Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: coolidge on April 21, 2017, 04:11:57 AM
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Ok it seems like everything is pointing to my garage slab. So a pour over it is, lots of work and money, but I am figuring a wood savings of 8 to 10 cord per year based on past usage.(2014/15)
So will zip ties be enough to hold tubing in place, I used staples last time.
Best kind of tubing.
I will keep runs 250 or under.
Add more insulation to outside concrete walls, bringing them to R35.
Vapor barrier on top of current Crete?
2" foam board?
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Will you be extending your insulation a couple of feet below your slab like we discussed?
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i am hoping so, excavation guy can't get me in until August right now.
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Have you thought of renting a mini for a few days and doing it yourself?
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I am curious what exactly you think is the problem with the slab though. I hope I don't have the same issue with my new floor! I went with 2 inches xps around the perimeter to decouple the slab from the frost walls and then 2 inches underneath. I went with a 6 mil vapor barrier between the foam and the radiant tubing. Then I went with 1 inch xps around the exterior perimeter of the frost wall and went down 24 inches from grade. I planned to have this foam keep the frost from working it's way through the frost wall and under the slab.
This design was very common with everything I had seen and read. I hope I didn't screw something up!
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Have you thought of renting a mini for a few days and doing it yourself?
Our mini also pivots at the cab, you can swing it clear over to the side which allows you to dig right next to a wall.
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I have no idea what is going on with it really, just that winter of 14/15 I used 8 cord to heat both, last winter 15/16 up to 16 cord and winter 16/17 will be 18 plus cord. Not burning that much wood.
Option B. Just run water to air exchangers, no radiant.
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So at first the slab wasn't an issue and now suddenly it is???? That makes zero sense to me. I know you said your underground lines aren't an issue but are they logstor or thermopex ?
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Makes no sense to me either, heating guy just left baffled, digging holes, insulation under slab not wet. Logstor pipe
Dynamite on order :bash:
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Maybe and IR camera would come in handy here as well? Should show cooler shouldn’t it wherever the heatsink is….
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How did you check under slab ? Is this a monolithic floating slab?
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IR camera shows nothing on outside of slab, cored a hole today, nothing, dug some holes outside, nothing.
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You did the pour? You didn't skip I insulation in the center of th slab did you? They do that done south to use ground as part of the heAt sink.
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A data logger there would come in handy but I have a feeling that if its your slab you should have a noticeable temperature drop on the loop heating the slab all the time.
Do the pumps for the radiant loops run all the time? 90% of the time? 50% of the time?
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Didn't skip any Insulation. Radiant pump runs 75 percent.
Wish I had that data logger today, 200 ran from 830 this morning until 230 this afternoon to bring the water too 180.
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Before ripping out the slab and replacing it, I would hookup a gas or oil boiler to it and make sure it is the problem. Or at least heat with a Modine for part of a winter till you can tell how much difference it is making. You really don't want to replace it all and have it end up no different.
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Didn't skip any Insulation. Radiant pump runs 75 percent.
Wish I had that data logger today, 200 ran from 830 this morning until 230 this afternoon to bring the water too 180.
HUH? Seriously something is very wrong somewhere.
I restarted my G200 last night, water was like 72 degrees. Did a charcoal trick, in five minutes was running pretty strong, so lets say from 8pm till a little before midnight it ran, in that time it brought the 200 gallons in the stove up to temp plus the 450 gallons in the shop.
Do you have temp gauges on the supply and return at the stove? If so what are the temps? if it’s obvious the garage is sucking all the heat, whats the actual temp of the supply when it gets there compared to when it leaves the stove?
I didn’t even have to go into my shop to tell when the waste oil boiler to FPHX pump kicked in, one time I checked and the supply and return were as close as possible with the inherent accuracy of the gauges, next time I checked supply was 142 while return was about 98.
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RSI, I have been heating half of this winter with the modine, it does use less wood, but my work materials need to be warm in order to use them, setting them on the radiant does that.
Underground pipe is good from what the gauges inside garage and back of boiler say.
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I am going to put thermal breaks around the slab if I can get a mini this week.
