Ferminator First Day Issues

[pablobobo]

Mad swings in temperature readings here, first time using this piece of kit.
So the probe is insulated fairly well with yoga mat material, touching the side away from the cooling unit.
I've seen anywhere between 18 and 26 degrees so I'm really confused as to what the thermometer is actually reading. It's been in for about 3 hours.
The fermenter is cold to touch, and the side thermometer is reading 18- is my guess as its so hard to see any colour on the strip.
Any ideas folks, is the beer too cold now and the reading is off? Can I sanitise my thermometer and stick it in to check?

 

[user 18729]

I would read the ambient temperature with a stick on jobby (they’re not very accurate) or perhaps look into buying a digital thermometer one day.

The important thing it to keep the temperature constant initially

 

[The-Engineer-That-Brews]

the probe is insulated fairly well with yoga mat material, touching the side away from the cooling unit.

I’m not familiar with the ferminator, but are you talking about the probe that provides the feedback to the temperature controller?
If so then from a control engineering perspective I would always recommend putting the temperature probe as close to the heating/cooling element as possible, and not insulating it - unless the controller is specifically designed to have a very high damping coefficient; otherwise the time delay involved is pretty much guaranteed to give you big temperature oscillations.

 

[pablobobo]

I’m not familiar with the ferminator, but are you talking about the probe that provides the feedback to the temperature controller?
If so then from a control engineering perspective I would always recommend putting the temperature probe as close to the heating/cooling element as possible, and not insulating it - unless the controller is specifically designed to have a very high damping coefficient; otherwise the time delay involved is pretty much guaranteed to give you big temperature oscillations.

The instructions say to keep it as far back from the heating/cooling element and to insulate it so now I don't know who to believe! It seems to be fluctuating less now, but still some way to go to the desired temperature. No action from the yeast yet so hopefully it's not too cold, because it's noticeably cooler inside the chamber. I'll give it the night and assess in the morning.

 

[The-Engineer-That-Brews]

The instructions say to keep it as far back from the heating/cooling element and to insulate it so now I don't know who to believe!

Ok in that case go with the instructions, as it sounds like the controller may be designed to work with that (i.e. with a really high damping coefficient) but maybe remove some of the insulation from around the probe.

 

[pablobobo]

Ok in that case go with the instructions, as it sounds like the controller may be designed to work with that (i.e. with a really high damping coefficient) but maybe remove some of the insulation from around the probe.

Perfect, I'll try that, I thought more insulation would be better but is there a chance that it's just keeping the probe warm? Thanks a million for your knowledge and time!

 

[RichardM]

Yes, you can sanitise a thermometer and check the temperature of the wort. Is that stick on thermometer movable? If so then I would move it down so that it is completely below the wort level.

 

[pablobobo]

Yes, you can sanitise a thermometer and check the temperature of the wort. Is that stick on thermometer movable? If so then I would move it down so that it is completely below the wort level.

Yup, so I sanitised it, it's reading 15 degrees in there now and the element has switched to a heat cycle. It reads 17 on the taped on probe. I'm gonna give it the night and see how it looks in the morning and update then.

 

[ChrisT685]

I've used my Ferminator 3 times so far and was also concerned about the temp fluctuating between +2 and -2 degrees of my target temp. I ended up checking the temp (sanitised thermometer etc) and it was a couple of degrees lower than I wanted so I upped the target temp on the control box and checked again after a while. It had raised to 20 degrees so then I rolled with it.

The end results have been great and I think noticeably better than heat belt in the garage. My Gamma Ray clone is the best thing I've brewed so far.

Next time around I'm thinking of going airlockless and placing the (sanitised) probe in the wort itself.

 

[pablobobo]

I've used my Ferminator 3 times so far and was also concerned about the temp fluctuating between +2 and -2 degrees of my target temp. I ended up checking the temp (sanitised thermometer etc) and it was a couple of degrees lower than I wanted so I upped the target temp on the control box and checked again after a while. It had raised to 20 degrees so then I rolled with it.

The end results have been great and I think noticeably better than heat belt in the garage. My Gamma Ray clone is the best thing I've brewed so far.

Next time around I'm thinking of going airlockless and placing the (sanitised) probe in the wort itself.

That's reassuring news Chris, someone on another forum said his was colder than the probe was giving him, so that's the 3 of us with a similar situation now. Do you keep it on level 3 fan the whole time? Provided fermentation happens (still no signs yet 18h in) I'm tempted to give it 3 days at 18c, level 3 fan and then move to level 1.

The manual says not to put the probe in the beer but that could just be them playing it safe. I'll probably try build a thermowell myself.

