I've received my wood stove which is good for 500 to 1500 sq ft. My camp will be 20 x 36  with one bedroom towards the back, and partially open loft on top. The stove will be on the far end of the house with 10ft of exposed flue pipe. I've seen the $250 vent blower kit for my model. I'm wondering if someone has a blower kit, how it works, and if it's worth it. I'm off grid so I'm trying to avoid unnecessary electrical use.

Thanks,
Doc

I can't give a first hand recommendation but a friend of mine has one and swears by it. It does blow out a lot of heat that he claims would otherwise go out the chimney.

I am going to try my stove as is and see how it does. The one I have is barely big enough for the place I'm building so if it struggles I might give it a try.

A stove with double walls - and air space on the sides- can create its own convection currents cutting down on the need for a blower.  I used to build them.

Of course even a single wall stove will create convection currents.  A blower can reduce heat concentrated in the stove area though.  Depends on your needs.

Since the blower is not blowing into a duct, I'd assume it's moving the air around a bit. I doubt it could move a significant amount of heat across the 36 ft cabin and down the hall to my bedroom. Considering the power draw on the battery bank, I may consider a paddle fan up top for better redistribution of heat. Any idea of the wattage needed to run a blower vs. paddle fan?

By "paddle fan" do you mean a ceiling fan?  If so, for any off grid situation I heartily recommend the RCH Var-Cyclone fan for a great silent running low power consumption ceiling fan. I've metered ours; approx 22 watts. A typical 50-55 inch AC ceiling fan uses about 95 watts. Using a DC fan means that the inverter does not have to run and that saves on power as well.  The small air blower on our propane wall heater draws 48 watts; 120 VAC.

Mfg website   http://www.nextekpower.com/power-shop/nextek-fanworks.html
Available at    http://www.thesolar.biz/RCH%20Fan%20Works%20DC%20Fans.htm  
and         http://www.altestore.com/store/Lighting-Fans/Ceiling-Fans-DC/RCH-Fanworks-1224V-Vari-Cyclone-60-Ceiling-Fan/p6681/

We have the 4 blade Vari-Cyclone fan with the Solar Converters variable speed controller. It helps immensely in distributing air in our cabin as the wood stove and propane wall heater run to warm the cabin from cold. We usually run it for 3 or 4 hours as we warm up the cabin and an hour or so in the morning as well when the wood stove is restoked. In summer we use it sometimes on a warm/hot day. Then we run it somewhat faster to create a cooling breeze. It takes a little more power at higher speeds.

The airfoil blades move more air for the same power when compared to a typical flat blade fan. I have also seen a few upper grade AC ceiling fans with the cyclone blades.



http://countryplans.com/smf/index.php?topic=2335.msg66813#msg66813

http://countryplans.com/smf/index.php?topic=2335.msg73720#msg73720

When I heated with wood pellets, I used doorway fans to spread the heat into bedrooms:

http://www.homedepot.com/h_d1/N-5yc1vZ1xn8/R-100080304/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

I think the integrated blowers on wood stoves and such are not much help, especially if you have a ceiling fan.  The ceiling fan will go a long way towards making the whole cabin much more comfortable, especially the sleeping loft.

I was under the impression that the inline blowers were reclaiming heat that normally goes up the vent pipe, not merely distributing existing heat around the house. Not true?

When I think of an add on blower/fan for a wood stove I think of a unit that blows air over the surface of the stove. Is that what your friend uses? I have also seen devices that are inserted into the stove pipe above the stove, small heat exchangers. Here are my thoughts on both. My thoughts only, no proofs.

Blowing air over stove:  This will aid in heat transfer from the stove to the room. In effect it will cool the surface of the stove. I believe that in turn increases the transfer of the heat from the fire to the stove metal and then to the air. So I guess it would be fair to say that would aid in keeping more of the heat inside the room, rather than up the chimney.

Pipe heat exchangers:  In some ways a good idea and in others a bad idea. The warmer a chimney runs the less creosote build up there is. With a rather long run of black pipe already in your installation it is my belief that your installation already is going to be extracting more heat from the exhaust than a stove in a room with an 8 foot ceiling or the pipe going out the wall behind. Removal of too much heat from the exhaust can lead to more creosote build up.

The stoves smoke path and secondary burn chamber with the secondary air supply will do a good job of burning most of the creosote burning gases, so maybe there isn't as much concern over extracting more heat from the pipe. I'm just cautious about trying to reclaim maximum heat and cooling the exhaust too much. But creosote will form anyways. Our chiminea chimney has very little build up, the least I've ever seen. But then there is no air control, no damper, just a straight shot up the pipe from the fire.


The doorway fan looks like a good idea in aiding heat to a room(s). Too bad they don't spec the power use.

FWIW/FYI  I've read that creosote condenses on the chimney surface when the internal chimney temperature drops below 250 F.

Speaking of heat exchangers. I'll be using a long run of stovepipe as my heat exchanger  

I'm intrigued by the door fan but think I'll put something in the wall so the door can stay closed. Maybe situated high on the wall between the living room and bedroom. Here's one with the wrong voltage, but this the idea: http://www.google.com/products/catalog?q=door+fans&oe=UTF-8&cid=10906493061157165324&ei=E2ThTPP3C6TSzQXNgoysAw&sa=title&ved=0CBQQ8wI#

Don, thanks for that solid info. The ceiling fan seems like a great idea to keep the upstairs a bit cooler and the downstairs a bit warmer. Maybe I can find something a bit more rustic looking to go with a bear rug, antlers and the like. The NexTek Varifan with the dark wood blades looks right.

