Need Advice Quickly About Cold Weather/kiln Operation

[DirtRoads]

The coldest weather I've seen with my kilns is around 25 degrees (F).  Kilns are enclosed carport with no wind blowing in .  In 25 degrees coldest room gets is about 40 degrees.  

 

Expecting a low of 11 degrees.  What temperature do I need to run kilns?  Seems like I read room temp needs to be 32 degrees (F).   What are the guidelines?

 

Kiln schedule is

 

Bisque kiln firing Monday morning - Outside Temp expected to be around 20 degrees

Glaze kiln firing Monday night - Outside Temp  15 degrees dropping to around 11degrees

Bisque kiln firing Tuesday night-  Outside Temp around 30 degees

Glaze kiln firing Wednesday morning Temperatures 35/47 .... back to normal

 

Should I just skip firing on those 2 days?

[Chilly]

What do your kiln and controller manuals say?  My controller says storage temp of -20 to +50 deg C, with an operating temp of 0 to 50 deg C.  (From memory)

[DirtRoads]

Thanks Chilly.  It says "in cold weather raise the temperature of the kiln's switch box to at least 32 degrees (F) (0 degrees C) before operating with a space heater." (its 0 to 50 C like yours)

 

So as long as it's 32 degrees on controller temperature, you can fun kiln.   I suppose that once kiln starts, temperature will keep rising and ambient temperature in room has no effect?     Can't imagine these low temperatures wouldn't affect the kiln's firing  but  it seems it's only the temperature on the controller that matters?

[Chilly]

I ran mine when overnight low was predicted to be 3 deg C,  My kiln is in a greenhouse! The minimum inside temperature that night was 14 deg C and the max was about 20.  Windows were open for ventilation and power cable entry, so I guess the heat from the kiln will keep the controller warmer than otherwise.  Good luck.

[bciskepottery]

You need the controller temperature to be above freezing . . . so the electronics (thermocouples, relays, etc) work properly. Once kiln gets going, the controller box will stay warm. Your controller is a computer; it doesn't work well in extremes. So, it might be good to have a heater on at the controller level for a pre-firing warm up and then during the initial firing schedule. Similar to folks using a fan to keep the controller from overheating during summer and hot days.

[akin4843]

what about if your kiln is an old manual one with no digital controller (like mine)? does the warming up still apply?

[neilestrick]

For manual kilns you do not need to heat it up. However you may want to put a space heater there to make loading less awful.

[akin4843]

For manual kilns you do not need to heat it up. However you may want to put a space heater there to make loading less awful.

Haha, true! Thanks...

[DarrellVanDrooly]

I don't know what my kiln manual says, but I fire in Colorado blizzards (down to -20 degrees) and my kilns do just fine.

 

Darrel

[hershey8]

I was worried because it will be about 5 degrees here in north Georgia in the morning. My manual kiln (Kiln sitter) just turned off and is in cool down mode with all peeps in place. My basement my hit the 40's by morning. But this sounds mild compared to Colorado. My Skutt has 2 1/2 inch thick bricks. Will this temperature make things cool too fast?  Right now basement is about 60 f.

 

                                                                                                                    ja

[kayleyvdb]

On 1/5/2014 at 2:28 PM, Chilly said:

I ran mine when overnight low was predicted to be 3 deg C,  My kiln is in a greenhouse! The minimum inside temperature that night was 14 deg C and the max was about 20.  Windows were open for ventilation and power cable entry, so I guess the heat from the kiln will keep the controller warmer than otherwise.  Good luck.

@Chilly it’s been awhile since this post but I’m wondering if you use a programmed cool cycle when temps are this low! If so, would you be willing to share? 

[Callie Beller Diesel]

@kayleyvdb I also have a kiln outdoors in an unheated garden shed. It’s not necessary at all to down fire if temperatures are in the 14 C (57 F) range. I don’t down fire even when it’s -20 C (-4 F).  The difference in cool off times between my summer and winter firings isn’t significant. The relative difference between top firing temperature/room temperature and top firing/freezing isn’t that great. 

[liambesaw]

I don't downfire ever, in fact I have a bisque load taking forever to cool down right now as it is, and it's below freezing

[Bill Kielb]

11 hours ago, kayleyvdb said:

it’s been awhile since this post but I’m wondering if you use a programmed cool cycle when temps are this low!

