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Heat for my kiln

Started by ForestMan, December 28, 2012, 08:16:49 AM

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ForestMan

I recently built a small homemade kiln.  It is 12x4x4.  I use a household dehumidifier that I ran a water hose through so any moisture runs outside the kiln, a fan, and two 500 watt halogen work lights as heat.  My problem is that the lights both went out.  I need to be able to heat my kiln, and I need to know where to find a heater to do it right.  I want to heat to about 120 degrees F for drying, and then 160 degrees F for bug kill the last three days or so.

Is there an inexpensive, off the shelf heater that will do this?  I notice most heaters come with thermal and tip-over safety trips.  This is great in a home, but how can I make my kiln work without spends huge money on an industrial heater?  Thanks.
There is nothing like the natural beauty of wood.

GeneWengert-WoodDoc

Putting a hot heater in a dusty environment (wood dust is explosive and also can catch fire at fairly low temperatures compared to 450 F for solid wood) certainly raises a safety flag.  To reach 160 F, especially within the wood, the heater itself would be considerably hotter.  So, most kilns will use a heat exchanger (steam in pipes, hot water in a pipe, hot air in a duct, etc.), to avoid a risk.  A few kilns use direct fire, where the kiln is part of a chimney, but the controls are sophisticated to minimize fire risks.

Incidentally, with any kiln if you are using the kiln to dry lumber to make money, it is a business and so if it catches fire and burns your home or office, insurance will not cover the kiln or the home, without a special rider.  A home is not covered if the fire comes from your uninsured business activities.  Check with your insurance agent to confirm this. 

If trying to make money, it would be prudent to incorporate your business as an LLC, have separate checking, invoices, etc.  you can easily file a schedule C with your taxes for a small operation rather than having a separate tax filing for the business.  Of course, check with an accountant or financial advisor for state requirements and precise advice for your particular situation.  Note also that a kiln is a piece of equipment and so would be considered depreciable capital in most tax advisors' minds.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

ForestMan

Gene,

I have read some of your work and you have my utmost respect as an authority in this industry. 

One of the problems we (the little guys) have in trying to start out is lack of capital.  We try to start up on a shoestring because that's what we have access to.  We carve out $100 here and $50 there, sometimes from the grocery budget if we really need something.  I would love to buy a Nyle 200 and be set for life in terms of drying, but that is beyond my ability at this time.  How can the little guy with a few basic pieces of equipment make a little nest egg to buy what we really need? 

In effect, we create the capital as we go.  The realities of the credit markets impacts us directly on main street.  I know I won't qualify for any loans, and I really don't want one.

In my case, I work full time, milk a cow once a day, feed pigs and cows, work with my wife on a million honey-dos, which really do need attention, I'm raising a six year old boy and a year-and-a-half year old boy, and my father-in-law who is dying of cancer moved in with us yesterday.  My plate is more than full. 

My little kiln actually works quite well, but I know I need the heat.

Is there a simple set-it-and-forget-it electric system that I could pipe through my little kiln (hot air preferably), that would create the required temperatures that I could buy or build for a very minimal investment?  Are their plans for making something like this out there somewhere?  It appears to be doing a great job with what I had, but I need a moisture meter to prove it.  Pass the beans ma, I'm saving for a piece of equipment.

But seriously, some of us are working very hard to pull this off in a piece-by-piece manner, without going into debt, without making payments on equipment, and within the time constraints we have available, to try to add a few hundred dollars a month to the family budget.  I have managed to make an extra $50 a month for the past ten months (on average).  Not much, but with cutting boards and a saw job here and there and occasionally selling a little wood, it has worked out so far.  All of my equipment is free and clear.  I am making zero payments on any of the equipment I am using.  I would like to keep it that way, if possible.

I know I am still at a hobby stage, but once things settle in my life and I have a little extra time available, I think I have the ability to take my hobby into a part-time business. 

I do have access to a Woodmaster 718.  All I need to do is put walls and a floor on my new shop I just built and add electricity and I'll be ready for a bit more production.  The Woodmaster (with dust collection) is free and clear as well.  It was a gift from my father, but he gave it to my brother and me together.  My brother has it now, but he is in school and can't use it much.  I'm giving him 20% of the business for use of the machine and his wife helping  to market for us and he has agreed to this. 

