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Author Topic: Wood Boiler Project.  (Read 8255 times)

Offline OKCPrepper

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Wood Boiler Project.
« on: January 26, 2013, 01:19:16 AM »
I wasn't sure where to post this thread, this seemed to be the best fit. I have been working on a wood fired boiler project for a couple months now. I was wondering if anyone else has taken on a project like this before and has any experiences both good or bad to share. I have watched several UTube video's on the subject.  I am a fabricator and used to be a foreman in a wood burning stove manufacturer over 30 years ago in a different life.

I am going this direction for a variety of reasons. The most important is I have plenty of wood available and it's a good cheap and renewable source of energy. I will be using this to heat my home (in floor radiant heat), my homes hot water, the greenhouse and Aquaponics tanks as well as a couple friends travel trailers that are parked on my farm.

I have taken ideas from each of the different design ideas I found on the UTube video's and combined them with several of my own. This is a pretty big project and beyond most peoples ability to build, I am willing to post some pictures if there is any interest in seeing the project.

If anyone has tackled a project like this, please let me know. The control systems are the one area I have some decisions to make yet. Electrical engineering is not my strong suite.



Offline Nicodemus

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Re: Wood Boiler Project.
« Reply #1 on: January 26, 2013, 10:56:26 AM »
I am very interested in following your Wood Fired Boiler Project. I hope you'll share it with us.


Offline Turnandshoot4

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Re: Wood Boiler Project.
« Reply #2 on: January 26, 2013, 11:36:47 AM »
Tagged!

Offline ID_Joker

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Re: Wood Boiler Project.
« Reply #3 on: January 26, 2013, 02:38:00 PM »
I am very interested in following your Wood Fired Boiler Project. I hope you'll share it with us.

Ditto!

Offline scoob

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Re: Wood Boiler Project.
« Reply #4 on: January 26, 2013, 06:24:52 PM »
I'm in.

Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #5 on: January 27, 2013, 01:14:00 AM »
I will take some pics Monday and post them. This wood boiler is going to be used in conjunction with a bank of solar hot water panels. My partner on my farm has gathered several of these (usually free) from from people that had roof mounted systems that had a pump or other part of the system fail and they abandoned the system after a hail storm and their roof was being replaced. The solar will be the primary 3 season hot water source, during the winter months the boiler will be used overnight or on those cloudy days.   

Here are a couple of the UTube video's I found to have a lot of good ideas or concepts. I have taken aspects of each of these and incorporated them into my own design. This first one is my favorite. This is a complete DIY home built system. I wish he had included some video of the construction so I could see what his hot water storage tank looked like. I really liked his use of a throttle body from a dodge caravan as a way of controlling the combustion air flow. 
http://www.youtube.com/watch?v=64a4Wz2owKg&feature=related

I paid close attention to the control device he points out. Here is a link to their site. I have a friend who is an electrical engineer, I will ask for his help in selecting the best device(s) for my project.
http://www.watlow.com/products/guides/controller/index.cfm

In this video, the guy worked mostly with a kit that is based on a 55 gal steel drum. This is not a boiler, but a type of wood stove. It looks to be in his basement and he is counting on the heat rising up through the house. A 55gal drum is not near thick enough for my liking. I did get some good ideas as to how he brought his combustion air into the firebox. I have done the same thing on my boiler. I will go into more detail as I post the pictures next week.
http://www.youtube.com/watch?v=pHty-Fo8opc&feature=related

I liked these next 2 video's for the details on his door, hinge and latch ideas. This guy has some serous fabrication skills and access to some plasma or water jet equipment for items like the latch. I saw some serous flaws in his overall design, I don't think the wall thickness of his 300 gal gas tank is near thick enough. I think his fire box is way to big for the amount of hot water tank he welded on the top. He also overlooked adding an ash tray in the bottom for easy clean out of ash. Again, I am taking little details from as many sources as I can find and putting them all together.
http://www.youtube.com/watch?v=LYfKm9MAb6U
http://www.youtube.com/watch?v=LMriI7UDb-c

This project of mine is not a cheap undertaking. I sources all of the things I could on Craigslist and EBay, but most of it is custom made. I have quite an investment in stainless steel, I have 4 SS heat tubular exchangers that sit right on top of the firebox. Not inside but just inches from the top of the fire box pipe.

