Power/pump surge?

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amamet

#1: Post by amamet »

This is my new bezzera mitica-top pid machine. Is this surging normal? I have it shown with a blind basket as its more pronounced. There is surging from the pump that is really audible. This is somehow affecting the grinders motor as well, as you can hear. You can also see the light on the back of the machine pulsing. It's a dedicated 20 amp beaker, ive moved the machine around my house and still does this. I plugged a microwave, toaster and a coffee maker into this outlet (one at a time, not all together) with the grinder and all work normal. This only happens with the espresso maker. It all seems timed with the blinking dot on the pid display

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Jeff
Team HB

#2: Post by Jeff »

Sounds like line-voltage drop if "dot" is heating element on. That usually has to do with the quality of connections in the wiring between the breaker panel and the outlet. If you have the equipment and skills to check the drop under load, I would do that.

Nunas
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#3: Post by Nunas »

I believe Jeff is correct and that the noise you hear is due to an IR drop (voltage drop), but it could be normal. Concerning your tests, First, the heater in your machine is cycling on and off, which is an intermittent heavy load on the wiring. The other devices you mention connecting in place of the espresso machine do not cycle on and off, providing a constant load. Thus, no pulsations. Moving the machine to other circuits in the house was an excellent idea. That eliminates an issue with the wiring in your 20-amp espresso machine circuit, since you get the same results everywhere. This leaves just the main connection in your load centre (beaker box/fuse panel). To test that safely, lug the machine over to a neighbour's house and try it there. If no pulsations happen, then call an electrician asap.

As for something wrong in the espresso machine, when the machine is started from cold, are there any pulsations, or does this only happen after the machine has warmed up? I don't know your machine at all, but most HX PID controlled machine's heaters stay on until they warm up, then they pulse on and off to keep the temperature stable. My machine also has a PID, but I don't notice any such cycling. As this is a new machine, has this pulsation always happened, or is it something that just started happening? It would be good to hear from owners of other Bezzera mitica-top pid machines to see if this pulsation is normal. On the remote possibility that there is something in the machine, I suggest you contact your dealer and ask about this, since the machine is likely under warranty. The dealer should also know if this is a common phenomenon with your make and model of machine.

amamet (original poster)

#4: Post by amamet (original poster) »

the pulsing only happens once heated up and reaches its set temp. the grinder definitely drops its pitch when the machine is on and heating up, as in the dot is lit up

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cafeIKE
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#5: Post by cafeIKE »

The service inlet is likely bad. Can you measure the no and load voltages?
i.e. With the machine off and while the machine is heating from cold.

For point of reference, drop on a 120v 20A circuit should be about 2 volts with a 120v espresso machine. Any more and the electrical service is defective.

JRising
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#6: Post by JRising »

It's normal for many machines.

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cafeIKE
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#7: Post by cafeIKE replying to JRising »

What's normal?

I've never heard a grinder or pump, vibe or rotary or geared, slow with a PID pulse on a single group machine.

I just checked my Niche, plugged into the same 20A circuit, and toggling full power on the 1800w DB makes Z E R O difference.

JRising
Team HB

#8: Post by JRising »

cafeIKE wrote:What's normal?
It's normal for a vibe pump's sound and output to change slightly with the voltage drop that corresponds to the element drawing power and shutting off. It's not ideal, it can be reduced with improved wiring, but it's not abnormal.

amamet (original poster)

#9: Post by amamet (original poster) »

Rotary pump

Nunas
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#10: Post by Nunas »

I've been thinking about your issue. While I still think your machine is likely normal, as well as your 20-A espresso circuit, there's another thing you might look into. On the older machines, with pressurestats, the on/off cycle is somewhat like the one you're experiencing. But most PID machines control the heater via a solid state relay. So, there's no real reason to pulse the heater so slowly. As Ike says, he does not experience the pulsations you describe, and as I said earlier, neither do I. So, I wonder if your PID settings might be off. Presumably, somewhere in the destruction manual, there's a list of recommended PID settings. It's a long shot...just chucking jelly at a wall here to see if anything sticks :lol: Also, it would be useful if you could give us the results of the test suggested in post #5.