Brewtus 2 temperature drops

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Andrey Sychev

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Mar 9, 2022, 4:10:44 PMMar 9
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Hi group. I recently replaced brew boiler heating element on my original Brewtus 2. With new heating element installed and replaced vibratory pump, deaerator and OPV I observe the following symptom: when machine is turned on initially, pump turns on as usual, machine heats up to set 93C temperature. But then, half an hour later, display suddenly drops into the 70C. What can be the culprit to check? Thanks

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Andrey Sychev

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Mar 9, 2022, 4:41:51 PMMar 9
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An update - it seems the longer machine sits idle but powered in the lower the temperature drops. After another 45 min it dropped to 50c…

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> On Mar 9, 2022, at 4:10 PM, Andrey Sychev <andr...@aol.com> wrote:
>
> Hi group. I recently replaced brew boiler heating element on my original Brewtus 2. With new heating element installed and replaced vibratory pump, deaerator and OPV I observe the following symptom: when machine is turned on initially, pump turns on as usual, machine heats up to set 93C temperature. But then, half an hour later, display suddenly drops into the 70C. What can be the culprit to check? Thanks
>
> Sent from my iPhone

Ira

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Mar 9, 2022, 5:11:12 PMMar 9
to 'Andrey Sychev' via Brewtus

Hello 'Andrey,


Wednesday, March 9, 2022, 1:10:40 PM, you wrote:


Hi group. I recently replaced brew boiler heating element on my original Brewtus 2. With new heating element installed and replaced vibratory pump, deaerator and OPV I observe the following symptom: when machine is turned on initially, pump turns on as usual, machine heats up to set 93C temperature. But then, half an hour later, display suddenly drops into the 70C. What can be the culprit to check? Thanks 

When it drops, is it really cold or is it really hot? It could be doing this because the sensor gets messed up when it gets hot and in that case the brew boiler should get really hot. If for some reason the steam boiler is not heating properly, that would also cause the brew


-- Ira

Andrey Sychev

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Mar 9, 2022, 6:04:51 PMMar 9
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Both brew and steam boiler water feels hot. Hard to tell the exact temperature without a digital thermometer though.

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On Mar 9, 2022, at 5:11 PM, Ira <laz...@gmail.com> wrote:


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Pitcher Pitcher

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Mar 9, 2022, 7:19:15 PMMar 9
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Could be the PID, or signal from PID to boiler. On Whole Latte Love there is a complete diagnosis of the complete system in their video library.

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Rob

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Mar 9, 2022, 7:21:10 PMMar 9
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Have you looked at your brew boiler temperature probe?  I was having the same issue on my B2 and the temp probe was apparently bad.  The coating on the wires at the boiler was crumbling and when i finally got a replacement, the old one disintegrated when i pulled on the wire.  Took a little work to clean out the hole it went into but the new one has been working perfect for quite a while, no more than a 1 degree drop in normal operation.

Andrey Sychev

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Mar 9, 2022, 9:16:02 PMMar 9
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I was leaning in the bad probe  direction. I did not get a good looks as I was replacing the busted heating element but entire top of the boiler was covered in insulation powder. I just had to replace the line to the brew pressure gauge as it was clogged by this stuff. Do you have the part number and the source? 

Coating is all crumbled up in the well as far as I can see. Do you unscrew the well or just pull old one and end up removing it anyway if the wire breakes?

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On Mar 9, 2022, at 8:24 PM, Rob <krob...@gmail.com> wrote:

Have you looked at your brew boiler temperature probe?  I was having the same issue on my B2 and the temp probe was apparently bad.  The coating on the wires at the boiler was crumbling and when i finally got a replacement, the old one disintegrated when i pulled on the wire.  Took a little work to clean out the hole it went into but the new one has been working perfect for quite a while, no more than a 1 degree drop in normal operation.

Andrey Sychev

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Mar 9, 2022, 10:18:46 PMMar 9
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Thesis part number came from someone doing Minore rebuild. Does that look like a valid probe replacement?

