Log drying kiln idea

[jrgatelogs]

In that case I wouldn't worry as the pressure from the fans will far outweigh any difference in buoyancy of moist air and it may be that heat is better conserved because as the warm air picks up moisture it cools and cooler air plus water vapour will fall even given water vapour is lighter than air normally.

Thanks for that. Which may explain the lower half of the kiln struggles to dry logs as the warm air from the radiator rises also the moist air dropping to the lower half. I’m now running the kilns 24 hours by topping the boiler up around 9pm, so not getting any condensation when the air cools, so hopefully they are constantly drying and should be dry in a few days, though I’m still getting 45% readings in the centre of the logs after 3 days drying.

[openspaceman]

21 minutes ago, jrgatelogs said:

Thanks for that. Which may explain the lower half of the kiln struggles to dry logs as the warm air from the radiator rises also the moist air dropping to the lower half. I’m now running the kilns 24 hours by topping the boiler up around 9pm, so not getting any condensation when the air cools, so hopefully they are constantly drying and should be dry in a few days, though I’m still getting 45% readings in the centre of the logs after 3 days drying.

It probably needs more recirculation within the kiln and maybe smaller logs. Have you measured the outlet air for moisture saturation?

[jrgatelogs]

It probably needs more recirculation within the kiln and maybe smaller logs. Have you measured the outlet air for moisture saturation?

I haven’t! I open the doors for a few minutes each day to let humid air out! I wondered if a industrial dehumidifier would assist and have it run a few stints each day for an hour or two!

To test the humidity do you have to purchase a humidity gauge of some sort?

[Woodworks]

12 minutes ago, jrgatelogs said:

I haven’t! I open the doors for a few minutes each day to let humid air out! I wondered if a industrial dehumidifier would assist and have it run a few stints each day for an hour or two!

To test the humidity do you have to purchase a humidity gauge of some sort?

A cube of logs will lose around 150 litres of water through drying. I doubt any dehumidifier is going to get close to removing the amount of water needed to dry your logs in the time spans you are hoping for

[openspaceman]

18 minutes ago, jrgatelogs said:

I haven’t! I open the doors for a few minutes each day to let humid air out! I wondered if a industrial dehumidifier would assist and have it run a few stints each day for an hour or two!

To test the humidity do you have to purchase a humidity gauge of some sort?

I agree with @Woodworks that a dehumidifier won't be effective.

 

The reason I asked if the RH of the outlet air was tested was to see how close to saturation you were getting, the aim is to get to near 100% saturation at the lowest temperature you can get down to.

 

For example ( and I'm picking these figures from thin air one would have to consult psychrometric tables to get real numbers) it's 15C where the kiln is and the air going in is at 60C, the air coming out should be around 20C and 95%+ RH. If the RH leaving is lower it means the air is not in contact with enough log surface and hence is not picking up enough moisture to be efficient, similarly if the exhaust temperature is higher then not enough of the heat input is getting into the logs.

 

I used to use earlier versions of these

 

Temperature and Humidity Data Logger - EL-USB-2

WWW.LASCARELECTRONICS.COM

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Temperature and Humidity USB Data Logger

 

[jrgatelogs]

I agree with @Woodworks that a dehumidifier won't be effective.
 
The reason I asked if the RH of the outlet air was tested was to see how close to saturation you were getting, the aim is to get to near 100% saturation at the lowest temperature you can get down to.
 
For example ( and I'm picking these figures from thin air one would have to consult psychrometric tables to get real numbers) it's 15C where the kiln is and the air going in is at 60C, the air coming out should be around 20C and 95%+ RH. If the RH leaving is lower it means the air is not in contact with enough log surface and hence is not picking up enough moisture to be efficient, similarly if the exhaust temperature is higher then not enough of the heat input is getting into the logs.
 
I used to use earlier versions of these
 

Temperature and Humidity Data Logger - EL-USB-2

WWW.LASCARELECTRONICS.COM

---

Temperature and Humidity USB Data Logger  

Thanks for the info. It’s sounds more technical than my knowledge. The thermometer is at the top of the kiln, which is just a shipping container, gets to 54 degrees tops, maybe 35 degrees. I’ll have to see what the temperature at the vents are.

[Jwarwick]

Just out of interest has anybody tried a waste oil burner for the heating side of things. Something I’ve always considered but not too sure how effective it would be.

[openspaceman]

1 hour ago, Jwarwick said:

Just out of interest has anybody tried a waste oil burner for the heating side of things. Something I’ve always considered but not too sure how effective it would be.

Not me but heat is heat no matter the source, pollution and heavy metals are another matter.

[Dan Maynard]

Waste cooking oil? Gates broken at our pub recently and they nicked all the old cooking oil from round the back.