Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: AirForcePOL on December 30, 2014, 01:42:07 PM
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Ok folks, I need some help figuring out what is going on with my system. Here recently I can't get a good burn time to save my life! It was 15 deg last night and I only got about 7-8 hours on a entire load. I've burnt all kinds of different wood from Locust and Walnut that was 15% moisture content to some chinese elm and oak that isn't exactly seasoned. It doesn't seem to make much of a difference. So, here are the details of my setup.
HM 5000e, 85 ft of 1" Rehau running into my basement and then it transitions over to regular one inch pipe that is wrapped in bubble wrap insulation. Once the pipe enters the basement wall it goes about 20 ft and then drops down 3 FT to my 20 plate HX. Once it goes out of the plate exchanger it goes back up and through a hole in a wall and then back down about 8 ft to my furnace HX and then back up and over and back out to the boiler. I drew up my setup and attached the picture if it worked. In the picture I also drew up a close up of my plumbing at the water to air HX. The round rings represent ball valves. I'm using a badger GPD25-10SFC on medium (27 GPM and around 27 FT of head loss). Temp on my stove is set at 184 with a 7 deg differential. I've tried different settings and it doesn't seem to make much difference.
Ok, now a little bit about my house. It's right at about 2100 sq feet now with a new room addition that I'm working on. We keep it around 68-70 most of the time. Some of the windows are really drafty and the house really doesn't heat well. When the wind blows the right direction my furnace will kick on about every 5-10 min even when the outdoor temp is around 25 or so. I had a Hardy H2 and could easily get 10-12 hours on a load with it.
What I changed with the Heatmaster is replacing my junk lines, going from 3/4 pex to 1" Rehau and I added a plate exchanger for DHW. I was hoping that I would be able to heat my 36x45 garage as well but how it's going now it won't be able to keep up. I don't think it is the stove that's the problem, I think it's something in my setup. Please feel free to give me your opinions!
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Try this link for the picture...
(http://i40.photobucket.com/albums/e217/01amercer1988/Mobile%20Uploads/20141230_143845_zpsevpvsyah.jpg)
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So really the only things that you changed was replacing the crappy line set and replaced the boiler? Any idea what your temps leaving your boiler are and what the return temps back to the boiler are? If those look ok I would guess that you aren't exchanging the heat from the boiler to the water very well for some reason, boiler fan runs constantly trying to heat up the water but can't get the heat into the water for some reason. Something is a miss since you went from an H2 that holds not nearly the amount of wood that the 5000 holds and you cant get more then 8 hours.
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yea replaced the boiler, added better lines and added a plate exchanger. I don't know what my return temps are but I know I am only losing 1 degree tops from my boiler to the water to air HX. When the stove calls for heat the recovery time really doesn't take long at all. Surely the DHW isn't taking that much heat, right? I don't use a lot of water as there is only 3 of us in the house. I just can't figure it out. The quality of my wood is about the same if not better than what I have burned before. I'm loading the stove plumb full every time and it's always empty when I go check it in the morning and when I get home. Could it be that my water to air HX is clogged both internally and externally and that it isn't transferring heat properly and is running longer than it should be to satisfy my thermostat? The air coming out of my vents is still very warm though. I haven't checked the hx for cleanliness though....I do have it installed in my return but I have been pretty good about changing my filters.
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On the 5000 the draft on the back is adjustable. If I run my draft at 100 percent open I burn substantially more wood. Have been playing with it seems like 40 to 50 percent gives best burn times. If your damper is wide open maybe tighten up a little. Getting about 14 to 15 hour burn time. Burning oak elm walnut. Heating 1800sf poor insulated and basement and dhw. This is first season with boiler so I'm still trying to figure it out.
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No, the boiler fan is running to heat the water in the boiler, the btus that are then stored in the boiler have to go somewhere. Whether they are used in the house to heat the plate exchanger and the water to air hx or lost somewhere else is what you are going to have to figure out. How often is the boiler cycling to reheat the water? No way you are moving 27 gpm through your system either, I think max efficiency of 1 inch line is around 15 gpm, anything over that causes lots of friction loss. You should optimize your system so that your return temps back to your boiler while your furnace is running is around a 12-15 degree drop. I think we really need to know what the return temps are to the boiler and then we can move forward with figuring out where your btus are going. Also on a side note, you should only fill the boiler to there point that you have just enough coals to start the next load and your boiler is still at temp. If you fill the boiler full it will burn the same amount as if you had filled the amount it needed to just make it the 12 hours between loading. I know that you are having loading time issues and this may be why you filling it full. Sounds like you have a big heat loss though with your indoor furnace fan kicking on ever 5-10 mins at 25 degrees. I assume nothing has changed since last year in regards to that though, you had the same amount of time inbetween it kicking on at the same temps.
