Brewzilla Temp problem

Hi All this is the second time this has happened to me
Today’s brew was going swimmingly well the mash temp was being held at + or - 1°c of my target temp which I verified by a trusted calibrated thermometer.Then halfway through the mash the digital read-out jumped from 65°c to 72°c and the heating element switched off. I checked the actual temp and it was only 62°c I had to ramp the temp up to 80°c to bring it back to 65°c . The last time this happened I ran the Brewzilla through a mash cycle using just water the temps were spot on ! Anyone else experienced this ? I should add that I use a digiboil to heat up my sparge water and it sits next to the Brewzilla on a worktop. This temp jump coincided with me switching on the Digiboil I’m clutching at straws now but would it be possible that the close proximity of the Digiboil is somehow affecting the Brewzilla ? Any advice much appreciated

Update.....
Yesterday I filled the Brewzilla with 10 litres of cold tap water set the mash temp to 72°c and switched on both elements periodically treating the temp every 5 minutes or so and the display was spot on . Once the temp was reached I turned off the 1900w element I put in the malt pipe and screens and added more cold water to drop the temp to 65°c to simulate adding the grain. The heater only switched back on once it dropped to 64°c but once up to temp switched off again .I circulated the wort for a further 10 minutes everything was OK. I even filled the Digiboil with water and replicated heating up my sparge water to see if this had any effect on the Brewzilla alas no everything was perfect . Has anyone else had a similar problem ? Or any ideas what it could be ?

Hi. Great to see a fellow sufferer. I may have an answer to your problem. I have had the same issue of inconsistent temp sensing in my Brewzilla V3.1 since I bought it last April. I contacted Kegland in Australia but they claimed they had never heard of such a problem. Like you, I tested with clear water and found no problem. However during heat up and cool down and at other random times the temp sensor reads between 0 and 20 degrees too high and therefore switches off heating. Yesterday I decided to try a brew without using the bottom plate, which does not seem to do much except get dirty and require cleaning. I noticed that the temp problem disappeared even with a fairly heavy mash (5.5kg in 25l). The temps shown were within 1 degree of my external measure. The only problem I had was that the pump did clog during the cooling process, but I don't really care about that.

My guess is that the bottom plate provides a heat shield which creates a false hot area near the temp sensor. Removing it leaves a larger area to recirculate. Apart from that I have been getting some great beers out of the Brewzilla.....

Hi @Philthebrewer Thanks for the info I too contacted Kegland and they pretty much told me the same
What type of false bottom do you have ? Is it the V1 or V2 ?
I have just ordered the new V2 along with a replacement thermistor in an effort to sort out my problems Nice to know I’m not alone here but sorry to hear you have the same problems
MM

Hi MM. I have a version 3.1 which means I guess it is the latest false bottom. I already have 2 screens in the mash tube (as supplied) so I am struggling to see why i need a false bottom at all. I also have a Braumeister with a pump inlet in the bottom which has no false bottom screen at all and works just fine, so I think I will just simplify my life and not use the false bottom. I also don't use the top mash cover as I have to move it off when I stir the mash (sometimes 2 or 3 times per mash.

The only other advice I have is to use a really liquid mash (25 litres of water) which helps keep the liquid moving around and should help temps stay more constant. I had thought it was important to have a grain to water ratio, but looking at tests by Beersmith, they found that this makes no difference at all. So the only risk is having too dry a mash resulting in incomplete conversion. I use Beersmith and get around 75% mash efficiency, which is similar to what I get with the more expensive Braumeister, so no complaints there.

Hi MM, I have the Brewster Beacon which I believe is the same all in one as yours. I used to have the same problem with temps overshooting whilst mashing or being under temp when heating the wort for boiling. I now have this under control by using my recirculating arm and the pump as this moves the hot wort from the bottom to the top etc.. creating a more even temp.

Philthebrewer said:

Hi MM. I have a version 3.1 which means I guess it is the latest false bottom. I already have 2 screens in the mash tube (as supplied) so I am struggling to see why i need a false bottom at all. I also have a Braumeister with a pump inlet in the bottom which has no false bottom screen at all and works just fine, so I think I will just simplify my life and not use the false bottom. I also don't use the top mash cover as I have to move it off when I stir the mash (sometimes 2 or 3 times per mash.

