Outdoor wood stoves

[django]

First off, sorry I called you Bill, Ben.
Johnson as far as I can tell, has no website. However, there is info about them on dealer sites. The closest thing to a comparison I found was between outdoor and indoor woodburners. Outdoor gets it's butt kicked as far as efficiency goes. and emmissions. http://www.woodheat.org/technology/outboiler.htm is an interesting page.... If you would like I can post a bunch of websites of different manufacturers etc... Let me know. Here's some.

http://www.cedarloglumber.com/johnson.html has a little on the Johnson.

http://www.outdoorwoodfurnaces.org/ is a thinly disguised advertisement for Pacific Western.

http://www.shol.com/mahoning/Descript.htm man is this thing UGLY.

http://www.heatsource1.com/

http://www.aqua-therm.com/pages/Tframeset.html

http://www.woodmaster.com/

http://www.northlandoutdoorwoodfurnace.com/index.php3

http://hardyheater.com/index.html

http://www.outdoorfurnaces.com/

http://www.heatmor.com/

 

[django]

A little better link for the Johnson

http://www.hud-son.com/woodfurnaces.htm

 

[Bill G]

I believe in having an open mind and looking at all alternatives. If you know of someone who has a warped door then they are not smart enough to get it replaced. Have I even looked at a Hardy. Well I had to laugh at that. Yeah I have many times along with many other brands. As to different firebox sizes I fully aware of that. As to the domestic hot water option I really do not care about it. I do not plan on firing through the summer. The links posted are very helpful in looking at other brands that do not have dealers in this area. Whatever brand I end up with it must be good because I wll end up with probably several units for different locations. The Aquatherm is one that has not made it to this area so the website will be helpful. The models that can be loaded with a forktruck scare me. I really can not see a business allowing an employee to dump pallets or wood into a furnace with a skidloader or forktruck. I wonder how OSHA feels on the issue.

Bill

 

[django]

Hi Bill,
If your going to buy several units for many locations, you should have some pretty good leverage when it comes to negotiating price.( especially if you buy in the off season) I asked you if you had seen more than one Hardy because you repeatedly mentioned the "smaller than the others" firebox, did you not? I don't heat my domestic hot water in the summer either,( too much smoke) but you may as well do it while your heating in winter, it pays for itself pretty quickly. As to loading with a fork truck or skid steer
that seems like it could be dangerous and I don't know if there are special considerations when doing this. Thankfully I don't have to use that much stove. I have more links if you want me to post them. I really want to see one of the Johnson Stoves in person, I am intrigued by them, but nobody around here has one.
As to the warped doors being replaced, of course they had them replaced. You can't control a stove with a leaky door. The door warping has nothing to do with how smart someone is .
Why will you be buying multiple stoves? Do you have rental's?

 

[bwalker]

Django, The johnsons appear to be plate steel. Not stainless fwiw.

 

[django]

Yeah, they're mild steel. That's O.K. with me. Whats fwiw?

 

[bwalker]

fwiw=for what its worth.

Django, Do you use antifreeze or some other corrosion inhibitor in your furnace? Also, why doesnt some one design boiler in a manner that water doesnt come in contact with the firebox? IE wrapping the exterior of the firebox with water filled copper tubing. This would eliminate the corrosion problem. Efficiancy might be a issue, but I wouldnt think it would be a big differance.