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Right, I was referring to the recovery time of when my boiler temp drops and the blower kicks on to get the water back up to temp. I will see if I can try and get a return temp tonight when I get home. I only load the firebox full to ensure that I make it through the night. The only thing that has changed is adding a new bedroom but it's unslated very well and shouldn't loose much heat at all. It's still only about 430 sq ft bigger than it was last year but with a bigger stove.
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What is kicking on and off every 5-10 mins? Your furnaces blower in the house or the Heatmaster outside?
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The furnace in the house kicks on every 10 min on average probably. The boiler kicks in every hour or so
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The indoor furnace kicks on every 10 mins and the boiler only kicks on once per hour? First off does the indoor furnace kick on any more often then it did last year at the same temperatures? I am very surprised that the owb only has to kick on once every hour with the indoor furnace kicking every 10. Also how long does the owb kick on for when it kicks on? Did you look at the rear damper door like dana asked about?
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Furnace inside doesn't seem to run anymore than it normally does. I'm going to try since plastic over the windows in my living room and see if that helps any. I had some on there last year but I took it down this spring. It cold be that the cold air from that room (north side of the house) might be making the thermostat kick on more than it needs to. I have messed with the damper a little bit but it seems to burn better on 100% as there's a lot less smoke. I just got home and the temp was 135 after 10 hours!
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i think your damper on the mf is the issue, its is burning and pushing the heat right out of the boiler. You need to get yourself a nice hot coal bed established, once it is established you need to work on not losing it. You also have smoke because your wood isn't very seasoned. Probably 30% moisture content.
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I would also check to see if you have any trapped air in your lines
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Based on your description and the diagram I don't see anything that would indicate any problems. The up and downs in the basement may cause some air trapped in the line during initial full up, but you have been up and running long enough now it should all be purged. Clogged or dirty hx, air in the lines ect would equal less heat transfer and longer burn times. Without knowing anything else I would say either you have a LOT larger heat load than you previously had, or somehow your underground lines became compromised, or the wood you are burning has a higher mc than you think. Start with the most simple changes (plastic on windows, different spot from wood pile) and go from there. Good luck!
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Thanks for all of your replies! I changed my settings on the stove to 184 with a 10 degree differential and I put plastic on the widows on the North side of my house which is my coldest room. I can already tell a difference in the room so hopefully I will also see a difference in my stove. I just filled the stove like I have been and I'll see where I'm at in the morning. It's 15 deg right now and going to get down to 11 tonight. As far as the air in the lines goes I feel like I got it all out within the first few days of running the stove.
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I have been keeping track of my furnace cycles for the last hour and a half. It started out coming on every 6 min and running for 6 min. I changed the swing setting on my thermostat from 1 to 2 and now I get about 22 min between cycles and it runs for about 9 minutes. I think my furnace cycles are part of my problem.
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Definatly you will be better with a wider swing otherwise you are re-heating your ducts every 6 mins vs. every 22 I have mine set the same way kicks on at 71 shuts off at 73 much easier on your blower fan as well.
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:post:
Not tryng to hijack the thread but how do you change the swing setting on your furnace? I have a gas forced air (gas as a back up) using a water to air HX. I have a similar short cycle issue with mine. Thanks for any assistance.
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Do you have a digital thermostat if so what kind?
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I have two, one older programmable Honeywell and a new Honeywell TH3110D1008, digital but just basic temp, heat/cool.
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You have to have a thermostat capable of adjusting the swing as per the operating manual I believe most new programmable thermostats are able to achieve this.
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Well it got down to 6 deg. last night. When I woke up this morning it had been a little less than 10 hours. The water temp on the stove was 155 and all of the wood was gone. I'm kind of wondering if I need a bigger stove...
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Did you completely fill it last night or how much wood was in it?
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You still haven't mentioned anything about your damper door on the owb. I think you are just burning the wood up and pushing it out of the stack. I think you need to meter it back to 50% like someone suggested.
Also I looked up the firebox volume of the h2. It is 16 cuft of volume. The heatmaster 5000 is 24 cuft of volume. You have 50 % more volume in your new firebox but can't get 2/3 of the burn time out of it :o . Something is wrong, the owb is producing btus because the wood is burning up but we need to figure out where they are disappearing to. Possibly pushed right out of the top of the stack if you have the damper fan open to much.