I used a 20" diameter 1/4" thick pipe 36" long for my firebox. I will have a SS hot water storage tank sheered and formed once I have a final location for my flu pipe. I will do all of the TIG welding on the SS. Right now my plans for the storage tank will be around 150 gallon. The water return will flow from the various buildings back to the boiler in underground insulated PVC pipe. The water will actually flow in PEX tubing, but housed in PVC rigid tubing to protect it from gophers and other underground critters that might like to chew on things. The return water will flow though the heat exchangers and then into the storage tank. 

The hot water will come into the house where it will be tied into a manifold and sent to the various other buildings it will be used in. The heating in the house will be done via an in floor radiant heat grid we laid out before pouring the floor. The concrete floor is sitting on 1" thick board insulation and a 6mil moisture barrier. This is to keep the heat we generate in the floor from soaking into the ground. We have 4 zones in the main floor so we can isolate a particular zone in case a leak were to develop over time.

The water in the Aquaponics tanks will be done with a heat exchanger mounted in one or more of the water tanks. The hot water and fish water will not be in the same system. I found several used SS heat exchangers for this purpose on EBay, lots of things from brewery's or commercial applications that are being salvaged out.

The heating done in the travel trailers will be pretty simple. Think in terms of the heater in your car. The engine provides the hot water, it flows through a fairly small usually copper heat exchanger called a heater core. Air is blown over the core to transfer that heat into the vehicle.  I'll do the same thing with a 12V fan ( solar powered) to circulate the air. Again, Ebay has lots of possibilities to use for this. The hot water will flow constantly to keep the place warm enough to assure there are no frozen pipes. The heat in the TT will be regulated by a thermostat that will control the speed of the blower fan.

This should give you a fairly good idea as to how and why I am building such a system. I am building an off grid homestead with the plans to make it as self sufficient as possible. We already have at least 3 years of wood for the boiler stored on site. We hauled in 3 pickup loads this morning. A crew has been working just a couple miles from the farm clearing trees along the roadside in preparation for new power lines being placed. They cut the trees up and leave them along the roadside for the locals to pick up. We did this last weekend as well. Nothing like free hard wood cut to size just for the taking.

We also had the trimming crew dump several loads of their shredded chips just inside the entrance to our farm. I recently watched the Back To Eden video posted in one of the other TSP forums and have already made plans to add that to our garden. My wife and a friend spread 3-4 inches of wood chips over the top of our in ground woody (HK) beds today.

Jack's podcast's have been a wealth of information for me and I felt it was time to start sharing some of my projects with the TSP community.



Offline Vulcan

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Re: Wood Boiler Project.
« Reply #6 on: January 27, 2013, 12:20:59 PM »
Gunna follow this one for sure!

Offline onesojourner

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Re: Wood Boiler Project.
« Reply #7 on: January 28, 2013, 04:38:41 PM »
I plan to mess with an outdoor boiler sometime in the next year or so. I ran 1000 ft of pex through my basement slab living areas. I never really planned for this to be a full time heating option but for the $500 investment for the pex and r5 insulation I thought it would be a fun thing to play with.




Have you looked into any of the rocket designs? I am limited on my wood so I want my system to be extremely efficient. I was thinking about something along the lines of this:

http://youtu.be/YTnr8ua54Uw


I wouldn't be looking for any super high temps but anything warmer than 80 degrees would help keep the house warm. Adding insulation around the thermal mass of the rocket mass heater, the mass of the water and the mass of the floor should probably make extra long burn times obsolete.


Offline Nicodemus

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Re: Wood Boiler Project.
« Reply #8 on: January 28, 2013, 07:48:33 PM »
That's thinking ahead right there.


Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #9 on: January 29, 2013, 01:49:28 AM »
I could see where the rocket stove idea could work for a small amount of hot water needs, but what I have planned will require a lot more BTU of heat input. I don't want to be stoking the fire box several times a day and I suspect you would have to with rocket stove.

I have a new resource I am starting to explore, I ran across a forum in one of the UTube videos on wood boilers that the focus of the forum is nothing but wood boilers, store bought and home made. There are topic area on electronics and controls which is the area I need to do a lot of research on. Here is a link. 
http://outdoorwoodfurnaceinfo.com/forum/

I have several pics of the project so far, just need to figure out how to attach them.

Offline onesojourner

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Re: Wood Boiler Project.
« Reply #10 on: January 29, 2013, 07:39:52 AM »
Use an image hosting site, picasa, flikr ect. then you just need to copy the image location and past it in the image tags here.

