New wood furnace install in basement of early 1800’s colonial

nomorecold Posted By nomorecold, Mar 23, 2019 at 1:50 PM

  1. nomorecold

    nomorecold
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    Mar 6, 2019
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    Hello everyone, first post here though I have done alot of reading. I picked up a new Hotblast 1551E wood furnace from tractor supply on sale with plans to have it heating by next season as my main/only in use heat source. I know im already on borrowed time for getting wood in but I have at least 8 dried cord and will work on that issue. I could write a book on what I have going on but ill try to keep it short and on topic.

    At first I thought everything was already decided for the chimney before I picked the furnace. I had an old boarded up basement window hole center of a gable end of the house and said perfect through that and up through the center of the roof peak as it has a big overhang. (Probably 35’ total height from ground for a close estimate total chimney height)

    Now I realize I dont have enough hole between the 8-10” square sill beam and stone foundation for an out of the box type of through the wall thimble. Even if I did, the bottom of the sill beam is so low to the ground the cleanout portion of the tee would definitely be in the ground. Then I thought maybe put in a well but dont want it to cause water problems down the road. Also I want to add a wrap around porch over this side of the house later on and that would probably make getting to the cleanout even more fun. All this without mentioning I would have two 90’s in the basement plus the 90 of the cleanout tee and probably need 5 foot of pipe (if not 6) layed horizontal from last indoor 90 through wall to outside type HT tee. I dont know how far a horizontal run you can have like this before you see problems and don’t want to have to clean it out more regularly if I dont have to.

    Enough reading on here and talking to people got me thinking of doing the work required to chase it through the house. I like the idea of reclaiming some of that otherwise lost chimney heat and the good draft and hopefully less routine cleanouts. I would be penetrating 3 floor/ceilings and 2 roofs as it has a roof built at more of a pitch over the original roof. The house is in the middle of renovations everywhere so opening ceilings and walls is no big deal now, some just happen to be open already, haha.

    Now between first floor and second floor I already have a problem. The floor joists on the first floor dont line up with the second floor and it looks like I would require two 30 degree type HT connections with 5.5-6 ft of pipe between to get my offset around 36” to go through second floor where I want. Just to be clear this is between the first floor floor and ceiling (bottom of second floor) that this offset is needed.

    If possible safely/legally I can see just building a rather wide chase around the HT chimney pipe and offsets to be aesthetically pleasing, possibly making some way to access if need be. But is this ok for draft and from a safety standpoint? Will a chimney sweep be able to go down say 20 feet from peak and hit these 30 degree offsets and go through them? Excuse my lack of knowledge on the cleaning end of this ordeal but I am assuming they have flexible bruhes and could work from top and bottom of the chimney with the first 30 degree offset being about 4-5 feet from the wood furnaces 6” flue outlet on the back. I just hope to heck that if thats fine I dont run into this issue again between 2nd floor floor and ceiling and probably more likely at the roof beams/rafters but I feel I'm being a bit optimistic... How many offsets can you run in an indoor, approximately center of house chased chimney?

    I’m sure I’m missing some info but dont want to put anyone to sleep thats still reading this so I will end here. I am open to and appreciate any suggestions from the professionals on here and nothing is set in stone at this point on a through the wall or roof installation. Thanks in advance for any help and I look forward to continue learing!
     
  2. 3fordasho

    3fordasho
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    Couple thoughts - with 35' of chimney height you most likely will not have lack of draft issues - even with 6' of horizontal run or a couple 30deg offsets. If fact the opposite may be true - too much draft. A barometric damper can take care of that. If you go with the horizontal run set up make sure that slopes up at least 1/4" per foot. Your comments about a through the house flue set up are true for a typical block/brick/clay chimney because they are not insulated. I've found that with insulated class A chimney setups they work just fine through a wall and up the side of the house, outside chase or no chase. A chase will be required for inside runs of class A where it passes through your 1st and 2nd floor levels.
    A flue cleaner like a sooteater will go through a couple 30degree offsets just fine. As far as recovering heat from the class A HT pipe, not much to be gained here as mine is never more than warm to the touch.
     
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  3. nomorecold

    nomorecold
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    Thank you for your help. You answered a couple questions I was thinking but didn’t ask!

    Very good point about the class A HT pipe itself not giving alot of heat in comparison to masonry. I guess I was just assuming if your worried about clearances around it and chases then maybe I could get some heat off it, but if the difference is negligible then it’s probably not worth it in my case of several floors/roofs and offsets. I was thinking of masonry setups I have seen and how well heat comes off, not class A as you pointed out.

    If I do end up going with the “through the wall” method I will probably chase it in anyways just for looks before I put a porch over it. It might run a season or two before that though and can save the money in the meantime. The chimney would be on the cold wall (gable end, centered) of the house as well which reminds me of another question.

