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Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Wed. Jan. 04, 2012 7:11 pm
by John27elec
Hi guys wondering about making a wood furnace ( design and have built for me ) wondering if any one has any exsperience in secondary combustion ideas or pre-heated combustion air if its worth my time setting up or just use standard old rememdies ?

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Wed. Jan. 04, 2012 7:28 pm
by whistlenut
If you think you are re-inventing the wheel, perhaps you need to sit down with an adult beverage and re-think your proposal.
Look over the AHS gassification units, and all the European Gassers.....you are stumbling into a minefield, but best of luck to you anyway! .
If you have PLENTY of cash floating around, why not goggle GARN.COM.......Shafer.com......Royall.com......Central Boiler.com, etc.

This is a coal forum, however I'm sure everyone here burned wood at one time or another in their past. We know wood burning also, but for reasons publicly stated here, we are "Black Rock Junkies", but support any form of staying warm that doesn't involve sending your hard earned money overseas, and does benefit American Companies and products. I don't want you to think that you are a 'Cobra slithering in a den of mongoose's, it is not that way. We are here to provide advice, and how you use it is your choice. PS: There are some extremely competent individuals on this forum, so consider yourself amongst friends!
PPS: Ever think of coal as a fuel you could learn to like? You sure seem to have a thirst for knowledge....and you are in the right place to get just that. Ask away.........after you enjoy that 'adult beverage'............

:bang: :whistle: :stretcher: :cheers:

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Wed. Jan. 04, 2012 7:37 pm
by John27elec
Thanks for that ... but I do burn coal I have a Keystoker A-120 Furnace and I love it ... just thinking of playing around with a wood furnace I have an unlimited supply of wood .. was thinking of using it to heat my garage .. I have the coal furnace to heat the house and my attached garage. Just looking for ideas on the wood furnace and it says in this section that wood is on this board index .. but no big deal

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Thu. Jan. 05, 2012 7:07 pm
by franco b
The trouble with wood is that when heated it releases half its potential heat as gas. If you don't burn that gas it exits the stove as smoke. So large amounts of gas that if you succeed in burning need large or more efficient (blower) heat exchange surfaces to absorb it if high stack temperatures are to be avoided. Heated secondary air at the right place.

When the charcoal stage is reached it behaves more like coal so air placement and requirement again change.

Any stove you build or have built will really be a prototype because you will find that there will be areas that work better if changed. Very hard to build anything as good as it can be first shot out of the box. Unless you can build something better than what exists it does not make sense to do it unless cost is much lower than buying.

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Thu. Jan. 05, 2012 8:27 pm
by John27elec
Well thats the thing cost ... I really don't care to spend like 8 or 9,000 dollars on one ... so I would like to take my ideas I have learned and read online about and have one built since a family member of mine owns a fab shop and basiclly just cost me materials. And ive read about secondary air combustion and gasifiers just seeing if there was any ideas out there floating around .

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Thu. Jan. 05, 2012 8:48 pm
by watkinsdr
Sell your wood and buy coal. :D

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Thu. Jan. 05, 2012 9:59 pm
by DOUG
I recently purchased and installed a D.S.Machine wood boiler. It is basically a 24" round cylinder for it's combustion area, but the unique feature, that I sort of like, is the after burner secondary air tube they placed in the top of the cylinder. It appears to be a tube inside a tube running the length of the firebox, with holes drilled out on each side for the preheated secondary air to ignite the gas from the wood. It must work well because it flames the gases nicely. Just food for thought.

As for low cost garage wood heater, it really is hard to beat a double barrel stove. I've built many over the years, but if you want one that will last, make it from used stainless steel barrels. I'm sure with your connections to a metal fab shop, you could build a nice low cost steel wood stove/furnace. You just need to decide what it is that you want as the end result and calculate from there. I've found some interesting designs going through old patents. Maybe you could get some good ideas there also to incorporate into your project?

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Fri. Jan. 06, 2012 6:42 pm
by John27elec
now with your double barrell stoves , heard they burn out pretty easy ? I was going to line one with fire brick and sand see how well that works.

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Fri. Jan. 06, 2012 7:28 pm
by ONEDOLLAR
John

The double barrel stove will serve you well.

I know a guy who took a 30 gallon and placed it inside the 55 and this the 30 was the burn chamber. He packed sand between the 2 barrels. He also lined the 30 with firebrick. This was 15 years ago and the stove is still going strong. For heating your garage you can't go wrong by doing this. At least that is my thoughts!

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Fri. Jan. 06, 2012 9:16 pm
by rockwood
Maybe build one of these...


Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Fri. Jan. 06, 2012 9:22 pm
by DOUG
Check out the 55 gallon 304 stainless steel barrel heat exchanger I made for my D.S.Machine wood boiler. Custom D.S.Machine Stainless Steel Wood Boiler

I was able to capture a good bit of heat which would have been wasted up the chimney with this. It gives of enough heat to keep the basement comfortable, plus I was able to place a pan of water on top for some humidity. The barrel kit feed door makes for a easily accessable clean out too.

The double barrel stove is a really simple low cost heat machine with fairly long burn times. Fifty pounds of sand placed in the bottom barrel with fire bricks on top of the sand keeps a nice hot bet of ashes for a quick start recharge too.The heat is quick and hot. Although realistically the used steel barrels I've used in the past only gave me 3-5 years before the barrel got thin. Using the 30 gallon inside a 55 gallon barrel with sand I'm sure would greatly increase the life expectancy, but probably at a cost of slow start up heat, but longer radiation without a fire trade off.

The bung holes offer an easy way to add a threaded black pipe for combustion air and secondary air. There are endless possibilities with building barrel stoves. The offer cheap fabrication with tons of heat potential and give you the satisfaction that you built it yourself. :idea: :)

Re: Need Ideas on Secondary Combustion or Pre-Heated Combustion Air

Posted: Tue. Jan. 17, 2012 1:34 pm
by Cyber36
Most decent wood stove already have secondary heat exchangers. Check out the Logwood.........