Kiln/flue curing chamber build design questions.

[Chillucky]

Ladies and gentlemen,

This is the year I finally build a flue curing chamber. My kiln just melted because the temperature controller failed to turn off the hot plate. So I plan to take the opportunity to build a dual purpose, programmable climatic chamber.

I will construct a (second) well insulated box, about 24 deep X 36 wide X 48 tall on the outside with a well sealed door that has an observation window. However, this time around I am going to attempt to have separate arduino controlled and programmable temperature and humidity sources physically outside of the chamber piping their heat and vapor in to avoid using a crock pot inside. Which clearly works well for most of you, but failed spectacularly for me.

My first (of many) question is has anyone used a home humidifier as a source of humidity in either a kiln or a flue? I believe that if I can find a relatively "dumb" one, I can just have it come on when the RH sensor falls below a threshold and turn off when it reaches it.

Put it in-line with the heating element and driven into the chamber by my 'harsh environment' computer fan ought to work I think. But I admit my engineering training never really got started.

 

[Yultanman]

If you are already operating your fans and temp via arduino then any simple humidifier can be tapped into a relay unit no problem. I wouldnt put it inline with the heat. Get a dht22 for the sensor and youll have humidity readings as well

i hope you share you end code. This is on my project list too

 

[Chillucky]

I will absolutely share whatever I learn, which will be everything, as I am starting out with no knowledge or experience with arduinos (or any electronics/engineering).

I had what I thought was a nice enough PID controller operating as a thermostat on the crock pot kiln. But that did not work out. I'm willing to have that be my fault, but either way I've gotta build a new thing.

My second overarching design question is re: a fresh air intake and/or vent. I see that AmaxB's flue has a solonoid controlled vent to let off excess humidity. My hope is to get away without such a thing by controlling the amount of humidity that goes into the chamber throughout the cure. Any thoughts or experiences?

 

[Knucklehead]

Ladies and gentlemen,

This is the year I finally build a flue curing chamber. My kiln just melted because the temperature controller failed to turn off the hot plate. So I plan to take the opportunity to build a dual purpose, programmable climatic chamber.

I will construct a (second) well insulated box, about 24 deep X 36 wide X 48 tall on the outside with a well sealed door that has an observation window. However, this time around I am going to attempt to have separate arduino controlled and programmable temperature and humidity sources physically outside of the chamber piping their heat and vapor in to avoid using a crock pot inside. Which clearly works well for most of you, but failed spectacularly for me.

My first (of many) question is has anyone used a home humidifier as a source of humidity in either a kiln or a flue? I believe that if I can find a relatively "dumb" one, I can just have it come on when the RH sensor falls below a threshold and turn off when it reaches it.

Put it in-line with the heating element and driven into the chamber by my 'harsh environment' computer fan ought to work I think. But I admit my engineering training never really got started.

I‘d like to hear more details about the failure. If what I am currently doing could burn my house down I would like to know before hand. I‘m wondering if a second PID with a temp set to turn off the crock pot if the first PID blanks out could work. Maybe? It would be cheap insurance.
Also how did the foam react? Did it burn or melt? Was there fire or did it come close? Did the foam scorch the wooden structure? Did the breaker trip and need to be reset? You could save some of us from our own catastrophic failure or worse. Thanks.

 

[Chillucky]

The first and most important thing to note is that my kiln was unattended. It is not at my home, but in a shop space I sublet and get to about once a week (thus my desire for a safe and automated chamber for the future).

I was unhappy with how it was performing. I was getting temps in the 80°f range with humidity approaching 100% with the thrift store, 300W crock pot on high and the temperature controller (I think) set to reach and hold 110°f. So I took the crock full of water out on a Tuesday evening, assuming it would work like the hotplate/electric fry pans I have seen here.

When I got back to it on Sunday, the door was stuck shut. I opened my observation window to find that the acrylic sheets that were acting as window panes were very warped. I pried the door open to find the crock pot's plastic deformed around the power control, and the cheap plastic thermometer/hygrometer I got from the home center was a lump on the ground.

The foam and tape was pretty much ok except for where it had been pulled on by the window. There was no evidence of flames. So, as failures go, not a bad one.

 

[deluxestogie]

My immediate thought is that your insulation was inadequate. Also, the crockery is required to dissipate the heat from the metal liner of the base.