Offline rikkrack

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Re: Wood Boiler Project.
« Reply #11 on: January 29, 2013, 08:03:40 AM »
 :popcorn:
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Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #12 on: January 30, 2013, 03:05:16 AM »
I got an account set up on Flickr. Here goes, hope I did it right.

Here are a couple pics of the boiler pipe and rear wall. This is a 20" diameter, 5/16 thick, 36" long pipe. Rear and front walls are 1/4" plate.




The holes in the back wall are where the stainless steel tubing heat exchangers will enter the hot box.



Here is a better angle showing the ash box and ash slots in the floor of the boiler. I will have a tray formed that will slid inside the ask box that can be removed to easily dump the ash. Ash will be saved for making Lye soap, coals will be saved for adding to soil.



This is a shot of the burner plate. This is a 15" x 30" x 1/4" thick piece of 304SS. This will mount in the top of the boiler towards the front. This will leave a 6" wide gap at the back of the boiler for the gasses to move up and travel back forward to the flu pipe. I decided to put the flu pipe at the front of the boiler, this gives me more room for my heat exchangers. The draft will pull the flames towards the back of the boiler and away from the door when opened.



This picture shows the burner plate lying in the bottom of the boiler, imagine it sitting in the top of the pipe just like this. On top of the plate are 2 pieces of 1.25" 304ss tubing. These are the secondary air tubes. They will be mounted below the burner plate on each side of the fire box. The holes will be pointing towards each other, providing air for a secondary burn to take place. That is why the need for the burner plate being made of stainless steel. The heat on that plate will be intense and mild steel would burn out much quicker.

Everything I have read says that by giving the fire this secondary air source, it will burn off any remaining gasses and that will make the boiler exhaust virtually smoke free. In the event of social unrest / collapse, a trail of smoke coming from a fireplace will not do well for ones OPSEC. The wood stoves I was involved in making years ago used a catalytic converter that mounted in the flu pipe to burn off these gasses. The method I have outlined here should accomplish the same thing.

There will be another pair of these tubes that will be mounted under the grate which will go in the bottom of the boiler pipe. Those will provide the primary combustion air. The have similar holes drilled into them, they will point up at the center of the grate. My research shows it is best to introduce the primary air under the wood for maximum efficiency.

All 4 of these tubes will be tied to a 3" air inlet. I calculated the total square inch area of the 3" pipe, then calculated how many 1/4" holes would be necessary in the 4 tubes to equal the amount of air the 3" tube could supply. It came out to roughly 56 holes. These tubes will be force fed with a 12V blower with the option to draft naturally. This will be controlled by the amount of heat required at any particular time. If the water starts to cool down, the fan speed will increase to intensify the burn. By using a 12v DC blower, the speed of the blower can be easily regulated with a rheostat. 

I have the grate materials being cut this week. I weighted the options of using a cast iron grate, but could not find anything that fit my dimensions. I use a machine shop that has water jet capability. I was discussing this with the owner, she told me she makes parts for several guys that build custom smokers. They use replaceable sections so when the grate burns out, you don't have to replace the whole thing, but can do just sections. I am having 2 pieces of 1/4" plate cut that are 36" long and 1.5" high. Every 2" on center will be a 1/2" deep, 9/16" wide slot. These plates will weld along the bottom of each side of the ash slots in the floor of the boiler.

I will cut some 1/2" x 1" mild steel bar stock that will fit down into the 9/16 slots. This will form the grate. The 1.5" space between each bar will leave room for the primary combustion air to blow up from under the grate and the ash to fall through into the collection tray. The hole spacing in the primary combustion tubes will match up with the spacing on the grate bars. This should make replacement of the grate easy should any of them burn out.

I will post more picture tomorrow night of the heat exchangers and next week once I have the grate materials in hand.

« Last Edit: February 02, 2013, 06:55:00 AM by Nicodemus »

Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #13 on: January 30, 2013, 03:19:44 AM »
I was wanting the image to show up in the post vs having to click on the link, guess I will look into posting pics a little more.

Offline Nicodemus

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Re: Wood Boiler Project.
« Reply #14 on: January 30, 2013, 07:37:51 AM »
Your flickr photos are set to private. I think you need to set them as Public.

When using flickr, a "Share" button will appear over an image in your photostream. Click on that and go to "Grab the HTML/BBCode". Make sure that the size you want is displayed in the drop down selection bar beneath the code and that the "BBCODE" radio button is selected. Finally, copy the code.

