Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: nd guy on February 10, 2018, 10:10:56 PM
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OK This summer the plan is to install ultra fins in the floor under my house and hook it into the wood boiler. I have been having problems with ultra clac. from ultra fin on figuring out how many fins I need. It's a double wide 28 x 56 built in 1997 with 2x8 floor joists 16 on center. Homark is the brand. My heat load near as I can figure is 600 to 700 gals. of propane a year to heat it to 70 degrees in North Dakota. I will be running 4 loops no longer then 300 ft each and the sub floor is 3/4 in. thick. How many fins do I need and what would be a good temp to run through them? 1/2 carpet 1/2 vinyl flooring. Will be doing DHW first with a flat plate and then the floor heat. Re Insulating the area under the ultra fins and then Tyvek the underside. Any thoughts on how to do this are appreciated. Thanks Ray
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Is there a basement under it or just the crawlspace? I have the same size and style house on a basement, the North half is always colder and I was looking into some underfloor radiant as well for the last few months. The Ultra-Fin, from what I understood, is typically sized for 1-on, 1-off in each joist space with 140 degree water. Like if the plates are 10" long, you'd space 10" without a plate and then add another plate, full length of each joist space. That's approximately $4k worth of Ultra-Fin to do your whole house, plus the PEX- are you only doing a certain section of the house or how are you getting away with 1200 ft of tubing?. I was using about double the propane you are, but again there's the basement if yours doesn't have one. Will you be adding a forced air coil under your furnace too, or relying solely on the radiant? I moved my furnace to the basement and put a hot water coil in, and have been heating that way for I think 7 years now, works very well aside from the fact that the North half is 5 degrees colder than the South half, this is in MN. Remember with the Ultra-Fin, it needs air space under the fin to the insulation, for convection to occur. I think I saw 2-4"?
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No basement just insulated skirting. My idea is to do the one side that is mostly vinyl flooring and has the bathrooms on it. I was going to leave the furnace alone and just run it as a supplement to the floor heat. We have to lift the furnace to get enough room between it and the a/c coil. Not a big deal but extra cost. Plus the DHW is on one end of the house and the furnace is in the middle. Yes you need 2 in between the insulation and the ultra fin so I was going to add a 2x4 to the bottom of the joists (in the areas of the fins) to gain 3 1/2 in of space. Sounds a little redneck I know. LOL Then cover the entire bottom with Tyvek. The area I'm planning on doing is 13 ft wide by 45 ft long. Thanks for the reply wreckit87.
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2" foam insulation between the fin and the Tyvek or what? Also curious what else you're heating to have a Heatmor 400 but not heating the whole house with it. We have an HVAC guy locally here that will lift a furnace and slide a coil in for $200 I think. I wouldn't touch it for that, but he does lol. Have hired him a couple times for mobile home jobs.
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What kind of furnace? LP? We don't lift furnaces. Got a crossover line under furnace?
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Yes the furnace is propane. Have a friend who is a HVAC guy and he said 6 in lift on the furnace is not a problem. I am currently heating my shop with the Heatmor. Yes it is overkill for my needs but the price was right and it's in good condition. As I stated before I will add a 2x4 to the bottom of the 2x8 floor joists and keep the R-19 insulation. If it needs to be 2x6 for more air gap then I will go that route. Thanks Ray
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Yes the furnace is propane. Have a friend who is a HVAC guy and he said 6 in lift on the furnace is not a problem. I am currently heating my shop with the Heatmor. Yes it is overkill for my needs but the price was right and it's in good condition. As I stated before I will add a 2x4 to the bottom of the 2x8 floor joists and keep the R-19 insulation. If it needs to be 2x6 for more air gap then I will go that route. Thanks Ray
Ohhhh I had a picture in my noggin of you just sammiching 2" foam under the joists with 2x4 strips perpendicular to the joists holding it up, was not picturing a new blanket. Gotcha!! Furnace coils are cheap, it sure is nice to be able to cut out the gas man completely :)
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I just try to do everything in house. Our way is to take the crossover pipe off and block the duck going both ways. Take a 12" flex into the end of a box that has a water to air coil in it. Reattach the crossover duck to the other end and then pull two 8" ducks from the sides of the box back up to each side of the blocked ducks. This backs the water coil away from the AC unit. and leaves the furnace in place. I just don't like fooling with gas lines and AC lines and maybe return air flow.
