Container kiln floor insulation

CHill8903 · August 15, 2018, 08:33:47 PM

For those of you that have built a container kiln with an insulated reefer, have you done anything to insulate the floor? I'm half through construction and wondering if I should fill the aluminum T-slat floor with spray foam? Anyone have any experience for or against? I'm in Pennsylvania so heating efficiency in the winter is a priority.

Southside · August 15, 2018, 08:40:20 PM

I would not fill the slots, there will be water that drips onto the floor or if you have a case hardening situation you will put water on the floor for starters.

Aluminum is horrible at transferring heat so the floor loss can not be that great or the companies that use them to ship food would have addressed the issue before now.

CHill8903 · August 15, 2018, 09:38:14 PM

I don't want to create a problem if I'm overthinking it. I will back fill along the outside edges so air can't blow underneath. I also figured it's something I could do down the road if necessary but it would be a little easier before the track is in. I think I'll see how it goes without.

Southside · August 15, 2018, 10:42:58 PM

I filled mine with washed stone, the wood chucks simply moved the stone out of their way... Oh well, they are neat to watch.

YellowHammer · August 15, 2018, 10:58:21 PM

I have open T slots, heating is never a problem. It's nice to have a clean, metal floor for periodic cleaning and water pooling. Most of the heat is generated by the compressor during the drying cycle, so is basically free, and mine has to spend a lot of time just power venting, anyway, because it hits max temps during the cycle.

During a sterilization cycle in the winter, however, air leaks are killers.

The bigger leaks are around the door seals, the built in screened vent, and especially the louvered kiln vents can be very significant, even when they are "closed". They are not airtight.

Certainly find and foam all of the refrigerator pass thoughts and access conduits. Seal the electrical pass through as well as the drip tube. Put a "P trap" in the drip tube to prevent airflow. Reseal the wall to ceiling joints. I've gone out in the cold mornings and seen vapor steaming from the vents even when they were closed. The door seals in mine were replaced and work great. During the winter, I put duct tape over the vents during sterilization to seal things up. Remember that the kiln system has a low pressure and high pressure side so will aggressively want to suck in and expel outside air. That's why small holes are big leaks.

CHill8903 · August 16, 2018, 06:15:12 AM

Thanks for all the insight, I have 2 stick built kilns and door seals and air leaks are a constant battle in the winter, that was half the reason for going with the container on this one since they are so tight to begin with.

YellowHammer · August 16, 2018, 07:52:03 AM

You are right, container kilns are tight, and stay that way. My door seals are as good as the day they were installed, although my stick built requires constant maintenance.

Typically, the only leaks in a container kiln are the penetrations introduced during the construction phase. Once sealed, they pretty much stay sealed, year after year.

The louvered vents are the only leaks I have, as far as I can tell and the only time they are an issue is in the cold of winter. They leak where the louveres are pin hinged into the sides of the fram. In order to pivot correctly, there must be some clearance for movement, and that's where the leaks are. It's not much, but since everything else is so tight in a container kiln, they are the ones I notice. At one time I used a couple magnetic car door signs as seals and placed them over the vents during sterilization.

I think you will really like the longevity and zero maintence of a container kiln, as compared to stickbuilt.