Example copied from my Flickr Account:
Code: [Select]
[url=http://www.flickr.com/photos/youarehere01/8187575394/][img]http://farm9.staticflickr.com/8348/8187575394_a069635573.jpg[/img][/url]
[url=http://www.flickr.com/photos/youarehere01/8187575394/]bottle01[/url] by [url=http://www.flickr.com/people/youarehere01/]NicodemusX[/url], on Flickr

Delete everything before
Code: [Select]
[img] and everything after
Code: [Select]
[/img]
So that only the following remains:
Code: [Select]
[img]http://farm9.staticflickr.com/8348/8187575394_a069635573.jpg[/img]
Your flickr image should show up.

If you don't mind that the image links to your flickr account and that a flickr link shows up underneath the image, you can leave everything that you originally copied and just paste it over here.


Offline rikkrack

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Re: Wood Boiler Project.
« Reply #15 on: January 30, 2013, 07:48:10 AM »
Sister Wolf had a video I found benificial. But what Nic said.

http://thesurvivalpodcast.com/forum/index.php?topic=21040.0
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Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #16 on: January 31, 2013, 01:33:46 AM »
Thanks Nicodemus, those instructions got me going. Is there a way I can go back into my previous post and edit the photo settings, or can it be deleted and I just repost it the correct settings?







Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #17 on: January 31, 2013, 02:40:42 AM »
Here is a pic of 2 of the heat exchangers. The trombone coil is something I picked up from EBay. It is roughly 75' of 3/4" stainless steel tubing. The larger tube is 2.25" stainless steel, the U bends are something I had left over from an old project I worked on years ago. I had some straight tubing cut and one end swedged so it would slip over the ends of the U bend. It makes the connection stronger and keeps it in alignment easier. There is roughly 285 square inches of surface area inside the 3/4" tubing and 960 square inches in the 2.25" tube.



From another angle. The 2x4's are temporary spacers. Steel support brackets will be installed once it goes together for the last time.



This picture shows the last 2 heat exchangers. One is a 2" diameter SS tube with 848 square inches of surface area, the other is a 1.75" SS tube with 174 square inches. 
 


From another angle.



There is no particular reason for the different size tubing, just using up left over materials. If I did not have those SS bends, I would have gone with a standard size of 2" and had each heat exchanger tube formed all in one piece to avoid the seams and additional welding. 

Here is a shot of the mock up to where I am now in the construction. The flu pipe is also SS, it is .062" wall thickness sheered and rolled into an 8" diameter pipe. I'll TIG weld the seam before final assembly. You can weld stainless steel to mild steel with a 308 SS welding rod or wire. You use 309 SS rod for welding SS to SS.



Last night I made a cardboard mock up of the front plate for the boiler. It will look just like the rear in size and will have the openings cut for both the fire box and ash tray doors. The support structure for the tubular heat exchangers will weld onto the front and rear plates. The heat exchangers themselves will not weld to any of the steel structure or supports. They will float on the supports so the materials can expand and contract with the different temperatures and not create any stress fractures due to differing rates of thermal expansion of the materials used.

Next week I will have my grating materials finished and get those tacked in place. Once that is located, I can drill the holes in the back wall for the primary combustion air tubes to go through.

I will also have my fire brick and can mock up how it fits in the boiler and then measure for any support or retention brackets needed to keep the brick in place. The upper retention bracket for the brick will also support the 1/4" SS burner top plate and the 2 secondary combustion air pipes.

I am going to use the fire brick on both sides and the far end of the fire box. This should prevent the steel pipe from ever burning out. Or at a minimum give me 20-30 years of use.

I will have a piece of SS plate that fits against the back end of the fire box that will cover the brick, this will hopefully prevent the brick from being damaged when logs are thrown into the boiler.

On top of this structure will sit a SS water storage tank. Right now I am planning on a 24"wide x 36" long x 30" tall tank. There will be a 9" diameter tube rolled and welded into one end that the flu pipe will run up through. The wall thickness will be .062". A tank this size would give me a net storage capacity of 104 gallons after you allow for the loss due to the flu pipe. The size of this tank is still being thought out, we will have at least 2 x 150gal hot water storage tanks in the house, one for the in floor heat and the other for sink and shower needs.

