Fermentation control question

[JRTurner1234]

Hi,

I've set up my fermentation temperature control and it's not as perfect as I was hoping for.

The temperature of the FV is fluctuating between 18.8C and 20.2C.

My question is, how much of an impact on the beer will this level of temperature fluctuation have? The yeast works between between 18C and 21C.

Thanks!
JT

 

[Covrich]

Only 1.4 degrees, I would say it would be fine to be honest and it is kept within a good range

 

[DoctorMick]

I've had much bigger fluctuations than that with no massive problems so I'd have absolutely no concerns about such a small amount. What are you using to control the temp?

 

[JRTurner1234]

I built a thermostatic controller using the stc-1000, which I'm using with a water bath and aquarium heater. My set up looks like this:

 

[MyQul]

As others have said it wont be an overall big problem, but depending on the yeast your using you will probably get marginally more esters due to the fluctuations than if you kept it at 18.8C

 

[clibit]

That fluctuation is not a problem. I also suspect it's a pretty good result from that kind of set up. It is not going to hold a temperature completely constant, I imagine.

 

[joiner_8]

I have just built my brew fridge and temperature controller using the STC-1000 control box, is there a way that i can fit a small light to the box to show when the heater is on and when the fridge is on

 

[Twostage]

I have just built my brew fridge and temperature controller using the STC-1000 control box, is there a way that i can fit a small light to the box to show when the heater is on and when the fridge is on

The STC has two little lights which indicate heat and cool.

Alternatively...

Not exactly small but if you've wired it up so it feeds multi sockets (one for heat and one first cool) you could rig up a couple of lights and plug them into the multi sockets. If you got coloured ones you could see from across the road what it was doing :rofl:

 

[Twostage]

I built a thermostatic controller using the stc-1000, which I'm using with a water bath and aquarium heater. My set up looks like this:

Can't quite see from the picture but does the heater go into a multiway socket ? If it does (it should go into a socket of some kind otherwise you've eliminated the fuse for the heater) then you can also add a fish tank filter pump to circulate the water when the heater comes on. That way you'll get a better distribution of heat. You could double wire it in.

 

[gobuchul]

I would suggest covering it up with an old quilt or blanket. Even a big cardboard box over the top would help.

It will make a big difference to the temperature changes.

 

[Steviewell]

That's a good setup you have there and 1.4C difference is decent control. The main difficulty in the control is because you are heating indirectly (i.e. the water surrounding the FV) so this will increase the overshoot. (basically the water jacket is hotter than the beer, so the beer will continue to heat once the heater switches off). HOWEVER I still believe this is a much better setup than sticking the heater into the wort itself.

I would suggest covering it up with an old quilt or blanket. Even a big cardboard box over the top would help.

It will make a big difference to the temperature changes.

I agree with this quote. What it will actually do though is help with heat loss. What you could do is use the upside down cardboard box over the top idea AND then insulate the box (loft insulation or a sleeping bag) which will really cut down on the heatloss. In turn you can then use a much lower wattage aquarium heater which should help with the overshoot.

All in though, I think your setup is cool, and like I say 1.4C is not going to cause any problems that I can see. These comments are only if you really want to fine tune, personally I'd just leave it as is. Nice work :thumb:

 

[Steviewell]

Ps another thought - any on/off control switch must have a deadband. That is to say if you set at 20c u will find the heater will switch off when rising temp reaches 20c but might not switch on again until falling temp drops below e.g. 19c. This example shows a 1c deadband - unless u have a very high end controller u are unlikely to have tighter control than 1c (plus any overshoot)

 

[Twostage]

Ps another thought - any on/off control switch must have a deadband. That is to say if you set at 20c u will find the heater will switch off when rising temp reaches 20c but might not switch on again until falling temp drops below e.g. 19c. This example shows a 1c deadband - unless u have a very high end controller u are unlikely to have tighter control than 1c (plus any overshoot)

STC-1000s can be set to .3 degree tolerance each way around your target temp. So if you set it for 20 and it drops to 19.7 it will switch on the heater and switch off again at 20. If you are also using to cool it would switch on the cooling device at 20.3.

 

[Steviewell]

Aye OK twostage, it's a £15 controller with low accuracy NTC sensor. My point is basically temperature stability around plus/minus 1c is pretty good, there are more factors to consider and I personally wouldn't overly worry about it. For the sake of some Homebrew the setup is fine. I am an instrument engineer in the process control industry, if the stc-1000 does all it claims then we must be doing something wrong and throwing money away on all the £1000+ controllers that we use! :)

 

[Twostage]

Aye OK twostage, it's a £15 controller with low accuracy NTC sensor. My point is basically temperature stability around plus/minus 1c is pretty good, there are more factors to consider and I personally wouldn't overly worry about it. For the sake of some Homebrew the setup is fine. I am an instrument engineer in the process control industry, if the stc-1000 does all it claims then we must be doing something wrong and throwing money away on all the £1000+ controllers that we use! :)

I wouldn't use an STC-1000 in an industrial situation either :shock:, horses for courses. They are surprisingly accurate, though, and do seem to operate within their indicated ranges.

Your absolutely right that even if they were operating at half their accuracy it would be fine for HB. TBH even a fish tank heater controlling itself is OK once you have it set right, just a pain to adjust if you want to vary the temperature.

 

[as13]

Hi,

I've been reading this thread with interest and had a look at the STC-1000 on the old eBays.

Am I right to presume that you drop the temperature sensor into your FV to monitor the temperature of the brew?

Does this not introduce an additional risk of infection?
Is the wire thin enough that you can still close the lid?

Thanks,
Andrew.

 

[as13]

Sorry - I should add,

I'm using a heat belt, not a water bath and aquarium heater as demonstrated above.

 

[JRTurner1234]

I cut a groove into a piece of polystyrene, put the termometer end into this and then taped it to the side of the FV. This is very accurate (I've checked!) and minimises the risk of contamination.

JRT

 

[as13]

Cool.

I wondered about sticking it to the side, but saw the issue being that you'd be reading somewhere between the air temperature and the temperature of the liquid.

Insulating with polystyrene is an obvious solution now you've mentioned it!

Thanks!

 

[gobuchul]

I stick my sensors directly against the side of the FV with a lump of blu-tack.

Works well and the blu tack seems to insulate well.