I know bubble gum and bailing wire can only get you so far, but if that is what you have, you have to start somewhere.  Right now I am debt free.  Can a part-time business survive long enough to gain the capitol needed to start a serious full-time venture (one day-retirement income)?  I expect it to take years, and I'm not in a hurry.  My boys need to grow a bit more to be really helpful.  I just want to stay as debt free as possible. 

Thank you for your great advice and any more you might pass on.
There is nothing like the natural beauty of wood.

bama20a

Quote from: ForestMan on December 29, 2012, 01:19:15 AM
Gene,

I have read some of your work and you have my utmost respect as an authority in this industry. 

One of the problems we (the little guys) have in trying to start out is lack of capital.  We try to start up on a shoestring because that's what we have access to.  We carve out $100 here and $50 there, sometimes from the grocery budget if we really need something.  I would love to buy a Nyle 200 and be set for life in terms of drying, but that is beyond my ability at this time.  How can the little guy with a few basic pieces of equipment make a little nest egg to buy what we really need? 

In effect, we create the capital as we go.  The realities of the credit markets impacts us directly on main street.  I know I won't qualify for any loans, and I really don't want one.

In my case, I work full time, milk a cow once a day, feed pigs and cows, work with my wife on a million honey-dos, which really do need attention, I'm raising a six year old boy and a year-and-a-half year old boy, and my father-in-law who is dying of cancer moved in with us yesterday.  My plate is more than full. 

My little kiln actually works quite well, but I know I need the heat.

Is there a simple set-it-and-forget-it electric system that I could pipe through my little kiln (hot air preferably), that would create the required temperatures that I could buy or build for a very minimal investment?  Are their plans for making something like this out there somewhere?  It appears to be doing a great job with what I had, but I need a moisture meter to prove it.  Pass the beans ma, I'm saving for a piece of equipment.

But seriously, some of us are working very hard to pull this off in a piece-by-piece manner, without going into debt, without making payments on equipment, and within the time constraints we have available, to try to add a few hundred dollars a month to the family budget.  I have managed to make an extra $50 a month for the past ten months (on average).  Not much, but with cutting boards and a saw job here and there and occasionally selling a little wood, it has worked out so far.  All of my equipment is free and clear.  I am making zero payments on any of the equipment I am using.  I would like to keep it that way, if possible.

I know I am still at a hobby stage, but once things settle in my life and I have a little extra time available, I think I have the ability to take my hobby into a part-time business. 

I do have access to a Woodmaster 718.  All I need to do is put walls and a floor on my new shop I just built and add electricity and I'll be ready for a bit more production.  The Woodmaster (with dust collection) is free and clear as well.  It was a gift from my father, but he gave it to my brother and me together.  My brother has it now, but he is in school and can't use it much.  I'm giving him 20% of the business for use of the machine and his wife helping  to market for us and he has agreed to this. 

I know bubble gum and bailing wire can only get you so far, but if that is what you have, you have to start somewhere.  Right now I am debt free.  Can a part-time business survive long enough to gain the capitol needed to start a serious full-time venture (one day-retirement income)?  I expect it to take years, and I'm not in a hurry.  My boys need to grow a bit more to be really helpful.  I just want to stay as debt free as possible. 

Thank you for your great advice and any more you might pass on.

smiley_clapping smiley_clapping smiley_clapping :new_year:
It is better to ask forgiveness than permission

GeneWengert-WoodDoc

You can get an electric "salamander"-type heater, but the fire risk would seem really high.  It is a risk, so not every kiln will burn down, but a high risk.  Electric heat is also many times more expensive than natural gas.  How about an old, hot air, gas furnace with a plenum?  I wonder if that would work.