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Do you have a thermal break between the frost wall and slab on the interior? I can't see exterior insulation doing much to isolate the slab, the frost wall will still suck the heat right out of the slab and send it to th ground. It was my understanding that the exterior insulation aroun the frost wall is to keep the frost from getting under the slab and heaving it.
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It's a floating slab. This is a test hole, no wet Insulation.
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It does look pretty wet under the slab though and is that the perimeter wall, if so how deep does the vertical insulation go?
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It is wet now, been raining hard, dug that hole last Tuesday. Insulation only goes down a foot.
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Personally, I think you found your issue, getthesides down a few feet and I think you will see a major difference!
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That's on my list, just need to get a mini, they are all out a couple weeks.
Would that be a good reason to buy one? Wife said no already.
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You have to totally isolate the slab from the earth. If you don't then the earth will suck the heat right out of the slab. Think foam tub with slab inside.
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The picture is an area I removed the insulation to see if it was wet, the slab does not touch earth anywhere.
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I see now. Looks like spray foamed the perimeter. Where would you be adding more insulation then?
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Picked up an E35 Bobcat Mini with 22 hours on it (just came off a 2 year lease), enclosed cab with a/c and heat, 2 foot bucket with the clam jaws just like new for 25K. I was offered 5K more than I paid for it a week later.
Anyway, I used 2" high density foam everywhere on my 50x60x16 shed with the perimeter only down 1 foot but that is about 4 to 5" below the 2" foam under my slab. 6mil vapor barrier over the top of the tubing which was stapled down to the foam and my cement contractor used wire mesh which he pulled up into the cement as he poured. Heats beautifully.
Coolidge are you loosing water anywhere?
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Honda, Digging down along perimeter, 3 ft below slab ( if possible) and adding 2" foam board.
Schoppy, Not losing any water.
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So you heated one year both garage and house with 8 cords. Next year it took 16?
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Ayup :bash:
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If you choose to add foam, how about digging out/down(on an angle) to avoid undermining the slab. This would be crucial on the eave sides of the building as well as where you drive in. I might require using 4' of foam but you never can get great compaction at the very top once something is undermined.
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I dug out about 5ft today, I am only going to be able to go down about two ft without the dirt from falling in from under the slab.
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I am having a hard time believing that your issue is frost getting underneath the slab. Especially since the first year was fine.
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I am having a hard time believing that your issue is frost getting underneath the slab. Especially since the first year was fine.
Yes I concur with that double the wood seems like another issue.
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Coolidge, is your garage a separate system from your OWB? Is it sealed and pressurized utilizing a plate heat exchanger or how are you doing it? Not sure what you mean by your pump running 75% of the time, my pump for the in floor system runs only when the T-stat calls for heat. What temperature do you maintain in the garage? Have you done a temp drop across supply and return for the garage?
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OWB sits about 14 feet from garage, I ran Logstor from unit to back of garage, maybe 50 ft run.
There is no plate exchanger. Primary circ. Taco 010
Secondary circ. Grunfos ( not shure of size)
Usually I keep thermostat at 68 to 70, so pump will run 75 percent of time.
Gauges at back of boiler, and inside garage show no heatloss in Logstor.
Garage. 28 x 40. 4ft of concrete wall on top of slab, 10 ft wood famed wall on top of concrete.
1- 12 x 12 garage door( insulated)
2- 3 x 7 man doors(insulated)
No windows.
Roof. 4" closed cell foam (R28) with 6" open cell foam over it (R24). Total R52
Wood framed walls 4" closed cell foam( R28)
4ft concrete walls 3" closed cell foam( R21)
Under slab 2" foam board
Thinking maybe just hook up another modine and scrapping the radiant altogether.
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Well as far as frost getting under there, if water got under there then frost can also get under there, perhaps someplace around the perimeter water and cold got into the foam and it is now leaking. We know that the stove is a little bit less efficient, we know the pipe is the best on the market and that there is no issue with it and we also see wet soil under the slab, I'm gonna go with the issue stemming from the perimeter walls not being deep enough and a high water table or leakage.
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How are you controlling the delta t of the floor back to the boiler? What is the delta t?
Radiant systems should be a separate pressurized system, but that's not causing you to lose all the btus.
