How to get constant accurate temp readings?

[snowshiva]

Would it be ok to have an aquairum thermometer in the fermenting brew?

I mean one of the ones with the temp probe on a long wire? Would it cause problems having the probe in the beer?

What would you guys suggest/what do you use?

[Dan]

if you sterilise it and its water proof you can put it in your beer. although watch out for none food grade plastics they react with chlorine based sterlisers.

heres another accurate method. fill a jug/jar with a litre or two of water and put the probe in that. Keep the jar on the floor next to the fermenter it will give you a more stable reading of the abient temperature than it would if left in the air.

[des]

heres another accurate method. fill a jug/jar with a litre or two of water and put the probe in that. Keep the jar on the floor next to the fermenter it will give you a more stable reading of the abient temperature than it would if left in the air.

Do you not think that might be a bit misleading when yeast is active as it generates heat and raises the temperature, where as the water in a jug will remain at a steady temperature a couple of degrees cooler than the environment. I have found by trial and error that in a cabinet controlled to 20 C that an active brew can reach the low 20's where a bucket of water will sit at around 16 or 17 C.

I have a probe in my HLT using a gland which works very well but decided against this for fermenter because of cleanliness issues.

Those little temperature strips that stick on the side of the vessel are said to work well, haven't tried myself though.

All I do now is keep the temperature of my fermenting cabinet set at 20C and find this works very well - I use a thermostatic switch from B&Q to turn a 200Watt heater on and off.

[Dan]

Dan wrote:
heres another accurate method. fill a jug/jar with a litre or two of water and put the probe in that. Keep the jar on the floor next to the fermenter it will give you a more stable reading of the abient temperature than it would if left in the air.

Des wrote:
Do you not think that might be a bit misleading when yeast is active as it generates heat and raises the temperature, where as the water in a jug will remain at a steady temperature a couple of degrees cooler than the environment.

Its mesuring ambient temperature. which incidently should be very close to the wort temp. the heat generarted by a 5 gallon ferment, even at high krausen, is very little.

[RabMaxwell]

I submerge my ATC-800 probe in my brews a piece of 3/8 tubing glued with Araldite to the cable then pushed into a 3/8 push fitting

[snowshiva]

Cheers guys, I didnt think the stick on type thermometers would be very accurate (never found them accurate with my coral tank). But I may give one a go.

I put my fermenter in a cupboard but my whole house goes cold during the night and hot when we get home due to the heating.

I used a brewbelt on my last brew but it came out very acidic and I was told this was due to the yeast fermenting at a high temp so I want to keep and eye one it.

[anomalous_result]

25L of wort wont react anywhere near as quickly to temperature change as 1L of water.

I'd see that as a good thing though, if you have your wort at temp and then ambient drops a bit and the heater kicks in then it'll hold its heat for longer so before any appreciable drop in temp is seen ambient will be back up to temp.

And thermodynamics never was my strong point, but if you have a cupboard that's regulated to 20C how can anything in it be less than that temp? Or is it just localised lower temperatures?

[anomalous_result]

but if you have a cupboard that's regulated to 20C how can anything in it be less than that temp?

no one said anything about temperature controlled cupboards

des did:

I have found by trial and error that in a cabinet controlled to 20 C that an active brew can reach the low 20's where a bucket of water will sit at around 16 or 17 C.

Just that bit that confuses me.

[anomalous_result]

Sorry, I should have said it wasn't mentioned in the original question that I was responding to and the reason an actively fermenting beer will be a few degrees warmer than a bucket of water in the same room is that fermentation exothermic.

I agree, the confusing bit is why a jar of water would be 4 degrees cooler than ambient.

[des]

no one said anything about temperature controlled cupboards

des did:

I have found by trial and error that in a cabinet controlled to 20 C that an active brew can reach the low 20's where a bucket of water will sit at around 16 or 17 C.

Just that bit that confuses me.

Sorry, I should have said it wasn't mentioned in the original question that I was responding to and the reason an actively fermenting beer will be a few degrees warmer than a bucket of water in the same room is that fermentation exothermic.

Dunno! don't mind in the least being wrong though

I'm just going on a trial I did with a bucket of water when I built my cupboard, after a few days water was still a couple of degrees below ambient. maybe evaporation, who knows? just had a look in cupboard now, thermostat set to 20C, ambient is 19C at the time and 30 litres of brew is at 20C.

looks like the brew is sitting at the selected temperature, the cupboard does fluctuate between about 17 and 23 degrees due to heater on and off cycles but a large volume of liquid will buffer this out and sit at an average I would suppose.

Just turned thermostat down to 19, will see what happens over next few days.

Brew is 3 days old by the way, started at O.G. 1052 and now 1022 and bubbling nicely.

[bandit]

Does that mean we will be drinking that one next week, Mr Fermenter ?

[des]

Does that mean we will be drinking that one next week, Mr Fermenter ?

Yeah - catch it while it still has that lovely yeasty twang!