Cheap heater/thermostat for warming cabinet.

[rae]

But I really wouldn't recommend a PID for a honey-warming cabinet ...

Nor would I. I would only settle for a 16bit microcontroller for accurate temperature resolution, with software (complex software) to handle the hysteresis of the containment with respect to temperature overshoot. I'd be logging the temperatures to a database (clustered, active/active for reliability), with replication to a failover site at least 100 miles away.

Er, no. Small fridge, 40W bulb, leave it on for 24 hours with a big bucket of honey in it. Job's a good 'un.

 

[peteinwilts]

no need to go too technical... A lamp and a thermostat in an old chest freezer works for me.

over 40 degrees and the enzymes start to break down reducing the quality of the honey.
i prefer 48 hours at 30 degrees...

 

[JamezF]

As I have an old 600mm wide chest freezer sitting around, I've just purchased a Dimplex 60W greenhouse tube heater from ebay for about £12, and a Siemens hot water cylinder thermostat with a 20C to 90C range for a similar price from Screwfix. Hopefully after a bit of wiring and woodwork this weekend I should end up with a neat little warming cabinet.

James

 

[Alabamaeee]

I deliberated for a long time over what to fit into my converted fridge.

After reading a thread on this forum I decided rather than buy a separate thermostat and wire up bulbs to buy an element with thermostat already fitted.

It has worked out well and has good temperature control

I went for the 100 egg

http://www.ascott-dairy.co.uk/acatalog/Poultry_Incubator_DIY_Kits.html

Pretty much the same heating set up as one of the biggest Beekeeping suppliers sells only a fraction of the price.

If the link above gets trashed Google Ecostat Incubator.

Previous thread on warming cabinets

http://www.beekeepingforum.co.uk/showthread.php?t=12990&highlight=ecostat

 

[itma]

As I have an old 600mm wide chest freezer sitting around, I've just purchased a Dimplex 60W greenhouse tube heater from ebay for about £12, and a Siemens hot water cylinder thermostat with a 20C to 90C range for a similar price from Screwfix. Hopefully after a bit of wiring and woodwork this weekend I should end up with a neat little warming cabinet.

James, I'd suggest a central heating *room* thermostat might be a better bet than a hot water cylinder 'stat, if you are trying to control the temperature of the *air* inside the old freezer. Just locate it where it won't be splashed, but can experience the typical temperature of the enclosure.
Most only go to 30C, but some *do* go up to 35C ... one example being the Sunvic TLX9000 series. For example http://www.ebay.co.uk/itm/SUNVIC-TLX9201-220-240V-10A-5-C-35-C-ROOM-THERMOSTAT-/270466665686

And any little (scrap computer?) fan, powered from a (correct voltage) fat-plug transformer will help to stir the air and even out the temperature.


ADDED - however if you really want to use that cylinder stat, one neat way might be to use an ex-pc cpu cooling fan and heatsink. If you attached the tank stat to the heatsink, then while the fan was running, your stat would 'see' a representative air temperature for the enclosure, smoothed by the small piece of aluminium ...

 

[JamezF]

I struggled to find a room thermostat higher than 30C when I looked, which was why I went for the cylinder version. Is there *really* that much difference between them? Neither is exactly a very high-tech device. Perhaps the room thermostat has a bit more thermal mass, but it can't be much. Are they designed to have a "wider" hysteresis loop?

I can certainly fit the cylinder thermostat to a fan and heatsink. I have more of those lying around than I know what to do with. I wonder if the fan really needs to run all the time. If not, I could connect a pair of 13A sockets to the thermostat and power the fan from a wall-wart plugged into one with the heater plugged into the other. On the other hand, does it matter if the fan runs all the time if the wall-wart is in the cabinet? It's only another form of heating, after all...

James

 

[Alabamaeee]

I fitted a 12V computer fan that i had lying around. It runs off an adapter plugged into the 13 amp socket, and it has a speed control on it so it just runs slowly and circulates the air nicely.

The Ecostat when set up correctly can keep the temp within 1-2 degrees of the set temperature. Tank stats and room stats are not as accurate, but I expect it depends on how accurate you want to make it

 

[JamezF]

I've found a 110mm 12V fan in my drawer of old fans and heatsinks, together with a reasonable size aluminium heatsink (though at the moment I'm considering just having the cylinder thermostat pressed up snugly against the freezer lining as that is metal, probably aluminium), and a 6V wall-wart, probably from a Sony Discman (I never through the power supplies away -- they always come in handy eventually That seems to turn the fan sufficiently quickly to circulate the air inside the freezer compartment. I could probably use an even lower voltage one, but the Sony was the first one I pulled out.

I think I'll leave the fan running all the time, even when the heater isn't on, to keep the temperature more even throughout the cabinet.

James

 

[Poly Hive]

Just to stir the pudding.

I had a chest freezer with a immersion thermostat wired to three 60 watt bulbs, and the stat was mounted about four inches from the top of the side.