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This might sound stupid but maybe overlooked make sure your lines on HX are crossing themselves so your getting the most out of it! What size is the HX
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Thats an interesting point I hadn't thought of. What you are saying is that you want you return line back to the boiler on the same side as the fan on the indoor furnace. If the lines are swapped so that the return line is on the house side of the fan coil you are going to be cooling your air as it leaves the exchanger. I don't think that this would make a 4 hour difference in burn times especially with 50% more wood but it could be a factor.
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By having the lines in not the right place it's obious that your temp across the HX are not going to be at the temp you need them to be it will be about a 30-40 deg drop in what your inside temp from boiler will be that said it will cause your boiler to continuously run because your house never maintains the temp needed to be ! Does that make sense
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Yes I filled it all the way last night. I have played with the damper a while back but I really don't think it made a huge difference. I am going to put it back to around 70% tonight. What do you mean by corssing my lines, aries? I will measure the hx tonight but I want to say it is 120-140k btu hx.
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ok, so i have my hx installed in my cold air return. As the air is flowing through the ducts, it hits my supply line furst and then the return. Should the air make contact with the cold or hot side first?
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I don't believe you are pushing all your heat out the stack my damper on my fan is open 100% it just produces a hotter fire in my opinion, I get alot less creasote in my heat exchanger.
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My setup is different than yours but if I open my damper 100% I'll gain heat quickly but it burns the wood fast as well.
I set my damper half way and have had better results.
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Well it got down to 6 deg. last night. When I woke up this morning it had been a little less than 10 hours. The water temp on the stove was 155 and all of the wood was gone. I'm kind of wondering if I need a bigger stove...
Didn't you buy the 5000 from Scott? He should of helped you size it, what does he say?
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When you plumb your water to air hx the air should contact the hottest water last as it exits the hx, IE your incoming line.
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I guess I'm a little confused on the lines to the hx crossing. How do you control where air hits it if its in the entire duct. I thought only needed to make sure lines were opposite on water to water hx.
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overcirculation could be the problem.i have had that problem before.
if you have any inflow of air after all the wood is burnt
and a circ pump that circulates alot of gallons it will cool quickly
just a thought
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When you plumb your water to air hx the air should contact the hottest water last as it exits the hx, IE your incoming line.
I agree with you on this Honda but I don't believe that is going to have drastic results on his burn times could be wrong I have been before :thumbup:
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I agree, I dont think that is the issue here. I think the issue is that the boiler may be burning up the wood with the fan OR I could sign onto the fact about cooling the water by over circulation. If we could find out what the supply and return temps are and what your pump is we could figure out how fast the water is being cooled.
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Sorry I thought you had water to water HX..
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How did you WB do last night ? Im using a 5000E also first year and fill it 2/3 full at 9:00 pm and at 7:00 am have very little wood left. I did find out that im getting better burn if reduce 50 to 70%, also if I don't have a good ash base I good through more wood, haven't quite figured out how to keep that base though. I do think I get about the same burn time if I fill it to the top or just about 2/3 full.
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90% of your problem is in your fan on the back of your stove! I have mine one third way open thats half way between closed and half way. I have my set up just like yours raheu pipe and all. You are pushing all your hot air out your stack, yes you will get a little more creasote but your burn times will go up drasticly, just try it a couple days and see what happens nothing to loose, by the way I am 100 feet from my1800 sq.ft. house and in 0 degree at night to 30 degree in the day 14 TO 18 hour burn times and stove still at 180 degrees at the end of the burn.
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I agree. Now we just wait to hear the results!
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Sorry guys I've been really busy the last couple days. I'm trying to finish up my room addition before my wife goes into labor (any day now). I bought a ton of coal on Tuesday and I've been playing around with that a little. I filled the stove at 630 last night and I'm still laying in bed sick right now but it's been almost 14 hours. I'm gonna go check it in a minute. I had cut back my draft to about 70% but then I changed it back when I started burning coal.
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Congratulations on the new baby as soon as that day comes, I also am waiting for a little boy c/section scheduled for Jan 13
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Congrats to you as well jwood! I'm having a boy also.
Ok, so this morning the stove was out. However, I changed the draft to 60% this morning and mixed a little bit of coal and loaded the stove about half way. It's going right on 12 hours and still some left in there. We had the doors and windows open a lot of the day to help with drywall dust also. I changed my pump to the first speed also. I won't change anything tonight and see how it goes. It's only going to get down to 31 tonight but it looks like a little below 0 for a low next week. I really like this coal too!