 

[ChrisT685]

That's reassuring news Chris, someone on another forum said his was colder than the probe was giving him, so that's the 3 of us with a similar situation now. Do you keep it on level 3 fan the whole time? Provided fermentation happens (still no signs yet 18h in) I'm tempted to give it 3 days at 18c, level 3 fan and then move to level 1.

The manual says not to put the probe in the beer but that could just be them playing it safe. I'll probably try build a thermowell myself.

I do keep it on L3. Tried it on 1 and 2 and got even bigger temp swings unseen to remember !!

Let me know how you get on with your thermowell

 

[MickDundee]

I’m not familiar with the ferminator, but are you talking about the probe that provides the feedback to the temperature controller?
If so then from a control engineering perspective I would always recommend putting the temperature probe as close to the heating/cooling element as possible, and not insulating it - unless the controller is specifically designed to have a very high damping coefficient; otherwise the time delay involved is pretty much guaranteed to give you big temperature oscillations.

I have a fermenting fridge rather than a terminator, but I’ve always stuck a dish sponge to the side of my FV and had the Inkbird probe underneath - that was from advice on here that said you should be recording the temperature of the beer not the air temperature because of the geothermal properties of fermentation.

Is this not right?

 

[The-Engineer-That-Brews]

Perfect, I'll try that, I thought more insulation would be better but is there a chance that it's just keeping the probe warm? Thanks a million for your knowledge and time!

Yer welcome :hat:
Hope it’s stabilised a bit this morning :-)
What tends to happen with insulating the probe is that it takes the controller longer to ‘realise’ that the temperature has got too high or too low, so it tends to result in a lot of overshoot unless it’s been designed to adjust the heater veeeeery slooooowly (which brings its own problems).

 

[The-Engineer-That-Brews]

I have a fermenting fridge rather than a terminator, but I’ve always stuck a dish sponge to the side of my FV and had the Inkbird probe underneath - that was from advice on here that said you should be recording the temperature of the beer not the air temperature because of the geothermal properties of fermentation.

Let's just say that there is some controversy on the issue...
My perspective is that from a control engineering perspective you are always going to get the best stability and response time by putting the feedback element (PID sensor) in close thermal contact with the heater/cooler. However as you rightly say, you've also got the factor that a fermentation can also be generating its own heat.
So what I do is a combination: I put the PID sensor close to the heater, but I also monitor the temperature of the beer itself with a separate sensor - and if the beer is getting a bit hot or cold I adjust the set point of the PID. Does that make sense?

 

[fgoulding]

On issue that I have seen is that the fan doesn't automatically change from Level 3 when the desired temperature has been reached. It should stop and allow the Ferminator to cool down until it needs to heat again. It's a fault which Brewolution knows about and they will replace the control unit if you contact them.

However, if your fan is ok, then I would buy a Kegland Thermowell (60cm Thermowell - bulkhead included) and use a step drill-bit to make a hole in the top of your fermentor. Then it's easy to put the probe inside. If you have a Tilt (or similar device) you will still see a temperature fluctuation but it will be plus/minus 0.5 degrees.

It's amazing how different the temperature of the wort is in the centre of an FV compared to the outer edges.

 

[RichardM]

Let's just say that there is some controversy on the issue...
My perspective is that from a control engineering perspective you are always going to get the best stability and response time by putting the feedback element (PID sensor) in close thermal contact with the heater/cooler. However as you rightly say, you've also got the factor that a fermentation can also be generating its own heat.
So what I do is a combination: I put the PID sensor close to the heater, but I also monitor the temperature of the beer itself with a separate sensor - and if the beer is getting a bit hot or cold I adjust the set point of the PID. Does that make sense?

But it's the temperature of the wort that you trying to control so it makes sense to measure the temperature of the beer, not the heating element. When people say to insulate the temperature probe they mean from the surrounding air, not from the vessel containing the wort.

 

[The-Engineer-That-Brews]

But it's the temperature of the wort that you trying to control so it makes sense to measure the temperature of the beer

I absolutely agree! You should measure the temperature of the beer, as that's what you are trying to control

What I'm trying to say (probably not very well) is that it doesn't necessarily follow that it's a good idea to use that temperature as the feedback signal for your heating controller, as it may result in temperature oscillations and hotspots next to the element.

The problem is that the vast majority of heating controllers are fairly dumb devices that don't have a 'look ahead' capability. They just look at the temperature from the probe and compare it to the set temperature. If the reading is too high or too low then the controller cranks up the power to the heater or cooler a bit.