The total square inch surface area of this tank will be around 4000. That combined with the 2200+ inches in the heat exchangers should give me enough surface area to absorb all the radiant heat needed from the fire box. This whole unit will be housed in an insulated steel or concrete block structure.

I'll post more pics in a week or so as the work progresses.

On a side note, an idea I am throwing around is how to utilize all of the extra heat available inside this building that houses the boiler. Moving hot air from place to place out of doors is not efficient, but I have an idea to take an old electric oven and remove the outer casing and mount it in the side of the block wall. There should be more than enough hot air available to heat the inside of the oven. That way we can use it for baking bread or roasting meat. Not sure how to control the temp inside the oven yet, possibly a series of vent holes to let in outside air to cool down the oven to the desired cooking temperature.

I've seen cob or clay ovens where they build a fire inside, once the clay is hot, they put bread inside and close off the entrance. I am planning on an outdoor kitchen for summer cooking to keep the cooling load on the house to a minimum. The boiler would be a winter only use, but it would save on some of the propane need we would have for cooking. If things get bad, everything will count. Just a thought at this point.
 

Offline onesojourner

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Re: Wood Boiler Project.
« Reply #18 on: January 31, 2013, 07:35:02 AM »
What would happen if you doubled the size of your storage tank?

What kind of insulation and how much do you plan to use?

Offline Nicodemus

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Re: Wood Boiler Project.
« Reply #19 on: January 31, 2013, 07:57:10 AM »
Thanks Nicodemus, those instructions got me going. Is there a way I can go back into my previous post and edit the photo settings, or can it be deleted and I just repost it the correct settings?

With the current version of the software, videos can't be posted, so those will have to remain links in the post with all of the YouTube Videos.

If you send me a PM with the links to the photos in the order they appear in the thread I'll go back and edit them in.


Offline Nicodemus

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Re: Wood Boiler Project.
« Reply #20 on: January 31, 2013, 08:03:42 AM »
That thing is a freakin' piece of art!


Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #21 on: February 01, 2013, 03:08:46 AM »
What would happen if you doubled the size of your storage tank?

What kind of insulation and how much do you plan to use?

I am going to have a lot more hot water storage available. As I said in the post, we will have two large storage containers in the house for it's hot water needs. I have been thinking about having a couple of round tanks built that would sight along side the boiler. A 24" diameter tank 72" tall would give me another 140 gal of storage capacity and sitting right next to the boiler would go a long way in keeping it hot. I'll have to look into the shop I use for my rolling and see how long their roll is, I believe it could handle 72".

I am also considering going with a round tank vs the rectangular one to sit on top of the boiler. A 36' diameter 36" long tank would be 158 gallons, less the flu pipe so around 150 gal. That would only be 12" wider than the boiler end plates, 6" on each side so that should not create any clearance problems. The round tank would be easier to fabricate, a lot less welding, that's for sure.

I haven't made any decisions on the kind of insulation yet. I am leaning towards building a concrete block structure to house the boiler in, vs corrugated tin like I see used in most UTube video's. With the wind storms we have here, I don't want to be repairing the building every couple years from storm damage.

I have a couple of shipping container doors left over from another project, I was thinking about a 3 sided block structure with one of those container doors on the 4th side. The roof would be removable so if there were some kind of problem with the boiler, we could pick it up with the backhoe or tractor and pull it out of the building for repairs or upgrades. I could use one container door on the front to access the fire box door and one on the rear to access the plumbing / control valves.

There are so many different ways I could do this, each one creates a bigger sucking sound on my wallet. What the he!!, it's only money. Better spend it while it will still buy something.

Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #22 on: February 01, 2013, 03:12:38 AM »
If you send me a PM with the links to the photos in the order they appear in the thread I'll go back and edit them in.

Thanks, I'll work on those links and send them to you over the weekend.

Offline onesojourner

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Re: Wood Boiler Project.
« Reply #23 on: February 01, 2013, 09:24:22 AM »
Have you ran any Heat load numbers on the spaces you plan to heat? What kind of BTU can you get out of your water at your given target temp? I am wondering if you could start one good fire and have enough stored heat to keep things going with out having to keep the boiler raging.

Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #24 on: February 02, 2013, 01:53:40 AM »
Have you ran any Heat load numbers on the spaces you plan to heat? What kind of BTU can you get out of your water at your given target temp? I am wondering if you could start one good fire and have enough stored heat to keep things going with out having to keep the boiler raging.

