Cartridge heaters to warm an FV

[oliwatts]

hi all,

I'm investigating options for the warming side of an FV temp control build.

Cooling will be via a maxi and product coil in a 70l insulated thermo pot.

I know there are methods for adding a heater inline to the maxi to warm the circulating glycol, but I can't find any reliable plans.

So:

I'm wondering about either using a high quality SS aquarium heater, or fitting a cartridge heater into an SS tube, so it can sit directly in the fermenting wort.

Any tips or thoughts welcome :)

 

[Twostage]

You can use fish tank heaters (I use 8 quid jobs from fleabay). I use a mixture of stc-1000 controlled and set and forget. I've been monitoring a set and forget and it varies the water temp by about 1.25 degrees near the surface and .2 near the bottom.

I use them both inside and outside the FV depending on size. 25 litre I put them through a grommetted hole in the lid. 10 litre I sit it in a 8 gallon tub of water and put the heater in the tub.

Experience has taught me that it is better to use an stc-1000 controller for the ones inside the FV so you don't have to open it up and risk contamination to change the temperature.:nah:

 

[ericmark]

I was also looking at a second heater and was wondering if a STC-1000 or a fish tank was best. I have something similar to STC-1000 but single relay at the moment. The tub of liquid seems good saving contamination but I was surprised to see with fridge door open how the temperature strip and temperature controller showed 4 degrees difference then realised it was because sensor is under a sponge for insulation but the strip is being cooled by ambient temperature on that day 8 deg C.

With fridge door closed likely little difference between measuring at centre and on the FV wall. But in a less insulated FV not sure on the errors. I still am not sure on errors. Use a FV full of water and test then maybe 0.3 degrees centre to wall if that. But with a fermenting brew then the unknown is heat from the brew itself. As a result I start at 19.5 and finish at 21 degrees and the question is would I need that difference if measuring from centre rather than wall. I would guess if using a fish tank heater there would be no need to vary the temperature as it's in the centre of the brew so risk of contamination is removed as no need to change temperature.

However I do kit beers and no lager if you need to cold crash then clearly very different. But since the STC-1000 has two relays then set fish tank heater to maximum so can't over heat but supply from STC-1000 so no need to access the fish tank heater when cold crashing?

 

[Twostage]

If you are using an stc-1000 then yes, set the fish tank heater to max (or at least above the max temp you are planning on).

There will be a difference between the centre of an FV and the outside edge. There will also be a difference between the top and the bottom. If you stick the probe to the outside of the FV and use multiple layers of insulation (I've tested three alternate layers of aluminium and kitchen roll) then it will read the same temperature as inside the FV at the same point.

The temp at the surface also varies the most as the warm water from the heater rises when it is on and the surface cools fastest.

I think (haven't prooved it yet, my USB temp probe has just decided it likes 20.13 degrees and sticks there) that the best place for the temperature probe of an stc-1000 is near the surface as it will then limit the maximum brew temperature.