Bob

 

[Chillucky]

Clearly not having the crockery on the element was the bulk of the issue, then. Despite what it might suggest or foreshadow about my engineering skills, I am not trying to do a post mortem on the first kiln build (2" foil-faced iso foam, caulked and taped seams inside a plywood box). I am trying to make a new programable climatic chamber!

 

[ChinaVoodoo]

I always put tile around and under my heat source just to be extra safe. Just loosely. There's no need for perfection.

 

[Chillucky]

This controller intrigues me. It's more expensive than the combined arduino elements I am thinking of, but doesn't require me to learn electronics or programming. The free app can handle a few simple "programs" for temp and humidity set points over time, tho it doesn't look at first glance like it could do a whole flue curing schedule without intervention.

Does anyone have experience with it? Looks like they sell it to home sausage curers and cheese makers for controlling those environments. Seems applicable.

The higher level design question of needing a vent becomes more important now. If I can reasonably expect humidity to go down as temperature rises just by not turning on the humidity source, this controller would work. If a well-insulated chamber would hang on to moisture during the temperature rises in the curing cycle, I will need to also control a vent and/or fan as well, so this device would not be a complete solution for me.

Any advice about the vent issue?

 

[Knucklehead]

This controller intrigues me. It's more expensive than the combined arduino elements I am thinking of, but doesn't require me to learn electronics or programming. The free app can handle a few simple "programs" for temp and humidity set points over time, tho it doesn't look at first glance like it could do a whole flue curing schedule without intervention.

Does anyone have experience with it? Looks like they sell it to home sausage curers and cheese makers for controlling those environments. Seems applicable.

The higher level design question of needing a vent becomes more important now. If I can reasonably expect humidity to go down as temperature rises just by not turning on the humidity source, this controller would work. If a well-insulated chamber would hang on to moisture during the temperature rises in the curing cycle, I will need to also control a vent and/or fan as well, so this device would not be a complete solution for me.

Any advice about the vent issue?

I’ve heard of Auber Instruments and best I can remember they have a good reputation. Based in Alpharetta, Ga. If you look at their products on Amazon, most seem to have 4.5 to 5 stars. The WiFi feature would be helpful for you since your curing chamber is remote from your location. The Auber Instruments website has a forum for discussion, some of your questions may already be posted there or you could post some questions for feedback.

Auber Forum - Index

Auber Forum - Index

www.auberforums.com

 

[ChinaVoodoo]

This controller intrigues me. It's more expensive than the combined arduino elements I am thinking of, but doesn't require me to learn electronics or programming. The free app can handle a few simple "programs" for temp and humidity set points over time, tho it doesn't look at first glance like it could do a whole flue curing schedule without intervention.

Does anyone have experience with it? Looks like they sell it to home sausage curers and cheese makers for controlling those environments. Seems applicable.

The higher level design question of needing a vent becomes more important now. If I can reasonably expect humidity to go down as temperature rises just by not turning on the humidity source, this controller would work. If a well-insulated chamber would hang on to moisture during the temperature rises in the curing cycle, I will need to also control a vent and/or fan as well, so this device would not be a complete solution for me.

Any advice about the vent issue?

I had two of those. One failed and despite being set for fail safe heat circuit off, it resulted in cooking and killing all of my seedlings.

I haven't used the other one in a few years. I think there is a problem with it. I'm not sure what the best humidity controller is, but I doubt it's that. I'm using a dedicated humidity controller now, but it's not very precise.

 

[Oldfella]

Ladies and gentlemen,

This is the year I finally build a flue curing chamber. My kiln just melted because the temperature controller failed to turn off the hot plate. So I plan to take the opportunity to build a dual purpose, programmable climatic chamber.

I will construct a (second) well insulated box, about 24 deep X 36 wide X 48 tall on the outside with a well sealed door that has an observation window. However, this time around I am going to attempt to have separate arduino controlled and programmable temperature and humidity sources physically outside of the chamber piping their heat and vapor in to avoid using a crock pot inside. Which clearly works well for most of you, but failed spectacularly for me.

My first (of many) question is has anyone used a home humidifier as a source of humidity in either a kiln or a flue? I believe that if I can find a relatively "dumb" one, I can just have it come on when the RH sensor falls below a threshold and turn off when it reaches it.