The only other advice I have is to use a really liquid mash (25 litres of water) which helps keep the liquid moving around and should help temps stay more constant. I had thought it was important to have a grain to water ratio, but looking at tests by Beersmith, they found that this makes no difference at all. So the only risk is having too dry a mash resulting in incomplete conversion. I use Beersmith and get around 75% mash efficiency, which is similar to what I get with the more expensive Braumeister, so no complaints there.

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Many thanks for the info and tips there is plenty of good food for thought there. I too have a Gen 3.1.1 but it has the old V1 false bottom which is quite a thick flat perforated plate The V2 appears to have a slightly stepped profile that may or may not help the junk move away from the centre where the thermistor probe is and sits fractionally higher above the elements.
I have also thought about adding stainless adjustable feet to the legs of the false bottom as the one I have touches the top of the tap (another bug bear of mine ) in an effort to clear the tap and allow more wort to sit below the plate thus reducing the possibility of it causing the problems discussed. Any thoughts much appreciated
MM

Here are pics of the V2 false bottoms

Mash Monster said:

Many thanks for the info and tips there is plenty of good food for thought there. I too have a Gen 3.1.1 but it has the old V1 false bottom which is quite a thick flat perforated plate The V2 appears to have a slightly stepped profile that may or may not help the junk move away from the centre where the thermistor probe is and sits fractionally higher above the elements.
I have also thought about adding stainless adjustable feet to the legs of the false bottom as the one I have touches the top of the tap (another bug bear of mine ) in an effort to clear the tap and allow more wort to sit below the plate thus reducing the possibility of it causing the problems discussed. Any thoughts much appreciated
MM

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Thanks MM. I had no idea there was a V2 false bottom. Great photos. I see what you mean, they may be trying to get the trub away from the holes. Can you let us know if this fixes the temp problem? I too wondered why they let the false bottom touch the tap, which seems a pretty poor design, which does not let the false bottom sit horizontal. I will have a measure up and see if I can add some SS screws to the bottom of the legs which at least lifts it up a bit. In the meantime I will bash on with 2 more brews without the bottom plate. If I get any burnt flavour then I will know I need it. If not then one less item to wash up ;-)

Hi Philthebrewer I will let you know how the V2 plate goes as soon as I get it
It’s coming from China so will be a few weeks yet

Hi MM. I was inspired by your comments to go and measure up the gaps. I found I had enough room to add 2.5 cm of extra height to the existing plate, without getting close to touching the bottom of the screens on the malt pipe. See photo below. I will probably try it out tomorrow. Thanks again for your idea.

Let’s us know how it goes hopefully that little bit of added weight will stop the plate jumping under the boil too

Hi MM and friends. I have now done 2 brews with the adjusted bottom plate (2.5cm raised) and it does not seem to help much. I used a different 5 step mashing profile for each brew (an oatmeal stout and a wheat beer) and each time the machine read the temperature as 5 to 20 degrees above my measured mash temperature, which is no real improvement on the old false bottom plate.
I have tracked down the problem to this: regardless of what I do, if the 1900w heating coil is turned on then the measured temperature shoots up way too fast and the thermostat turns off way too early as a result. The problem is slightly improved if I remove the bottom plate but it makes no difference whether I run the pump or not, fast or slow.

I suspect this is a design fault of having the sensor way too close to the heater. I don't get this problem at all in my braumeister 25l which also has the sensor is in the bottom centre but the heating coil is around the outside of the tank bottom and there is a stronger pumping action.

Understanding this, what I now do is run the Brewzilla manually when the 1900w element is on during mashing. When I hit my target temp I turn off the 1900w element, use the 500w element and set the machine to maintain the mashing temp (e.g. 67 degrees). It does a good job of maintaining temp with only the 500w element, but of course cannot raise the temp much with this.

Long term, what I would like to do is disconnect the temp sensor in the unit and instead connect a temp probe into the mash to the thermostat in the base. I first need to find a compatible temp sensor.

If anybody else with a Brewzilla 35l has measured the temps during an actual mash as I have I would be keen to know if they have the same problematic results.