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Yes wreckit87 cutting the propane bill would be great!! Furnace coil is not out of the plan but won't cure the cold floor issue. LOL.
shepherd boy that is a great idea. Thanks.
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No basement just insulated skirting. My idea is to do the one side that is mostly vinyl flooring and has the bathrooms on it. I was going to leave the furnace alone and just run it as a supplement to the floor heat. We have to lift the furnace to get enough room between it and the a/c coil. Not a big deal but extra cost. Plus the DHW is on one end of the house and the furnace is in the middle. Yes you need 2 in between the insulation and the ultra fin so I was going to add a 2x4 to the bottom of the joists (in the areas of the fins) to gain 3 1/2 in of space. Sounds a little redneck I know. LOL Then cover the entire bottom with Tyvek. The area I'm planning on doing is 13 ft wide by 45 ft long. Thanks for the reply wreckit87.
Doing floor heat on just one side might make for some cold rooms on the other. I'm sure you'll figure it out. I had a similar issue in my house on the north side, cold floors. Added less than 200' of 1/2" pex under the floor and balanced it out. Grundfos 15-58 on low speed idling along. Blower still carries the main heat load.
Is there a restriction in ductwork causing ineven heat? I've seen a cross duct come loose or kinked over, all.kinds of things.
Side note, ever see what a cat does to flex duct? :)
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Doing floor heat on just one side might make for some cold rooms on the other. I'm sure you'll figure it out. I had a similar issue in my house on the north side, cold floors. Added less than 200' of 1/2" pex under the floor and balanced it out. Grundfos 15-58 on low speed idling along. Blower still carries the main heat load.
Is there a restriction in ductwork causing ineven heat? I've seen a cross duct come loose or kinked over, all.kinds of things.
Side note, ever see what a cat does to flex duct? :)
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Did you use transfer plates or anything when you did it? My cold spot is about 13x35 ft and I have a 200ft roll each of 5/8 and 3/4 pex leftover from jobs that I'm probably never going to use elsewhere, was thinking of just talon hanging one run in each joist space until I'm out of pipe and run a 15-58 on low from a wireless thermostat in the living room, feeding off the return line after my forced air HX with close tees. For whatever reason my crossovers are 4x10 rectangle off the top of the trunks, buried in the joist space so it's gotta go up out of the main trunk then back down to the second trunk on the north half, even with all the vents shut on the south half I still get no air in the NW bedroom or living room just East of it. Damn WalMart house lol
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No transfer plates, tube talons on the side of the joists near the top, about 160 F water, 1/2" pex, reflective bubble stapled up underneath to make a fairly tight hot air space. Approx. 70-80F surface temps on the hardwood floor above. Only one run per joist bay so its a bit uneven, but I don't care.
The hot air space spreads the heat out pretty good really. Does take about 160 F water but , hey, that's what I have anyway.
Double wides have some of the most restricted ductwork I've ever seen. Some are pretty much impossible to balance.
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E Yoder, my floor plan is very open and there is carpet in all the rooms expect where the floor heat is going. All the duct work is fine (thanks for the tip) but when you get a run of days below zero and I mean 20-30 below LOL the floor gets a little chilly even with insulated skirting. Plus this will be a great time to update all the plumbing.
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Yeah, chilly... I can imagine! If you have the insulation down it would be interesting to see if there's air leakage coming in around the rim joists and blowing between the insulation and the floor..? I saw that once in an upstairs (Cape cod type house), the cold air made for some miserable floors.
