Rapt Fermentation Chamber, large temperature fluctuations

[lassebn85]

Hi Fellow home brewers!

Recently I bought a Kegland Rapt fermentation chamber + Rapt Pill.
I'm having issues with it experiencing relatively large temperature fluctuations.
They promise stability as shown in the example below

However, in my case, using my fermentation chamber, I'm experiencing the following:

In their example, you can see that the built-in temperature sensor of the ferment chamber deviates by +/- 0.5 degrees from the target temp, while the Rapt Pill/beer temperature remains more or less spot on the target.
On the contrary, I'm observing that it is the Rapt Pill's/beer's temperature that deviates by -0.5 to +1.0 degree from the target temperature (which aligns with me setting the cooling abd heating hysteresis to +1.0 and -0.5 degrees, respectively). at the same time, the temperature in the ferment chamber jumps up and down between -7 and -1 degree from the target.

Why isn't my refrigerator behaving as promised in their example? In their example, it is evident that when the beer/Rapt Pill reaches the target temp, the ferment chamber's temperature will be within +/- 0.5 degrees of the target, meaning the beer is spot on the target.

My setup is as follows:

• Cooling hysteris 1 degree
• Heating hyseresis -0,5 degree
• Compressor cool down 5 minutes
• Mode Switch Delay 15 minutes
• Cooler enabled Yes
• Heater enabled Yes
• Fan always on Yes
• Bluetooth enabled Yes
• Allowed sensor diff 5 degrees
• Sensor timeout 130 seconds
• NTC Beta 3950 K
• NTC ref. temperature 298, K
• NTC ref. resistance 1000000 oh
• Relay cycle time 120 seconds
• PID heating No
• PID P coefficient 0,5
• PID I coefficient 0,0

Can anyone figure out why my ferment chamber's cooling and heating are triggered by the beers temperature instead of the ferment chambers, as shown in Keglandsexample?

Kind regards
Lasse

 

[KepowOb]

Ideally, it should be going based off the beers temperature.

If not, your fermentation temps would get way too high.

Looking at what's going on in your graph, the fermenting beer is keeping within the temp ranges you set, which is perfect. The air temp around it doesn't really matter at all.

Their example graph doesn't really make sense tbh, nothing is that perfect. A bit misleading even maybe, but based on the temps of your beer staying within range, it looks like it's working fine imo.

When it warms up a little, the cooling really kicks in and it looks drastic on that graph, but it's normal. With so much thermal mass, a very small change in air temp around it would barely have any effect at all.

The only thing I can maybe think of for the example graph they have is it was with water as an example or something. When beer is fermenting it's producing heat, it'll never stay so perfect like that.

 

[Kickass]

Your beer is fluctuating by no more than 1.5 degrees. Much less most of the time. I’d say it’s working beautifully.

 

[day_trippr]

Beauty is in the eye of the beholder
I have a pair of BrewPi controlled chambers holding their respective beer temperatures within +/- 0.3°F of set point right now...

Cheers!

 

[lassebn85]

Thanks for the solid replies (y)

 

[day_trippr]

If the complaint regards the chamber temperature, as long as the beer temperature is staying inside a respectable window there's no concern. While I mentioned my BrewPi chambers regulate the beer temperature quite tightly the chamber temperature can be all over the place.

For example, this log segment shows the chamber temperature running up to almost 72°F while the beer temperature remains close to the 67°F target. This ping-ponging between heat and cool cycles is an "end of fermentation" thing with BrewPi that I just live with rather than fight

Cheers!

 

[TomSellers]

Can anyone figure out why my ferment chamber's cooling and heating are triggered by the beers temperature instead of the ferment chambers, as shown in Keglandsexample?

The chamber is triggered by the temperature that the Pill reports, which is the beers temperature. Looks like it is working as intended.