Conventional kiln venting

[Hokiemill]

Hey all,  I'm still toying with the idea of a self built tiny (500 to 1000 bf) conventional heat and vent kiln.  Any of you out there with small to medium heat and vent kilns - can you give me any details on your venting mechanism.  I'm particularly interested in the Northlands as they appear to use a heat recovery ventilator (air to air heat exchanger) - at least that's what the website says.  I was wondering about the venting capacity (cfm) and if there is a particular brand of air to air exchanger that has already shown it is viable for use in kiln conditions.

Thanks.

[Kedwards]

The air-heat exchanger is not really all that efficient and i think it has been discontinued in NK. I have a lot of photos on assembly of the kiln  that show the mechanisms. It uses a pretty high velocity vent fan and a timed intake vent that cycles over conventional heating coils.

[Den Socling]

Other people, like Don Lewis would know more than me, but heat recovery from vents is a pretty old idea that hasn't taken off. From what I've read, the cost of an effective heat recovery system is too high. The payback isn't there unless you are drying something that takes a lot of venting. Not something you do with most hardwoods.

Northland's idea of using a cycle-timer to vent could work just as a cycle-timer can run a DH kiln. But, if you were drying anything that had a lot of value and you didn't want to spend a lot of time, I would think that a humidity controller should open the vents.

There's a lot of electrical actuators available to open vents but, IMO, the best for the buck is a truck brake actuator. You can pick up these pneumatic actuators from the local car-parts store or junk yard and 'energize' them with a cheap solenoid valve.

[Don_Lewis]

Geez Den...getting pretty humble there...

The best heat recovery system now marketed can reduce energy consumption by no more than about 15%. And it is quite expensive to install, if you do it right. 15% can be a lot of money in some kilns. There are some ways to make much greater savings in consumption but it has to be closely looked at from the technical side and rarely will pay..