forced air anyone?

have there been many discussions about forced air rocket stoves? maybe the use of a heat driven fan ducted to the intake lid? seems this would boost temps and eliminate smoke back. thoughts?

Hi Ron; Sounds like your thinking a turbocharger on a rocket stove ! I'm sure you could build such a thing , but you really don't need one. In fact a duct tube placed over the feed tube could impede air flow rather than boost it, as well as get in the way of feeding your dragon ! A dry , properly built RMH, with dry wood (ROARS) all by itself ! Having said that, I will admit to using a small electric fan on the feed tube of a newly built stove with a still wet mass to force air thru the system to (force feed ) the newly hatched dragon. After you have a dry warmed up mass you won't be worried about boosting temps any higher or having smokeback ! Using a heat driven fan to blow air around the room would be fine although they seem rather spendy to me.

Ronald B. : I have found little use for a forced draft fan for any Rocket Mass Heater, limiting such application (usually ) to the final vertical chimney !

It can be of some use during the extended COB drying stage, Otherwise- I have seen Greater problems in weird Frankin-stoves, and Almost Clones
of Rocket Mass Heaters that could use some assistance on days that the wind blew from a direction that disregarded the RMHs need to be-
( like ALL Wood stoves ) on the lee or downwind side of the house !

Having said this , you might take a look at The Aprovecho Newsletter for August (22), by going to Aprovecho.org, there is an Article on forced air,
and the difficulty of finding measuring points that give repeatable results ! Hope this is timely and useful ! Big AL

So, i have a "priming" fan on the chimney, for thoses days when the system is cold and doesn't want to draft. Or when i get southern wind.

On my batch rocket, it cools the fire, by drafting too much, and that results in smoke.

i see. thanks very much for the input guys.

I have thought of this: http://store.colemans.com/cart/us-gi-thermoelectric-fan-used-p-2608.html?zenid=m0u6hr4g149jm1c7svelbstih5

Put on top of the barrel to create a forced air off grid heater. You can put a big insulated shroud around the barrel, and use this fan (it blows down when set on the stove) to force the air into the building you want to heat. Good way to get heat somewhere else in the building than the stove, but cheaper just to build a second stove.

An induced draft (fan in the chimney pulling air) would work--the exhaust should be cool enough any good dryer vent booster fan will survive and you can't get CO poisoning from pushing exhaust into the room through any leaks in the pipe.

A whirly-bird turbine vent on top of a stack should work, too. Problem with those is they work TOO well when you don't need them (like during a blizzard).

I am going to try 2 computer fans in front of my preheated air inlets that inject air to the back of the burn box that is 24 inches deep.

I am also curious about the fan ideas. My partially cobbled heater sometimes smokes a bit, and is very fussy about our tight house. What about direct air feeds near the burn chamber? (I can't run the bathroom fan or dryer during my burn)
And I have a question about ending the burn: Is the chamber hot enough to completely burn the wood as is dies down? I am worried about smoldering that can cause carbon monoxide.

Linda C-McK. : Welcome to Permies.com, our Sister Site, Richsoil.com, and A big Welcome to the Rocket And Woods Stoves Forums!

A little more information please, Your location,and ~square ft of heated space, and size of your system, and how old your house is! look at your Authors
name space and L@@K at mine! At the top of the page to the right of the Permies Sun is the Permies Toolbox, find and click on [My Profile] to enter the
personal information you feel comfortable with! It may help you find a Fellow Permies neighbor who is interested in many of the things you are and has
Rocket Mass Heater RMH or Cob Experience !

Most of us have reached the time of the year where we can use more indoor heat and humidity, and have a bypass on our drier vent to divert that air
to a water/lint collection bucket ! This problem is a rather common finding with RMHs, and actually is as likely to indicate a major air leak or series of air
leaks high up in your house, especially if you have Roof vents, as most houses do today ! Remember to plug of the drier vent hole in the side of your
house !

To understand the basic concept Google : Stack Effect and Whole House Stack Effect !

A new Fire/Smoke and a new Carbon Monoxide Detector should be in every home in America, If the Greenest house is one that is all-ready standing,
how green is a house lost to fire ( 30+yr fireman on a soapbox ) know personally how to install, test both devices and replace batteries twice a year !

