding off the top. I had cavitation issues earlier this year with both on top. since switching pump has had no issues. May I ask what excessive delta T is?
I think my issue with house heat it the lack of baseboard heaters inside my house. my house is only 1600 sq ft. so that big plate exchanger should heat this place fairly well I believe. Slim I wish you where closer to NY because Id love to have you redo my whole system because I don't think its hooked up that well. I am going to turn temp down to 180 today(we have a cold front coming through) and see what happens. What abut the temp differential? leave at 5 or go more? Thanks again.
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I do 190 set point with a 12 degree differential. Second season with my boiler and it's running better than ever.
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Correct me if I'm wrong but I think having my differential at 5, the blower kicks on a lot more often and then burns more wood. am I way out to lunch with that thinking? I think I am gonna play around with settings this week to find out. Agriffin, is your boiler a conventional or a gasser? Wonder if that makes a difference because they burn different.
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Natural draft units should have a smaller differential as they take a while to get a fire rolling after the damper opens....forced draft units can have a bigger differential bc they recover much faster....I personally don't like differentials any bigger than 20°...too much expansion and contraction on the steel IMO
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The biggest difference I see in shorter burn differentials is in creosote build up. The fire never gets hot enough to burn it out. Higher burn temps using more fuel is almost always linked to conversion of heat to water inside the furnace. Your fire needs to work harder to keep the higher temps. With enough heat extraction in the exhaust this is kept to a minimum.Stoves with a chimney straight out the firebox are less efficient with heavier heat draw. More heat goes out the stack. More heat conversion inside your house has got to help. More baseboard or splice in a cast iron radiator will give a big lift.
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The biggest difference I see in shorter burn differentials is in creosote build up. The fire never gets hot enough to burn it out. Higher burn temps using more fuel is almost always linked to conversion of heat to water inside the furnace. Your fire needs to work harder to keep the higher temps. With enough heat extraction in the exhaust this is kept to a minimum.Stoves with a chimney straight out the firebox are less efficient with heavier heat draw. More heat goes out the stack. More heat conversion inside your house has got to help. More baseboard or splice in a cast iron radiator will give a big lift.
great post. I read it 3 times but I understand what you posted. thanks. I was thinking about needing more baseboard but now I'm convinced. sounds like a new summer project.
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so I turned temp down to 180 and differential to 8 gonna leave that way till Wednesday then try different differential and see where the sweet spot is till I can add more baseboard.
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Correct me if I'm wrong but I think having my differential at 5, the blower kicks on a lot more often and then burns more wood. am I way out to lunch with that thinking? I think I am gonna play around with settings this week to find out. Agriffin, is your boiler a conventional or a gasser? Wonder if that makes a difference because they burn different.
Mine is a conventional stove, but it does have some firebrick and one zig-zag the smoke goes through before going out the chimney. When it's firing well, only hot air comes out the chimney meaning better efficiency. I never had those good burns with a differential set at 5. My stove is forced air with air coming up from the bottom and across from front to back from under the loading door.
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I go with 180 with a 10 difference. My stove usually shots over 2 degrees so it gets to 182. I have tried several different settings and this works best with my stove and burn times.
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What kind of burn times are you achieving with your 190 degrees F and 12 degrees F temperature differential a griffins? :-\
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Agriffin, mine is almost like that except I don't have fire brick and my chimney comes down into firebox. Good ol shaver. I want to cut that sucker off but don't know what the side effects would be. I barely ever have just clear air coming out of chimney. Before I posted this topic I thought it was stupid of me but ive learned quite a bit so far.
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I run my heatmor at 185 with a 15° differential. Works great. Very minimal creosote build up due to the long, hot burn. it mild weather i will run 172-180.
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What kind of burn times are you achieving with your 190 degrees F and 12 degrees F temperature differential a griffins? :-\
If you mean how long at a whack does the blower run to get back to 190, I've not timed it.
If you mean how long between fills, it's anywhere from 12-16 hours. Last year was much colder than this year and I had to really fill it to get 12 hours. This year I don't fill nearly as much to get it. Plus, last year I was leaving a thick amount of ash and coals. This year I keep more firebrick exposed and shovel out ash much more often; seems to be working better this way.
My settings are 190 SP, 10 diff. However, the ASD is at 1 or 2 (not sure what ASD is) so the blower kicks on at 178. So I call it a 12 degree diff. As for wood, I use 90-95% hardwood (mostly maple with some oak), 24" long or so, almost all rounds. Rest is white birch, red pine, and some aspen. I'm thinking the drier wood is contributing too, as last year I burned wood as I cut it from a 10 cord delivered load of 8' logs, so they had a lot of ice/snow stuck to them.
