BIODIESEL & SVO DISCUSSION FORUMS





Page 1 2 3 4 5 

Moderators: Shaun, The Trouts
Go
New
Find
Notify
Tools
Reply
  
home made Outdoor wood boiler
 Login/Join
 
Member
posted
Ok im taking a previous idea i had and trying to combine it with an old one i mentioned here and lets see if you guys can find any problems with it or any suggestions. Any way i currently heat and cool my house with a heat pump which is ok depending on the outside temperature, if its below 30 degrees farinehiet then the heat pump is pretty much useless as it does nothing more then make the electric meter spin, so i also have a wood stove which i really like. The bad part about the stove is you have a bunch of dirt coming into the house from the wood, the fear of causing a house fire, and the fact my wife and i are gone for an average of 10 to 11 hours a day so during that time i dont keep a fire going and the heat pump runs. The fear of buring the house down and the need to be able to burn for long periods of time led me to outdoor wood boilers which alledgedly can burn for 96 hours (Yeah right) after seeing the price tag on them i was a little scared off given most small units where starting at 5 to 6 thousand dollars and if i added just a few more thousand to that i could put in geothermal. Given the price and the fact i wasnt impressed with the thickness of the metals used in some of the units i saw i thought about building one. The units i looked at seemed like nothing more then an old fuel tank with a 55 gallon drum welded inside them and the fuel tank was filled with water so it litterally jacketed the stove leaving a big potential for leaks and problems.



Here is my idea, i weld up an airtight fire box roughly 2ft by 3ft in size, i then bend copper water lines in a radaitor style form and run these along side of the sides of the fire box on the top of the box i have a stainless steel baffle like radiator that i picked up from a local scrap man. I plumb the coils i made and the radiator together around the firebox then place insulation around the coils and make a larger box to go around the whole thing and make a jacket ( bolted together not welded ) i end up with an inlet pipe and an outlet pipe coming off the stove, the inlet side is plumbed to an old water heater that the thermostat went bad in and the outlet side then runs underground through copper pipes which i take the 2 inch thick closed cell insulation board and make a box and make a box to suround the pipes i run undeground. I then run the lines inside the house to an enclosed radiator with a squirell cage fan behind it operated by a thermostat mounted to my existing duct work. The water goes through the radiator and then back to the hot water tank next to the stove outside in a cheap tin building say 8ft by 8ft square placed about a 100ft away from my house. Then wire up a squirell cage fan to the draft openings on the welded up stove and wire up a magnetic switch to a plate that as long as it has electricity the opening on the motor houseing stays open when it doesnt have electricity the plate drops and chokes the fire ( this way if the electricty goes out the fire cant blaze and boil the water causing an explosion ) When the temp of the water drops below 160 the fan kicks in and blows across the coals reignighting them, when it gets to 180 the fan kicks off and lets the natural draft do its thing. Another temp switch could be mounted to a damper so that if the temp drops and the fan kicks in the damper closes and all the heat from the re ignighted coals stay in the fire box until the water gets to the right temp. The water is then pumped back into the old water heater for storage and cycled constanlty through the whole setup or maybe cycled every so many minutes.



After thinking about building the unit i thought about placement of the unit and wouldnt you know the perfect place is right next to the old cistern that isnt used anymore. Previously i had mentioned here and idea to pump the cool water in the cistern through insulated lines into the house where it would go through a radiator in my duct work to help cool the house and i dont see why i couldnt just put two shut off valves in the wood boiler unit i intend on building and in the summer time use my pump and coil to cool the place and then in the winter shut the cool side down and stoke the fire in the boiler, anyone have any suggestions for improvements? Also before anyone asks the reason i thought about using and old water heater for storing the hot water is it allready has the safety valves and crap hooked up plus if it ever starts leaking it wouldnt put out the fire like the water jackets on most of the setup ive seen.
 
Location: ky,usa | Registered: February 22, 2003Reply With QuoteReport This Post
Member
posted Hide Post
None,
How about doing a drawing of this and posting it. Could help us visualise it better.
regards
dva
 
Location: Yorks,England | Registered: June 30, 2001Reply With QuoteReport This Post
Member
posted Hide Post
Hey I hope this works Im new posting on fourms I think your Idea is sound but with all the automated fans you are going to go through alot of fuel {i dont know what you are burning wood/pellets/saw dust} a pellet hopper system would keep your stove full if you are not going to beable to tend to your stove all day long
quote:
ak
 
Location: Lake Cowichan Canada | Registered: March 20, 2005Reply With QuoteReport This Post
Member
posted Hide Post
Another tack you could take would be to scavenge conventional gas boiler parts (maybe even install this bit inside the house) and make a wood fired "gas convertor" that runs outside. Using standard gas fitting practise there will be nothing unsafe or flakey about the kit inside the house. I'm not sure about relative efficiency though. Obviously there's heat going to waste from the convertor, but running the hot water lines from an outside boiler would also incur waste.