A picture is worth a thousand words, and will probably eliminate 10,000 words we will not have to ask !

Membership has its privileges, with 27,000+ fellow members and also a very extensive file of past forum topic threads available by the Permies Toolbox
Search Engine [Search] a few clicks away you can expect to come here 24 / 7 / 365 and find answers or a least the questions to ask to find your answers

I hope is was timely and useful,for the good of the Crafts ! Think like fire! Flow like Gas! Don't be the Marshmallow ! as always, your comments and
Questions are Solicited, and Welcome ! Big AL

Lat Note ; i have not directly answered your Fan Question, it might be possible to increase your problems in the rest of your house, to strong a fan could
actually cool the fire and make carbon monoxide more likely immediately after the fan was turned off at the end of your burn ! A. L.

Allen Lumley,
Thanks for the nice welcome.
My cabin does have a tall peaked roof, and may leak a bit from the top ridge poles...I'll post a couple pics and do some more reading.
🔥🔥🔥🔥🔥

Linda C-Mc K. : O.K., I understand a little more about your situation! The land of the Willi-waugh and the Windigo. Hell, it aint everyday you get to use
words like that in polite conversation ! But when the wind blows we aint talking about a little zephyr!

I often use the fine people at Cold Climate Housing Research Center / Univ. of Alaska Fairbanks as a teaching resource, and would have recommended
their You-tube Channel*, or their in-house video versions , to use because they are knowledgeable in their field. Check them out !

Here at Permies we have lots of very talented people, but as much as many of us can honestly say We know Cold You/THEY KNOW COLD !

Seriously, their video series is hard to beat, and I have never found a technical faulting their Craft !

They do have an extensive history and a library of documentation on the Russian style Masonry Stove, and who Erects houses on Permafrost in a week?

We do have a little edge on rocket mass heaters, and are holding a 'gather' of experts in sunny Montana this Month !

Your system appears fine, and I sympathize with living with a less than perfect system, and now believe your house is tight, Two things, 1) keep track
of wind direction -to see if there is a pattern to your smoke-back episodes, is the wind always out of the east or southerly when this happens. In an
ideal, perfect world the wind would always blow in a constant direction, allowing you to easily plan how to place your houses Chimney / stove pipe on
the Lee side of the house, What if anything do you have for a wind diverter or storm hood on the top of your chimney? / Stovepipe? Now ?!

2) You asked about adding outside air feeds for your house, or for your Rocket Mass Heater! It may be a very good idea in your particular case, I would
arrange for an energy audit of your place, and talk with someone about the pay back time in fuel saved for an Air To Air heat exchanger.

When you add on the certain savings not spent on repairs to your house from water vapor migrating into your insulation and then freezing there and
having less problems, potential problems with mold and rot, your payback time will really be close to doubling your savings ! For the Good of the Crafts !

Think like Fire! flow like a Gas! Don't be the marshmallow! as always, your comments and questions are welcome and Solicited ! Big AL

Late Note : *There is however a lot of crap out there on U-tube use a suspicious eye when viewing anything there ! A.L.

Late, Late Note, that is a lovely big clean-out door next to your RMH, Air leakage at any clean out would also cause your problems, tho I expect that your
problem would be there almost all of the time not intermittently ! Always recheck your clean-outs for tightness periodically, and any time after a house
party, there is something fascinating for monkey brains and moony fingers about those little doors, and they get played with while the host and hostess
is busy ! a.l.

Thanks again for your extensive answers!
I added a wind diverter to the stack and that helped quite a bit, but not quite enough when gusty.
We also added a fresh air intake, and a door to close when not in use(or to close when things go backwards).
I capped it with bricks that can be uncobbed when we make a final design top lid. So far, the fire burns best in the mouth of the tunnel.
Still a work in progress.

We have a fan under the house in the air intake tube that we can turn on, but it doesn't really help with the burn. Making a taller outside stack and using very dry wood is better than a fan. The fan can be used when the stove is cooled down to get the air moving the right direction up and out the stack.
Also, we have a door on our stove and we feed it horizontally. The air vent tube is passively providing air, and only gets dampened when the coals have burned down.
Alaska homes are encouraged to be very airtight and don't feed the dragon well.

Happy Spring! We can feel the heat of the sun now in Fairbanks.💛