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So how is the boiler running now?
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Yes update please!
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It's been running ok I guess for the conditions. I have been getting about 9-10 hours durring these last couple days. It was -6 last night and I loaded at 10 pm. at 7am I still had about a hour left. I have been mixing coal with the wood as well. I added some heat ducts to the new room that we added on which will help on the furnace in the house cycling so much. I have determined that the thermostat calling for heat too often is the issue with my system. I spent some time last night insulating in my basement. I put R30 between the floor joists in the basement because in some areas there wasn't any. I could feel a difference in the house last night. However, my wife just sent me a text and said that the temp is at 127..... so it only went 8 hours on a entire firebox of wood and a mixture of coal.
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That's discouraging hmmmm so it wasn't your fan on the boiler, I don't know what else it could be unless there is that much load on your boiler.
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Personally I am only getting 8 hour burn times out of these negative temps with my h4 which has a 22.6 cuft of firebox and yours has 20 cuft of firebox. I think that you need to crank that fan opening WAY back to 40% or something. Everyone else said that they saw a big difference and operate it under 50 % open.
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Airforce I am running my fan 100% open getting at least 12 hr burn times heating 2500sq ft and dhw even with temps -15 to -20 and high winds. When your stove shuts down and is idling for a few minutes how much smoke is visible from the stack?
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I cut the blower down to 40% and it's burning good that way. I can't find my moisture meter but I'm sure my wood quality has a lot to do with it too. The wood I'm burning now was alive last spring which is Chinese elm or I think I've heard it referred to as Siberian elm before. It only has 18m btu per cord I think. The only other wood I have is oak but I'm not sure What the moisture content is on it. It's crazy windy at my house all the time. Right now we have 20-30 mph winds and it's 23 deg currently. It really sucks the heat right out of the house. I can tell a huge difference on the North side of my house where I insulated last night. I still haven't had time to measure my return temps but it's on my long list of things to do.
My house is very hard to heat and the wind direction changes everything. The wind changed directions tonight and it's coming out of the North now. I'll let you guys know how tonight goes in the morning. Thanks again for trying to figure this out!
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Wood quality should make a BIG difference. 18 MBtu is terrible wood. That's soft maple territory. When I switched from Cherry (19 MBtu) to Hedge (30 MBtu) my burn times increase nearly 50%. Now, you probably won't be able to get your hands on Hedge, it's not easy to get. But, if you really wanted to see where you burn times could be, break down and order a truckload of seasoned Oak. In my area you can get a truckload of Oak or Hickory for $75. Red Oak and Hickory are in the 23-25 Mbut range. I think it would be worth it just to see the difference. It might just be enough to get you from 8-10 hours up to that 12 hour mark.
Or, if you have a good coal bed established, toss in your green Oak. At least try it for a couple days to see if you can tell a difference.
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You're correct, a Siberian Elm is also known as a Chinese Elm. I burn up a lot of dead tulip poplar, can't burn that stuff straight when it's this cold or I have to literally pack my boiler clear full to make it thru the night. If I mix it with some ash, wild cherry or red elm burn times increase a lot.
Doesn't help you a lot now, but might want to consider starting a few windbreaks in the future, ours is made up of several different species of pine and arborvitae. I can stand on the back porch and look to the south and it looks absolutely miserable out once you get past the south end of the windbreak.
Check with your local SWCD (Soil and Water Conservation District) and they might have some cost sharing on planting a windbreak.
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I have a little bit of hedge cut but not too much. There's a good size hedge tree down the road that I can go cut that's about 24 inches in diameter but obviously it won't be ready to burn for a while. I might try to buy a load of oak. The issue is making sure that it is actually "seasoned". I had a really nice coal bed this morning when I checked it after 8-9 hours. The load from last night was almost gone. Agreed on the firewood. Not only is it not great wood but the moisture content doesn't help. I'll keep you guys posted. Thanks again.
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The more I read on this forum the more confused I get.
I can not solve this problem of course, but to clear up a few things in my mind, I have to ask,,,
Did you have these issues with your old owb ?
If not, it's the new set-up, if so, it's the house.
I read this over a couple of times and there is no indicated diff. temperatures in the lines posted.
I also noted your w/a exchanger is on the return side of the furnace fan. cold air intake.
Did you have it there with the old boiler?
Probably doesn't matter, I don't know.?
I;m not trying to upstage anyone, but my burn times on Woodmaster4400 with a wheel barrow of maple /ash are upwards of 16 hours.@ -10f./-15f.
