Thermostat controlled light-bulb (for home brew)

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LarzGearbox

37 posts

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#108533 31-Aug-2012 13:14

I realise this might fit better in a forum about home-brewing, but figured the people here would be more knowledgeable about all things electrical.

I'm wanting to build a box, insulate it and wire in a light bulb attached to a thermostat to keep it at a certain temperature (around 20c), this will be used to store my homebrew barrel and ensure the best possible brew.

The only thing I'm a bit unsure on is the thermostat and light stuff, I found this, which is pretty much exactly what I want.....

http://www.homebrewtalk.com/f51/cheapest-diy-fermentation-chamber-possible-292207/

Anyone know where I can get an appropriate thermostat from (ideally cheap if not free), can I pull apart an old heater???

Any risks?? I assume having a light bulb turning on and off for a week inside a contained wooden box or so isn't too much of a fire risk??

bmoff

158 posts

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#679780 31-Aug-2012 16:37

Jaycar Cat# QT7200. I use one to temp control a cabinet I use to grow mealworms in.

Niel

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#679789 31-Aug-2012 16:47

When I was working at an R&D company for a navy (not NZ) I was told they use 40W bulbs as that is the maximum that will not set an oily rag on fire if accidentally left on it. So use a low wattage bulb.

The thermostat out of an oil fin heater works well, and if out of the range you want then you can adjust it (there is a small set screw on the back). You also get a thermal switch which is at a fixed temperature (you buy it with what you want). Both of these options however will have a hysteresis of about 5 degC.

Digital controllers are nice as they give a readout, but can get expensive.

I'd be more concerned over mains safety and house insurance. You need to use double insulation everywhere, and cable tie wires together so that if one comes loose then it will not touch where it should not touch.

I'd put polystyrene around it. Will reduce the power used and reduce the risk of fire.

I'd also consider adding a small fan to circulate air inside the box else you probably get hot and cold spots.

You can never have enough Volvos!

gzt

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#679836 31-Aug-2012 18:03

Brewing heatpads are usually around 25W so maybe that is all the power you need.

A radiant barrier like tinfoil on the inside of box might be useful if you have some around.

You could monitor the temperature and see how it goes. It is possible you may not need a thermostat.

timmmay

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#679872 31-Aug-2012 19:09

Maybe a premade heat mat would be safer, easier, and maybe even cheaper. I know they have them for greenhouses, you just adjust the insulation/ventilation to get the temperature set where you want it.

gzt

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#679877 31-Aug-2012 19:21

$50@brewshop

Projects are more satisfying and can be quicker than a trip to the shops if you have parts lying around.

Warehouse sells a single electric blanket for $9.95. You would not want to fold that into a mat but it would work well in some configurations.

Btw, I'd feel safer with a low wattage lightbulb in an enclosure of my own design if cost was the issue.

B1GGLZ

1961 posts

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#679879 31-Aug-2012 19:23

I used to use aquarium heaters in my Hydroponic tank (outdoors and uninsulated) when living in Rotorua. Set to 23 degrees and worked very well. I often wondered if they would work just as well in a brew tank.

nickb800

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#679880 31-Aug-2012 19:29

What I did for heating back when I brewed was to use an aquarium heater. These can be had for ~$20 on trademe, and have a built in thermostat. Get a barrel that's bigger than your brew barrel, place the brew barrel in it and surround with water, then drop in the aquarium heater.

E.g. http://www.trademe.co.nz/pets-animals/fish/other/auction-508386823.htm

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Niel

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#679900 31-Aug-2012 20:57

Maybe wrap an electric blanket around it with a temperature sensor (those indoor/outdoor ones with a sensor on a wire), then adjust the blanket setting to get the correct temperature? Electric blankets run on low voltage so it is safe from the controller onwards, but the wire spacing might be an issue so when you wrap it give the second layer an offset so its wires go between the wires of the first layer.

You can never have enough Volvos!

timmmay

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#679924 31-Aug-2012 22:11

I once spent a weekend building a home theater system cabinet cooling system. For US$120 I could've bought one pre-built and spent the weekend relaxing.

Pock

156 posts

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#680032 1-Sep-2012 11:01

timmmay: I once spent a weekend building a home theater system cabinet cooling system. For US$120 I could've bought one pre-built and spent the weekend relaxing.

Yeah, but where's the fun in that!? I've built loads of electronic projects and all the fun is building.

chevrolux

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#680544 2-Sep-2012 21:02

I use an electric blanket with one of those wall timers. Have it going for 2 hours a day and the results are excellent.

LarzGearbox

37 posts

Geek

#680631 3-Sep-2012 08:04

Thanks for all the responses.

Looks like I'm going to end up shelling out for a heat pad. I remembered I have a 7 day timer thing, so will use that in the mean time and keep my eye out for a thermostat option for the future.

minimoke

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#680807 3-Sep-2012 13:06

I've used a heat pad for years. After many trials I learnt that keeping temperature bang on isn't critical. I even got to the point where I didn’t bother sterilising the gear as a quick wash was all it needed. Back on topic the heat pad works fine except on a freezing Christchurch night when I might wrap the barrel with a towel. Given the amount of gear I have a pad also saves on storage space.