How does my graph look?


Sweet webpage. How did you do that?


@Jesse if that was aimed at me, see post #2683 here

it’s dead simple to follow, just remember to create the mkdir private folder in /var/www otherwise it doesn’t work

i used to get a free domain name as it’s just for fun.


@mikmonken Great info, thanks Mik.


Very helpful stuff thanks for sharing @mikmonken. Main problem I see with applying these changes is because the web interface is in development when you update it would you not have to manually edit/move the files all over again? I wonder if @Elco would consider applying some of these changes (two versions, password protection etc) to the standard web interface? It may be too complicated for the average user to have two interfaces though.


So I completed a brew on Sat. “Bishop Finger Kent Strong Ale” and put in the fermenter with temp set to 64 F at collection. Now sitting at 65F and will move up to 69F until FG is reached. Here is my graph. I noticed that it cycles every 30 to 40 minutes due to the heat in the gauge and not using the best installation. I have to say though the fridge and beer temp settings are pretty close.


Looks allright.
May I recommend the snipping tool (standard included with windows) for better (cropped) screenshots?
And if you keep the beer setting enabled, we can see whether the drop around 15 Mar, 18:00 was intentional.

[Solved] BrewPi losing precise control

I’m new to BrewPi and the forum. I am operating an Arduino with brewpi-arduino-uno-revC-0_2_10.hex. Control appears to be working fine, but after about three days in fermentation the wort temperature started to peek higher than I think it should. I would appreciated some assistance with determining the cause and what can be done to prevent it from happening in the future, or should it be left alone? Chamber is a standard refrigerator and an insulated 20w FermWrap heater(insulated) attached to a poly conical fermentor.


BrewPi assumes the heater heats the air, not the beer. When it heats the beer instead of the air, it might cause overshoot, because the air does not heat up and it keeps heating.


Thanks Elco, I reconfigured my chamber to use a small space heater rather than a wrap in direct contact with the fermentor.


My apologies for jumping on an existing post, but I’m looking for feedback on my graph and potential adjustments I should make on my settings. Am fermenting in a stand-up commercial beverage refrigerator with a glass door. The fermentation bucket is sitting on the floor of the chamber, with a thermowell in the center of the bucket. Fridge sensor is towards the back of the chamber. I don’t have any heating element set up. Any suggestions on how to get the beer to be a more constant temp? It oscillates over 24 hours or so…

Here is a close-up of a 24 hour period:

Thanks in advance!


It looks like at midnight, the fridge temperature is dropping without any cooling action, causing the beer temp to drop as well. Because this looks like it is due to the temperature outside the fridge, and the fridge has no heater, I don’t think it is something that can be corrected by BrewPi.


Hello there,

Not wanting to create a new topic since my question is pretty much related, I’ll post it here.

So, I finished setting everything up and yesterday I placed in the chamber a 15L bucket with hot water ~35ºC to test how long it would take to drop to the goal temperature 19ºC and check if everything was running smoothly.
Before placing the hot water the system was shut down (so the chamber temperature was the same as the room temperature) off. The room temperature is around 24ºC and I’m using default settings.

My setup:

  • Fan connected only when heating,
  • 50W 7M cable heater,
  • Vertical freezer (1.5m tall).

This is the graph at this moment:

And a detailed one:

So, the things I noticed were:

  • I thought the temperature drop would be faster (took almost 15 hours to stabilise in the goal temperature),
  • The temperature went below the goal before stabilising and it ended up using the heater,
  • There was a peak at 18h in which the freezer door was opened for a while.

My main questions now are:

  • Is this what I should be expecting? Namely the duration and going below the target before stabilising. In case it is not, how should I tune the system?
  • Should I connect the fan also when cooling? Or only when heating should be enough? The heating cable is on the bottom of the freezer.
  • Do you usually set the chamber temperature to a low value in order to cool the wort faster? In case you do, which value is a good one?


I would run the fan when cooling. This can reduce overshoot too, because the back of the fridge will not get much colder than the air.

In fact, I would run the fan continuously on low power, so even after compressor turn off, you have heat transfer between the back of the fridge and the air.

