RAPT fridge...I bought 1....Review

[usastman]

I was able to purchase the RAPT fridge from Kegland after a long wait.
Fridge spatially is good ...can hold my two 30L alrounder fernenters.
I did not purchase additional probe lead. I did a double brew - whacked fermenters in - set temp. Set the temp and connected to wifi. This allows me to see temp real time - and track the temperature.
Unfortunately the temp bounces around a lot by a couple of degrees either side of set temp. The fridge is continually cooling then heating..?
After fermentation i bought a temp probe...calibrated ...hoping this would make things better. I am washing some yeast and have containers in fridge. Set temp to 5 deg....fridge currently sitting at 7.5 deg - has been at 3 deg...?
Considering purchasing and Inkbird temp controller and using that.
Bit disappointed after shelling out $800.
Hopefully there will be firmware updates that fixes the issue. I am a bit concerned of my next power bill ...as fridge is continually in a cycle of heating and then cooling....time will tell.

 

[usastman]

 

[clickeral]

Whats the heat and cooling limits? obviously on the inkbirds you can set down to a .3C difference so set of 4C 4.3C it starts cooling and 3.7C it starts heating?

May need to be a 1C either side? also should have a compressor delay of at least 3mins right? can you adjust settings on these?

Fermentation will put off heat but it should be able to hold temp, +/- a certain range

My glycol setup as an example overshoots by about .1c when cooling and I have the heater belt set at .3c before it comes on (same with cooling)

 

[MHB]

You should be able to adjust the hysteresis (gap between when the fridge turning on and off).

There are issues with setting the band too narrow (fridge turns on and off more often) but remember the beer inside the fermenter will be a lot more stable than the air temperature..
You need to read the operators manual a bit more carefully. I doubt the heater is turning on, but you should be able to set that to.
Mark

 

[usastman]

Thanks Mark - only problem ...no manual provided. Videos coming....but a manual would have been nice.
I has seen the hysteresis setting...but was sure if smaller setting or larger was better....no manual to look up.
The screen would show when fridge was cooling or heating. I get that mass of fermenter will be fairly stable ....but i hoped it wouldnt be too much to keep near or about the set temp.
I have since turned of fan setting - seeing if temp stabalises .....not sure if fan shoukd on/off......no manual...?
Wanting to provide feedback to others who may purchase

 

[Grmblz]

Here we go again, typical KL V1.0 with the early adopters being used as beta testers.
Firstly fan needs to be "ON" otherwise you will get temperature stratification, hot layer of air up high and cool layer at the bottom.
I use STC 1000's (they're probably very similar to what's running your fridge) hysteresis is set to 1.0c, compressor delay set to 5 min's (good luck finding these settings without a manual) most importantly get the probe and tape it to the fermenter under a bit of insulation, this will (should, if the controllers any good) slow things down and prevent the on/off nonsense, ideally the probe should be in a thermo well in the centre of the brew, but a bit of polystyrene or wet suit material taped over the probe works almost as well.

 

[usastman]

Thanks grmblz ...have something to adjust...thanks

 

[MHB]

Do leave the fan on.
You will get closer to your set point with the fan running and it will cool the brew faster.
I looked online for the manual and there wasn’t one that I could find, said after you register you should have access and making setting adjustments was mentioned in the video. But yes I agree no manual is a real fail and Grumblz has a point, you are probably helping create the FAQ that later brewers will rely on...
Mark

 

[duncbrewer]

Second hand Fridge, heat belt or two heat belts if two brews, a brew pi and temp probes or a couple of brewpiless and add some ispindels and you'll have about 650 dollars in your pocket. Wifi and web readable and you can build a ispindel repeater to display your results as well as relay to the web. The PID controller on the brewpiless I'm using keeps temp within 0.2 degrees and isn't cycling the heating and cooling that often, see the red or dark blue bars on the bottom of the graph. I haven't linked the ispindel into this brewpiless as I connect that via brewspy and leave brewpiless to get on with the control.
That said the stc 1000 I used before did a very good job but required physical adjustment and viewing by line of sight.

 

[usastman]

Duncbrewer - i was heading down the road of second hand fridge etc. But decided to go the turn key solution - splurge. I assume when i set my kegorator or kitchen fridge to 5 deg....it sits on 5 deg. I expect the same from a purpose built fermentation fridge. For 800 large...?

