Rocket Appartamento sudden pressurestat problems

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by luna »

Hi there,

we own a Rocket Appartamento espresso machine for a few years now (since 2017 actually) and it worked fine until recently when the pressure started going over the range limit and we tried adjusting the pressurestat but it did nothing, so we bought and installed a new one. Now we have a new problem. When we turn the machine on the pressure first rises into the "green zone" and then immediately drops and stays down. We also replaced the whole switch part. Did anyone have a similar issue and does someone have a clue what else than the pressurestat should be replaced?

Thank you all for your help in advance - we really need all the coffee now more than ever :)

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Team HB

#2: Post by homeburrero »

Since you have a new pStat and it's sometimes failing to heat, the likely culprit is a failing relay in the controller.

First, verify that you have the typical Appartamento wiring scheme where the controller does the heavy switching of the element power. To do that unplug and uncover the machine, and visually trace the two wires from the pressurestat. If both of them go down to pins on the controller then you have a case where a low current continuity through the pressurestat tells the controller to open or close a relay that powers the heater (resistencia).

The controller may also open the resistencia relay as a safety measure when it senses that the reservoir is out of water. On your machine, where I think the green light blinks when it's low on water, that's not likely the cause unless the light is blinking when it fails to heat.

The fix is typically to replace the controller, although people with electronics expertise can troubleshoot and repair them, usually with a replacement relay and/or transformer. (Boyt Enterprises in Washington is one place here in the US that can do that.)

Sometimes people will try a little test - - With the machine open and powered up they will give the controller a little tap with a wooden spoon, and if that causes it to start heating they have more confidence that it actually is a bad controller relay and not a pStat or a protective thermoswitch malfunction. Doing anything with the machine open and plugged in is potentially dangerous -- you could damage the machine or electrocute yourself, so leave that, or especially doing any troubleshooting that involves measuring voltage drops inside the machine, to people qualified in electrical appliance safety.
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luna (original poster)

#3: Post by luna (original poster) »

Dear Pat!

Thank you so so sooo much! We took all the wires out of the controller and put them back again and guess what - it works!! I hope it stays that way but I really believe it will. Thank you again! You saved the day(s)! :)

Greetings from Germany,

luna (original poster)

#4: Post by luna (original poster) »

Me again :) So, the machine works great as long as the controller box is outside the machine (laying on the table turned with the wires facing up) but when we put the box back in and close the machine up, it works fine for an hour or two but then the pressure drops down all of a sudden and never goes up again!! :? What is that about? Should we repace the controller or just the pressurestat wires? :|

Thank you for your help again!

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Team HB

#5: Post by homeburrero »

If the wires and connectors look clean and feel tight they are most likely fine and you have a controller problem. It makes some sense that it might work OK when cool and fail when warm. It might be time to replace the controller. Try to get the same controller as your original. The Rocket part number, A190004524, may be used for different controllers.

The newer Rocket controllers support a feature called Eco Mode, which can turn off the heater after 90 minutes of the machine being being turned on. If you get one of these, ask the vendor about jumpering it up to work like the old one that does not have the Eco feature.
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#6: Post by JRising »

You may want to read through the other Appartamento thread on this that is still being contributed to today as well as:

Rocket Appartamento over pressure/loud squealing?

which is much older but explains it the possible issues and the different ways your machinie may have been wired from the factory.

Your issue, from your description and the way it works when the control box is hanging out, is that the relay on the control board is burning up inside. There isn't much left of the contacts, sometimes they get stuck shut (actually spot welded because of the carbon build-up) and the machine will overheat, sometimes they don't make contact at all and after warming up once the machine cools back down for good until switched off and on so the relay makes another attempt. Sometimes it works fine (apparently when hanging up-side down).

It is possible to replace the relay in that board. There are threads on these forums about doing so so that your old controller is available as a spare.
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