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OWB to heat kiln?

Started by xlogger, February 06, 2015, 06:59:53 AM

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xlogger

If anyone here uses their OWB to supply heat to their kiln I'd like to talk to them. I would like to build a box near my boiler and use it if possible. Please PM me so maybe we I might ask a few questions. Thanks, Ricky
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

beenthere

xlogger
Ask away... we're interested too.  ;)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

GeneWengert-WoodDoc

With an OWB, are you planning to use hot water or will you have steam.  Hot water works, but steam is often better has it is hotter and provides for more energy transfer per foot of pipe.  Hot oil is even better, but for some reason we do not see many hot oil boilers in the US or Canada.  I have seen more in foreign countries...lower maintenance is a big advantage.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

xlogger

I was hoping to use the hot water going threw a heat exchanger with a fan behind it for my heat source. I was thinking about building a small one maybe that would hold up to 12 foot slabs or lumber and about to 5-6 foot high that I could load with my forklift. Also put in a dehumidifier.
Some answers I was going to ask was probably more on the construction also. This would be my first kiln and was wondering about how much room extra for walk in to check on drying and maybe some extra room behind lumber so just in case I had some hand size slabs to add while the bigger load is drying.
I got a PM from Red Oak, he going to send me some info on his.
I've got an heat exchanger on my hot tub and was thinking the setup is close to use for a kiln with some thermostat to control the temp. Not sure how hot I can get it inside. My water is around the 180°.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

Your idea is not impossible, but it is going to be tough.  First, drying requires a lot of energy to evaporate the water.  So, you will need more heat than you might be getting from this system you propose.  For example, 1000 bf of lumber requires about 6 million BTUs.

I am not sure why you need a humidifier, as the wood is already providing about 4 gallons of water per 1 % MC loss per MBF.

A kiln is basically an insulated room with fans, heat exchangers, doors, etc. For safety, two exits are required.  The fans sizes are easily calculated.  In addition to the lumber pile, you need room on both sides for the air to move and for an operator to work.  In a small kiln, it might be only 30".  Once the moisture is evaporated, you need to get rid of it, usually by venting.

There are a lot of subtle design considerations for a kiln, so certainly use a standard design, rather than try to start from scratch.  For example, NYLE sells plans for a kiln that uses a refrigeration trailer (reefer van).  They have other small kiln plans.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

xlogger

sorry dehumidifier. I changed it
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

red oaks lumber

iv'e been using my owb to supply heat for my kiln for over 10 yrs. i have a 200,000 btu heat exchanger which is plumbed using the hot water from my woodstove hanging from the ceiling in my kiln which holds 15,000 bf. using a wall therostat to control the temp, i have no problem finishing at 150 deg. even in the dead of winter when the kiln is changed,starting temp will be around 35 deg. 12 hours later it will be around 100 deg.
since switching to using only heat from my stove my kiln operating costs have dropped by 60%. the whole shop is heated from scraps the shop is creating everyday.
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

GeneWengert-WoodDoc

Red oaks...do you know your water temperature?
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Southside

Franklin buncher and skidder
JD Processor
Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
Enough cows to ensure there is no spare time.
White Oak Meadows

scsmith42

FF member GA_Boy (Mark) used to heat his kiln by an OWB as I recall.  I don't remember if it was steam or simply hot water though.

Hopefully he will chime in.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

red oaks lumber

i run my water temp at the stove 195 deg with my set point and 190
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

GeneWengert-WoodDoc

The 195 F is much better than 180 F.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

xlogger

With a click of a button I can get to 190°. Now I just need to come up with a building design and hope to get started. But when I start getting ready someone calls and wants something asap. I didn't know this retirement life was going to be so busy :D. I still think I would like to add a solar kiln also later.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

My suggestion is that you visit a commercial kiln that is the same size as you want.  This will give you design parameters. Including fan size and location, vent size, heat pipe location, and so on.  Although you build your own insulated walls with insulation that can withstand the heat, a commercial kiln door is usually best for ease of opening, safety and long life.  Repair is easy as well. 

