Inkbird probe position with a plastic fermenter.

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JohnRB
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Inkbird probe position with a plastic fermenter.

Post by JohnRB » Mon Jan 23, 2017 2:48 pm

I use an Inkbird ITC-306UK Controller to control either heating trays or heating bands on standard 23l plastic fermenters.

I usually tape the probe to the outside of the FV using a packet of tissues for insulation. Ideally, I would like to measure liquid tepmerature directly.

I could drill a small hole in the lid and dangle the probe through but the probe isn't long enough (50mm) to cope with the krausen on a vigorous fermentation.

Then again I could drill a penetration through the side wall of the FV for a small thermowell. I've no experience of these. Are they available for a reaonable price? And are they worth the effort?

Then again maybe the setup I'm using (probe taped to outside of FV) is fit for purpose. Any thoughts welcome.

Thanks in advance.

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Re: Inkbird probe position with a plastic fermenter.

Post by MTW » Mon Jan 23, 2017 3:27 pm

Answer not relevant - mis-read the post :oops:
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orlando
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Re: Inkbird probe position with a plastic fermenter.

Post by orlando » Mon Jan 23, 2017 3:44 pm

JohnRB wrote: Then again maybe the setup I'm using (probe taped to outside of FV) is fit for purpose. Any thoughts welcome.
It is. You just need to set the inkbird to offset for the real temperature in the wort. Take a series of measurements of the wort temp during your next fermentation and check against what the IB is set to. You should see a fairly consistent difference, so just calibrate to take it into account or set the IB with the difference accounted for and you should see a pretty consistent ferment at the temperature you really want. I found about a 1/2 a degree was usual for my STC 1000.
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Re: Inkbird probe position with a plastic fermenter.

Post by Matt in Birdham » Mon Jan 23, 2017 9:20 pm

I agree with Orlando. I would caution against measuring the beer temperature directly (in a thermowell or equivalent) when using a simple on/off temperature controller. The lag between beer temp and chamber temp is such that you will overshoot constantly in both directions, maybe by a degree or more. I have tried this without success with my stainless conical and thermowell, and subsequently moved on to a more sophisticated Brewpi setup. I saw a very interesting post once where someone had logged temperature differentials using an STC1000 and three probe placements; chamber temp, taped to side (under insulation) and thermowell. Chamber temp gives the most stable temperatures (fastest change of temp occurs in the chamber), but with a large (and varying) difference to beer temp, thermowell the most unstable and the best was taped to side. This was relatively stable and much closer to beer temp than chamber temp (unsurprisingly) but with much less lag.
Now that I log both chamber and beer temps I have found that, once fermentation kicks off, chamber and beer temp can vary by up to 5C, which is pretty significant (biggish beer, WLP002 which goes off like a rocket). As fermentation finishes up, this difference resolves to 0 (usually about 4-5 days in).

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Re: Inkbird probe position with a plastic fermenter.

Post by MTW » Tue Jan 24, 2017 10:19 am

The reason I wiped my first reply (above) was that I don't have experience of using a belt or heated tray in combination with a taped-on probe. [I have a tube heater in a fridge, positioned under a wooden shelf, but allowing airflow]. So I'm not sure if your direct-contact heating may change things. Otherwise, I can totally vouch for an insulated probe on the side, half way up the wort level. I use two layers of bubble wrap over the probe, which seems to create just the right amount of protection against rapid swings in air temperature from the heater and fridge, while still reacting to heat from the fermentation. I have checked regularly with a thermopen and it really does mimic the centre-top wort temperature very well indeed throughout, almost always within half a C. In the absence of a multi-probe setup, it's a pretty good bet, but only experimentation will show how your heating method may affect that.
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Re: Inkbird probe position with a plastic fermenter.

Post by JohnRB » Tue Jan 24, 2017 11:23 pm

Thanks everyone for the thoughts and ideas. Reassuring to know I was working along the right lines.

I've just started to ferment a New World Pilsner and, when that's done, I'll think about calibration and insulation.

John

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Re: Inkbird probe position with a plastic fermenter.

Post by BrannigansLove » Wed Jan 25, 2017 12:09 pm

I use plumbers clay to stick to the side of the bucket about halfway up.

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Re: Inkbird probe position with a plastic fermenter.

Post by Kev888 » Wed Jan 25, 2017 2:38 pm

You have the right idea for your method, that the more you insulate a probe on the fermenter wall (and the better contact it has with the fermenter) the closer it will read to the temperature of wort inside the wall. As Orlando says, a minor compensation can help if you do find there is a slight temperature differential; this will tend to be greater the more difference there is between the wort temperature and ambient temperature.

IMO the method is perfectly fit for purpose, at least at homebrew scales, provided you can keep that differential to modest levels. No single probe location is perfect, the wort temperature isn't completely uniform even if you do use an immersed probe or thermowell. So its really down to personal preference between factors like intrusions into the fermenter, possible extra disinfecting requirements, leads hampering the lid slightly and/or having to do something (sanitary) with the probe when the lid is removed, or measuring the FV wall rather than wort directly - all these work, just have slightly different pros and cons.

You are heating the fermenter quite directly with belts and pads, so many probe positioning issues related to using warm/cool air in cupboards or fridges don't apply in this case, especially if the probe is insulated from the air around it.
Kev

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Re: Inkbird probe position with a plastic fermenter.

Post by shepp » Wed Jan 25, 2017 4:41 pm

I wrap a strip of foil and foam radiator insulation around my FV and tuck the probe inside that.

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