It is indeed a management decision you are making to be debt free, and so I would try to help in that even though I would argue that capital debt is OK.  In any case, if you try to make this a business, cash flow in the wood business is terrible, so you need adequate cash to carry you through poor cash flow (poor sales), like in January or deer season, etc.  so, do not spend all your cash on equipment;keep a good amount in reserve for rainy days.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

learner

Here is what we did for our De-Humidifying kiln.  Visit the salvage yards and ask them about gas fired heater blower units.
They will usually sell you one if it comes in as salvage, for so many cents per pound.  The one we got came out of a mobile home and cost $40.
You can use natural gas or convert it to propane very easily and cheaply.  Then build you a small shed next to your kiln and duct the hot air in.  This will keep the dust away from any flames and virtually eleminate any fire hazard.  You can also install a small to medium pore filter to prevent ignighted particles from entering the kiln.
Then all you need is a thermostat that will allow you to run it up to 160 degrees.
Good luck with whatever you decide to do ForestMan.
WoodMizer LT40 Super Hydraulic, MF-300 FEL, Nissan Enduro 60 forklift, 2 Monkey Wards Power Kraft Radial arm saws, Rockwell series 22-200 planer, Prentiss 210 loader

Kcwoodbutcher

I'm surprised the DH unit compressor doesn't put out enough heat to keep the chamber warm. I'm also assuming the unit is inside the chamber and the chamber is well insulated.  You really don't need 120 degrees in the drying cycle with a DH unit, 110 to 115 will do.  Many home units have a compressor safety cutoff at 115 degrees. 135 is all you need to kill bugs and I use a small electric milk house heater for that.  With the fan in the unit the elements don't glow red. The safety cut off must be higher than 160 degrees because I have set pitch in pine at that temp. My biggest concern was the fans but they survived. PM me if you would like any details of the setup.
My job is to do everything nobody else felt like doing today

SawyerBrown

The issue may be the amount of capital needed to set this up, but I'm surprised nobody has mentioned Solar.  (Especially in Texas where the sun shines all the time, right?   :)  )  There are some really great plans out there for solar kilns, and I've just started to research some small solar panels to power a couple of small fans ... just enough to move the air a little bit.  Seems to me it should pay back in relatively short period of time instead of paying for propane / electricity / etc.  I'd sure be interested in whether they actually work, how much longer it takes, whether you still need dehumidification, etc.
Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

GeneWengert-WoodDoc

The heat demand when first starting a kiln is quite large, especially in the northern half of the country.  So, solar for initial heating is too expensive.

For maintaining 120 F with solar, we would need a large collector with a storage system...probably around 100 sq ft...with necessary ducting.  To achieve 160 F and maintain that value in a kiln would require an extremely well insulated kiln and again, a very large solar collector, which means expensive.

Solar powered fans are reasonable for air dried lumber where velocity is not a critical parameter.  For lumber much over 20% MC, we need more air flow and so larger panels, which again means money.

A common problem with household DH units is that the coils like to freeze and so the unit must be shut down part of the time to avoid this.  When shut down, there is no heat generated.  So, auxiliary heat is required.  Household units are limited in the temperature that they can run at, so if we want higher temperatures, the units are best removed from the heat to avoid shortening their life.

When we look at a ten year investment, and then consider all the options, commercial DH looks pretty good, especially if the building is well built.  Short cuts to reduce capital expense usually shorten the life of the investment, but sometimes (like if we do not want to get a loan for equipment) lower capital is the way to go.  In other words, "the same shoe does not fit everyone."

I have seen in some cases that the lumber, after drying, is put in another small chamber where there is the required heat and humidity.  It is then heated to set the pitch, sanitize, etc.  using a second chamber reduces kiln degradation, increases kiln throughput, and allows (if the chamber is masonry and cleaned after every load) much less fire risk.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

learner

Gene, what am I missing here?  If the lumber is cleaned of all sawdust, air-dried and re-cleaned before placing in the kiln, then where is the fire hazard from dust coming from?  I mean the combustion point of paper is around 840F and wood even higher, so what am I missing Sir?
WoodMizer LT40 Super Hydraulic, MF-300 FEL, Nissan Enduro 60 forklift, 2 Monkey Wards Power Kraft Radial arm saws, Rockwell series 22-200 planer, Prentiss 210 loader

jimF

I know of a person that died from a fireball that came out of an oven that had harmless wood flakes in it.

