Heat

[JHEPP08]

Back for more help. I got a ebac 3000 which is a nice unit . Originally I was going to use lights for extra heat. What does everyone else use?  It's a well insulated chamber . 8x12 . Not huge. Hold 1800 + bdft . Thinking electric heaters or LP. What about home furnace? Also I'd need need a thermostat. I have a lot going on it would be nice to set it an go..

Also what do you guys use for vents when you hear it? The original owner just did low heat nothing high.

Thanks

[GeneWengert-WoodDoc]

Generally, once the unit gets running, you will not need extra heat.  However, to get the kiln up to the minimum required by the manufacturer in order for the compressor to work, you will find that fast heating is best; slow heating can lead to stain and wastes time, especially for frozen wood.  This means using strip heaters or propane heaters (without direct flame into the kiln due to fire hazard from wood dust) for most people.  A home furnace could be used.  The best answer is based on money...what is least expensive and functional for you?  The wood itself does not care where the heat comes from...heat is heat...but your pocketbook will care.  Lights are a poor source of energy for initial heating as they are not efficient heaters for their size.

[Ga_Boy]

When you use components in a kiln chamber remember to take in to account the environment.

High Heat
High Humidity
Acid in the humidity

Normal components will not last.  Example:  I ran sealed conduit inside a insulated shipping container, used sealed switch boxes for the lights and fan switches which were standard switches.  Still had to replace the switches every 3 to 4 months.  The heat, humidity and acid ate them and they quit working. 

You need components that are rated kiln duty, made of stainless steel and high grade aluminum.  Cost is a factor.  You have two  options

Option 1:  you spend a little extra and buy it once.

Option 2:  you spend a little less and you many replacement.

You usually spend about the same amount, the difference is do you feel the pain once or do you spread it out over time. 

There is a risk in both. 

The risk with option 1 is you cut in to your cash to operate your business. 

The risk with option 2 is when you break down, it usually occurs at that worst possible time and it may cost you a business opportunity. 

The answer is never easy.




Mark

[JHEPP08]

Yea I agree, was just wondering if any certain models people recommend. It doesn't matter to me if its elec or lp . I'm leaning towards electric . I see everyone using baseboard heaters. But is there a ideal size that's reasonable? My kiln is a small reefer box like for a pickup. 8 wide by 12 long so we're not talking very big

Thanks

[JHEPP08]

Another question would be when I get a heat source should I place it behind the fans so they suck the heat through an blow it through lumber or in front of fans so the air takes it that way? Hope this makes sense

[logboy]

I would wait and run a couple cycles of lumber through before changing or adding anything. My kiln has a hard time getting up to temp, but its much larger than yours and sitting on an uninsulated concrete pad. Run a couple loads of air dried lumber through it so you cant screw anything up, and see how it goes.

[Ga_Boy]

Placement of heat source would depend on how you are adding humidity.  If you are using steam I don't think it matters.  If you are using a fine mist, suggest that you place your heat source so your mist is blown across the heat source. 

My misting system was just behind the fans.  The heating tubes were placed so th fans blew the air across the tubes. 

The temp probe and RH sensor was down stream of the heat source.

Make sense?

[JHEPP08]

The system was turn key but it'll only get to 120 but it's hard on it so I want additional heat to help it get warm. The ynit it self works good.

No you lost me . I'm either going to use lp heat or electric for auxiliary heat I think mount on the wall with sheet metal behind it to help get heat out

[Ga_Boy]

I have a drawing of the placement of the misting system, fans, heat source, RH sensor, and temp probe.

I'll dig it and and e-mail it to you.

[JHEPP08]

Ok sounds good be interesting to see . Thanks

[GeneWengert-WoodDoc]

With a DH kiln, the heat source location does not matter...obviously, the heat does have to get into the air stream.  But, not all the air through the fans goes into the DH unit immediately.  Most of the air is circulated a few times and the mixing that occurs is why the location is not important.

In addition, you will use heat mainly at start-up, and so the DH compressor will not be running.

So two things for you to document.  1). How hot can the compressor go?  Many have a limit of 120 F; some less and some more.  2). What is the minimum operations temperature?  Many require at least 85 F.