 

[Crofter]

Some good ideas

Ben I have thoought the same thing regarding separating the firebox from the heat pickup liquid. Of necessity the inside of the boiler cant be much over 180 F to prevent actually boiling and losing the water. At this temperature the acidic products of combustion condense on the sides and bathe the metal in a pretty aggressive black soup. 90 % of the corrosion occurs on the fire side of the metal not the water side. Adding glycol and some other chemicals helps reduce water side corrosion. Glycol as antifreeze of course is necessary if there is possibility of losing your power supply for circulating long enough to freeze. It would be nice to have copper coils in sand, say around the firbox to pick up the heat. Firebrick could line the box and temperatures could be high enoug on the surface to prevent condensing creosote. The elimination of the 75 or so gallons of water that acts as a cushion or heat flywheel to store the temperature peaks and dips increases the risk of boiling and almost immediately percolating out all your heat exchange fluid. In otherwards it makes regulating the energy input more critical which is not so easy with the nature of burning wood. I am not sure that that system would be nearly as efficient. Maybe it would be adding another middleman to the transaction. LOL! Now wasn't that a long winded dissertation. Glens will think I'm after his job LOL!

Frank

 

[django]

I use a corrosion inhibitor and a sludge conditioner. Both Central Boiler products. No anti-freeze. My pipes are 4' deep in the ground so in theory, if my pump stays running, the water won't freeze. I also have a generator. Glycol Based anti-freeze really screws up the heat transfer. Contrary to what many people think (as I thought when I started out) the waterjacket almost never fails, it is the firebox that fails, allowing water into the firebox which really speeds up corrosion. That's why nobody worries about the water coming into contact, they corrode inside out. It is my opinion that the copper tube method would result in significant reduction in heat transfer due to the small surface area of the tubing that would actually contact the firebox. Air is a lousy conductor of heat. Contact of surface area is the reason they work at all. A 1/2" air gap between firebox and waterjacket would render one of these completely useless. I also use a product called ASHTROL( Central Boiler) in the firebox for reduction of creosote and corrosion inhibing. Central Boiler has a very comprehensive parts catalogue, very nice.

 

[django]

I was actually typing my response at the same time as crofter. He beat me. Glad to see we seem to agree with eah other!
"Heat Flywheel" I LOVE IT!! You can bet I'll use that one!

 

[Crofter]

Django Do you have figures on the difference in heat transfer with a Glycol solution vs straight water. It is just used so commonly in industrial heat exchange i thought it was good. It does have the advantage of bumping up the boiling point of the solution. I have about 150 ft of 6 inch Sch. 80 pipe that I was thinking of using but don't want to use that much glycol. Maybe I am putting too much emphasis on frost proofing.

Frank

 

[django]

The figure I see most often is a 20% reduction in heat transfer. Or better put: 20% more heat input to get the same result. Pacific Western recommends a product called Dowfrost. ( Dow Chemical) OH BUDDY is it expensive.

 

[bwalker]

Pacific Western recommends a product called Dowfrost. ( Dow Chemical) OH BUDDY is it expensive.

Thats interesting. A college buddy of mine works engineering for Dow in Midland. He gets me stuff really cheap ie free. Gave me this stuff to melt ice on my driveway. Never seen anything like it.

 

[django]

Hmmmm............ Wonder what it would cost to ship a 55 gallon drum to Northern Ohio...... I wonder what the mix ratio is to prevent freezing a -30F. Is it 50/50 like E. Glycol?

 

[bwalker]

Django,I will call him tonight and get the low down on the dow product. Do you know the products trade name?

 

[django]

Dowfrost is all I know.

 

[django]

http://www.outdoorwoodfurnaces.org/guide_frames.html

This link talks about several considerations for outdoor stoves and mentions an 18% loss in heat transfer for Glycol. This is also the link that mentions Dowfrost.

 

[bwalker]

Django, I just looked up dowfrost on dows site and I see it is a propylene glycol fluid. PG is worse heat transfer wise than standard ethylene glycol automotive type antifreeze.

 

[django]

Huh. I wonder why they recommend it then? They specifically say it is superior to automotive anti-freeze. This warrants further investigation.

 

[django]

Perhaps this will help: I'm not sure what is meant by "good" heat transfer properties.

http://www.arctichill.com/dowfrost.htm
http://www.dow.com/heattrans/family/dowfrost/
http://www.itsgreatstuff.com/heattrans/info.htm