Modifying a wood furnace to increase efficiency

[abafred]

Originally Posted by Geo NR Gee

Well, my secondary burn modification to my wood stove is a success. After the fire was started and burning for about 10 minutes, there is a lack of smoke coming out the chimney. Its just amazing.

In the firebox I can see the flames are now a dark red mostly and dancing. The additional openings for the secondary burn air did not effect the closing of the factory damper and in fact you can really see how much better the fire burns at the top of the stove when it is dampered.

In all it took about 4 hours to fabricate it from start to finish. The cost was.....nothing really but some electricity and some welding supplies which were minimal.

Good info - thanks. I'm a newbie here so please excuse my ignorance. I've read this thread 3x and may still be missing it - is your secondary air forced in or what? Thank you.

[nexsuperne]

The secondary intake doesn't need to be forced. The secondary air on my burner comes in to the bottom of the burner, runs up the inside wall of the firebox (collecting heat from the fire) and then puts this super heated fresh air into the top of the firebox. This makes for a cleaner, hotter burn.

[chadb]

+1 on flue damper, fire bricks, and flue thermometer.

Flue temperature is very important. Too low = creosote buildup, too high = damage/fire (all that creosote buildup can ignite). I believe my thermometer has 150F - 400F marked as "Burn Zone".

If you have smoke coming out the chimney you aren't burning all the gases and you're getting creosote. If anything glows, or you hear a noise like a train and flames shoot out of your chimney, you're burning too hot. The thermometers are fairly cheap.

I agree with comments about most houses being drafty enough to bring in fresh air. Also the stove is not going to pull in your warm air. The hot air is rising up to your ceiling. The stove will pull in cold air from the floor.

Just my two cents. Wood is all I heat with, other than a baseboard heater in my bathroom and my one in my son's room to keep him comfortable.

[Daox]

Well, if you're going to modify a stove for efficiency you might as well put a dedicated intake on it. That eliminates pulling air from the warm house.

[abafred]

Originally Posted by Daox

Well, if you're going to modify a stove for efficiency you might as well put a dedicated intake on it. That eliminates pulling air from the warm house.

Makes sense but let me clarify that this is being used in a shop not a house if that matters. Question: If the house/shop/structure is not air tight, wouldn't heating efficiency be increased by bringing in cooler air from inside? or - will efficiency actually be increased because outside air will be even colder?

[Kip]

Morning guys,
My first post, love the site!

This thread is great. I am searching for info on how to heat my new shop and boy there sure is more here than meets the eye! I was just going to shove a chunk of wood in a drum and set it on fire but it seems its not that simple!

I hope no one minds me posting on this thread, but like I said. I'm looking for info here on heating my shop.

So, if there are no objections, I will begin my questioning.

I have a new 30x30 metal building and I need it heated. The building is made of commercial materials just like all the others, nothing special. I was thinking of getting the double barrel wood heater kit like you see on sites like Northern, but now, after reading all this stuff. I'm not sure if I should go this rout. Here in Louisiana, the winters are not as bad as some other places way up north like Shreveport. But, we have very wet winters. Wet and temps hover just above freezing makes for a cold day for a boy like me.

Should I go with a barrel system, or should I go with something else?
So barrels have removable lids, some don't. Some have had unhealthy products in them, so I was wondering about that also. Basically, I don't know where to start.

So if any of you wouldn't mind giving me a spoon full of the infinite wisdom of wood heaters, I would be much obliged.

EDIT: Happy New Year Everyone!

Thanks,
Kip

[Xringer]

Hello Kip and welcome
I'm no expert on wood stoves, but I know everyone is going to want more details about your building.

#1, How good is the insulation?
#2, Is 30x30x 18' high ceilings?
#3, How many sq ft of windows?
#4, What type of windows?
#5, Are the doors insulated? (Any garage doors?)
#6, Will the area require heat every day? (for how many hours?).
#7, Do you have a good source of wood (or other solid fuel)?
#8, Is the roof suitable for solar collectors? (Sun exposure good?)

That's all I can think of right now..


IIRC, a typical generic 30x30 living space would need approximately 18,000 BTUh for cooling or heating..
Depending on external factors.. Like 1 to 5 above..

The Average climate in Jackson, Louisiana (in pics)
seems like a nice place to live.. If you don't mind the dampness..