For most heating in a DH, you will need a lot of heat in a short time.  One advantage of LP is that a large amount of BTUs can come from an inexpensive unit.  If you will have frozen lumber, consider LP.

[JHEPP08]

Yea I was wondering if a ceiling mounted lp heater would work

[red oaks lumber]

open flames need oxygen, you'll starve the flame out. the best and cheapest method for heat is with a hot water heat exchanger operated with a outside wood stove. you'll go broke trying to heat up frozen lumber using heat  ;) in the summer months we use the electric heat from the kiln, the electric bill goes up $800 per month. thats right it goes up by $800 /mo.

[JHEPP08]

How big of a kiln? Do you recommend any boiler systems? I have a nice wood furnace. Like everyone I'm trying to be on a budget lol
Thanks

[Den Socling]

I would connect the OWB to a couple lengths of fin pipe. Add a proportional valve and a simple controller.

[red oaks lumber]

my kiln is 15,000 bf. with a heat exchanger they come complete with fan and thermostat, i don't have a recommended stove. i can have a frozen load up to 100 deg. in 12 hrs.just from the wood heat
there are 2 ways of life.. 1) doing things right  2) doing things on budget.    my way of thinking, spending more up front saves way more in the long haul.

[JHEPP08]

Oh ok my kiln is around 1800 bdft . Does anyone have any plans for this? Like what thermostat to use etc. like I said I have a nice wood stove furnace that has squirrel cage etc to push heat into hvac

[MikeON]

I've also been thinking of using my wood boiler to help my little Nyle L50 DH kiln reach temperature, especially for setting pitch.  There are lots of water to air heat exchangers selling on ebay at very reasonable prices, but I'm concerned whether the acids in the kiln would damage them.  Another option would be pex pipe.

[red oaks lumber]

iv'e had my exchanger in the kiln for 10 yrs ,no problems

[JHEPP08]

I've seen the exchanger an fans .. But is there a water tank or something? Anyone have a diagram I been trying to find 1 but can't find 1. I could heat multiple chambers if I plummed it that way right?

[GeneWengert-WoodDoc]

With LP, you certainly want a heat exchanger rather than having a direct flame.  The fire hazard with dust is extreme.

When an exchanger is used for drying pine, the pitch that is evaporated will coat the walls and much of the exchanger with a protective coating.  If or when the exchanger is hot, there will not be coating, but it will coat as the exchanger cools...the evaporated sap will condense on any cool surface.

[Ga_Boy]

I'm working on a block diagram of a conventional kiln configuration.  Should be able to send it to you in a day or so.  Marking a drawing in Word can be difficult at times.

[JHEPP08]

Haha ok just a basic 1 like what I need etc. I have a really nice wood furnace id like to use. But I'm not sure on the size of radiator or water tank etc

Thanks!

[GeneWengert-WoodDoc]

There is a large demand for heat when you first start the kiln.  Here is an example:

Let's assume that we have 1000 BF of green (75% MC) red oak lumber.  It is a typical Iowa spring day, so the temperature is 20 F. so some of the water in the wood is frozen.

When we are starting the kiln, the walls, floor and the lumber are 20 F.  The compressor is not suppose to be operated until the air is heated to 85 F.  The walls, floor and roof are all insulated with 6" of foam board.  To heat the kiln and lumber with its water to 85 F will require about 300,000 BTUs per day, with more demand at the beginning.  Heat losses for this heating up period of 24 hours through the wall, roof and floor will be 1000 BTU per hour; subsequent days about 1500 BTUs per hour.  During heating up, we can ignore this heat loss, as it is small.  So, in rough numbers, we need to have a heating system that can provide about 50,00 to 60,000 BTU per hour (or 15 kW).  Note that with a smaller system, heating up will take longer.  With white woods and some fast drying species, like white pine, slower heating can lead to discoloration issues.  Once up to temperature, we often need no additional auxiliary heating, especially if we used 8" of insulation and have the floor insulated as well.  (If you have a concrete floor, it should have insulation under the concrete and also insulation around the foundation.)