There are requirements for a kiln, such as two exits, both with handles on the inside.  A couple of interior lights are a great idea.  Vents can be troublesome when on the roof, so they are often on the front and back walls.  Concrete is best if river rock instead of limestone.  Fans need to be of the correct size, volume-wise and need to be reversed every two hours.  Finally, a good control system to control temperature and RH is critical for best quality.

Note that the heating system is just one part of the kiln.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

LeeB

Gene, why is river rock better than limestone aggregate?
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

dean herring

Is fan reversing done auto by kiln controls?
Failure is not an option  3D Lumber

Den Socling

Lee, if you are drying something like Red Oak, the acid dissolves the limestone.

LeeB

'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

GeneWengert-WoodDoc

In the simple systems, a clock timer controls fan reversal.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Ga_Boy

I used a Heatmor Unit running at 190 to heat a kiln.  The chamber was a 20 foot insulated shipping container.  It worked well, the door seals on a shopping container are outstanding. 

If you go this route, run your electrical cables outside the chamber as much as possible. 

Let me know if you have a question. 




Mark
10 Acers in the Blue Ridge Mountains

Billikenfan

I  use it to OWB. I have a shipping container that is insulated and stainless steel lined.  The lining is important because the acid in the oak will eat regular metal.   I heat it to 190-195.  I have a 235k btu exchanger in the container.  There are 2 side louvers that open when the humidity hits a certain level.  Another door opens with a fan any bring in fresh air as the humidity is leaving.  My boiler sucks a lot of wood when I put a fresh load in.  But I can dry 2 cords or firewood in just 3-5 days depending on the split size.

Scott
2015 Woodmizer LT40  Hydraulic 35hp
Mountain Home Firewood Kiln. Beaver Wood Eater Firewood Processer.  John Deere 260 Skid Steer.

beenthere

Scott
How many cords of firewood do you have to burn to dry 2 cords of firewood in 3-5 days?
What species are you putting in the kiln, and is it split? 

Pics of a kiln load would be great.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

thecfarm

Billikenfan,welcome to the forum.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

Billikenfan

Thank you for the welcome.  I'll get some pics when I unload it.  I bought it from Mountain Firewood Kilns several years ago.  It's hard to tell how much I burn because of what I burn.  I burn all my splitter trash, sawmill slabs log cut offs, and the punky stuff to junky to sell.  I would guess if I had all good wood it would take 1/3 to half a cord depending on weather.   These zero Temps make a big difference.
2015 Woodmizer LT40  Hydraulic 35hp
Mountain Home Firewood Kiln. Beaver Wood Eater Firewood Processer.  John Deere 260 Skid Steer.

Billikenfan

Here are a few pics.  The basket with wood holds 2/3 of a cord.  I put in 3 baskets at a time.  The front gate on them swings so I can dump them out.  The pictures are in my gallery.

Scott
2015 Woodmizer LT40  Hydraulic 35hp
Mountain Home Firewood Kiln. Beaver Wood Eater Firewood Processer.  John Deere 260 Skid Steer.

oakiemac

I just started using a wood boiler to heat my kilns.
works good until the outside temp drops below 10 degrees then the boiler struggles to heat the shop, lumber bldg., and both kilns. My boiler is home made so not as effieceint as some others. I have the water temp. set at 175 degrees. Might bump that up some.
Mobile Demension sawmill, Bobcat 873 loader, 3 dry kilns and a long "to do" list.

thecfarm

@Billikenfan,this is how to put a picture in your post. Got any of the OWB? I burn alot of junk wood in my OWB to heat my house.That is why I brought it. I burned almost all softwood in it for 2 years steady.

I like to go to whatever post or start a new topic first to include a picture.Go to your gallery,it will open in a new window.Click onto your album,then click onto whatever picture you want,it will get bigger,than scroll down a little to find,Insert Image In Post,click onto that,click Yes and that is it. Some have to copy/paste the link to work.I like to hit the enter key at least once or twice to move the picture down away from what I am typing. The enter key really helps to leave some white space if posting more than one picture. Use the preview button to see how it looks and modify it if needed.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

xlogger

How do you try to heat the kiln, with a heat exchanger or just let the water run threw a few pipes with a fan inside the kiln?
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

Ga_Boy

I used aluminum finned copper tubbing.  I ran four 20 foot lengths of the finned tubbing and the fans blew the air across the tubbing to heat the air.  Some mount the fans to radiator type heat exchangers. 