    In the through the wall scenario, the wood furnace would be backed up to a roughly 24 foot stone wall of the houses foundation. All foundation walls are a couple feet of field/rubble stone I believe. The house (and open, unfinished basement) footprint is roughly 24x36, a perfect rectangle with pretty much symmetrical rooms throughout first and second floors and centered 8’ hallways, 24’ lengthwise. I was thinking I might benefit from the furnace being centered in the basement instead of at an end of the house to spread the heat more evenly. What I was worried about is the far end of the house from the furnace being colder than the rest since it would be at the end of the 25ft or so of plenum run and 6” metal duct lengths besides being furthest from the wood furnace itself. Maybe this is a negligible difference as well and I’m over thinking it?

    It’s probably worth mentioning at this point I plan to run the wood furnace in series as the pass through unit with my old fuel oil furnace pulling cold air from vents and sending its output air to the wood furnaces original blower location. (They will be removed and probably enlarge the openings into one rectangular duct if I can) The fuel oil furnace I have is old but works fine and I plan to upgrade the blower or at least get a new one before using this setup. This way I can pull cold air through vents in the rooms above, not the basement floor, as well as have the furnace take over if we are away and the fire goes out, sleeping and too lazy to get up, warmer weather comes, etc. No shut offs or electronic dampers to fail either and I have read the heat spreads better this way.

    Another thing I am wondering is how much heat will radiate off the wood furnace? I have read they still heat their area to a point, in the way a wood stove would. The basement is unfinished but since I don’t want to use another source of heat I need it to keep the water main and lines from freezing at minimum and the main runs through the cold foundation wall. Right now I have a 6” flex duct running to the main off my fuel oil furnace trunk line. I am hoping I won’t have to run a duct with the wood furnace and just radiant heat will keep it warm. In either situation the furnace will probably be 10-12 feet furthest from pressure tank and water main line entry point.

    Thank you again for the help!
     
  4. 3fordasho

    3fordasho
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    The 2" clearance requirment for class A is necessary in the event of a chimney fire where it will get much hotter. Normal operation its just warm to the touch.

    Yes centered in the basement would be an advantage, both in shorter more direct duct runs, and the furnace would not be right next to a un-insulated stone foundation wall. And yes there is quite a bit of radiant heat off most wood furnaces, especially the front and some off the connector pipe from the back of the furnace to the start of the Class A.

    I have a parallel set up and the wood furnace blower does not move the air as well as the LP furnace blower. If I could have done a series set up and let the LP furnace blower do the work I'd have better air flow.


    I have a Drolet Tundra with glass in the loading door. When fired up the furnace room is the warmest room in the house even though there is no supply air ducts dumping into that room.
     
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  5. brenndatomu

    brenndatomu
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    My vote is for a centrally located furnace, unless the are some other extenuating circumstances that come into play, it is all around a better solution...and the offset you will need to do the make the chimney work is no big deal.
    You do need to make sure that your supply duct work meets the recommended clearance to combustibles (CTC)...if you plan to use the existing ducts, you may need to modify...especially the first 10' or so...
     
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  6. nomorecold

    nomorecold
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    Great information here, I really appreciate it!

    I plan to completely redo all the ductwork, hot and cold. It will be all metal supply, 6” from combustibles first 6’ I believe, then down to 1” after that. Reason being I have pretty tight clearances in the basement with large beams the size of the sill and 6x6 PT posts under them, now supporting the originals on several jack posts. (The house had a significant sag in the floor and one vertical beam/log from the ground in the whole basement when I got the place. I usually try to be an overkill type of guy so I don’t worry later on, haha) The main supplies off the plenum will be kind of mid height through the basement in some places because of this. I can live with it though looking at the pros and cons and it is an unfinished basement after all. Proper plenum height from top of furnace can be maintained at 15-16” height, flush with first duct runs off each side of it and still be 6” from 6” PT posts that are the low point of the ceiling.

    Also, I think I will have to go double wall right off the back of the furnace to keep required clearances there. The first thing attached to the furnace would be a double wall tee if possible, that way it won’t have to be taken apart to clean from top to bottom. The tee will have a very short vertical length before it attaches to the first ceiling box/floor pass through from the basement and turns into class A HT rated chimney pipe.

    I might have to look into a telescopic double wall piece for here if they have such a thing in that size. It will be doing the first pass through between a floor joist and beam running parallel to each other. I think I am going to have to use a ceiling box down here in the basement so the proper clearances are met between the floor beam and joist. This will leave me with a guesstimate of maybe 12-18” length needed between tee on back of furnace and ceiling box/class A attachment point.

    Im going blurry eyed and been writing this for probably an hour, so I think thats it for now. Off to do more looking over and measurements. Thanks again for the help!
     