20-30L of beer has a pretty big thermal mass - so its temperature only changes quite slowly in response to the temperature of the heater. That introduces a time delay into the feedback loop - and simple controllers do not respond well to time delays like that.

In particular when the controller is thinking 'oooh... the beer is still a bit cold, I'd better increase the heater power a bit more', the heater itself is already MUCH hotter than the set point. This typically has two consequences: (1) the beer close to heater gets too hot; and (2) you the beer temperature continues increasing after the controller has shut off the heater, resulting in an overshoot, and you can get quite big oscillations building up.

As I said above, that may not be a problem if the controller is heavily damped (i.e. it only increases the heater power veeeeery slooooowly). But very commonly you are likely to get oscillations.

My own preferred solution to this is to use the controller to maintain the heating element itself at a good steady set temperature - it's very good at this. In parallel, once a day or so, I monitor the temperature of the beer itself using a separate temperature sensor (an LCD thermometer on the side of the bin would work), and if the beer temp is too high or too low than I adjust the set point of the controller up or down a degree or two.

Does that make sense? I find this quite difficult to explain coherently without going into control theory

 

[RichardM]

I absolutely agree! You should measure the temperature of the beer, as that's what you are trying to control

What I'm trying to say (probably not very well) is that it doesn't necessarily follow that it's a good idea to use that temperature as the feedback signal for your heating controller, as it may result in temperature oscillations and hotspots next to the element.

The problem is that the vast majority of heating controllers are fairly dumb devices that don't have a 'look ahead' capability. They just look at the temperature from the probe and compare it to the set temperature. If the reading is too high or too low then the controller cranks up the power to the heater or cooler a bit.

20-30L of beer has a pretty big thermal mass - so its temperature only changes quite slowly in response to the temperature of the heater. That introduces a time delay into the feedback loop - and simple controllers do not respond well to time delays like that.

In particular when the controller is thinking 'oooh... the beer is still a bit cold, I'd better increase the heater power a bit more', the heater itself is already MUCH hotter than the set point. This typically has two consequences: (1) the beer close to heater gets too hot; and (2) you the beer temperature continues increasing after the controller has shut off the heater, resulting in an overshoot, and you can get quite big oscillations building up.

As I said above, that may not be a problem if the controller is heavily damped (i.e. it only increases the heater power veeeeery slooooowly). But very commonly you are likely to get oscillations.

My own preferred solution to this is to use the controller to maintain the heating element itself at a good steady set temperature - it's very good at this. In parallel, once a day or so, I monitor the temperature of the beer itself using a separate temperature sensor (an LCD thermometer on the side of the bin would work), and if the beer temp is too high or too low than I adjust the set point of the controller up or down a degree or two.

Does that make sense? I find this quite difficult to explain coherently without going into control theory

Yes, that makes sense...and I remember getting confused by PID controllers when I did my degree 35 years ago, so any more detail would probably be wasted on me :-)

I use a fridge with a tube heater. They are controlled by an STC 1000, which just turns either the heater or fridge on or off as required, there is no control of amount of power to either. It seems to work pretty well. The temperature probe is in a thermowell and I see little variation in the temperature. However, I have recently bought an infrared thermometer (for checking the temperature in my Ooni pizza oven that was my retirement present to myself recently), so it would be interesting to use that to see the surface temperature of the fermenter.

 

[The-Engineer-That-Brews]

... my Ooni pizza oven that was my retirement present to myself recently)

Ooooh NOW I’m jealous! Please post a piccy or two on the foodies forum?!

 

[pablobobo]

On issue that I have seen is that the fan doesn't automatically change from Level 3 when the desired temperature has been reached. It should stop and allow the Ferminator to cool down until it needs to heat again. It's a fault which Brewolution knows about and they will replace the control unit if you contact them.

However, if your fan is ok, then I would buy a Kegland Thermowell (60cm Thermowell - bulkhead included) and use a step drill-bit to make a hole in the top of your fermentor. Then it's easy to put the probe inside. If you have a Tilt (or similar device) you will still see a temperature fluctuation but it will be plus/minus 0.5 degrees.

It's amazing how different the temperature of the wort is in the centre of an FV compared to the outer edges.

Yeah I have a smaller thermowell that I didn't get around to installing due to lack of drill, for sure will have it on my next one. A little worried that I'll have to plug it in where the beer is, as opposed to the lid, as it won't reach all the way into the beer from the lid.

Can Brewoloution send back an updated unit that is programmed to change levels? That would be ideal, and ease my worries that my unit is not up to par. I'm in contact with them at the mo, but they are quite slow enough with the replies.