10 Acers in the Blue Ridge Mountains

xlogger

Getting ready to start building the Kiln. Going to be 14 ft long to hold 12 ft lumber. Mostly going to kiln dry 8 or 10 feet.
Now a few questions.
If I pour a concrete floor and put insulation under the slab will that work
or should I just build it on a wood floor alone with maybe using 2x8's?
Was thinking about 8 ft high and 8 ft wide. Do you think this is plenty of walk behind room to get behind a 4ft stack of room
with some kind of pipes and blowers?
WDH, didn't look like you put in a walk in door, I was thinking I should have one, what you think on that?
Ga boy had Aluminum/copper pipes, how do you think pex pipes would work with a couple fans behind it or how many fans in 14 wide kiln?
Wonder if pex pipes in concrete floor would heat hot enough if I did pour a slab?
I did  plan on putting a DH in there also.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

Ga_Boy

Regarding the heated slab; I think this has been discussed before and for a reason that I do not remember was determined not to be a good approach for a wood kiln.  It may have been something about the time required to raise and lower the temperature.   Heated floors are for consistent heat over time by not ideal to raise or lower the temperature 10 degrees in  a few minutes. 

The pix tubing is a thought for a heat exchanger.  Check with you local HVAC guys, they may have a source for a water to air heat exchanger that is not cost prohibitive.  For fans, you will need at least 2 with 3 being better.   I used a 20 foot insulated shipping container.  The door seals were excellent, it made a very efficient kiln chamber.  Used a powered exhaust fan to dump hot and humid air when needed. 

Drying wood is all about the ability to precisely control the temperature and humidity and to raise and lower the temperature or humidity in a short time frame measured in minutes.




Mark

10 Acers in the Blue Ridge Mountains

xlogger

Thanks Mark, I know I have lots to learn on the controlling the heat end of this. I was thinking if I could put the pex in the floor it would be out of the way and I still could rig it up with the fans at the top pulling the hot air up and pushing it around the pile of wood. That was just an idea I wish it would work but probably have to run the lines like you did yours. I still need to see if I can find a thermostat that will control the water flow hook up to a 3 way zone valve in the water line. If any of you with using a boiler for heat how do you control the water temp?
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

xlogger

I google thermostats and found an old topic here that Dave Sheppard found a thermostat on QC Supply. Dave if you see this did you get the one there part# 20254 that shows going to 220°? Its digital and that what I would like if it did work for you.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

thecfarm

@xlogger,2 ways to contact a member,one way is put an "@" in front of a members name. This will bring them to a post as I did with you. The other is to send them a Personal Message,PM. @Dave Shepard please see the above post.  Should be a ballon below each members user name to PM them.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

WDH

I find that it is a good idea to check the load in the kiln each day.  I also need to fill the wet bulb reservoir each day as well.  So, I open the doors each day just enough to check the load and fill the reservoir.  There is not much heat loss at all as the doors are only cracked open, and the wood in the kiln is a huge heat sink.  The temp comes back up to the pre-door opening level quickly.  Also, when you open the door, you are venting water vapor from the air in the kiln.  The whole point is to get the water out.  So, on a small chamber like you are building, another door is not that important, and it is another thing to build and seal. 

I would make sure that you have at least 30 - 36" of free space in front of the load and in back of the load for good air exchange.  If You are only putting in one stack of 4' wide lumber from a depth standpoint, I believe that 8' is not enough depth. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

xlogger


Thanks, that's the kind of info I need to know, so maybe 10 ft wide?
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

Ga_Boy

The environment in a kiln is harsh, high temp, high humidity with wood acid in the humidity.  The wood acid will and does eat most items. 

I mention this so you know to buy components that will withstand the harsh conditions.  I used sealed conduit and light switch housings and still had to replace light switches every few months. 