You can also increase the beer to fridge Kp to make it faster, and increase Kp to counter overshoot. You do have some integrator windup. Increasing Kp will help with that. I think your beer to fridge Ti might be a bit low. Increase it so your integrator does not build up as quickly as it does.


@Elco, I’ve updated the configs and settings as you suggested:

  • Now the fan runs constantly,
  • Moved the chamber temperature sensor to a place closer to the door placed in the middle of the freezer,
  • Increased Beer to fridge Kp to 8,
  • Increased Beer to fridge Ti 15000.

So, it looks like the temperature drop is way faster and the chamber/beer temperature is much closer.

However, there seems to be a big fluctuation on the fridge setting temperature that didn’t occur previously.

Here goes a shot that shows the different tests. For each one of them I increased Kp and Ti. The last one includes the fan. The second one is a detail of the last test.


If beer to fridge Kp is higher, you will also get a more aggressive fridge setpoint, this is expected.

You can smooth it out by increasing the delay time of the the beer-to-fride PID filters.


Hi all and @Elco ,

My setup: Raspberry Pi 3, Original Arduino with SSR and Rj11 temp sensors from the brewpi-shop. An old fridge with a 200W heater and a bathroom fan.

I have an IPA fermenting at the moment, it was set at 18 degrees for the first four days, then ramping towards 20.5 degrees over the course of 3 days. The fridge temperature probe is taped to one side of the fridge, midway between the door and the wall, while the beer temperature probe is inside a thermowell in my fermenter (I have insulated the entrance point so to keep the temperature more stable). The heater and the fan are both below the beer, separated by a plate that I drilled a few holes in to allow circulation in the fridge. I have to say that my fridge is situated outside in a garage, the room-temp shows the temp, its not as cold at the moment.

My questions are as follows:

  1. At 18 degrees the heater never turns on, but the beer temp stays stable, is the beer itself or the fridge generating that much heat??? The fridge temperature seems to increase rapidly when cooling is turned off.
  2. I have not touched any settings on my brewpi, but the temperature deviates by almost 0,15 degrees on the hot side, now that doesnt sound as much but I´ve seen other other people keep the temperature much more tight (Elco showed a graph here: Controlling overshoot). My fridge temperature and fridge setting never seems to be in sync, is that normal?


One more question:

My fridge goes out from pin 5 and my heater from pin 6 from the Arduino. But the screenshot shows differently, is this correct? As my pins are inverted I mean. I tried to change it but then it heats in reality when it should cool.

Thanks for any input on my setup.


From your description, it seems like:

  • You have your outputs inverted
  • You swapped the outputs

Somehow it still seems to work.

Check that:

  • When it says cooling, the compressor should be ON
  • When it says heating, the heater should be ON

If you have your SSRs directly connected to the Arduino, it should be set to not inverted.
You might need to swap your pins.


So I just tried to swap them again and will post the results soon. What I have now is the correct pin assigned to heater and fridge, and not inverted. Thats what you meant? I have checked that my outlets are connected to the correct SSR, while the Arduino pin was swapped as you stated.

When you say that the relays are connected directly to the Arduino, I believe so, but I do have this on top of my Arduino (, this still means that it is connected directly?

This is the image showing how I connected my devices: (exception being that I have pin 5 to cooler and pin 6 to heater outlet.

Yesterday evening I checked on the fridge and heater because of image 3 in the first post where the fridge temp spikes very quickly after cooling ends. And, the heater was on, seems like its always on! But it seems like I can still keep the temperature I define.


Sounds like you indeed needed to set your outputs to non-inverted.
Based on your schematic, that seems correct.


Thanks, lets see how it goes!

According to the brewpi documentation:

“Here you can set whether the output/input should be inverted. Because the shields have a
transistor that inverts the signal behind each output with a terminal, you should set this to
inverted. For devices you add yourself, without a transistor, do not invert the signal.
For the door switch, it depends on the type of switch you have.”

Does this mean that if I had the cooler to pin 6 and heater to pin 5 I would choose inverted? Or are the “shields” I´m using not having any transistor as the original shields do? I´m simply extending the pin so I can screw.