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[tinner]

Been reading here quite a bit with the intention of possibly building one of these. It would be a gasifier type construction. I feel that I have a fairly decent understanding of things with one exception. I see some of these units are running 50 to 75 cfm blowers while others are running single and two speeds up to 500cfm. Are the smaller blowers being run on gasifiers? And why the two speeds? I would think they would be running on high when calling for heat and off when idling.
I have done some searches and quite a bit of reading. Please excuse me if I have missed something obvious.

[beeman]

iam still new but i think the smaller biowers are used on just regular boiler check with jacklehe made a great looking one with lots of pic

[tinner]

oh yeah. i have read his build thread twice. Not bad for a "country boy" well a "skilled trade" country boy.
His words as IIRC. 

He has done an awesome job!!

Thanks for the reply.

[Scott7m]

Check out the design of the portage and main and heatmaster e series boilers.  They are not a gasification unit but are incredibly efficient without the hassles of the gassifiers.  Yoder heating has ran EPA approved gassifiers and the. E series design and can't tell any difference in efficiency.

But the big huge fans are for gasifiers, the small ones re for standard boilers

[tinner]

Thank You Scott7m

Will do!

[peacmar]

The multiple speed units on the gasifier units are used to fine tune the input air flow based on conditions. A lot of commercial units don't allow for the best range of adjustment. Primary:secondary airflow in a gasifier is 1:5 respectively and depending on design constraints, the fan speed is changed to achieve a specific heat output value. Although I feel personally that this method is more of a cost savings issue more than anything. Why pay big money for a mass run of custom sized fans when you can take something cheaply available and adjust it till it works?

Read the fourth and fifth posts, they explain fan sizing and pertain to both gasifier and regular wood burners. The burning is the same in both types, its the control we have that differs.

http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=1182.0

Determine your heat load needs first, then you can design everything from there. If you have any other questions feel free to ask, we are all happy to help.

[tinner]

Thanks!

Will do!

[jackel440]

oh yeah. i have read his build thread twice. Not bad for a "country boy" well a "skilled trade" country boy.
His words as IIRC. 

He has done an awesome job!!

Thanks for the reply.

thanks for the compliment

I felt the need to use the large 500 cfm blower as I need to pressurise the burn chamber.Then I needed to supply air to the gasification chamber.Then I had to take into acount the distance of the refractory chambers then the turn back up the exchanger pipes through the water jacket.Then turn back out the back to exit the horizontal pipe to the exhaust stack.While the whole time carrying particulate matter through the tunnels from the gas burn.You would be amazed at the fine powder that is carried out the stove through the exhaust.

pacmar has great research and nfo on his thread to study i would definatly suggest reading there.

[tinner]

thanks,
i have read it once or twice already. and i am sure i will ready it a few more times...lol