Most standard off the shelf items will be eaten in a kiln.



Mark
10 Acers in the Blue Ridge Mountains

Dave Shepard

Quote from: xlogger on March 12, 2015, 07:10:32 AM
I google thermostats and found an old topic here that Dave Sheppard found a thermostat on QC Supply. Dave if you see this did you get the one there part# 20254 that shows going to 220°? Its digital and that what I would like if it did work for you.

I never did by a thermostat. I was trying to build a kiln using science and proven technology. The person I was working for at the time was trying to build a kiln using cheapness and idiocy. He won the fight, but lumber quality lost the war.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

WDH

Xlogger,

I believe that my chamber is about 10'4'' wide.  However, I have the Nyle L53 Dehumidification unit in the back of my chamber on a table, and it is about 16" deep which leaves me about 24 to 30" from the back of the load to the dehumidification unit.  The Nyle plans call for a minimum of 12" from the load to the unit, but I feel that is a little to close.  I added more room due to input from Yellowhammer when I went to see his kiln. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

xlogger

I need to ask a question about the vents. If you keep your DH running do you still need them? I know I have lots to learn about drying but need to get the kiln build correct first. I've got some 2" cedar slabs that I need to get started on first.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

Vents can often remove more moisture per hour on a sunny day than a DH can.  So, it depends on the DH size and how much you want to spend for electricity.  Venting is free.

If you want a DH kiln, then it is probably wiser to skip the solar part and insulate the structure fully.  Drying is faster and less expensive than with solar.  That is, a  VT solar kiln works well when the sun is shining, but is not energy efficient when it is dark.  High heat losses at night mean expensive DH operation.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

xlogger

Gene, I am planning on insulating the whole kiln. Probably going to need a book on drying. A while back you suggested one, I think you wrote it. What was it again? I can put in a vent, what would you suggest? We might level for the pad next week I hope, so I need to make sure I build the structure correct after that. So far I'm planning on building it 14 ft long, now 10 feet deep after some suggestions here and thinking I might go 8 ft tall with swinging doors to load with forklift. I'm thinking that mostly I will have in it is 8 ft lengths but though that I would be sorry later if I built it that short. Also the class at VT on solar is coming up, not sure I will go now since I'm not going with a solar kiln. Would that be much help with what I'm doing?  Thanks, Ricky
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

Nyle does sell plans, or perhaps someone here has a set.  No sense re-inventing the wheel !

Drying Hardwood Lumber is the best book on hardwood lumber drying.  Out of print, so download it and print it.  Actually a copy store like UPS can download, copy and bind it.

There are likely several classes in the next five months specific for DH, like the one in WI in August that would be better for your needs.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

oakiemac

xlogger, how many board feet will your kiln hold? If you are looking to use a DH unit, I have a nyle L50 which I think is rated for about 1000bf. I bought it used and used it for a while but now its been in storage. If you are interested let me know.
My 2 working kilns now have a Nyle 200 and an Ebac in them but neither is working so I use them as conventional kilns which surprising enough work just as well as the DH.
Mobile Demension sawmill, Bobcat 873 loader, 3 dry kilns and a long "to do" list.

xlogger

Probably will not have over 1000 bf ft in it at a time but it should hold more. My plans are to build it to hold 12 ft long but mostly 8 ft will go in it. I'm getting lots of good advise here. As of now I think my plan is to build it like I was planning on when I started and just use heat from my OWB to heat it with maybe having a dehumidifier. I'll probably air dry good before I put wood in. I'll have the chamber built and I'm sure after I work with it and learn what not to do I'll make changes.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

4x4American

Boy, back in my day..

GeneWengert-WoodDoc

Appreciate that the difference between DH and conventional is a hardware difference mainly.  Given the same temperature and RH in the kiln, both will dry at the same speed and with the same quality.  The big difference is in costs...capital and operating costs.  Plus some conventional kilns can get really hot (180 F) which means fast, and some DH units can run at 90 F which is hard to do with many conventional which means possibly higher quality with thick, green species like oak.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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