First timer advice on heatpads

[MashBag]

I can.

Probably 'une 'erring rouge'.
Not really an issue on a 25 litre batch.

A real issue with a 500l fermentation.

Consistent is what the yeast likes.

 

[matt.]

After just 6 days a big drop using SafAle S-04 yeast. Temp has been between 19.7 & 24.2 degrees
Looking good.
Trub settled now.
I'm in no rush so leave a little longer?

 

[MashBag]

Nope ready to bottle imo. At very least all the headspace needs to go.

 

[matt.]

Nope ready to bottle imo. At very least all the headspace needs to go.

Thanks. Yes, more head space than I wanted. I lost 3+ litres due to excessive amount of Protafloc added at last 10 mins of boil. I kept it back in the fridge but it didn't fall clear. So 7 litres instead of 10.

 

[MashBag]

That's only 10 minutes bottling. C'mon pull your finger out.

 

[matt.]

That's only 10 minutes bottling. C'mon pull your finger out.

Boil, 1 hour. Last 10/15 mins, Protafloc. But I added half a tablet to 10 liters. Much too much. I did the same to the previous brew. Why? I ask myself that as well.
Next brew, much less, or maybe none at all.

 

[peterpiper]

Many thanks.
I followed those points but can you clarify ' offset ' please.

I just meant how the difference between 'average' liquid temperature, and the sensor temperature, varies with sensor location due to temperature gradient.

With say a 15°C desired ferment temperature, and surrounding air at 10°C, temperatures of the FV outer wall might be: 11°C near top of liquid; 15°C around middle; 19°C near bottom; and 21°C underneath (touching heatpad). So the offsets: -4 and sensor near top; or +6 and sensor underneath, should both maintain the same temperature in the vessel.

With lower air temperature, the larger the gradient, and the offsets needed.

A sensor probe in the liquid, should be more accurate than one fixed outside the FV at the same height, where it's being cooled by the surrounding air.

 

[matt.]

Thanks.
I see y

I just meant how the difference between 'average' liquid temperature, and the sensor temperature, varies with sensor location due to temperature gradient.

With say a 15°C desired ferment temperature, and surrounding air at 10°C, temperatures of the FV outer wall might be: 11°C near top of liquid; 15°C around middle; 19°C near bottom; and 21°C underneath (touching heatpad). So the offsets: -4 and sensor near top; or +6 and sensor underneath, should both maintain the same temperature in the vessel.

With lower air temperature, the larger the gradient, and the offsets needed.

A sensor probe in the liquid, should be more accurate than one fixed outside the FV at the same height, where it's being cooled by the surrounding air.

Thanks. I see your point.
Is it ok to dangle the heat probe of my inkbird into the wort?

 

[foxy]

I just sanitise the temp probe and put it straight into the wort either through a hole in the lid or under the lid if I'm using a stockpot or similar. Between brews I leave the probe in a mug of chemsan (lazy) but obviously you could clean and dry it if you need to move it. If you are using an air-lock you will need a suitably sized grommet to push it through to keep it air tight.

By the way, I use the probe in the wort to monitor its temp not control it. I only control the temp of whatever the FV is in (chamber, trub of water, fridge).

The reason behind the thermowell is that the probes aren't food-safe and are going into an acidic environment. Also there are a lot on the market which are not waterproof.

 

[Twostage]

The reason behind the thermowell is that the probes aren't food-safe and are going into an acidic environment. Also there are a lot on the market which are not waterproof.

Good call re: the food-safe. The probes fit nicely into siphon tubing so I'm going to make some 'thermowell' jackets with just the metal probe sticking out sealed in place with food grade sealant (which I thought I had but can't find , probably in the one box I didn't look in).

 

[matt.]

Good call re: the food-safe. The probes fit nicely into siphon tubing so I'm going to make some 'thermowell' jackets with just the metal probe sticking out sealed in place with food grade sealant (which I thought I had but can't find , probably in the one box I didn't look in).

Nice idea. I like that. Presently the probe is sellotaped to the outside of the FV. It's not really a reflection of the liquor inside.
So; I long plastic tube. Good call.
What if the metal probe wasn't sticking out? Wouldn't the temperature be pretty accurate. That would avoid the food grade sealant issue.

Thanks again.