  7. nomorecold

    nomorecold
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    Oh and forgot to add, I think I found max offsets allowed to be 4 30 degrees as I am understanding. Wrote in the link below as no more than two pairs of offsets allowed and no angles allowed in chimney except 15 and 30 degree. (Page 12 with chart) I am thinking I will need all 4 if I am lucky once I start looking between 2nd floor and attic, then attic and roofs...

    https://www.duravent.com/docs/product/L150_W.pdf
     
  8. hedge wood

    hedge wood
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    Make sure before you get to far into this project that you are going to be able to get insurance on the house after you put this wood burning furnace in. In my area its getting harder to get house insurance with burning in the house.
     
  9. nomorecold

    nomorecold
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    Thank you for bringing this point up. Currently I do not have insurance on the house and getting to where I probably should. In all honesty and probably stupidity, my plan was to get the furnace installed making sure to maintain proper clearances and have it working before getting insurance. My thought is the insurance company can’t just change their mind if they tell me now it will be fine then I get it installed later and they want to give me a hard time. Its there, it’s properly installed you can check, insure it or ill find someone that will basically at that point. I think at least half if not more of my neighbors have wood heat in use daily here, almost on the Canada border in northern NY state so I am hoping it wont be too big of a problem when I get to it. The house definitely had it at one point too. True open fireplaces by the looks, haha.

    To me the house pretty much has to have wood heat. First winter here and around $700-800 a month to have 1-2 rooms warm with a pellet stove and the rest of the downstairs anywhere from 50-67 with some rooms shut, upstairs with a door between in the 50’s if your lucky. I know its a drafty old place but believe wood heat to be able to put a bandaid on that for now.

    I did get a chance to check out the second floor ceiling/attic joists and they seem to be in line with the first floor so no additional offsets needed there! However, I do think I will need the other pair of offsets afterall to clear the first and second roof peak beams and maybes rafters. At least its looking good for only having 4 offsets total in the chimney (two pairs) as stated in the Duratech instructions.

    Now the problem that has came up is required top of wood furnace door to ceiling height - 48” and minimum ceiling height - 77” which comes out being the same thing basically on flat/ideal surfaces. They show the measurement going vertical from top point of door to ceiling which if you go by my ceiling height I am 1.5” short of meeting this 48” from top of door or 77” total floor to ceiling height requirement. To make matters worst, my floor joists (quartered logs lengthwise) hang down from the ceiling being an unfinished basement so if you count them im down to around 69.5” total floor to ceiling height. Watching your head on the beams I can just walk around down there, me being about 6’ height.

    How do I look at the floor joist (piece of log) in this equation? Is the low point of the joist looked at as ceiling level or the actual floor above like I am calling the basement ceiling? Does the clearance to joist only come into play when the top of the wood furnace door is directly below it? Can I reduce clearances here safely by installing a manufactured insulated heat shield (like what you would normally put under a stove on a combustible floor, cant think of the name) above the furnace/door on the ceiling with at least a 1” air gap from the floor joists? This would make about a 6-7” height air gap between joists with the joists themselves having at least 1” air gap from shield.

    If that isn’t possible looks like ill have to dig down in the dirt 7-8” and hope I don’t make a low spot to collect moisture or water and rot the furnace out. I don’t really like the idea of that!

    Thanks again everyone for the help!
     
  10. Seasoned Oak

    Seasoned Oak
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    Insurance cost can be so high it can cause one to abandon the wood heat idea.I have a friend who built new and to this day has NO wood heat because the extra insurance cost made it too expensive.That said, some companies dont charge a dime extra.
     
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  11. brenndatomu

    brenndatomu
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    Sounds like you should have no trouble finding insurance in your area...as for the ceiling height issue, I'd say the beams are your ceiling...you'd hafta contact the manufacturer to see if they will allow a heat shield to reduce that clearance spec. Or find a different furnace that meets your clearances better...or dig that whole area down...might be a good place to install a sump pump then.
     
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  12. Highbeam

    Highbeam
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    Dig it out, pour a slab or set pavers. I can’t imagine hauling armloads of wood to this thing and ducking under each joist.
     
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  13. nomorecold

    nomorecold
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    Ok, thats what I figured but didn’t want to make extra work if I didn’t have to there.

    I guess Ill dig it down, and actually that height was off a small existing slab so ill have to break that up. Really the ground height around it is about 2-4” lower than the slab so Ill only have to dig down 4-5” at most hopefully, once the old slab is gone. If I get a water issue ill deal with it but it will be close to the center of the basement area of 24’ x 36’ and most of the basement stays nice and dry except one corner.

    The stairs to first floor are about center in the house so the furnace will be around 8’ from the bottom of stairs if I had to guess and im planning on the wood to be put through a hatch im going to make in an old boarded up basement window hole.
     
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