Hi philthebrewer
I think you are part way on to solving your problem. I didn’t realise you were using the 1900w element for your mash. Apparently this is a NO NO and the instructions state that only the 500w element should be used with the malt pipe in place in order to prevent the temperature fluctuations that you were getting.
I too queried the location of the temp probe with Kegland and they stated the probe was in the centre of the 35L model and further away on the 65L model. I asked them why the probe on my 35L Digiboil which is a Brewzilla without the pump was on the outside they but failed to answer!
Good luck keep us posted

Thanks MM. I did not get such a detailed answer from Kegland. They just said that "we have not had any other reports of inconsistent temperature problems", which is not strictly true.....

Unfortunately it is not possible to get the mash temp up using only the 500w element. I did try the 500w only and got around 2 degree rise in half an hour, which clearly is a "NO NO" as far as real brewers are concerned. It is around 12 degrees right now in my brewing room but I use a nice little jacket for the brewzilla, so that is not the problem.

Thanks again for your help, I will now continue to use the brewzilla knowing its imperfections and working around them

Hi Philthebrewer I use both elements to heat up the mash water temp to about 72°C. I pause the programme and set my mash temp to about 66°C and then turn off the 1900w element. Then add the malt pipe and mash in and by the time it’s done I’m usually at about where I want to be temperature wise.
It’s maintaining the temperature that’s my problem .

Phil, as MM has said. I only use the 1900w together with the 500w to get to temp and when there only use the 500w.
My temp stability is much better since I put a jacket on it and keep my brew room above 18c. The last time I did a brew I did check the temps independently and from memory I think there may have been a couple of degrees variance,but not enough for me to worry about or record.
I have a the previous 3.1 version with a upgraded controller, don’t now if that makes any difference.

Hi, my suspicion is that the bottom plate becomes partly packed with particles from the mash and since the pump is still running you end up with an air gap under the plate so that the level of fluid being heated is shallow and heats up far quicker than expected, so the temperature probe is reading the correct temperature for that liquid. This would account for why it works fine with plain water or without the plate. I suspect that this will be more likely to happen if wort with grain particles is allowed through the overflow pipe. I'd expect this to be more likely to occur with total mash & fluid volumes that are significantly below the maximum height of the overflow pipe so allowing more volume to be pumped up than is easily replace from the mash pipe. Pushing down the central mash pipe so that the cone attachment rests on the top grid should also minimise this risk.

Anna

DocAnna said:

my suspicion is that the bottom plate becomes partly packed with particles from the mash and since the pump is still running you end up with an air gap under the plate

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I see where you are coming from but I dont see how you would get air in there to form an air gap?

Pulling a vacuum under a few litres of wort? I could see the pump starting to struggle though.

buddsy

DocAnna said:

Hi, my suspicion is that the bottom plate becomes partly packed with particles from the mash and since the pump is still running you end up with an air gap under the plate so that the level of fluid being heated is shallow and heats up far quicker than expected, so the temperature probe is reading the correct temperature for that liquid. This would account for why it works fine with plain water or without the plate. I suspect that this will be more likely to happen if wort with grain particles is allowed through the overflow pipe. I'd expect this to be more likely to occur with total mash & fluid volumes that are significantly below the maximum height of the overflow pipe so allowing more volume to be pumped up than is easily replace from the mash pipe. Pushing down the central mash pipe so that the cone attachment rests on the top grid should also minimise this risk.

Anna

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I agree. It is only logical that the more liquid that is above the grain bed (within the confines of the malt pipe), the less there is below it (over the heaters and the thermocouple). There is no possibility of a vacuum because there is a 2 cm gap between the outer wall of the grain pipe and the inner wall of the main vessel. If (as is frequently the case judging by these posts) the liquid is not draining through the grain bed fast enough, or is not flowing through the central return pipe, then there is a risk that this could happen. So, the temperature of the mash is not going to be the same as the liquid temperature at the base where the thermocouple is.
I've mentioned in earlier posts that I believe that the key, or at least one possible solution to maintaining a reliable mash temperature is to get the maximum flow possible through the grain bed and the return pipe (without carrying any grain bits down to the pump). I'm still working on how best to achieve this, but so far I have found that getting the grain crush right, using rice hulls in the grist, and fitting a SS mesh sieve over the top of the return pipe have all helped . . . . but it is still work in progress