I’ve felt the need for a warming cabinet a few times in the last year or so. A late batch of cider failed to get started in the cold weather, and a warming cabinet, or warming pad, would have stopped the cider from ‘hanging’ and eventually being spoilt. Last Autumn I wanted to experiment with making biofertilisers, but many of them need some warmth to ferment properly. Again, a warming cabinet would have allowed me to experiment with the biofertilser. Finally, I have just bought some mushroom spawn, to grow edible mushrooms. They too need some warmth, so I finally got a grip of myself, and made one.
A quick disclaimer here. I didn’t bother looking to see how other people have made their own warming cabinets, I just knocked this one up. Please don’t copy this unless you can’t find anything better.
DIY Warming Cabinet. The Start.
I had been considering building this warming cabinet for some time, and had actually made a start on it late last year, but had been distracted. I wanted to make the warming cabinet using mostly materials that I had that were not being used. The site that I chose was in an outbuilding. The house would have been warmer, but the smell of rotting fish (biofertilzer: fish hydrolysate) would not have gone down well….. I had previously constructed a large rack on which to stack unused beehives. The shelves were large, in order to accomodate a lot of hives, so I decided to repurpose one level to use for my warming Cabinet.
One useful benefit of this building is that we had used it to breed greyhounds in about 13 years ago. So I had insulated the wooden building with four inches of insulation, and then lined the inside. This meant that my new warming cabinet would not be leaking heat to the outside. The rest of the construction was really all about providing, regulating, and then maintaining heat.
The picture below gives an idea of how big this warming cabinet will be. It shows a 5 gallon plastic fermenting vessel sat in the warming cabinet. It should hold at least 6 of these if I want it to. Cider anybody?
The picture also shows the first part of insulating the warming cabinet. The shelves are 12mm plywood, which wouldn’t be great for retaining heat. Luckily I had a roll and oddments of the silver foil insulation that I had used in my loft. It looks like bubble wrap sandwiched between thick foil. I just stapled it to the underside of the top shelf, and on top of the bottom one.
I cut the side panels from some old 19mm birch ply. Again, it was left over from another job. I had enough of the metallic insulation to do the sides, and a little left to partially cover the doors.
The picture above shows my failed plan to insulate the back walls. Despite knowing that the outer walls were going to be warm enough, I thought that I would try a layer of Aluminium foil (normal kitchen stuff) stapled on top of bubble wrap. I thought that this would give me a surface that would be easier to keep clean. Sadly the foil was too thin and kept ripping where I used staples, leaving the bubble wrap. Were I to do this again, and ran out of the proper foil, I would use gloss paint instead. The picture also shows the electrical cable and socket base for the power supply. It should be a socket capable of dealing with high humidity, but I didn’t have any available. I will replace it the next time that I pass somewhere selling them at a reasonable price.
Heating and Temperature Control
The picture below shows the two methods that I can use to heat my warming cabinet.
The white tube at the back is a greenhouse heater. It’s one of only two things that I had to buy. I bought it on ebay. The red pad on the bottom is a heat pad. I bought it to use to keep our pups warm. Unfortunately it doesn’t have it’s own thermostat, and neither does the green house heater, so I bought a plug in thermostat. Mine was a bit cheaper than the one in the link, but it works in the same way. Once the temperature that you set is reached, the plug socket is switched off, turning off anything plugged into that socket.
My plan is to use the two heating methods for different purposes. The current socket is for use with the greenhouse heater, and used for mushrooms, and anything else that doesn’t need direct heat. The heatpad will be for fermenting liquids, which can be stood directly on top of it. I’m not sure how effective the air thermostat will be for that, but I have a thermostat used with soil warming cables, and I may be able to tape the probe from that to the outside of one of the vessels.
The last job was to make some doors. I had wanted a way to use some perspex sheets, inside of the doors, but it was starting to make the job a bit complicated, so I gathered up a selection of old hinges and bolts. Luckily, when I offered up the first door to check the cutting, I saw that the wood could slide in and out rather that be hinged. This saved a lot of messing around, so I cut the second to size, and used a couple of screws to keep the doors in place when they are slid backwards and forwards. The picture below shows the doors partly open. You can see that i have used two different materials for the doors, ply and OSB, because that’s what I had available. It would have looked nicer to use the same material, but not if it meant spending more money.
The Picture below shows the doors shut. The inside should stay warm and dark.
There are still a couple of small jobs to do before the warming cabinet is finished. The doors need some handles. I’ll look for something cheap if I can. if not I’ll use some scrap wood. I also need to wire the plug socket. I decided to wait, as I’m out tomorrow, and if I can find a cheap socket that will be better in a humid environment, I’ll get it. Otherwise it’s a quick job to do, and will be finished tomorrow.
Overall I’m delighted with my warming cabinet. Using materials that I had available has kept the cost to below £30, with only a better plug socket still to purchase. The insulation should reduce the amount of energy that it uses to operate, and it has been easy to make, using the existing shelving that I had previously built. I still need to wire it up and test it, but that should be realtively easy to do. Most importantly, I can now get my mushroom spawn started off, and then begin making some biofertizers ready for Spring.