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If you mean how long between fills, it's anywhere from 12-16 hours. Last year was much colder than this year and I had to really fill it to get 12 hours.
Very nice burn time between filling. 8)
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Adam
I believe RSI is correct it is a flow issue. A 15-58 can easily move 80,000btu. At 5 gal/min with a 20deg differential. This should b plenty of btu to heat your house at 1500 square feet.and take care of the DHW. With no problem.
My G-200 had all kinds of hot water in it. But could not get it into house. I had a 1 1/4 black iron manifold with four 007 pumping threw it at the same time. This was my restriction. Changed the flow around and now it is 100% better heat, and continuous hot water. I have worked with slim on a few installs. You said you were in New York ,I am above Albany, in Saratoga co. If you want I could take a look at your system. May be something simple. Or easy to fix.
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smokeless, so u think my circulator is pumping to much? I'm not questioning you just want to understand it. do the plate exchangers and circulators have to be sized properly for optimal performance? That was my thought on the 15-58 being too small for the bigger exchanger. if I posted a pic of exchangers and oil boiler would it help? Id love to have someone who knows their stuff to analyze my system. system was installed before we bought the house and was done cheaply. Thanks
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It isn't that you are pumping too fast, it is that the increased flow may have changed the flow pattern a lot in the boiler.
I am wondering if the pumps being opposite may be a problem. I don't know what the inside of your boiler looks like but if the ports are just fittings welded to the back of the water jacket, the water may be flowing right across from the return to the other outlet. It may have actually decreased the circulation inside the boiler.
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There you go again rsi. You may b correct ,that inside the boiler it could b cross flowing from (port to port) to fast and not picking up the heat. Adam can you take some pics of your system. And try to put them on the forum. If not email them to me n I will. Most importantly the piping on the back of the boiler ,to the house and to the garage. Or maybe draw it out. And use arows for flow direction. We will help you figure it out! Send me your address you might b close by. I could stop in sat or sun. Smokelessny@gmail.com
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Looks like the shafer 165 has two upper ports fairly close to each other. Maybe 1" pipe. Is that like yours Adam ?
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ambonci,in my experience if you got dry wood usually smoking is due to insufficient air to the fire.
my homebuilt stack pipe comes down within 4 inchs of the of the bottom of the firebox.
with nat.draft it can smoke a fair amount,but with a blower that cleared that up.
one thing though.on the factory builts can you control air intake or is it all or nothing.
mine is controlled via a small door i can adjust.
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I missed your changing only one side of your inlet outlet. RSI is right!, counter flowing two systems could defeat the purpose of getting better circulation in the boiler. That's why you notice no difference going to 190.
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It isn't that you are pumping too fast, it is that the increased flow may have changed the flow pattern a lot in the boiler.
I am wondering if the pumps being opposite may be a problem. I don't know what the inside of your boiler looks like but if the ports are just fittings welded to the back of the water jacket, the water may be flowing right across from the return to the other outlet. It may have actually decreased the circulation inside the boiler.
You are correct they are just threaded pipe out of water jacket. Some one told me that they may cross flow but I had no time to change the other one before the holidays happened and now its to cold to mess with it. Basically I a not getting true 180-190 degree water to the plate exchanger? the other pump on top has nothing to do with any plate exchangers, its hooked up to a reznor heater hanging in garage. separate feed and return, I'm not arguing but just thought id throw that out there.
Duke, once blower is off its nothing, fire just smolders.
Ben-You are correct on the ports. I will take some pics tomorrow after work and try and post if not I will email them to you. You are like 80 miles away from me I'm in the catskills. doesn't mean your not welcome LOL. you guys are great.
By the way I am running 180 with diff set at 8. today was high of 13 and windy as a SOB and wood consumption was better, not great but better. Thermostat set on 72 inside but actual temp 70. oh well keep on trying to fix things. thanks guys ill have pics tomorrow.
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I have tried last year to to run 190 with 8 degree differential. What I quickly learned my boiler in undersized for my home and no matter what high limit I set it to, it will never be reached during the single digits with high wind in this old farm house. Works great when the temperature is in the mid twenties or higher, delivers hotter air to the home and the furnace cycles less. I just wanted to point out higher set point makes no difference if your heat demand is so high you will probably never reach 170 - 180, as your furnace blower just runs and runs... and when it kicks off for maybe 1 minute and back on. The people who have experienced this it will resonate hard. Sellers claim a approx square footage of heat but have no idea what your home conditions are such as insulation, windows, and other factors. If you live in a drafty old farm house, poor insulation, or had problems keeping your home warm with propane or other means you have to at least double the square foot rating. Hard lesson I had to learn... Please take my advise.. OWB are wonderful but can't create miracles.