If it makes you feel better 0 degrees is really cold for people but to a kiln  that is firing cone 6 (2232f) it’s at best 50 degrees colder than what we would consider comfortable to fire a kiln at. Who would worry if it was 50 outside?  Maybe 2% faster cooling at top temp so the fire down schedule would be very minor to compensate. If the first hour average cooling was 500 degrees per hour then you would be offsetting it slightly by adding about ten degrees to the rate for the first hour. I would try without at first Unless you are not already using a schedule to fire down for a specific look. Then I would just use that schedule.

[Chilly]

On 11/7/2020 at 8:30 PM, kayleyvdb said:

@Chilly it’s been awhile since this post but I’m wondering if you use a programmed cool cycle when temps are this low! If so, would you be willing to share? 

I think the only time I run a programmed cooling cycle is when I'm firing fused glass.  Can't remember ever needing one for bisque/^04 firings.  I have run cooling cycles for some ^6 firings, but not in my kiln, only at a community centre.

 

As others have said, cooling is such a slow process.  My kiln drops 200C in about 2 minutes and then takes the rest of the day to drop to ambient.

[Dick White]

Just my opinion, but there seems to be some misunderstandings about programmed cool cycles. Such controlled cooling relates to promoting formation of microcrystalline structures in a glaze over a few hours while it is still hot enough that there is some residual fluidity in the melted glaze. For cone 6 glazes, this is in the temperature range of 2000℉/1100℃ down to ~1800℉/975℃. As Chilly notes above, a kiln will immediately drop 200℃ in just a few minutes, and another 200℃ in just a few more minutes, and now it has gone through and dropped out of the critical temperature range for development of these glaze surfaces. Whether it is summer or winter, this rapid drop from peak temperature will occur without controlled downfiring. Yes, the full cooling time back to ambient seems like forever, but the vast majority of that extended time is the last few hundred degrees,  which is not when controlled cooling is used. In fact, controlled cooling below 1500℉/800℃ is basically irrelevant because the natural cooling rate of the kiln below that temperature is slower than you would program, and thus the kiln controller would effectively turn itself off anyway in a futile effort to cool faster. And for bisque, controlled cooling is irrelevant, there is no glaze development involved. And yes, for fused and slumped glass, controlled cooling is necessary to properly anneal the glass.

[SMMC]

On 1/9/2014 at 9:50 PM, DarrellVanDrooly said:

I don't know what my kiln manual says, but I fire in Colorado blizzards (down to -20 degrees) and my kilns do just fine.

 

Darrel

Reviving this old post. I'm in MI with an old manual Duncan and hope to fire it in sub zero temps. Finger crossed it goes well. 

[Hulk]

A bit lower glaze fire peak/target and an hour hold 100F below said peak (then all three zones on "low" until 1850F) cleared up some problems for me, per Tony Hansen's article

https://digitalfire.com/glossary/drop-and-soak+firing 

For bisque, am slowing down through the important temps on the way up, and, if firing red or dark clays, on the way down as well.

[Dick White]

9 hours ago, SMMC said:

Reviving this old post. I'm in MI with an old manual Duncan and hope to fire it in sub zero temps. Finger crossed it goes well. 

A manual kiln is not affected by extremely low temperatures. Fire away.

FWIW to others reading here, a digital controller may refuse to start at extremely low temperatures, because it must rely on the electrical signal from the thermocouple to "know" what the temperature is inside the kiln and decide what to do about it, i.e., to turn the elements on for more heat or not turn the elements on for more heat, that is the question. The problem is that thermocouples do very strange things at sub-freezing temperatures, so the controller is programmed to not start if it senses the temperature is too low for the thermocouple to be relied upon. 

[Bill Kielb]

Not that it matters but Thermocouples are fine below zero, just kiln controllers don’t support their output. At 32 degrees they are 0 millivolts and can easily measure temperatures colder that -300 f. We use them all the time to measure freezer temps. For whatever reason, kiln control companies have chose to not support below 32f. Must save them on components. It is a fair point though as most controllers won’t start at this temperature, but almost all electronics easily function below zero without damage, so a bit confusing to those that do not know this. Good point!