I didn't go with a floating slab for a couple reasons. One of the major reasons was the fact that I couldn't find any good way to isolate a floating slab for radiant. It has to have ground water somewhere around the slab pulling the heat out but I would think you would easily be able to see that on one or more of the loops. How many loops did you go with?
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Well I am tired of running a shovel, but I have found the problem. There is water between the vapor barrier and Insulation. Now how too fix?
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Pics buddy pics!
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Well I am tired of running a shovel, but I have found the problem. There is water between the vapor barrier and Insulation. Now how too fix?
You used closed cell insulation correct?
A lot of the time when father was still doing septics a lot of problems could be solved by installing a perimeter drain to get rid of the excess water.
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Just stuck my hand in between plastic and insulation, came out wet, no real way to take a picture. Would you think that was the problem, the water under the insulation?
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We use water to transfer heat over great distance effectively, it can be your friend or your enemy, it's kind of like drowning cause you can't swim in the lake or enjoying the nice weather today by being on the water with a fishing pole in your hands!
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Insulation only wet on the surface touching the plastic.
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Thermal images.
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Now that is interesting, just went out to stoke the fire and the low water alarm is on, ran in and added some. Ohhhhhhhhhhhhh :bash: :bash: :bash: :bash: :bag:
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So are you thinking there's a break in the Pex in the slab that's causing the moisture?
The low water cut off will trip after only dropping maybe 10 gallons, it's pretty high in the tank
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Never happened before, anything is possible at his point.
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Has the floor ever frozen, I need to see your manifold, I recall seeing thermal imaging that looked like a loop may have had little to no circulation
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Don't believe it ever froze, usually start heating in Sept. but there is one strange area that showed up this afternoon.
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Did you do 5 inches of stone under the slab as a capillary break? There must be ground water moving in and out from between the insulation and slab. If water had just gotten between the insulation and slab it would make it's way up and out.
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All sand
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That may becausing your issue. Why did you go with sand under the slab? Here is a really good article. http://www.greenbuildingadvisor.com/blogs/dept/musings/polyethylene-under-concrete-slabs
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Good article Honda, thank you
Local gravel guy said it would be good to use for drainage.
It wouldn't surprise me if the vapor barrier or foam board was compromised from the pour.
I guess pouring over the existing floor is really my only option?
Sh:t like this isn't in my toolbox, so I do appreciate all the help, suggestions.
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Good article Honda.
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Interesting read, I’ve seen several done the wrong way. Most notably a slab at an ag dealer, they wanted a heated outdoor slab for power washing equipment. I don’t recall any gravel being used under it for starters, the vapor barrier went under it, then they were placing sand on the vapor barrier to fill any imperfections before placing the insulation, then to top it all off they filled any irregularities in the foam board with sand.
I’ve also read numerous other articles, vapor barrier on top on the insulation then they just stapled the pex down right thru the vapor barrier.
Still weird that it worked the first year then failed the second. Only thing I wonder is did you have a dry year the first year, then it got wet the second and water found its way under the slab?
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I ended up following exactly how that article said to do it. First we put down 4 inches of clean round stone, then 6 inch high beveled at 45 degrees on top around the frost wall with 2 inch xps , then2 inches of xps foam board down on the whole floor, then vapor barrier and then stapled the pex right through the vapor barrier. I went back and forth with that placement of the vapor barrier for a while on some of those green building sites with some guys. Ultimately they said if you add up the holes from the staples your are going to end up with about 1 1/2 square feet of 'missing' vapor barrier which is fine. My concrete guy would have put sand under the whole thing for sure if I didn't say anything. Everything I read said that the stone is very important as a capillary break so as to not carry water up through the soil to the insulation and the slab. I haven't hooked mine up yet but I hope it works! I still need to build my closed system radiant manifold.
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My 50x60x16 shed is a floating slab and I just pulled up my pictures taken during construction. I couldn't remember where my poly vapor barrier was. I put down a bed of pea gravel over my sand base then the vapor barrier then my high density 2" Styrofoam which had the pex stapled to that. As soon as the shed was done, I put up rain gutters and downspouts with buried tubing to route the water away from the shed. No issues since construction.
Do you have rain gutters and downspouts with drainage pipe to carry away water Coolidge?