If I were doing it up here, I'd definitely want to do it the convertor gas way. For the insurance of having the water part of it inside, in case the fire went out anytime when it's -20C out. Of course, for heating purposes you could fill the system with a non-toxic antifreeze, but that would cost quite a bit I think, and you'd probably have to change it out every so often.

Of course, if you've got a heat exchanger that's standing away from the house a bit, like on most aircon systems (haven't seen a heatpump system in the flesh) you could build a removable insulated shack over the top of it and just put a good "12 hour" woodstove in there to keep it toasty. ...

my 0.02

Road Warrior
 
Location: Niagara, ON, Kanuckistan. | Registered: April 20, 2005Reply With QuoteReport This Post
Member
posted Hide Post
I like the idea, but as you mentioned there is a risk of boiling and an explosion if you use a sealed system. You really must build in an escape valve of some sort to the boiler. Even something simple like a verticle pipe with a flap of metal on top - steam lifts the metal flap venting safely.

You also need to be certain that the radiators and so on inside the house have sufficient exchange area to shed the heat, otherwise you risk it all getting too hot for comfort.

Have you thought of building something like a brick oven? The brick helps trap heat and you can then build all your plumbing into the brick work. That should reduce the risk of water boiling in the pipes.

Hope some of those ideas help, and be safe!
 
Location: Kent, UK | Registered: April 21, 2005Reply With QuoteReport This Post
Member
posted Hide Post
i have built my own it has been 4 winters and no problems...i am working on another plan right now to get better efficiency from it

i have the barrel in a barrel model now...42 inch pipe around a 36 inch pipe...it has never boiled over as it is near air tight..open to air so no explosion is possable
 
Registered: May 06, 2005Reply With QuoteReport This Post
Member
posted Hide Post
Approx. how many gallons of water does your boiler hold? How many times do you fill it per day? How much wood does it use a year?
Why cant you burn veggy oil with a drip line in this or maybe you do? New here so may have missed a lot
 
Registered: May 29, 2005Reply With QuoteReport This Post
Member
posted Hide Post
the stove ihave now holds only about 150 gallons...on the coldest ontario winter da i fill when i leave for work and refill when i return from work...i use about 9 or 10 bush cords (4x4x8) i heat an old 1 1/2 story brick farm house..all my domestic hot water and keep a 50 x 30 shed around 50 degrees...i light the stove in mid october and ran it this year till the end of april...i have not though of dripping any kind of oil into the fire box.....i am thinking of building a new stove with the barrel over a barrel concept of years ago...but with the lower barrel being just a well insulated fire box and the upper barrel being full of tubes that the heat and smoke would travel down and release the heat to the water surrounding the tubes....the ends would have to be removable so i could brush the tubes..and dry wood would be a must..but i think i am going to try it
billie
 
Registered: May 06, 2005Reply With QuoteReport This Post
Member
posted Hide Post
i am currently looking at building my own water boiler. does yours heat domestic hot water too or just heat the house and shop. i have a largewood furnace, water capacitiy and types of tubing and pump to move the water are my biggest questions. do you mount the water pump at the stove or in the house at the heat exchanger. any and all info would be great. thanks Mitchell goss
quote:
Originally posted by billie:
i have built my own it has been 4 winters and no problems...i am working on another plan right now to get better efficiency from it

i have the barrel in a barrel model now...42 inch pipe around a 36 inch pipe...it has never boiled over as it is near air tight..open to air so no explosion is possable
 
Registered: June 26, 2005Reply With QuoteReport This Post
Member
posted Hide Post
just stumbled on this board havnt read to much yet but i think ill be spending some time here,i built an outdoor wood stove 3 winters ago and am looking to build version 2.0 for another house i am building, also i used to be a mechanic and still enjoy building toys,i recntly became interested in bio diesle. eager to compare ideas on outdoor furnaces and learn more about bio diesle
 
Registered: July 11, 2005Reply With QuoteReport This Post
Member
posted Hide Post
You might want to look at just a forced air system I ran across. 100000 btu's up to 2400 sq ft
http://www.outsidewoodheater.com

Wishing you a warm winter!
 
Registered: July 27, 2005Reply With QuoteReport This Post



Member
posted Hide Post
I have an inexpensive wood furnace installed in my basement. I have done quite a bit of research into efficiency and clean burning. Using forced air heat with a small furnace like mine is not really a good way to go. The best way to get maximum efficiency is to burn the fire very hot for short periods of time (1-2 hours) storing the heat in some way to be used as needed. Even in the coldest climates, a 2 hour burn twice daily should provide enough heat.

A source of secondary air for combustion is also better for clean burning and high efficiency. Primary air would come in under the wood to provide combustion and gasification, secondary HEATED air should be introduced above the flames for combustion of the gasified wood. This is how the modern high efficiency wood stoves work.

The easiest way to store heat is with a boiler and large insulated tank. As stated by another here, the water jacket needs to be small so that the firebox wall temperatures are maintained at a high temperature for clean burning without creosote production. There are several of these type of boilers being marketed - most being called "wood gasification" boilers - but are quite pricey.

