Mara X brew temp

pete4eyes

So I’ve been happily using my Mara X since April this year and installed a serial to usb TTY cable into the gicar to monitor the brew temp sensor reading. Simply connected to my laptop and viewed in “putty” you can read out the boiler temp and target temp as well as the brew sensor temp.
In idle the brew temp is reading as it should, let’s say 92 degrees.
Now the problem…
As soon as I start to pull a shot this brew temp reading starts to rise to over 100 degrees and then starts to decline a little to the end of the shot.
Is this normal? I would think not but perhaps with the sensor location at the bottom of the heat exchanger path, maybe it is?
Just looking for validation to calm my concern that something is wrong, or not…?

Tjyven

pete4eyes Cant answer if it is normal but have you messured the temperature in the group head or portafilter while pulling a shot?

pete4eyes

@Tjyven
I’ve not tried measuring the group head temp as I’m not sure how to do this accurately beyond buying a group head thermometer which I don’t really want to spend money on… which I appreciate isn’t much help… might try measuring with a voltmeter temp probe stuck inside the portafilter, though not likely to be super accurate it might tell me circa 90 or over 100 degrees I guess.
A very sensible suggestion, thanks!

DavecUK

It’s normal

pete4eyes

DavecUK perfect. Thanks Dave. It kinda makes sense, I guess the mass of the group head and the temp that is it controls it for the most part. I probably should have left it alone…