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I don't, it was on my-builders hit list, but didn't get done. Problem with gutters so builder says " they will fall of when snow slides of". We had some good rain yesterday and more today. There was no standing water in any of my holes I dug. Will have to keep an eye on the holes today.
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Hmmmm. Low water alarm today again.
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How much water are you adding Coolidge, is it possibly overheating and boiling off a bit or are you legitimately losing water?
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Added, maybe another 30 gallons today. No visible steam or water from top of boiler.
no pumps running in garage, just running the house right now, no leaks there.
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Wow you got a definite issue somewhere. Can't believe you haven't seen 30 gallons. Maybe flatplate or sidearm leaking into your domestic. I would think with house water pressure though that it would be pushing into the boiler loop.
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Domestic leak-through would feed back to the furnace.... Would be nice to be able to pressurize each line separately and see if they lose pressure.
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No plate exchanger. Have a turbomax for hot water. Will do more investigating sometime.
Couple more days and I am shutting down, had enough!
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Please do not drink your water until we find the issue, I can't see any possibility of our boiler water backfeeding into your domestic but just in case, it could make you very sick! Can you be home tomorrow if I make a trip up to check it out?
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I topped my G200 off after shutting it down as Slim recommended and it took less than 10 gallons to take it up to the float opening. I am running the pumps now to make sure everything is mixed up well before taking my sample and sending it in.
You have to have a leak somewhere Coolidge.
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Please do not drink your water until we find the issue, I can't see any possibility of our boiler water backfeeding into your domestic but just in case, it could make you very sick! Can you be home tomorrow if I make a trip up to check it out?
FYI, far as the wife’s aquariums, 0 PPM of nitrites are best, even a trace can have long term effects though, 5 PPM is considered lethal , up to 40 PPM of nitrates is considered normal, lower the better though, if it approaches 80 PPM you have serious issues. Out of curiosity I checked our well water, 0, 0, 0 far as ammonia, nitrites and nitrates. Also zero on pesticides and insecticides, zero arsenic, lead, copper and bacteria.
Unless you have crazy low house pressure I can’t see boiler water mixing with the house water, the other way around of course. I had a gauge once on my system when I still ran the nominal 1” pex, ran about 5-6 pounds on the boiler loop in the basement. However, better safe than sorry.
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I've seen this happen once in my lifetime so I'll throw it out there. The guys furnace had a large drip pan under the heat exchanger that caught condensation from the A coil and for his cold start furnace manifold. What happened to this guy was his heat exchanger for his OWB was leaking and draining into this drip plate and down the sump pit. The only reason we ended up finding it was he happend to see water dripping into the sump pit and he said wait a minute, we don't get water unless the furnace actually runs not the fan. Just throwing it out there. Good luck Coolidge
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couple sticks of dynamite should remedy the situation. :bag:
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Ready for Crete.
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Coolidge do you have every loop numbered and marked for supply and return?
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Ready for Crete.
I would put the loops more uniform distances apart you will have hot and cold spots like that.
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They are marked
Had 1300 ft of pipe, there is 1250 there, I have a six loop manifold, I could tighten the middle up and add a short loop.
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I would agree with you guys about the distance between line but since it is in a garage and no one is walking on it with bare feet I don't think anyone will notice. On another note check out the program LoopCAD. It has a 30 day full program trial. Awesome program!
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I would agree and being that is closer to the center it should be fine.
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So did you find a leak?
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Haven't looked yet.
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Interesting, by looking at the insulation on the walls your vapor barrier is sprayed on ?
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thats 2" of closed cell foam sprayed too the original concrete. I don't know why i put that insulation on the walls, there is insulation on the outside already.
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thats 2" of closed cell foam sprayed too the original concrete. I don't know why i put that insulation on the walls, there is insulation on the outside already.
Better to ponder why you did it than wishing you did it.
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My plan is to strap that Insulation and put up some plywood, on walls that don't have shelving or benches anyway.
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Did you leave a spot for the supply/return from your OWB to come through the floor, or any other penetrations you need?
Is your garage a pressurized closed system separate from the OWB system? If it isn't, how are you tempering the water from the OWB?
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I am leaving the OWB lines where they are( orange pipe).
Running an open system from boiler, there is a mixing valve down in that mess somewhere.
Would it be beneficial to pressurize the system?