Here are a couple of links:
http://www.alternateheatingsystems.com/
http://www.dectra.net/garn/Wood_heat.htm
 
Location: Boonsboro, MD, USA | Registered: February 28, 2003Reply With QuoteReport This Post
Member
posted Hide Post
Hello, I have been developing in my brain, a combination fuel, boiler system. But before I continue. An answer to your pressure problem, and (flash to steam problem) you should install a Boiler trim out package, with the installation of ALL boiler systems. It contains a float vent valve, service check valve, air scoop, ET -30 expansion tank (Very Important)and a backflow and fill valve. You can get it from Graingers, or Johnstone Supply, in the US. The Tank placement is VERY important. It must be in the HIGHEST position in relatioship to all other items in the boiler package. Normally above the boiler about 2 feet. The expansion tank has a rubber bladder inside, and allows the pressure from the boiler system to expand within it, instead of bursting a weak place in the boiler system. I will come back later, and complete the design of the boiler system, which is only in my brain at this time. I currently have a Pellet stove. Not worth the time in my opinion. A 40 lb bag of pellets have 192,000 BTUs of heat per bag. if my house has a loss of 60,ooo BTUs per hour at minus 10 F, One bag will only last 3 hours and 20 minutes. In a 12 hour period, I would require, 3.75 bags of pellets, at a cost of (currently $4.50 per bag if you can find them) This would cost me $16.88 in pellets for a 12 hour period, and at an outside temperature of munus 10 degrees. To calculate this, One must base it on a given outdoor temperature. Well, anyway, pellets ar not a good value. I'll get back to it later. Thanks Kirb
 
Registered: January 01, 2006Reply With QuoteReport This Post
Member
posted Hide Post
Kirb,
You should consider installing insulation, draught prevention and air/air heat exchangers to minimise heat loss through vents.
There is no point in wasting the heat you obtain, regardless how inexpensive your heating fuel is.
 
Location: Perth W.Australia | Registered: August 10, 2001Reply With QuoteReport This Post
Member
posted Hide Post
This is something I have given a great deal of thought to. The reason outdoor wood boilers currently available are so inefficient like has been stated before, is because a water jacket surrounds the firebox, which keeps the combustion temps too low to fully combust. The IDEAL wood boiler would be setup like this:

Firebox which is lined with refractory, and has primary air inlet under wood. It keeps enough heat in the chamber to gasify the wood, which would then ideally move into a secondary combustion chamber above the main chamber, and separated by a panel or ledge. Into the secondary chamber, add your secondary air to combust the gas. AFTER the secondary chamber, add your heat exchanger. Be it copper tubing coiled or whatever, pull off enough heat to bring your exhaust gas temp down to about 350-400F. That should make you a really nice boiler. You should probably dump your heat into a tank for holding and just pull what you need out of the tank. That way you can burn at optimum efficiency, and keep overall costs down. This is the type of system used on the AHS and Tarm offerings. All the chambers should be refractory lined.


In search of wvo.....
 
Location: Albion, Mi | Registered: April 10, 2003Reply With QuoteReport This Post
Member
posted Hide Post
John: do you mix that with water? If so at what percent does what to the freezing point of water?
 
Location: Louisville, KY | Registered: November 22, 2005Reply With QuoteReport This Post
Member
posted Hide Post
Glycerol eh, novel idea (to me anyway) John. Do you have any boiling point and heat transfer data comparing it to other common antifreeze solutions?

Thanks Genn
 
Location: location, location | Registered: August 05, 2002Reply With QuoteReport This Post
Member
posted Hide Post
Great idea. Be careful to look at the whole system carefully to make sure no contingency leads to boiling the water instead of just heating it. The steam explosion would be frightening and dangerous.
I'm sure a lot of folks in this forum do this but let me just say my wife and I are small scale bio-diesel produceers. We make it for our volkswagen rabbit(1984) and our home heating. We have a good quality forced hot air oil furnace and are running 20% alternative fuel consisting of 1/2 biodiesel, 1/2 filtered waste vegetable oil. It works fine and I think we will gradually increase the percent of this mix over time.

Good luck to all experimenters.
 
Location: Moravia, New York,USA | Registered: May 29, 2002Reply With QuoteReport This Post
Member
posted Hide Post
quote:
Originally posted by farmerscotty:
You might want to look at just a forced air system I ran across. 100000 btu's up to 2400 sq ft
http://www.outsidewoodheater.com

Wishing you a warm winter!


Strange... you sell them ... so you did't just run across them... you've been using this product for 18+ years
 
Registered: July 28, 2006Reply With QuoteReport This Post
Member
posted Hide Post
Well that is true......but is does work and work well. I ran across it when I bought mine!

Smile Have a good day!

farmerscotty in Missouri
 
Registered: July 27, 2005Reply With QuoteReport This Post
  Powered by Social Strata Page 1 2 3 4 5  
 


© Maui Green Energy 2000 - 2014