 

[Nullnvoid]

I think it's probably an innacurate assumption that your kitchen fridge or kegerator stays on the temp you set it on. It would fluctuate as well. You just don't know this until you start fermenting in a fridge

For my own system, I have a freezer an inkbird and both a Fermzilla and Fermenter King. I now also have a thermowell in both fermenters. When I used to do what GMBLZ said and tape the probe to the side of the fermenter under a stubby holder I got less fluctuation either side of the set temperature, than I now do with the thermowell. It is probably my settings on the inkbird but there is now definitely a 1degree +/- swing using the probe in the thermowell as the liquid heats and cools.

With thermowell

Without thermowell

 

[duncbrewer]

@usastman
I completely agree with you. It should just work, it's not rocket science it's fridge science. I'm not rapt about your reports that's for sure.

As you can see on my data chain, actually very little going on at all with heating or cooling, though this is day 3 of a saison ferment so activity is reducing. I had to return my Hop missile as the bottom edge of it was razor sharp ( i could cut paper with it ) and had my power supply for Maltzilla blow up first time I turned it on. So problems aren't unknown. Suggestion from the producer of the hop missile was never happened before and file or sand it down. The fact I returned it to the supplier as they wanted to check it and they didn't send a replacement but filed mine down suggests the rest of the batch had problems as well.
There's always the not of merchantable quality option to exercise if it doesn't work properly. It's very bad for the fridge compressor cycling on and off in rapid succession. Also inefficient on energy. You haven't got the fridge jammed up between cupboards and no air circulation by any chance?

 

[duncbrewer]

@Nullnvoid
I find there is a discrepancy between the temp probe in thermowell and the ispindel reading but that is only if thermowell measures near bottom of fermentasaurus and the ispindel is floating on the top. Difference in height about 30 cm.
I also think you get more cycling when there is air around the temp probe which there is in the thermowell. I used to use blu tack to hold the sensor on the side and then foam over the top and that possibly also helped stability.

 

[Nullnvoid]

That's an excellent point about the difference in height. Makes sense.

It doesn't really concern me, either way I'm making beer that I enjoy and other people also enjoy so I must be doing something right.

In my opinion, I guess until you start measuring what is happening in a fridge/freezer at regular intervals like we do now, you don't really consider what is happening inside and you assume it's at the same temperature the whole time.

 

[clickeral]

If you take some screen shots of each setting function I can probably have a guess at what each one is, ive used a few different controllers now

 

[Half-baked]

I agree it’s very poor form not to have a manual available, but want to hear a bit more about @usastman’s process before making judgment.

Particularly, where was the temp probe? If it was dangling in the air, then even the best temp controller will have quite big temp fluctuations…

 

[duncbrewer]

@Half-baked agreed, dangling temp probe in my keg fridge is up and down with the fan and then with the compressor cycling on and off. Much steadier reading stuck to the side of a keg with blu tack . It's the beer temp that matters not the air temp.

 

[postmaster]

I was able to purchase the RAPT fridge from Kegland after a long wait.
Fridge spatially is good ...can hold my two 30L alrounder fernenters.
I did not purchase additional probe lead. I did a double brew - whacked fermenters in - set temp. Set the temp and connected to wifi. This allows me to see temp real time - and track the temperature.
Unfortunately the temp bounces around a lot by a couple of degrees either side of set temp. The fridge is continually cooling then heating..?
After fermentation i bought a temp probe...calibrated ...hoping this would make things better. I am washing some yeast and have containers in fridge. Set temp to 5 deg....fridge currently sitting at 7.5 deg - has been at 3 deg...?
Considering purchasing and Inkbird temp controller and using that.
Bit disappointed after shelling out $800.
Hopefully there will be firmware updates that fixes the issue. I am a bit concerned of my next power bill ...as fridge is continually in a cycle of heating and then cooling....time will tell.

Got one myself and just fermenting a pale ale. I changed the hysteresis gap heating and cooling to 1 deg. I am using the pale ale profile and it seems to be performing okay. Left the compressor delay to 54 minutes. Since it has been rapping up a deg a day I did notice it was heating a bit more, I only have the fan on when its cooling or heating. I have the probe attached to the fermenter with a piece of polystryene as insulation.

 

[Grmblz]

The temp probe is behind a small plastic grill in the right hand side wall about a third of the way up, interesting choice of location
Given the intended usage (temp controlled fermentation) of this product, and the accepted wisdom of measuring the liquid temp rather than air temp I find this whole add-on sensor thing a bit Heath Robinson, especially at its $900 price point, it's almost as if it's an afterthought or a MacGyver fix for a product that doesn't work as intended. Will be amazed if the Rapt V1.1 doesn't address this issue.

 

[mynameisrodney]

I thought you got the best control when you had both a beer temp and chamber temp reading? Like the brewpi does it. So from that perspective it does make sense to have the chamber probe where it is, but I agree, its pretty poor not including the beer probe.