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I've never pressurized a floor, just mixed and dumped the furnace water right into the floor loops. Used mixing valve or injection mixed on a big slab.
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Seems like it would be hard to balance flow , keep a loop from getting air bound and also what do you do if you want to stop heating te floor in the cold months as far as freezing goes?
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If you want to run glycol then just need a plate exchanger, my snow melt isn’t pressurized and works just fine.
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I have mentioned before and I'll do it again Honda, Eldon is in Va, he can get away with a lot of stuff down there that folks up here would nail your private parts to a stump and push you over backwards for doing.
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Seems like it would be hard to balance flow , keep a loop from getting air bound and also what do you do if you want to stop heating te floor in the cold months as far as freezing goes?
You're right on the separating the floor to run glycol.
By balancing flow do you mean achieving hydraulic separation between the floor circ and furnace circ?
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Correct me if I'm wrong but if you are sending water directly from the OWB to the slab via a mixing valve then there would be no need for a separate circ, one would do the job in Va. not sure that would work for a week long power outage at 20 below zero or anything below freezing for that matter, anytime a slab is used, I certainly would use a plate and anti freeze north of the Mason Dixon!
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Never heard that phrase before Slim, good one!
I used a pressurized system with a plate heat exchanger like mlappin said so I could just use antifreeze in the floor and not the entire system. Can get pretty cold in Wisconsin and the last thing I want is a burst pipe in the floor if I have to shut it down for some reason.
What ever works for you though.
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I guess wood burning is about gone here, loosing 25 to 30 gallons every other day. Would be impossible to run another piece of Logstor under the road, if that is the problem. Might have time tomorrow to dig a little deeper.
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Boy I would be surprised is it's a logstor failure.
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I hope not, got some testing going on, there is NO circulation too the boiler at this time, need to squirm into the crawl space ( not shure if I can fit) and see if there is any wet spot from the radiant.
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My first year with an OWB I had issues like that. It was not the unit I have now but it wasn't the unit's fault anyway, I used sharkbite clone push fittings back then. I was told they are just as good as sharkbite-WRONG! Lost all my antifreeze treated boiler water back then.
I replaced all of them using mostly crimp fittings but only using sharkbite where I needed push type fittings. No problems since.
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No shark bites, Logstor to copper to zones. I am going to have to refire today, wife, kids and animals are cold.
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Bonus, Found the leak, black iron nipple for my pressure relief valve rusted.
FEWWW :thumbup:
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Bonus, Found the leak, black iron nipple for my pressure relief valve rusted.
FEWWW :thumbup:
:post:
LOL, hows that saying go, if you can’t be good then be lucky?
My father was a union tin knocker before entering the state of retired bliss, several places he’d work for in the past he was the guy they always send out to find a mystery leak in a roof, most of the time it was because somebody got lazy and didn’t properly tool the caulk after applying it, some were real head scratchers though. Tough ones to find were either slate roofs or standing seem copper roofs, usually on the copper somebody made a bad solder joint.
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Just happened to catch a drip in the basement from underneath my storage tank, there was 6" of foam around that nipple, started digging and wala.
That one is fixed.
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We bought a combine cheap years ago, got it home then found out why, sit long enough and it would loose prime.
Talked to the local dealer, claimed they had their guys work on it numerous times and could never figure it out.
Pressure washed everything, gunked it all then pressure washed again, ran the engine to dry everything out, couldn’t find anything.
Next day was climbing up the service ladder to get behind the engine, happened to be looking right at the shutoff solenoid on the injection pump and seen a tiny little drip. Went and got a flashlight, watched it, would get one tiny little drop every 12-15 minutes, wouldn’t leak at all when warm. Sometimes would only take four days to loose prime, sometimes a week or better. replaced solenoid and end of problem.
Dumb luck on that one, as the drip would land right on a hose and follow that elsewhere.
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Crete done.
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Boy you don't screw around!
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No time, winter is coming
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Had one of my trusted resources do a heatloss analysis on just my house, can't remember the number she gave me, but it equals 5 cord of wood too heat plus domestic hw.
I am shooting for 8 cord to heat both house and shop next year, we'll shoot, that's all I got left anyway.
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Lol, right around the corner!