Generate stable moderate heat

Hello.

I am building a hatching box for bee queens. In it, i need to be able to hold a stable temperature of 37 degrees celsius (98.6 F). Typically, i'd have an ESP32 with a temperature sensor and generate the heat with an old fashioned light bulb, controlled with a relay.

However, modern light bulbs generate little heat and the old ones aren't easy to find. I was thinking there might be a different way to generate the heat i need. Does anyone have any tips for how this might be done, safely of course, using mains electricity?

Underfloor heating mat maybe?

Or high power resistors on heat sinks, powered from low voltage?

How many watts of power should the heater consume?

There exist heating mats used to help seeds sprout, that may be a solution. Should be fairly low temperature heating.

Another option, maybe more of a direct replacement: heat lamps as sold for terrariums, giving reptiles a place to bask.

Infra red lamp ?

weedobooty:
Hello.

I am building a hatching box for bee queens. In it, i need to be able to hold a stable temperature of 37 degrees celsius (98.6 F). Typically, i'd have an ESP32 with a temperature sensor and generate the heat with an old fashioned light bulb, controlled with a relay.

However, modern light bulbs generate little heat and the old ones aren't easy to find. I was thinking there might be a different way to generate the heat i need. Does anyone have any tips for how this might be done, safely of course, using mains electricity?

Once you know the heat value needed, you can select wire-wound resistors that will produce the needed heat at the unknown voltage you are using.
Paul

I've used these in an industrial application ... a bit pricey, but rugged and produces lots of heat in a small package. Will faintly glow orange when run near their power limit.

I've had exactly this problem myself, having once built a temperature-controlled incubator (for starting seeds) using a 100w light bulb as the heat source. Following non-availability of incandescent bulbs, I changed the heat source to a large resistor bolted to a large heat sink. The combo was, alas, much more expensive than a light bulb, but still not too unreasonable. The assembly works very well.

The heat sink I used was here:

The resistor was a 60 ohm, 300w "strip heater" obtained from All Electronics Corp. It cost $14 back in 2017. Unfortunately that item appears to no longer be available, at least not from All Electronics. However, large power resistors of similar value are available. Of course, the resistance value would need to be appropriate for your mains voltage.

MPJA also sells temperature controller boards, if you don't want to build your own.
S.

These heating pads are great:

I’ve run them at 10 and 12 volts.


Google

PTC Heating Element


Go to Amazon and search for:

arduino heating pad

Cool heating pad, uhm I mean Hot!
I think the bees will find it very attractive ...

That’s my wife’s nick name Hot Honey ;).

:blush:

jremington:
How many watts of power should the heater consume?

I really don't care how many watts it consumes as long as i can keep a stable temperature of 37 degrees C.

So… how many watts of power do you need to keep your box at that temperature?

weedobooty:
I really don't care how many watts it consumes as long as i can keep a stable temperature of 37 degrees C.

You might not care from the point of view of electricity cost etc, but in order to design a suitable heater you should have some idea of the required power output.

Hi,
If you have some method of circulating air in the box, high wattage chassis mount resistors should do the job as heating elements.

MFG_UAL10.jpg
Tom.... :slight_smile:

MFG_UAL10.jpg

What is the wattage of the "old fashioned light bulb"? 15, 25, 40, 60, 75; 100, higher?

For a similar project (puppy house), I used a 300W, 240VAC 3D printer silicone "hot bed" heater, 75W at 120VAC.

Where I live heating elements like this:


Are available. They're used in these kind of electric heater and work with 200v AC:

There are also heating elements available that work with 12v and are used for car seats. And also heating elements for electric blankets.
You could also use a hairdrier heating element.

weedobooty:
I really don't care how many watts it consumes as long as i can keep a stable temperature of 37 degrees C.

As others have said, you will need some idea of the power requirement to maintain the temperature.
Also, unless the hatching box itself is located in an environment of constant temperature, you will need a temperature controller. You stated a need for a constant 37 C. Plus or minus what?
S.