I'm going to modify my post, my experience with a conventional boiler only... With Natural draft... When setting such high limits your going to burn more wood and if your demand is so high your boiler / blower will run wide open and wood consumption will be greater... I hope I covered myself here.
Going to modify my post once more..... Lastly Green wood can cause huge issues when the house is demanding a large heat load. For example you go outside the water is 155. crap that is getting pretty low so you throw in 3 or 4 large pieces of fresh green wood close the door and go watch football. Your game hits half time, its cold as a witches nipple outside so you decide to check the boiler temperature again...WHAT! WTF 125 degrees.. At this point throwing more wood in is going to lower your boiler temperate, and at the same time your blower hasn't cycled off in 2 hours. Your damn football game is ruined cause you have the boiler door open hoping for the Hail Marry. Yes, finally after 2 hours of the door being open I reached 180 barley any wood left, so you have to slowly add your green wood in to get a respectable fire again. You check the clock the game is over its 12:30am and you have a meeting in the morning and you start to curse the world. You been out in the cold so long sucking down too many brewskies by the time you get inside and warm up you can barley remember your name and stumble to bed, as you stumble to bed you wake up your wife she is not happy to see you trying to take off your socks, she instantly knows you drank too much. See being out in the cold for too long and drinking, when you hit warm air your body metabolizes the alcohol differently, warm air it will make you very confused... on worst occasions the warm air makes you want to pee and if you drank too much watching the boiler there is a good chance your going to pee in the corner of your bedroom, or miss the toilet and waking up to the misses demanding what the fu$@# just happened, Thinking you were partying all night but you were just trying to keep the place warm. Its happened to me, and will happen to you if heat demand is high enough and trying to recover with green wood. I can use green wood all day long in shoulder months but when the demand gets high enough you need seasoned wood. Yet, with a undersized boiler even dry wood may not be enough, and a high set point is only a dream during the coldest months. Why I wrote this I have no idea... stay warm... and keep the wife happy.
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Thanks for the early AM smile, I've been there!
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I have tried last year to to run 190 with 8 degree differential. What I quickly learned my boiler in undersized for my home and no matter what high limit I set it to, it will never be reached during the single digits with high wind in this old farm house. Works great when the temperature is in the mid twenties or higher, delivers hotter air to the home and the furnace cycles less. I just wanted to point out higher set point makes no difference if your heat demand is so high you will probably never reach 170 - 180, as your furnace blower just runs and runs... and when it kicks off for maybe 1 minute and back on. The people who have experienced this it will resonate hard. Sellers claim a approx square footage of heat but have no idea what your home conditions are such as insulation, windows, and other factors. If you live in a drafty old farm house, poor insulation, or had problems keeping your home warm with propane or other means you have to at least double the square foot rating. Hard lesson I had to learn... Please take my advise.. OWB are wonderful but can't create miracles.
I'm going to modify my post, my experience with a conventional boiler only... With Natural draft... When setting such high limits your going to burn more wood and if your demand is so high your boiler / blower will run wide open and wood consumption will be greater... I hope I covered myself here.
Going to modify my post once more..... Lastly Green wood can cause huge issues when the house is demanding a large heat load. For example you go outside the water is 155. crap that is getting pretty low so you throw in 3 or 4 large pieces of fresh green wood close the door and go watch football. Your game hits half time, its cold as a witches nipple outside so you decide to check the boiler temperature again...WHAT! WTF 125 degrees.. At this point throwing more wood in is going to lower your boiler temperate, and at the same time your blower hasn't cycled off in 2 hours. Your damn football game is ruined cause you have the boiler door open hoping for the Hail Marry. Yes, finally after 2 hours of the door being open I reached 180 barley any wood left, so you have to slowly add your green wood in to get a respectable fire again. You check the clock the game is over its 12:30am and you have a meeting in the morning and you start to curse the world. You been out in the cold so long sucking down too many brewskies by the time you get inside and warm up you can barley remember your name and stumble to bed, as you stumble to bed you wake up your wife she is not happy to see you trying to take off your socks, she instantly knows you drank too much. See being out in the cold for too long and drinking, when you hit warm air your body metabolizes the alcohol differently, warm air it will make you very confused... on worst occasions the warm air makes you want to pee and if you drank too much watching the boiler there is a good chance your going to pee in the corner of your bedroom, or miss the toilet and waking up to the misses demanding what the fu$@# just happened, Thinking you were partying all night but you were just trying to keep the place warm. Its happened to me, and will happen to you if heat demand is high enough and trying to recover with green wood. I can use green wood all day long in shoulder months but when the demand gets high enough you need seasoned wood. Yet, with a undersized boiler even dry wood may not be enough, and a high set point is only a dream during the coldest months. Why I wrote this I have no idea... stay warm... and keep the wife happy.