I'm heating a 1600 bungalow with 70 ft loop of 1 pex.
If the experts can;t pin it, I doubt this will help any.
Cheers
KK
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Probably did not help,, but I made Junior Forest Ranger :thumbup: :thumbup:
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It does sound like your wood choice.
I've been burning tulip poplar for a month now. It burns great during the 30+ days but the last couple of
nights its been in single degrees and its been difficult.
Our burning practices are a little different, I batch burn and have a large water volume and my stove is inside my
outdoor shed. I load my stove (3) times per day with poplar on those cold days. If I were to use oak like last year
I add wood (2) times per day.
Sounds like your stove can keep up but just need hard woods.
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I am going to have to say your problem is one of two things. Best case scenario is when your fan shuts off it gets hung up on the two little screws on top. It looks closed but if you have one of the retrofitted heatmasters it can't truly close unless you gring the two screw heads off. Worst case scenario,your stove is undersized. My cousin has a brand new energy star rated house built by an anal builder. Insulated to the max. He's heating,or I should say trying to heat 2800 square feet. He too is only getting about 8 hours of burn time. I'm may make some enemies but I've had three Heatmasters and loved them but they don't heat anywhere in the ballpark what they claim. You would be better suited with a 10,000.
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And don't worry about seasoned wood,with your stove it's not going to make any noticeable difference.
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What size word are you burning?
Granted mines home made but if I want it to heat up fast or expect a large load (going to run the sidewalk to melt snow) I load mine up with all split wood, splits don't burn near as long, they do burn hotter though which allows more heat to escape up the stack. If I need a really long burn I fill the stove with nothing but rounds that are 12" or larger.
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if the wood is free,it don`t matter how many thousand btu its got
but i guess if u pay u want the best u can get
i don't always have the best wood but i cut extra to make up for the quality
also like fryedaddy i batch burn
got a store in the basement and burn 2 fires at night before bed then 1 in the morning wide open.
a total of maybe 3-4 hours of burning per day
thermal store never gets below 160
and the best is no smoke
imo not enough people try the storage option which has been proven in europe
and it sucks every last btu out of wood even when the quality is junk
idling is not a good way of burning wood
just my opinion
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Ok, so I hooked my thermometers up to my furnace coil. I'm losing 1 deg or less from the boiler to the house. I'm losing in between 10-12 deg from the inlet of the coil to the outlet and I haven't checked it but let's figure another 1 degree from the house back to the boiler. So let's say 15 degree difference. Any ideas? Checked my wood moisture content today and it's at 19-25%
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Sounds about right I typically lose 15 degrees inlet to outlet on my 18x18 heat exchanger when house is calling for heat
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I have a feeling that my new room addition is most of the problem. I took my infrared thermometer around the house last night. The floor is always cold in the new room. There is a 7 degree difference in the temp of the floors just by measuring on both sides of the entry door. The floors in the new room were 62-63.5 degrees throughout the room. It's on a crawl space and the crawl isn't insulated. I'm going to buy some insulation and put it in the floor in the crawl space maybe tonight.
I think what's happening is that the cold air from the new room is making it's way into the dining room. The new room entrance is off of the dining room and the thermostat is also located in the dining room. I think the cold air is making the thermostat run more than it should. The rest of the house stays comfortable most of the time.
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If you can buy a closed cell spray foam kit and spray it from underneath the floor it will seal any air infiltration the batts work but not as well.. My houses walls are R-13 and r16 last year I closed in my back porch and bought one of these kits I sprayed ceiling and walls this room is the warmest place in the house the thermostate rarely calls for heat I should have made the investment when I built my house 10 years ago and sprayed all my walls with it... But at that time the quote was $16000.00 for spray foam and $5000 for batt so I went the cheap way and paying for it now..
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Definitely not an expert, but I can share my recent experience. I cut a load of marginal wood this past weekend. I have no idea what species, but its soft. Since burning this wood, I have woke up to nothing but ash in my firebox. I'm going back to the woods today to find better wood. I also think that Heatmaster recommends E series running the fan at 100%. Its frustrating to woke up to a cold stove.
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justinb, guessing that soft wood you might cut to fan back to keep from burning as fast. Lot of discussion on fan speed. I know guys running at 40% and 100%. Im at 100% and have had it at 50 to 70 % at times I have a 5000E . It seems to depend on how good the wood is. Green, dry, oak, Etc. I just started to burning coal going to see how it goes for a few days.