Put it in-line with the heating element and driven into the chamber by my 'harsh environment' computer fan ought to work I think. But I admit my engineering training never really got started.

My thoughts on a home humidifier is that it would be, 1: way too big for the job and may cut in and out to much. 2: expensive to run. You can get smaller USB powered units very cheaply. A lot safer as they are low voltage. I'm going to try one in my new kiln. Keep an eye on my kiln build thread as I will keep it updated as I go.
Cheers Oldfella

 

[ChinaVoodoo]

How would you construct an ultrasonic humidifier from scratch, I wonder. The transducer is nearly the same as the metallic alarm "speaker" in an alarm clock. I think it is just a matter of sending a signal of the right frequency. Maybe a step-up transformer attached to a speaker is all you need.

 

[Oldfella]

How would you construct an ultrasonic humidifier from scratch, I wonder. The transducer is nearly the same as the metallic alarm "speaker" in an alarm clock. I think it is just a matter of sending a signal of the right frequency. Maybe a step-up transformer attached to a speaker is all you need.

Google it.
Oldfella

 

[ChinaVoodoo]

Google it.
Oldfella

Well, crap. I'll just ask tobacco questions.

You were right though. Google had the answers. It's pretty much as I theorized.

 

[Yultanman]

My second overarching design question is re: a fresh air intake and/or vent. I see that AmaxB's flue has a solonoid controlled vent to let off excess humidity. My hope is to get away without such a thing by controlling the amount of humidity that goes into the chamber throughout the cure. Any thoughts or experiences?

I realized i was over thinking this when i got onto servos and solonoids and think that a louvered exhaust/intake with arduino controlling the fans would be sufficient

 

[ChinaVoodoo]

I realized i was over thinking this when i got onto servos and solonoids and think that a louvered exhaust/intake with arduino controlling the fans would be sufficient

There are competing factors. I think you want it as sealed as possible for efficiency, and maintaining humidity during kilning. During kiln-use, if it's exposed to the outdoors or an unheated Saskatchewan garage, you may get a lot of ice or condensation and louvers may stop working, so you would have to block it off completely.

So for venting during curing, because you need to get rid of moisture in the leaves, what I feel works better, (and it was my experience with a 225 cubic foot curing shed), that two small 1.9"OD pipes through the wall with a single fan blowing out one of them, and one passively letting air return. It's easy to seal and doesn't affect heat loss all that much but was big enough that a decent snail shaped (princess auto) fan can remove enough moisture.

 

[ChinaVoodoo]

I don't know if this is the exact fan, but this little thing or something like it was sufficient to vent a 4'x8'x7' (internal dimensions) tobacco shed.

 

[Oldfella]

I had two of those. One failed and despite being set for fail safe heat circuit off, it resulted in cooking and killing all of my seedlings.

I haven't used the other one in a few years. I think there is a problem with it. I'm not sure what the best humidity controller is, but I doubt it's that. I'm using a dedicated humidity controller now, but it's not very precise.

Hi China, what brand of controller are you using for humidity control? I've got three one is temperature only (used for home brewing)the other two are both temperature and humidity I'm thinking after reading this that I might use the temperature only one as a failsafe. Re the use of solenoid control you can get a little bit over kill here, the more complicated you make it the more things you have that can go wrong, and when it goes wrong very hard to troubleshoot. Read all the posts on kiln building and keep it simple. Nearly everyone here has built one and all seem to have different ideas but on the whole they all seem to work. My first kiln was an old fridge and crock pot with a computer fan and a temperature controller only I never worried about the humidity. It performed well. The downside was probably poor insulation. My thoughts are that if you start adding more electronics to it then you should have a service and maintenance manual. The reason I say this is because when it all goes wrong (which it will at some time) you will never remember what went where, when or how.
Cheers Oldfella
I presume that fan is variable speed it looks a bit savage.

 

[ChinaVoodoo]

I have one of those Auber instruments plug and play dual temp and humidity jobbies. I don't trust the temperature side as I had a failure before on an older model. And then I have a C.A.P. - HUM-1 which is analog and doesn't have very tight control, but can simultaneously control separate lines for humidifier and dehumidifier.