I think you are right, it won't take a lot of heat being produced in the fire box once we get the water temps stabilized. Keep in mind a series of solar hot water collection plates will be the primary hot water source. This wood boiler is a back up for cold winter months. We will want to be monitoring the temps and as they cool off in the fall, we would increase our hot water storage capacity. It will be easier to maintain the temps if we keep everything stable and not let the floor in the house for example get too cold and then have to expend a lot of energy to warm it back up. Same with the greenhouse and travel trailers. Those won't be as well insulated so they will have greater temperature swings.

We have on the house, we went to great lengths in insulating it, estimated heat load is less than 1.5 ton. We have not run the numbers yet on the boiler, I keep changing it. I have several friends helping out on the various construction projects. Two of them are engineers, one electrical engineer and the other an aeronautical engineer with a background in Geo Thermal.

The greenhouse would be difficult to calculate at this point. The greenhouse itself is 20'x36'. The quantity of the Aquaponics tanks and size and quantity of the grow beds are not know yet. We are utilizing several methods of passive solar heating for the greenhouse. Three sides have large 24x24x48" concrete blocks that set end to end. The hoops of the greenhouse are bolted to these blocks. The outside of the block will be lined with 1" board insulation and a moisture barrier, they will then be buried. The side facing the interior of the greenhouse will absorb heat through the day and then give that heat back in the night. This should help stabilize the interior temps and minimize the need for our hot water heat source.

I am modeling the Aquaponics from the UrbanFarmingGuys set up, using 275 gallon totes for the fish tanks. Initially we plan to house 500 Tilapia and then once we work out the bugs, up the quantity to 1000. Being a tropical fish, the need to maintain a consistent water temp is important.

I have the idea that one tank will be used strictly for heating, meaning the first tank in the system will house a heat exchanger. I want the water temp as stable as I can get it before it goes into the fish tanks. This tank could also be used for growing Duckweed or other plants for fish feed. I think it is best to keep the fish water separate from the hot water system so I would use a water to water heat exchanger like this image I just pulled from EBay.



Here is an example of something I am looking at on Ebay for heating a travel trailer. Add a 12V fan and your in business.

Offline joker77c

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Re: Wood Boiler Project.
« Reply #25 on: February 15, 2013, 03:57:19 PM »
I have been thinking of this exact idea.  Questions though.

How do you keep it from just becoming a huge bomb?  Maybe I missed it but what happens with the expansion?  I am to young to really remember boilers but I would assume there is some kind of safety relief valve?  And if there is a valve how much water is lost on average, if it was steam it could be used to turn a turbine to gather electricity?


Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #26 on: February 16, 2013, 03:03:49 AM »
How do you keep it from just becoming a huge bomb?  Maybe I missed it but what happens with the expansion?  I am to young to really remember boilers but I would assume there is some kind of safety relief valve?  And if there is a valve how much water is lost on average

Great question Joker, for starters I have no water plumbing that will be in direct contact with the interior heat of the boiler. I am catching the radiant heat from the outside of the boiler pipe so the chances of creating steam are much less. There would always be a concern of that in the event of a loss of water flow for some reason, such as a pump going down. For starters there will be pressure relief valves in each of the hot water storage tanks that will be housed inside the boiler building.

The water temp will be kept in the 170 - 180 degree range via a control unit so I guess technically this should not be called a boiler but a wood fired water heater. This unit will have temp sensors mounted in the water storage tank that will be mounted directly above the boiler. The combustion air that is force fed into the firebox will also have controls on it to regulate the amount of air, choke off the air and the fire will cool down rather quickly. The controller monitoring the water temp will regulate the amount of combustion air to maintain the desired temperature of the water. These controls will also make the wood burn at a more controled rate.

You are right in that if you were to great steam, it could potentially drive a generator. The dangers in that kind of system are much greater due to the higher temperatures and high pressures generated by steam. I have no plan to try and do that.

I have a large 5000 watt solar system for power, lots of low current draw 12volt LED lighting, 12V chest freezers and a very large high efficiency 110V commercial fridge. My biggest current draw in this system is going to be the power required to move the hot water around during the winter months. For that reason we have designed our lighting system that we could cut our lighting draw back by as much as 75% and still have minimal lighting. I am kicking around the idea of building an outdoor fridge to use in the winter, I can use the hot water to actually warm the fridge if the temps were to get too cold. That would mean we could potentially shut down some or all of our refrigeration during the winter months which would also free up needed power. 

