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[Canuck87]

Im starting off with a tank I came across for $400. Its not home yet but will be this week. I am going to copy Peatmoss's design.  Next I have to go to a scrap yard and try to find the burn chamber and secondary combustion pipe. I am not quite sure how big they have to be in relation to each other. About 12" diameter I think for the secondary combustion. I also have to get some refractory material. Hopefully I will only have to burn every 2 or 3 days in the dead of winter. Heating a 1200 sqft house with basement. Furnace will be inside the shop (36'x32') and have the option to heat that also. Escaped heat will warm the shop some during the winter.... And the summer    Trying to decide on what to run for lines underground to the house, maybe pex wrapped in aluminized bubble wrap inside flexible tubing. I'm not sure if I want to spend the money on commercially made line.

Any advice would be appreciated

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[rogeroverout621]

That tank looks huge!  How may gallons?  Very interested in your build, hope you are able to show off your progress.  Lots of knowledge on here hopefully some will be willing to share.

Just a thought for you,
I did something similar to what you are thinking with the underground pipe.  It works,  but some days I wish I would have used the good stuff.  I am seeing some heat loss and not sure how long my homemade stuff will last.  Also, there are so many variables to these systems, it would be nice know I am wasting minimal effort and expense of gathering wood to heat the the ground!

Looking forward to your progress.

[HandyMark]

Holy crap. I can not wait to see this build. I always wanted to be able to burn a truck load of wood truck and all.

[Canuck87]

Not sure on the exact dimensions of my tank or the volume. They said it was 5000 gallon but sitting beside a 2500 gallon tank you could tell it was way more than twice the size. I paced it out and I think it is about 24' long with a 8' diameter putting it around 9000 US gallons I will measure it when it arrives this week. Just the steel will add alot of thermal mass. This thing weighs almost 6000lbs. If I fail it will pay for itself at the scrapyard 

[petemoss]

That's a huge project ! 9000 gal will be great. that would run me for 12-14 days. very cool.     

[peacmar]

9000 gallons will net you a massive amount of thermal mass. When I finish phase 3 of my project I will be heating a 2500 sqft home and a 3500 sqft shop comfortably with only 1000 gallons. Burning 90 lbs of timber a day once a day. Insulate the hell out of everything to keep efficiency. My underground lines run in 6 inch pvc drain pipe. Pipe is surrounded by a foot of 3/4" clear wash stone buried 48" deep. The gravel prevents water from sitting around the pipes and stealing my heat. I pushed 1" pex through from the house to the burner wrapping the pex lines in those swimming pool "noodles" pushing 4 feet at a time. Tape the hell out of them with duct tape to keep them in place. I bought 100 noodles at wal-fart for $.50 each at the end of summer and figure them to be around R-12 insulation. In 150' of underground run I only lose 5-8 degrees water temp from burner to house during the deepest of frost in Wisconsin.

[rosewood]

Nice score for a tank like that...more like a steal. Just something to consider if you fired that thing every few days to reheat a 60-80deg differential ,hope you hav the day off from work cause it's going to take 6-8hrs to get that thing up with a roaring fire and a constant supply of wood. Myself I think I would use 2000gal of that tank and use a 3000gal insulated reserve tank.

[Canuck87]

The heating season is about to start so i'm going to have to actually get to work on this thing. I picked up a 500 Gallon Propane tank from the scrap yard for $300, It weighs about 1200 lbs. I found a good deal on some 4" sch 10 pipe but i'm not sure if it would be thick enough. Right after the secondary combustion chamber where its hottest could be a problem? I cut the opening for the burn chamber in the end of the big tank and next ill take the end off the propane tank for a door. Im going to weld the burn chamber in last because I am planning on welding the fire tubes through the back end of the tank so they are a straight through pipe to clean. The end I plan on building a bolt on access panel where the exhaust will cross over to the tube heading back the other direction.

Part of the reason I want such a big thermal reservoir is to eventually have solar thermal panels heating the tank also. I want to be able to not touch the system for at least 6 months through summer and still have enough domestic hot water and space heating even through cloudy colder weather times.

Anyone have any problems from using thin pipe for fire tube? I'm thinking I should not cheap out and just get some sch 40. I have been researching for a while and have a few ideas/questions.

It seems pretty important to have a minimum return temperature so I plan on adding a thermal valve on the return that will add hot water if needed to keep a minimum of 140f?
 I seen a few global hydronic boilers cut open, the return pipe was about 4 feet long 1" dia. drilled every 6 inches with small holes to return the water above the firebox . It was completely corroded away while most other places weren't corroded much at all. Welds looked like they took some abuse also. I may use welding rods with high nickel to make sure they don't get corroded.

What kind of water should I fill it with or does it matter as long as I add corrosion inhibitor. I have hard water at home but it may be possible to fill it only with water run through my softener. Would it be worth it to fill with reverse osmosis? I can get a 1000 gpd R.O. membrane but it would probably take at least 10 days to fill.

For my underground lines I may do the sprayfoam in place wrapped in plastic method that I have read about. I would fill around it with crush and maybe some drainpipe and crush below also. Looking at some commercial lines I realize they don't have much insulation between the pex and the soil.

The tank is 26' long and 8' diameter. I was guessing the weight based on its size but i didn't account for the ends. Lol the hiab I borrowed from work barely managed to lift it onto the trailer.

I will try and add some more pictures this weekend.

