What kind of heater are you using?

I currently have a 17W heating mat that is apparently underpowered for brewpi chamber heat. Would others be willing to post pics or description of their heating setup? Looking for inspiration.

I’m using a 150W Ceramic heating bulb (black / designed for reptile enclosures). The size is WAY over-speced, but with the latest PWM code, BrewPi adjusts how long the heater goes on for. Since changing to the bigger bulb (was using a 60W) element, my chamber is a lot more responsive… especially when ramping temperatures.

I paid about $5AU for the bulb on ebay.

I’m using a 60W tubular heater (as a lot of others are):

Second on the 60W tubular heater

Nothing yet, still building my fermentor but I bought this https://www.elektronicatekoop.nl/prem-i-air-eh1712-buis-verwarming-45-watt-30-cm now you guys are worrying me 45watt is not enough…

Thanks everyone for your posts. I encourage people to keep posting pictures or descriptions as it will probably be very useful for others.

I ordered a 150W ceramic bulb (black, $6US, on ebay). Will post a picture once it’s here and installed.

@charliwest See fridge-not-heating-to-reach-set-point for a suggestion on how to tune brewpi for your heater.

I’m using a hair dryer set on low. Get the best of both worlds as the fan does well to circulate the chamber air so your not getting temperature gradients.

I’m using a “My Heat” heater.

I’ve yet to finish my freezer build but this worked pretty well in my pre-BrewPi days.https://www.amazon.com/Lasko-100-MyHeat-Personal-Ceramic/dp/B003XDTWN2?th=1

I use a 30W heating belt with no issues at all. I have a 5 gallon SS brewbucket, and the fridge is in my garage that gets down to 5 deg C in winter.

I’ve manage to hide/embed the belt into the back panel of the fridge (which distributes the cold air with vertically spaced vents). Even though the back panel cover is plastic, the belt is low watt density enough not to melt anything.

Even though the heater is somewhat separated from the main fridge chamber (with no fan to recirculate while heating), I don’t have any issues with overshooting using the default Brewpi settings (it holds <0.1 degree difference the entire time).

I installed my 150W heat lamp

and would agree with @sbowler that it is probably too much. While the 17W heat mat called for heat almost constantly even with an increased value for heater1 Kp, it did manage to keep temp. On the other hand, the 150W heater turns on much less and sometimes calls for cooling to compensate. I reset all the advanced values when I installed the 150W heater.

In this graph image

you can see the part labeled “1” (in blue) is the 17W heater with default brewpi settings. The part labeled “2” (in red) is the 17W heater with heater1 Kp set to 500. Lastly, the part labeled “3” (in black) is the 150W heat lamp. Notice the fridge temp swings wildly compared to the lower powered heater. Maybe @Elco or someone more knowledgeable with PID can suggest an adjustment to make. My only thought is to lower heater1 Kp, which “I think” would turn the power on for less time during each 4 sec PWM cycle while in heating mode, but that’s just a guess based on my previous experience.

Either way, as @Elco has suggested in other posts, it seems 50W to 100W is probably the best recommendation for anyone buying new.

That’s interesting. Whilst 150W is definitely more than I need in most situations, I generally don’t see the off/on/cooling behaviour that you’ve observed. My most recent brew had the heater on 100% of the time (PWM, on for about 0.5 secs every 4 secs).

There are also lots of variables to consider:

  • Size of fridge (mine is full size)
  • If you run a fan - All the time/only when cooling/not at all
  • Ambient temperature

I can share my Kp/Ti/Td settings, but it would probably be better to get @Elco’s thoughts on how to tune your setup.

@andylytical I think you should mainly try to get a smoother fridge setting. Try increasing the filtering in the beer-to-fridge PID.

My guess is that you should set the heater1 Kp to 10, Ti to 3600 and Td to 30.

@sbowler Thanks for your comments. It’s good to know that maybe something isn’t quite right on my brewpi for my setup. For the graph you posted and your current setup, have you adjusted any of the settings on your brewpi? I’d be interested to see your settings if they are not the defaults.

I have a full size, upright freezer (consumer style with removable shelves). The freezer has a fan on when it cools.

I did an experiment this weekend. Since I had adjusted the herter1 Kp when I had the 17W heater and since the brewpi ran for a good 2 weeks in that mode, I wondered if perhaps there was historical data being taken into account in the PID algorithm. When I installed the 150W heater I found a “reset to defaults” button in the Advanced Settings. However, another forum post mentioned the “Reset Photon to Defaults”, which I found at the bottom of the Advanced Settings window. So this weekend I used the “Reset Photon to Defaults” button. I had to re-add all my temperature probes and heating/cooling outputs. One thing that was unexpected was that the brewpi remembered my temp profile and the beer I was monitoring. In the end, resetting Photon to defaults" didn’t help. @Elco, does my theory make any sense, that the brewpi has historical data that could be affecting the PID algorithm since I’ve changed my heater from 17W to 150W?

@Elco, I will try your suggestion and post back. I think I’m also going to browse the forums for re-setting brewpi to factory defaults. In my mind, that is the most accurate test.

The reset to defaults button is the one you mentioned. But I don’t think it is needed in this case.
The algorithm does not really remember the past, only in what the integrator accumulates.