 

[foxy]

Nice idea. I like that. Presently the probe is sellotaped to the outside of the FV. It's not really a reflection of the liquor inside.
So; I long plastic tube. Good call.
What if the metal probe wasn't sticking out? Wouldn't the temperature be pretty accurate. That would avoid the food grade sealant issue.

Thanks again.

The probe is accurate in a thermowell, I have a spare stainless steel one but the cost of postage would be as much as one from AliExpress. See my post 25, you could just use a male thread to hose barb and screw it to your fermenter lid.

 

[peterpiper]

Nice idea. I like that. Presently the probe is sellotaped to the outside of the FV. It's not really a reflection of the liquor inside.
So; I long plastic tube. Good call.
What if the metal probe wasn't sticking out? Wouldn't the temperature be pretty accurate. That would avoid the food grade sealant issue.

Thanks again.

Yes. Steady state temperature, from a probe inside an immersed tube would be exactly the same as from an exposed probe.
But after any change in temperature, the enclosed probe reading would always lag a while longer, this would lead to increased temperature swings, around the desired temp (hysterises). So with controller hysteresis set to 0.5°C, the hysteresis, with an enclosed probes thermal lag, might be 2°C.
You could put probe down one side of a folded tube (fold at bottom), to avoid needing any sealant.

An externally mounted sensor is likely to have longer lag, than one contained in a dip tube. But both of these lags, might actually be insignificant, when compared with lag due the liquid thermal mass. Where a 24W heatpad, might take about 5 minutes to raise temp of 23L batch by 1°C.

eg. with controller hysteresis set to 0.5°C:
1) An (exposed) sensor in middle of vessel. After sensor goes 0.5°C under set temp, and heating turns on, it might take 10 minutes before heating turns off again.
By then the base temperature overshoot might easily have risen to say 10°C, ie a hot yeast/trub layer; the overshoot at sensor might end up being 3°C; and the hysterises cycle might last 20 minutes.
The average brew temperature, will stay pretty constant with variations in ambient temperature.

2) An external probe, between heatpad and base. This has the least lag. The cycle time might be 1 minute; trub layer overshoot 0.5°C; at middle middle of vessel there's virtually no temperature cycling.
Brew temperature (particularly towards top), will vary with ambient temperature.

The best would seem to be an external bottom sensor, but with the fermenter in a well insulated container, recticell box, or a defunct fridge, to keep a more consistant ambient temperature.

 

[MashBag]

Presently the probe is sellotaped to the outside of the FV. It's not really a reflection of the liquor inside.

Do you have any insulation over it?

 

[MashBag]

The best would seem to be an external bottom sensor, but with the fermenter in a well insulated container, recticell box, or a defunct fridge, to keep a more consistant ambient temperature.

Fermentation jackets are also very good (and take up no great space when not in use)

 

[old dog new tricks]

Hi just seen this I am also blessed with Scotland's lower temperatures.

I got a cheap 50w fish tank heater, sliced a bung sealed it up can sit in ,my plastic FV and heats no problem from 18 - 24.

I also use it in trubs with smaller DJs ec does a great job of keeping a constant heat

 

[matt.]

Hi just seen this I am also blessed with Scotland's lower temperatures.

I got a cheap 50w fish tank heater, sliced a bung sealed it up can sit in ,my plastic FV and heats no problem from 18 - 24.

I also use it in trubs with smaller DJs ec does a great job of keeping a constant heat

That's interesting. How do you regulate the temperature when the heater is in the FV?

 

[old dog new tricks]

That's interesting. How do you regulate the temperature when the heater is in the FV?

the heater has a temp control set it before i fit it.

if i need to adjust its a DJ size bung so very tight fit and easy to cover to prevent too much air getting in

£6 or £7 on eBay or Amazon does the job and drops in and out when needed.

Only issue is 18c is lowest setting

 

[MashBag]

Tbh it is an established (old) idea.

The latest incantation is to set the heater to max and use an inkbird. Stainless heater are also preferred over glass.

But to be fair there is now a plethora of easy more hygienic options.

 

[matt.]

Tbh it is an established idea.

The latest incantation is to set the heater to max and use an inkbird. Stainless heater are also preferred over glass.

But to be fair there is now a plethora or easy more hygienic options.

I recently bought an ink-bird. How would you link it to the aquarium heater? Where would the ink-bird probe go? I don't have a thermowell. Just using a plastic bucket for the FV.