Thanks for any advice

[peacmar]

Sch40 would be better if you plan to leave the pipe bare, use the thickest steel plate you can work with for the first face the flame will meet also. I am only using Sch 10 pipe for the 3 I am currently making. I originally chose Sch 40 but after some calculations found that Sch 10 transfers heat much more quickly. I will be coating the front face and first few inches of the pipes with a paint on ceramic heat barrier used in kiln construction for knife making. It's kinda pricey stuff and available on any knife making supplier on the web and there are various manufactures of the product. But I feel the increase in thermal conductivity is worth the extra cost associated, and the barrier will prevent any degradation of the steel surfaces while still transmitting heat in a more controlled manner. Also keep in mind that industrial seem boilers use tubing of .120" thickness or less, which is less than Sch 10 in most cases.


Copper is usually used for a return line to the tank in large systems, especially solar. The copper takes many times longer to react and break down, and galvanic processes within the copper to steel connection also cause an anti corrosive effect.

softened water would be better than tap as it will protect your heat exchangers and lines from internal build up. If you treat the water and test it yearly it will be fine. No need for an expensive system here.


Also make sure your lines have very good drainage all around, drain tile is not necessary though. It just moves the water from one end to another.

[woodman]

Holy crap with a tank that size have you priced what it is going to cost you for water treatment? My boiler holds 150 gallons and it took nearly a gallon of certified labs water treatment to get it in spec. If I do my math right you could be looking at between $2500.00-$3000.00 for water treatment alone! I would contact a garn rep since they deal with large volumes of water maybe they have a more economical route.

[Scott7m]

Your going to do all of that work, and them skimp on line? 

Most folks who try to make there own end up having 3.50-4.00/ft in it before they tear it up trying to pull it through. 

[Canuck87]

    I am going to install my own line. I have seen commercially made lines that only have 2" of foam surrounding the lines. A high quality foam has abour R-5/inch which means that line is insulated to R-10 give or take. Thats far less than my house walls are rated and they don't have to retain temperatures near boiling. That is my deciding factor for installing my own. I talked to a local spray foam contractor and he has installed lines sprayed in a trench for mines around this area and apparently it works great. My plan is to have the lines buried with 6" of 2 or 3lb closed cell spray foam on all sides. Also the line will be a steady downhill to the boiler and I was considering putting corrugated drainage pipe underneath the Heat transfer lines.

    I have been looking into water treatments. I was worried it was going to be expensive, One call to the local wood boiler company confirmed my suspicions. After that I found a company online that specializes in Corrosion inhibitors. My current plan is to buy boiler treatment in bulk from Accepta. I have a $330 US quote for about 60 litres which is twice what i need for the initial application. From what I have read it is made mostly out of caustic soda which is cheap. I considered just adding a bunch to the tank but that could go horribly wrong. Its not a really big expense for the peace of mind. I have read that Garn uses some sort of cleaner before they add the corrosion inhibitor but considering most people don't add it to their homebuilt boilers I don't think I need it.

I decided to go with the Sch 10 pipe for the tubing but I also got a piece of 5" Sch 40 (10 ft) that I will use immediately after the secondary chamber.
     

[Canuck87]

So today I finally did some work on the boiler. Its been a busy summer but I have some much needed time to work on the boiler now.

    I picked up about 80 feet of Sch 10 4" and got an old piece of 5" Sch 40 (10 ft) for the first piece connected after the secondary combustion chamber.
I decided to take the cheap deal on the banged up sch 10. After Peacmar mentioned the fact that commercial boilers use such thin pipe I think sch 10 is enough. I'm sure it will last at least a few years, if it corrodes right through eventually then I guess ill rebuild it then with some better stuff.
A copper cold return line is a very good idea, I have added that to my plan.

    The only piece of pipe that I could find at the scrap yard for the secondary was 18" diameter  . I plan to cast my own refractory on the inside which will reduce the ID to about 14"? maybe even 12", I have not decided exactly how thick I will make it.

I started tapering the secondary chamber down to 5" pipe size and cut some elbows to make a 180 back to the face of the boiler. Where the exhaust fan will be. I need some tips for the plasma cutter to finish getting the secondary chamber ready to weld, I am almost half done forming it down to 5". The 5" 180 bend is ready to weld but I have to pick up some 6010 to weld it.
I am anxious to test out the Synchrowave 250 that I picked up Friday.
     I have been enclosing my pole barn over the summer also so I have half finished projects all over the place. Finally got a 100 amp service all hooked up so at least I have some power in there now.

Thats where im at now so hopefully i get some more work done tomorrow. Next on the list I think I will start building the fan enclosure and intake pipe. Monday will be a good day after i pick up some plasma cutter parts and welding rods.

Thanks everyone for all the info and comments 

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[woodman]

I give you a lot of credit for taking on a project of this scale. Will be fun to watch it progress.

[peacmar]

I'll try to dig up the link to the water treatment I use, I ordered a ton of it a while ago so haven't looked for it since then. At the time it cost about $25 a gallon a one gallon treated 300. But this was based in taking a PH reading and testing nitrates. After that you just do a home test once yearly and add a small amount to adjust. There is also a boiler water treatment company of sorts right in my back yard,(or down the road) in waupaun Wisconsin. It's who Garn uses. I send them my water sample every year for $25 they send me a small concoction to poor in and I'm done. But then there is always the tried and try method that boilers have used for decades, run it to boiling and remove all absorbed oxygen, then never let it get below 140 degrees Fahrenheit. I did this my first two years running year round and the inside still looked like new. Only when the AC worked too hard to expel the hear the boiler was bringing into the house for hot water did I finally give in, treat it, and shut it down for the summer. But record summer highs will have that effect I guess....