Quote from: MountainDon on November 15, 2010, 10:52:04 AM
FWIW/FYI  I've read that creosote condenses on the chimney surface when the internal chimney temperature drops below 250 F.

Is creosote an issue for rocket mass stoves?

Quote from: AdironDoc on November 15, 2010, 01:38:48 PMThe NexTek Varifan with the dark wood blades looks right.

Not nearly as efficient at moving air though. The white vari-cyclone can be painted with spray paints if that would help.

Quote from: NM_Shooter on November 15, 2010, 03:14:00 PM

Is creosote an issue for rocket mass stoves?

Not that I've heard any of their advocates mention. Good question though as it is claimed to make more full use of the heat.

Anyone know the temperature of the gases emitted at the tail end of the exhaust on a rocket heater?

My local Amish run wood stove supplier has fans that are activated by the heat of the stove.  You simply sit them on the top of the stove and off they go.  I think the prices are about $100 and $150 for the sizes they carry, but I don't remember the cfm.  This article in treehugger talks about them.

http://www.treehugger.com/files/2006/02/stove_fan_that.php

Poppy: The EcoFan looks great, takes no power, and moves up to 150CFM. The available blower for my Napolean Timberwolf stove claims 110CFM and draws 35W at 120V. Efficient stove-top conversation piece that uses no power and costs less than an electric blower? This is a no brainer. thanks for the link.

Doc

I read someplace that there is an upper temperature limit. But I don't remember where or how high a temperature. What I do recall is that I've noted that I had seen the top front of our stove go above whatever that temp was. The highest I've seen the stove top with my infrared thermometer is about 750 F, so........

650 or 700 depending on where you look

http://www.wttool.com/landing/caframo_ecofan.php?gclid=CO3ZzYORp6UCFUtJ2godGWHCIw

http://www.lehmans.com/store/Stoves___Hearth_Accessories___Heat_Powered_Fans___Wood_Stove___88510?Args=&partner_id=bcngoog&gclid=CPvm7IGRp6UCFYHu7Qod8he1Hw

Funny...I saw those stove-top fans in a catalog last year. Got the idea one evening to make a small prototype out of two beer cans...it worked like a charm. Didn't spread alot of heat, but sure is fun to watch...lol...

I have an inset wood burner in my UK house, which is simply sat on a steel shelf and I welded up a 6" pipe flue above it and out the wall

the fireplace has fans which suck in at the bottom circulate at the rear and cross in tubes above the fire itself.

The usable output easily doubles with the fan on , rather than just having it sat there.

also use a circulation fan to get that hot air back down from beneath the roof.

above the steelpipe is well hot enough for me

So amazon also has the amish style fan:
http://www.amazon.com/Caframo-Ecofan-Original-Black-Nickel/dp/B001AYVXRY/ref=pd_bxgy_k_text_b
They also have this version of a door fan:
http://www.amazon.com/Achla-Designs-Room-Minuteman-Doorway/dp/B001FXVJ1U/ref=pd_sim_hpc_5
Which makes me think that if someone is off grid, why not use a computer case fan, they are 12 volt and might be easily rigged up and cost a lot less.
Like this one:
http://www.newegg.com/Product/Product.aspx?Item=N82E16835705040
It is ball bearing and moves 96CFM.  and you can even find the metal grills:
http://www.newegg.com/Product/Product.aspx?Item=N82E16811998059

So, after I made that post, I remembered a project from long ago, like the 70's, for circulating heat. You need a vertical duct with a small fan at the top.  The eco friendly solution was to use some Number 10 cans (available from your favorite restaurant for free), and some ever popular duck tape.  then mount a small fan at the top.  This contraption hangs a few inches from the ceiling and the fan pushes the warmer air down to floor level.

Although this thread went to sleep some time back, I thought I'd add follow-up info for anyone doing a thread search for super low power consumption ceiling/paddle fans. Don posted a few links to 12V/24V fans that consume 22Watts. I didn't want to run low voltage all the way to the fan so I kept looking. I've found a line voltage ceiling fan made by Emerson called the "eco" line that claims to take only 21Watts (presumably on low??). AC Input with a DC motor. Nice choices too but a bit pricey to be sure. But this model puts out a whopping 359 CFM per watt spent blowing away the other energy star models by a huge margin.

http://www.amazon.com/Emerson-CF788ORB-Carrera-Outdoor-Ceiling/dp/B004NL63GC/ref=sr_1_1?s=hi&ie=UTF8&qid=1329096833&sr=1-1

http://www.hansenwholesale.com/ceilingfans/reviews/emerson_midway_eco.asp

That is an impressive amount of air per watt.

I wonder what blades those energy efficiency figures were pulled with. As amazon pictures the fan it appears to have traditional flat blades that are wider at the tip than at the root. The second link illustrates many models with the taper to the tip design. Smaller width at the tip coupled with a pitch change towards the tip like an aircraft propeller gives highest efficiency. Tapered tip and reduced pitch blades also produce less noise, speed for speed.

Variable pitch blades won't work in reverse though. They'll go round and round but not move air well.

Manufacturer's site notes 18W on low setting without lights and that the blades have a sharper angle than traditional. I'm not sure all their decorative blades have the same aerodynamics. Nevertheless, I'll spring for the fan as I'm running batteries. As the fan will likely run for extended periods when the woodstove is on, a small amount of wattage will really make the difference. The website in the link I provided had the best fan price, but the accessories like downrod and light kit are overpriced. Thus, I'll buy the extras at BigBox. Will post impressions once installed.