# In the process of designing heat system and dry kiln appreciate



## just_sawing (Jan 15, 2006)

Since I own and operate a Sawmill I am going to build a Dry Kiln. Where I am putting it , it is close enough to the house to reap some heating for the House. 
What I am looking at is installing a 500 gallon holding tank in the Root cellar and pumping water from the kiln during peak periods to it using the tank as a heat battery. In the summer I would not pump and would not have a heat build up but about Sept I would start collecting and since this is a open foundation it would be simple to vent if we have to hot of weather. 
This is not the primary system but a simple way of not loosing excess heat from the Kiln. The kiln walls will be 6 inch insulated freezer panels so it will be fairly efficient.
The non insulated door acts as a Dehumidifier system since the fan bank blows through the stack when the moist air hits the door it will condensate and drop water like a hose was on it.


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## TnAndy (Sep 15, 2005)

Where you have 'water battery', is that a water tank ? What is the purpose of the 500 gallon tank in the root cellar ? Don't you want the root cellar cold instead of hot ? I'm kinda missing something here.

On using a 'non insulated door' for moisture collection...that might work in cold weather.....but in the summer, my guess is "not much".....the surface simply won't be cold enough to condense much moisture. I think you better plan on venting the hotter, moister air out the top someplace, and pulling cooler, dryer air in near the bottom.

Woodmizer had a really neat design for a solar kiln they made and sold for a while. It looked similar to the shape you show. The roof was some metal trusses on about 3-4' centers, but they cantilevered over the high, back wall. 

That back part was weighted and the roof trusses hinged on the back wall, so you could raise the WHOLE roof ( pivoting on the back wall ), and drive in the front to load/unload the kiln. THAT is something important to consider....ease of loading and unloading !

They use double walled plastic ( like a greenhouse ) on the roof, and the walls were conventional wood/insulation. Whole thing on a concrete slab floor. They use vents in the upper part of the back wall that opened automatically ( green house type vents ) when the temp got up enough, and it would draw air in near the bottom. 

Looked like a cool, simple design. Call Woodmizer.....even though they don't make the deal anymore, they probably still have the plans.


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## just_sawing (Jan 15, 2006)

The Root Cellar having a 500 gallon heat sink (Water) will negate using it as a Root Cellar.
I have already used the door setup summer and winter but you are correct I will have venting. 
The Calculations that I have done puts the Kiln Hotter than I need. I run a relaxed Schedule on drying for better quality. Storing that heat even a little is better than none.


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## just_sawing (Jan 15, 2006)

Having worked on this farther I have decided to keep the root cellar cool and use a military Aluminium Fuel Tank (650 gal) next door to the kiln in a insulated room Freezer panel and then buried in sawdust of the heat bank. This will allow a longer transfer period (All summer if needed) to gain as many BTUs as possible. This will also lower my Home Owners insurance having a water tank close enough to the house for fire. 
This Appears to be a win win for everything.


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## biggkidd (Aug 16, 2012)

This looks like an interesting idea. I hope you will keep posting as you go along. 

Good Luck

Larry


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## SolarGary (Sep 8, 2005)

Hi,
Interesting idea.

If you get the 650 gallons of water up to (say) 150F, and you can use the heat from the tank down to about 80F, then the heat stored in the tank is 

(650 gal)(8.3 lb/gal)(150F - 80F)(1 BTU/lb-F) = 380,000 BTU or about the equivalent of 5 gallons of propane burned in an 80% efficient furnace.

I guess that the way you get the heat from the kiln to the heat storage tank is that the tanks inside the kiln heat up, and you pump water from them into the insulated storage tank?

Another option to get some of the excess heat from the kiln to a storage tank would be to use an air to water heat exchanger (or two) at the peak of the kiln -- similar to this one: http://www.builditsolar.com/Projects/Sunspace/LowCostHtStorageNathan.pdf
You would have to be careful with freezing problems in the winter if you are in a cold area.
I'm not sure how much heat the lumber that is being dried takes away, but if the kiln was empty or the wood in it was near dry, I think this air to water heat exchanger (or two) would deliver a useful amount of heat to your heat storage tank on a sunny winter day -- that is, it would help with space heating through the winter.

A collection of solar Kiln plans here: http://www.builditsolar.com/Projects/WoodDrying/wood_kiln.htm

Gary


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