I can therefore recommend that RS part number 697-4562 (AVX NJ28MA0103HCC 10k thermistor) is a valid replacement NTC thermistor for the temperature sensor used on these devices.

https://coffeesnobs.com.au/forum/equipment/brewing-equipment-pointy-end-1500-3000/836201-expobar-minore-brewtus-ii-repair-rebuild/page2

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On Mar 9, 2022, at 9:16 PM, Andrey Sychev <andr...@aol.com> wrote:

I was leaning in the bad probe  direction. I did not get a good looks as I was replacing the busted heating element but entire top of the boiler was covered in insulation powder. I just had to replace the line to the brew pressure gauge as it was clogged by this stuff. Do you have the part number and the source? 

Rob

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Mar 10, 2022, 11:29:24 AMMar 10
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I unscrewed the brass probe from the boiler, took some work but not as bad as you probably had with the heating element.  I used the exact part below.  I usedTeflon valve packing when I put the brass probe back in. I used a food grade heat sink compound inside the probe to make sure there was good thermal transfer and then RTV 4500 silicone on the top of the brass probe. 

Andrey Sychev

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Mar 10, 2022, 12:24:08 PMMar 10
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Thanks for details. I think I may have failed to mention - looks like temperature drop occurs only when machine sits idle. Initially when turned on it gets to set 93c but begins to drop gradually if unused. Flushing a couple of oz through the brew boiler gets it back to target temperature. Is that failing temperature sensor or something else?

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On Mar 10, 2022, at 11:29 AM, Rob <krob...@gmail.com> wrote:

I unscrewed the brass probe from the boiler, took some work but not as bad as you probably had with the heating element.  I used the exact part below.  I usedTeflon valve packing when I put the brass probe back in. I used a food grade heat sink compound inside the probe to make sure there was good thermal transfer and then RTV 4500 silicone on the top of the brass probe. 

Rob

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Mar 10, 2022, 12:47:21 PMMar 10
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What you are describing is exactly how my machine was behaving before replacing the probe. Temp reading would impossibly drop from 95  to 70 in about 1 minute and then within a minute be back to 95.  I had previously replaced the control board due to issues with the steam  boiler refill not working after the machine came up to temp but the AKO controller is still the same one.  Not sure if I still have the video of the behavior, it's not on my phone any longer.

Rob

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Mar 10, 2022, 2:20:19 PMMar 10
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Re read your post. I think you need something to check.the temperature coming out of the brew head to verify. I use the Klein Tools MM400. It's got a basic.temp probe that I just push up against the screen in the middle of the flow. It is coming out at the low temp or does it take time to heat up? How low is it going on the display? If the temp is too low to practically come back up to 93.or whatever you are awt at, I would think it has to be the probe.


On Thursday, March 10, 2022 at 11:24:08 AM UTC-6 Andre wrote:

Andrey Sychev

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Mar 10, 2022, 6:41:05 PMMar 10
to via Brewtus, Rob
Thanks, I’ll give it a try. I was making coffee this morning and the temperature on the display stayed put after a short flush. Hard to say if it was 93 though. Will get a thermometer and check before messing with replacement.

Andrey Sychev

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Mar 11, 2022, 1:44:55 PMMar 11
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I used my AstroAI multimeter that also came with a K type temperature sensor. Interestingly enough set to 95c temperature was reading in the 70c+ degrees at the brew group and 80c in the steam boiler while my Bonavita control was also off by 10c degrees from the set 98c. I think these readings were inconclusive at best but i may have to invest into a better thermometer…

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On Mar 10, 2022, at 6:41 PM, 'Andrey Sychev' via Brewtus <bre...@googlegroups.com> wrote:

Thanks, I’ll give it a try. I was making coffee this morning and the temperature on the display stayed put after a short flush. Hard to say if it was 93 though. Will get a thermometer and check before messing with replacement.
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