TUTORIAL
Controlling temperature in the kitchen
You’ll also need a hole through to the smaller box for
the wires for the heater.
The second step is to mount the smaller box so that
it’s held in place while the insulation is packed around
it. We did this with some 18 mm-wide wood that fitted
in perfectly; however, you will have to improvise as
your gaps are unlikely to be the same as ours. We
screwed the wood to the smaller plastic box, then
positioned this box at the appropriate place inside thelarger one, and screwed it to that as well. This held the
smaller box off the bottom of the larger box and with
gaps all around it. We filled these gaps with cut-up bits
of plastic. We packed it in quite densely as this should
provide more insulation.
The insulation should also cover the top half of the
box, so we need to extend the sides of the smallerbox upwards. We happened to have some modelling
foam left over from a previous project, so in the spirit
of reducing waste, we used this. Really, you can use
any moderately stiff plastic sheet. We tried a few
options for holding them in place, but found that
T-Rex tape worked best. It doesn’t have the most
aesthetically pleasing look, but we’re building with
rubbish, so aesthetics aren’t our top priority. We built
the walls up as high as we could without blocking
the lid.
You’ll also need insulation on the lid. We just
happened to have an Amazon Prime padded envelope
the same size as the lid. We filled this with more cut-
up plastic to add extra insulation and taped it to the
inside of the lid. This padding on the lid should push in
and fit snugly with the padding around the side of the
main box.
It’s worth noting that we’re not worrying about if
any of this is food-safe – this is because whatever
food we put in this heat box will be in its own food-
safe container, and this contraption shouldn’t come
into contact with any foodstuffs.
That’s everything in the right place; it’s time to wire
up the electronics. Your 12 V input should go into the
temperature controller, but it also needs to go to the
heat pad – the temperature controller doesn’t power
the heat pad directly, it just turns a relay on and off.
The wiring goes like this: 12 V goes into one side of
the relay. One heat pad connection goes into the other
side of the relay (it’s not polarised so can go in either
way around), and the other heat pad connection goes
to ground. You can do this using the screw connectors
in the back of the temperature control unit, so no
other soldering or wire joints are necessary.You’ll also need insulation on the lid. We just
happened to have an Amazon Prime padded
envelope the same size as the lid”
”
Right
While it may not
look pretty, our
temperature-
controlled box is both
insulated and helps
reuse waste plasticREDUCING WASTE
We could have built this temperature-controlled box in many ways, but we chose to
use otherwise waste plastic as the insulator. Humanity is currently producing huge
amounts of single-use plastic that then ends up littering the planet for generations
to come. As makers, we can find ways of using this resource rather than just
consigning it to landfill. This build was one attempt to do that.
If you’ve got other ideas for how we can reuse rather than waste plastic, we’d
love to hear them. Drop us an email at [email protected] or message us
on social media.