[Geo NR Gee]

Kip, how tall are your ceilings? My shop peaks out at about 20 feet. I installed the heat pump return air intake at that peak and have been able to pull the hot air and recirculate it across the ground level.

I can put in a total of two 5 gallon containers worth of wood (throughout the day) for about 12 hours of burn time in the stove and the shop is kept at 65 degrees all day. Any warmer than that, then it seems too hot.

When I arrive in the morning, its dropped to 59 degrees where the heat pump is set at. Within 30 minutes or less after throwing a few logs in the stove, its back to 65.

So far this winter, the electricity bills have been from $20 to $26 per month. That includes using the lights, welder, compressor, tools, and heat pump.

Last winter, it was $140 and up per month (heat pump only) and the winter before was $250 and up (oil furnace).

We just got the approval to install more insulation on one wall and put in a fresh air intake for the wood stove. Yesterday, I walked around and could feel the cold air being pulled in from around the doors and the uninsulated and unsealed windows. So installing insulation and sealing up the cracks and leaks will help even more in lowering heating and cooling expenses.

I do have one important suggestion. Season the wood before you burn it. That alone has helped me to get a really clean and long lasting burn. Plus the wood is not so heavy when carrying a load to the stove!

[SimpleManLance]

Originally Posted by chadb

+1 on flue damper, fire bricks, and flue thermometer.

Flue temperature is very important. Too low = creosote buildup, too high = damage/fire (all that creosote buildup can ignite). I believe my thermometer has 150F - 400F marked as "Burn Zone".

If you have smoke coming out the chimney you aren't burning all the gases and you're getting creosote. If anything glows, or you hear a noise like a train and flames shoot out of your chimney, you're burning too hot. The thermometers are fairly cheap.

I agree with comments about most houses being drafty enough to bring in fresh air. Also the stove is not going to pull in your warm air. The hot air is rising up to your ceiling. The stove will pull in cold air from the floor.

Just my two cents. Wood is all I heat with, other than a baseboard heater in my bathroom and my one in my son's room to keep him comfortable.

I also heat with wood 99% of the time. As long as its above 45* I'm burning wood in our wood furnace. here is the gauge i use. I try to keep it in the orange, its about 18" off the back of the stove.

I would recommend a out side air intake. If the wood burner is sucking in cold air from the floor it still has to replace that air with outside cold air.

[Kip]

Guys,
Thanks for the response.
Geo NR Gee - I see you are in Seattle. Small world, my sister lives in Kent, and will be here this weekend. Meanwhile, back on the ranch......

To answer a few questions.
The building is 30x30x18 (Will try to post a pic)

It is only a workshop, I have not completed the inside yet, a few more circuit to run, then the insulation and T1-11 to cover it up. I don't want this to end up costing me much more that 500 or so. My electric bill for the shop is only about 30 bucks a month, and that is with the air compressor, welder, and all that stuff that goes in a shop.

I would like to keep the electric bill as low as I can. I wanted to go with a wood burning heater as I have 100 acres will all the wood I can handle....

There is insulation in the building R-19 in the walls 8 inch I think, and the ceiling has a thermal layer of insulation about an inch thick. I fight with the heat here more than I fight with the cold. But the builder suggested the thermal layer instead of other type of insulation.

#1, How good is the insulation? Not sure what you mean, I think your asking the "R" value. The walls are R-19 and the ceiling I really couldn't say. Insulation is new.

#2, Is 30x30x 18' high ceilings? Yes, 18'

#3, How many sq ft of windows? There are 3 windows, 2 in the front, and 1 in the back. 3' square maybe (each).

#4, What type of windows? Single pane, non insulated

#5, Are the doors insulated? (Any garage doors?) No, I have 2 roll up doors, 1 4'x10' door, and the other is 18'x10' 1 personnel door, metal.

#6, Will the area require heat every day? (for how many hours?). No, I will only heat while I am working or fooling around in the shop. I am away for 2 weeks a month, I work offshore on a 14/14 rotation.

#7, Do you have a good source of wood (or other solid fuel)? Yes, too much wood if you ask me....(or too much work)

#8, Is the roof suitable for solar collectors? (Sun exposure good?) I would think so, but not the rout I wanted to take, solar power just isn't for me.

Anyway, Here a re a few pics that I hope will shed some light on the subject.

I couldn't upload them to the site, something about a security token, but I put them on my SkyDrive. Here is the link. http://sdrv.ms/U6WQdR