^^^^^This is the reason i went with a bigger boiler than needed when i made a new purchase this year. Last few yeras i had a TimberWolf 5000, very similar to a ridgewood: almost identical actually. They said it was rated for 5000sqft. The unit worked great, i have no complaints about how it functioned, it never lost a solenoid, never lost any water, never had to change door seals or awaqastats...overall it fucntionally was ok....the problem was that it could not keep up with my heat load when we went through 35 days straight of temps below 0°F last January-February. I was heating 2800sqft including DHW. As you stated, when it was in the teens or 20's, it kept up fine...12 hrs no problem. But when the real cold weather came, i was loading every 6-8hrs...i would come home to work everyday with water temps around 130-140.
So, i added on a dog kennel facility this summer that was going to be heated. now i am up to 4,000sqft plus DHW....i knew there wasnt a chance in hell that timberwolf was going to keep up...i would be loading every 4 hrs. I got rid of the timberwolf to a guy heating his 1500 sqft home and bought a Heatmor 400dcss. (by the way the guy that has my timberwolf loves it, keeping up great even in negative conditions the past few nights, i believe it is perfectly sized for his situation). I went with a unit that was rated for 10,000sqft because i took my previous experience into consideration.....i wanted to go BIGGER than i needed...not to much bigger, but i wanted that cushion. SO far this thing is great....past few nights have been -10°F. Dog kennels kept at 70°F, house at 72°F Garage at 65°F and 140° DHW all day long....she is getting 12 hr burns no problem, only loading about half full.
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Hi Adam.
It appears that you have no dedicated circ on the oil boiler side of the heat exchanger? that needs to be a loop, Continually circulating threw your boiler. And in a counter flow threw the exchanger. ⬆️⬇️
Also the circulator on the boiler, try to get that turned so the shaft is horizontal. It will help the longevity of the pump.
I'm trying to get pics up.
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I think I know what your saying. I need a circulator to feed the oii boiler at all times? what does that help by doing that? when u get pics up if kinda show me where it need to be. Thanks again. wat do you think if the pictures of the OWB? the circulator on the oil boiler try to get horizontal or the one on the OWB? Thanks Ben.
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It's hard to tell by pics alone. But yes you need to tie into the 1 1/4" copper manifold and flow it threw the boiler. Also make sure you have checks or zone valves in each zone to prevent ghost flow. I would really like to see both of those heat plates mounted to a 3/4" plywood mounted to the concret wall. I have a pic of one slim did. 👍👍
Yes the circulator on the OWB try to get that shaft horizontal ,the one on bottom.
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the one on the bottom is horizontal for my house heat and the other one for my garage heat is vertical. I plan on putting them both on the bottom this summer. I'm clueless what a manifold does and how it will help. Thanks again for taking the time to look at the pics.
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For this year heat season. Install a circulator on the oil boiler under the heat exchanger. Use the port on bottom of exchanger. Cut into the one line.
The top port goes where I couldn't tell ? The top portfolio the HX tie it into the 1 1/4" manifold before the circulator, or into the boiler up high. not on the out flow of existing circulator!!!
This will heat the boiler water to max temp. Then when house calls for heat it turns on existing circ. sending hot water to the zone.
So u still have a return from the zone you need to hook in. When you cut in for the new circ put a T in the bottom of the boiler. Return it there. This should help greatly.
Your system now operates like this I think. Water in boiler➡️ Circulator➡️Air scoop➡️Zones➡️50plate exchanger➡️Back into boiler.
So in theory your boiler has to warm up first then the zones. The HX is only transferring heat when the zones are calling.
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Hi slim I down sized Adams pics maybe you can post them please thanks.
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so really I'm not utilizing the whole 50 plate HX which is why my house essentially runs out of heat? If slim gets those pics up maybe you can draw on them to give me an idea on what needs to be changed. Ben I sent you a message.
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If you want full size pics at unlimited resolution, first post them to Photobucket, Flickr or even Facebook then paste the link to the picture here.
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That's not the right site that's my web page. Need to go to face book to get the pics. (Search ) P C wood boiler systems
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Just wanted to update this topic a little bit. after much advice I had turned down my boiler temp to 180(from 190) and m differential to 13(from 5) Boiler is working much better, less wood consumption and now I actually have a nice bed of coals. after conversation with Ben he suggested I put a circulator in to pump my oil boiler with hot water at all times. I have yet to do that and most likely will do in the spring, but I have not forgot about it just been too busy with work and getting snowmobiles ready, and on the warm days splitting wood. Just wanted to say thanks for all that posted on my topic.