Anyway, I'll bet you'll love your warm floors when you're done.
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E Yoder, When the time comes I will look into air leaking. Thanks for the tip. Yes I hope my plan works as well as the wood stove does!!
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Mine has a full basement with 3" closed cell in the walls and rim joist. Entryway is tile and the kitchen/dining room are vinyl, floors are still cold with a 65 degree basement and 72 upstairs. Living room and the one bedroom don't necessarily have cold floors, but pretty much cold everything lol. I took the stat off the wall and temp'd a 5ft piece of stat wire on to move it around, seeing if I could manipulate it a bit. Set it on the living room floor and it read 6 degrees less than it did on the wall 2 minutes prior. It's currently sitting on the back of the couch on the North half set at 70 instead of 72 like it was while hanging on the wall, a little warmer in the living room and little cooler in the bedroom (south side) but still not comfortable on the couch. Hate it. I'm fairly certain the majority of the cold plows right through the North wall and across the floor. Stupid bay window in the living room doesn't help either, I can feel the air blowing through the switch plates when it's windy. Should've foamed that too when I put the siding on but was 19 and poor
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wreckit87 when I was 19 I was in the same boat!! LOL!! Neat idea of moving the T stat around may have to try that. Thanks Ray
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Should've foamed that too when I put the siding on but was 19 and poor
Yep, I did our entire shop with Plyfoil (foil/bubble/foil) a long time ago, got it for nothing as I worked at a place that distributed it, get a roll back with water damage? Chuck it in the dumpster per SOP then pull it out after clocking out for the night, 2nd shift is good for stuff like that. Take it home, cut the water damaged stuff out, hang the “good” stuff and roll the crap back up and chuck it back in the dumpster.
Shop is a 1000 sq ft smaller than the house and takes at least twice as much to heat. Course the house doesn’t have any big doors for equipment on it but still.
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Ok I was wondering which pump would work better a Grundfos 15-58 or an ecm style pump. It will be just one zone with two runs of tubing and using a separate t-stat to turn the pump on when the call for heat is there. Trying to keep it simple. Any more ideas would be great. Thanks Ray For now not doing DHW.
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Either should be about the same. The ECM pump will use about half the power. If it doesn't run all the time then the power savings might never pay for the price difference.
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I wouldn't waste the money on an ECM for that application. The draw of a 15-58FC is down in that $8-10/mo neighborhood running 24/7, so you might only be saving $20 a year on electricity by going ECM. That'll take a long time to justify the added cost IMO
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Yup, two loops you could probably run the 15-58 on low speed to save watts. ecm also... But it's a small savings. But ecm would pay after a while. Depends on how long term your plan is . So far I haven't done much with ecm, but it's coming.
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Would either pump last longer or perform better with the constant switching on and off by the T-stat? Thanks for the replies guys. Ray
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I would guess the 15-58 would since there are no electronics.
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I would guess the 15-58 would since there are no electronics.
Don’t remember where I read it, but a recommendation to ensure long life of a PC or other electronics that are used daily is to not shut em off. Every time they power up everything expands a little from internal heat, shut it off everything contracts a little, enough of that and eventually a component fails. Have two Mac mini’s in the house, neither have been shutoff except when we are going to be gone for more than a few days.
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This is the same reason it is recommended for a well pump to stay on for a minimum of one minute. I put an oversized pressure tank on mine recently to a acquire a 3 minute fill time hopefully yielding some more life out of it.
I've been thinking about this myself - to run a 15-58 in low 24/7 would cost $4.50/month at my electric rate. Assuming that operation could be reduced to a 50% duty cycle (in the ballpark?) doesn't amount to enough worth even considering.
On another note, I've got three 250 watt solar panels on the shelf that might be worth installing in the system. The cost of deep cycle batteries is discouraging though. The returns seem dubious at best.
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Yes on the well pumps. Most single phase motors over a certain size have starter switches in em, the more starts the sooner it fails.