In that chest I used to warm up to 270 pounds of honey and it worked a treat. I was remote from the premises so we used a timer to shut it off or put it on again if needed and that set up worked very well indeed.

BTW so does blowing warm air through your supers pre extraction.


At the end of the day the techie stuff is to warm honey to a reasonable temp it ain't rocket science and there is a risk of over engineering. KISS all....

PH

 

[oliver90owner]

Tank stats and room stats are not as accurate

It's not accuracy that is needed, just reproducibility within the range required. Hysteresis is not so important but may depend on the system design. Modern triac controllers are far better than mechanical bi-metallic strip relays, IMO.

One or two incandescent light bulbs were adequate for many for a lot of years, so any sophisication beyond that may only be an exrtra expense or added complication. The tungsten bulbs were neither ideal nor the safest approach, but did the job. I would not advocate making one where the heater, or any high voltage connections could come into contact with liquid.

Being safe and failng safe are the two important design requirements.

RAB

 

[itma]

I struggled to find a room thermostat higher than 30C when I looked... Is there *really* that much difference between them? Neither is exactly a very high-tech device. Perhaps the room thermostat has a bit more thermal mass, but it can't be much. Are they designed to have a "wider" hysteresis loop?

I can certainly fit the cylinder thermostat to a fan and heatsink. ... I wonder if the fan really needs to run all the time. ...

There are some cheap 35C designs, but 30 is definitely more common!
Here's the PDF datasheet for another that can be found on eBay http://url=http://www.horstmann.co....tral-Heating/HRT3UserandInstallationGuide.pdf

Actually, a room stat should have a lower thermal mass (more sensitive, because air has such low thermal capacity) and likely a tighter hysteresis characteristic - the HRT3 (linked above) claims a 'switching differential' of 0.5C

But whatever you go with, I'd suggest that you use a known-accurate thermometer to actually measure the temperature, using the "stat" to hold the desired temperature, regardless of what the dial setting that gives you that result might claim.

I was thinking that moving the air over a small heat sink (in intimate contact with a tank stat) would be the best way of maximising the responsiveness of the tank stat to changes in the chamber air temperature - so I'd suggest that the fan needs to be running to achieve that.
In any case, I think the fan would be best running all the time the chamber is in use.

 

[JamezF]

BTW so does blowing warm air through your supers pre extraction.

I did have it in the back of my head that it would be handy if whatever solution I make is suitable for warming entire supers of OSR honey prior to extraction.

James

 

[JamezF]

One or two incandescent light bulbs were adequate for many for a lot of years, so any sophisication beyond that may only be an exrtra expense or added complication. The tungsten bulbs were neither ideal nor the safest approach, but did the job. I would not advocate making one where the heater, or any high voltage connections could come into contact with liquid.

Being safe and failng safe are the two important design requirements.

This is one of the reasons I've gone with a greenhouse tube heater. It's pretty much "wipe clean" if honey is spilt on it, and has no external electrical connections so even if it gets the odd splash of water it should be fine. It's probably a far "nicer" environment than the one it's intended for.

Another reason is that we seem to get through light bulbs at an astonishing rate here. We're straight off an 11kV transformer and whilst I've tried to persuade Western Power to wind things down a bit, we're still at 245V+. I reckon a lot of modern light bulbs are designed for around 230V and we're at the margins of the design spec. Running them at that voltage *and* at 35C+ is just asking for regular failures. With incandescent bulbs becoming more awkward to get hold of, it's easier to avoid the entire problem in the first place.

With the tube heater I've got pretty much all the bits I need to do the job, too. If I add up the cost of bulb, lamp holder and a bit of cable, the difference between the two is barely a few sheets of foundation.

James

 

[JamezF]

But whatever you go with, I'd suggest that you use a known-accurate thermometer to actually measure the temperature, using the "stat" to hold the desired temperature, regardless of what the dial setting that gives you that result might claim.

Yes, I was thinking that would be a good plan to get it set up. After that it really doesn't matter what the controller reading is as long as it's repeatable.

James

 

[Alabamaeee]

Tank stats and room stats are not as accurate


One or two incandescent light bulbs were adequate for many for a lot of years, so any sophisication beyond that may only be an exrtra expense or added complication. The tungsten bulbs were neither ideal nor the safest approach, but did the job. I would not advocate making one where the heater, or any high voltage connections could come into contact with liquid.

Being safe and failng safe are the two important design requirements.

RAB

Rab,

That's the main reason I chose the EcoStat, A wall wart supplies the heater and the heater is enclosed. Also as it's mounted at the top of the cabinet with a continuous fan running means no chance of liquid hitting it.

I checked it yesterday as I have some more honey to go in, and over two hours of running at 38 degrees it sat within 1 degree.

If anyone is a back to the land type it could also double up as an icubator heater and produce a few chicks for the smallholding