Is drywall lowering my homemade kiln temps?

[Tints123]

Long story short I built a homemade kiln to dry firewood. We used paper faced insulation followed by foam board followed by plywood. And spray foamed any open spots

We used a propane forced air heater commonly used on job sites and we're able to get the room to roughly 220 degrees Fahrenheit.

My father recently sheet rocked the entire room without telling us before hand. Cause he can't just chill and be good with the results we had. When all the plywood had been sheet rocked over our temps maxed out around 180 degrees.

This leads me to believe that sheet rock in some capacity absorbs heat rather than reflects it.

Should I rip off the sheet rock? Should I add more plywood? Is there any material that doesn't absorb heat that will make the room hit an even higher temp?

 

[kevin j]

The gysum is probably boiling off water. That is how gun safes work: the inside lining of sheetrock gives up water and the latent heat (boiling) keeps the temp from rising. The 30 minutes or whatever fire rating is how long the water lasts until it boils off.

How long have you run it? Once the water is gone, it may stop absorbing heat, then you are back to the conductive heat loss (R value) of the original wall, plus some more resistance from the sheet rock.
I don’t know if the paper becomes a fire hazard then or not.

 

[ArtB]

Room size,
door sealing
painted plywood
was a gapleft between ply and DWall?

Sounds like measurement error at first guess or different location of tstat.

 

[U&A]

The gysum is probably boiling off water. That is how gun safes work: the inside lining of sheetrock gives up water and the latent heat (boiling) keeps the temp from rising. The 30 minutes or whatever fire rating is how long the water lasts until it boils off.

How long have you run it? Once the water is gone, it may stop absorbing heat, then you are back to the conductive heat loss (R value) of the original wall, plus some more resistance from the sheet rock.
I don’t know if the paper becomes a fire hazard then or not.

Great explanation sir[emoji1303]


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[homemade]

Make it foil faced. Line it with tin foil to reflect the heat in.

 

[Marshy]

I would question how you are taking your measurements. You should have a dry and wet bulb measurement to more accurately determine your air temperature. If you are measuring surface temp with a point and shoot pyrometer then it can very significantly based on emissivity of the surface. You need to use bulb temperatures.

 

[Tints123]

Thanks for all your replies.

Should I just keep the plywood or remove it?

Someone also mentioned metal sheathing or aluminum would work

 

[SuperDuty04]

I’d leave it but as said above,I’d line the walls in tinfoil to help reflect the heat back. That will probably give you your biggest heat rise.

 

[NSMaple1]

Sounds like it's all sealed up. How is moisture getting out?

 

[Marshy]

Tin foil on the walls wont help do squat IMO.

We need to know how the OP is measuring the temperature...

 

[SuperDuty04]

Tin foil on the walls wont help do squat IMO.

We need to know how the OP is measuring the temperature...

This makes ZERO sense. Explain why? Ever wonder why survival blankets are tinfoil?

 

[Del_]

The kiln has infrared heat loss.

Nothing you described is a barrier to infrared, unless I missed it. The infrared barrier should be on the inside. Old sheet metal roofing would work well.

I'd leave the drywall: 1) because dad did it.
2) it's not hurting.

 

[Tints123]

So we ripped down the sheet rock and added more ply then ran aluminum roof coating over it.

We measure our temps and relative humidity with some gauges we bought from inkbird.

The aluminium roof coating is drying as a type this. I was able to go from 30 to 140 degrees in about 6 minutes but nothing was in the kiln so that's easily achievable

 

[Marshy]

So we ripped down the sheet rock and added more ply then ran aluminum roof coating over it.

We measure our temps and relative humidity with some gauges we bought from inkbird.

The aluminium roof coating is drying as a type this. I was able to go from 30 to 140 degrees in about 6 minutes but nothing was in the kiln so that's easily achievable

What are you measuring temperature with? This discussion is pointless without explaining what your are measuring with.

 

[Marshy]

This makes ZERO sense. Explain why? Ever wonder why survival blankets are tinfoil?

Thermodynamics

 

[Del_]

This makes ZERO sense. Explain why? Ever wonder why survival blankets are tinfoil?

Survival blankets are made of plastic with a thin film of metal sprayed on them.

The metal forms an infrared barrier.

 

[Marshy]

Right. Survival blankets block infrared. They are no tinfoil.

 

[ChoppyChoppy]

How are you venting the moist air?

Indirect fired heater I hope?