Mythos problems

I’ve been using a Mythos for a little over a year and it has been mostly great… until recently. In the morning I’ll turn the grinder on, fill the hopper with beans, and wait for it to heat up a bit before dialing in. Lets say that my dial in is: 17g-37g-34s, and I’m pulling shots at those specs wonderfully and consistently until… the first rush of the day, I’m grinding shot after shot and the machine gets hot so the cooling fans kick on, and now I’m screwed! Doses are no longer consistent and are off by a gram or more and the shots are pulling for 4 or 5 seconds longer to hit the target yield…WTF? I adjust my grind setting coarser to compensate and to try to get things back on spec, but there’s no consistency. Some shots are only off by a couple seconds but some are off by a lot more.
Once the chaos subsides and the grinder gets a chance to cool down, the fans shut off. After adjusting my grind setting and dose-time back to where they were originally, things become consistent again and it’s all back to normal… until the next busy rush.
Anyone else experiencing problems like this, or have some advice for me?

Are you using volumetrics or weighing every shot?

Check the declumper,my experience heavy usage usually the declumper is already ruined

1 Like

Weighing every shot.

Clump Crusher is super clean. And if it weren’t, that still wouldn’t explain why the shots get so out of whack once the fans kick on. Though it would explain the variance in the doses, but it would be happening all the time, and not just when the fans turn on.

wait i didnt read properly, so in a rush hour the extraction time will get longer even with after you weigh every shot? What espresso machine are you using? im curious

Yes the shot time will increase once the cooling fans turn on. Using a LM GB5 2 group semi-auto.
I’m guessing that once the grinder fans turn on, the burr heating element might be turning off, so basically I’m going from grinds exiting the chute at 120F to around 80F within a couple minutes. I’m not sure that shift in temp would really throw it off by the amount that is happening, so I’m pretty confused by it.

Leave that sucker on 24/7.


I can certainly do that, but why? Mind telling me your theory on how that is going to fix the problem?

I wish it was that simple/complete of a fix! But it should hopefully reduce the variance your experiencing. The info I was given was that it takes 12+ hours for the milling chamber to become saturated to the temp the element is intending to provide and only then will the grinder perform as advertised.


Whoa! 12 hours? That is crazy! I thought it only needed 20 minutes or so… hmmm I will keep it on 24/7 for the next few days and let you know how it goes. Thanks for the insight.


We had a similar problem during our rushes, we actually unplug the elements on our mythos during the rush and plug them back in after its calmed down. Solved our issue. We leave the element on 24/7 otherwise. Hope it helps.

Better? Worse? Same?

I didn’t notice a difference, so I just unplugged the heating element and haven’t plugged it back in. Things have been a lot more consistent this way.

Interesting! Good to know.

Mine is left on 24/7 and I’ve never had a problem with it :slight_smile:

1 Like

If it had worked perfect for a year and then changed, something is different. Can you tell if the problem is changed weight or changed grind? If it’s the weight that gets wonky whenever the fan is on, I’m guessing something on the control board has become sensitive to the electrical noise generated by the fan. If it was mine and I could get to the control board, I’d unplug and re plug every single cable and connector I could find to see if that helps.


My experience from small cafe is that Mythos with turned off heating element is more consistent.
I don´t realy understand the idea of the heating element. Doesn´t work in small cafe (1kg/day) and it is unnecessary in heavy duty cafe since grinders warm up by itself grinding shot by shot.

Same problem for us too. We are a large, high volume cafe in NZ with two Mythos grinders.They get clumpy when a rush ensues but basically we turn off the heaters during the day but turn them on at close. That way the machine is heated up when you need it when opening the next day. We clean them both every day unscrewing the front panels and brushing around them. So far this is working for us but not happy as they are only a few months old. Design fault with Nouva Simonelli that needs an answer from them!

This article should answer most of your questions