Most wood put in a kiln is rough sawn. Saw dust stick to it and is blown off while drying.  The dried fibers poking up from the surface gets broken off.  Even planned lumber has some dust on it. This dust or fibers does get collected around heating elements or bulbs.  With constant contact with the heating elements the dust chars and is easily ignited.  The ignited dust can then be blown into the stack.  With airflow in the kiln, the ignited dust can set the stack on fire.  If the lumber is treated it is much more flammable.  Salts used to treat lumber are catalysts and other treatments reduces the combustion temperature.  We had some friends that built a new barn with salt treated lumber and hung a light bulb on one of the posts, went in for lunch and a visitor's son happened to look out during lunch and saw flames on that post.  It was put out without much damage.  All organics and dust should be considered combustible.

learner

Thank You jim.  That answered my question very well.  I'm convinced that the only SAFE way to introduce heat to the kiln is in such a way that any dust or particals can't reach the Source of the heat.
WoodMizer LT40 Super Hydraulic, MF-300 FEL, Nissan Enduro 60 forklift, 2 Monkey Wards Power Kraft Radial arm saws, Rockwell series 22-200 planer, Prentiss 210 loader

GeneWengert-WoodDoc

I do believe that the combustion point for wood is closer to 350 F.  The US Forest Products Lab indicates that red oak will ignite at about 350 in less than 20 minutes.  Also, as we get smaller particles that temperature drops. 

At 200 F you can char dry wood given enough time.  The decomposition is slow, but it is occurring.  Wood in contact with steam pipes has ignited.   A brief summary is at
www.fpl.fs.fed.us/documnts/fplmisc/rpt1464.pdf


Wood dust can be explosive too.  With a salamander, the red glow means over 1000 F at the heating element.  Likewise with a blue flame.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

learner

I think that for the purposes of drying lumber to a commercially acceptable MC, 135 degrees F, is acceptable.  With 160 degrees F for setting the pitch.  Correct me if I'm wrong about that.  The report you sent Gene, indicates that they were using Centrigrade temperatures.  No offense Sir but I really hate the metric system.  ;D  I'm only 52 but Not willing to learn a new system.
So I'm thinking that if the temperature is kept at or below 160 degrees F, and there are NO ignition sources that come in contact with the dust, then things should be relatively safe.  Yes, I think blown air, at the proper temperatures, will keep any dust away and provide the needed temperatures to properly cure the lumber.  I think the main problem with using air is the re-circulation of contained air.  In other words pulling the air in the kiln into the heating unit.  If you filter it then there shouldn't be a problem with dust getting to the heating system.
WoodMizer LT40 Super Hydraulic, MF-300 FEL, Nissan Enduro 60 forklift, 2 Monkey Wards Power Kraft Radial arm saws, Rockwell series 22-200 planer, Prentiss 210 loader

kelLOGg

Quote from: ForestMan on December 28, 2012, 08:16:49 AM
I recently built a small homemade kiln.  It is 12x4x4.  I use a household dehumidifier that I ran a water hose through so any moisture runs outside the kiln, a fan, and two 500 watt halogen work lights as heat.  My problem is that the lights both went out.  I need to be able to heat my kiln, and I need to know where to find a heater to do it right.  I want to heat to about 120 degrees F for drying, and then 160 degrees F for bug kill the last three days or so.

Is there an inexpensive, off the shelf heater that will do this?  I notice most heaters come with thermal and tip-over safety trips.  This is great in a home, but how can I make my kiln work without spends huge money on an industrial heater?  Thanks.

My kiln is 6 x 6 x 16 with a home DH unit but it doesn't last more than a year or two when used at temps higher than typically encountered in a home. (I now need to buy my third unit :() I also have two 1000W baseboard heaters (from Surplus Center) in the kiln but have not used them yet. Given the short lifespan of the DH units I am planning to turn them off, turn on the electrics for heat, vent to remove humidity (and heat too, unfortunately) and turn on the DH again. Then repeat the whole process until the MC is <9%.

How do you plan to use yours? I think electric baseboard is cheap to buy, safe?, and for a small kiln would not be too expensive to operate. One 100W unit would have the same operating costs as your two 500W lights.
Bob




Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

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