I am considering starting a thread on off grid living. I will look into past posts to see what has been already posted, but I do believe I have some well thought out systems that people would benefit a lot from. I have two engineers working with me on my design. Even with all we are doing, it could come down to a juggling act if we encounter long periods of cloud cover. I have plans to order a PTO driven generator to run off one of the tractors. This could be used if we have large current draw needs such as welding. I have 2 TIG welders that I use in my business, one would move the farm with me in the event of economic trouble.

I am currently working on the grate in the fire box, will be posting more pics of the project in a week or so. I am having quotes done right now for several stainless steel storage tanks being fabricated. They will be either 30" or 36" in diameter and 60" tall. That is the limit of the width of the roll that fab shop I use for my metal forming has. Right now the plan is to have around 500 gallons of hot water storage inside the house in the basement, and at least 300 gallon of storage in the building that will house the boiler unit itself.

I should explain one more detail I have not gone into yet. The water that will move through the boiler system is in a closed loop. None of this water will be consumed.  Everything I have read or seen so far indicated that the water loss at those temps is very low. One system I took several ideas from used less than a gallon over the whole winter.

The boiler water will run through the radiant floor to heat the house. The hot water for showers and kitchen use will be generated in a special tank that will have a water to water heat exchanger similar to the one that will be used in the Aquaponics tanks. There will be a smaller tank, size yet to be determined that will have this heat exchanger mounted inside it. The boiler water will flow through the exchanger. The consumable hot water will flow around the exchanger to heat it up and then be stored in the 180 gallon tanks. Right now I am thinking 2 of those tanks for shower water and one for the radiant floor. Those calculations will be left up to the engineer's in this project, I am mainly the fabricator and overall concept designer.

Offline joker77c

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Re: Wood Boiler Project.
« Reply #27 on: February 16, 2013, 09:34:28 PM »
Thanks for the explanation on that.   How do u plan to address heat loss through the solar collectors at night?   I wouldn't think you would want to run 180*water through a giant radiator on your roof in the winter?  Don't mean to be a pain with all the question.  Been looking for a brain to pick on this subject.   This is a brilliant project and I will be looking forward to future posts.

Offline OKCPrepper

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Re: Wood Boiler Project.
« Reply #28 on: February 18, 2013, 12:39:40 AM »
How do u plan to address heat loss through the solar collectors at night?   I wouldn't think you would want to run 180*water through a giant radiator on your roof in the winter? 

I have no problem sharing the knowledge I am acquiring on this. The solar system will automatically shut down once the temp sensors show the drop in heat gain. At that point if the need is there for additional hot water, then the wood boiler will take over. The solar panels will have automatic drain back valves so the water would not freeze in the panels overnight during the winter months. That is part of the reason for the large quantity of stored hot water.

Our solar panels are actually ground mounted vs on the roof. The wood boiler will be in the same general vicinity as the solar collectors and all of this plumbing will be underground in insulated pipes. These will go into the basement where all of the water circulation pumps and control components will be located. The distribution of the hot water will also be controlled from that location.

We are still in the construction phases of the house. It is so well insulated that we are heating with nothing more than a 20,000 BTU propane heater right now. We shut it off during the week and turn it on when we are there working. We are able to maintain a constant 52 degrees day and night with no supplemental heat. I ran the propane heater this weekend and we saw a temperature gain from 52 to 63 degrees in less than 12 hours. It is clear that we will be able to heat the home with nothing but hot water. If we properly manage the radiant floor going into the winter, keep it at a constant temperature, we will likely not even need the wood boiler part of this system to heat the house, only in a long period of winter weather with heavy cloud cover would we have to rely on the boiler to heat the home itself. This means all of the heat energy create with it will be available for hot water for showers, cooking, cleaning and of course the Aquaponics.

The Aquaponics greenhouse will likely be a big heat loss, but time will tell. We plan to insulate the fish tanks to help maintain the temperature. The water returning from the grow beds will flow through the heat exchanger before going back to the fish tanks. We are incorporating lots of passive solar techniques in the greenhouse to help minimize the temperature bounce and limit the amount of wood we will need to burn over a typical winter.


Offline backwoods_engineer

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Re: Wood Boiler Project.
« Reply #29 on: February 19, 2013, 02:51:24 PM »
  :popcorn: Awesome thread!  :popcorn: