Hello group
I have a La Cimbali M20. The pump did not auto fill when the boiler level ran low and my heater
blew. I took the heater out. Ordered a new one. I took a picture of the wiring before.
I have at least two problems...likely three.

1. This is a 2 group ~4KW unit. It has a heater with 6 terminals two rows of three.
two black wires, to red wires, to white wires.

My understanding is that the columns are the terminals for three heaters. I connect same coloured
wires top and bottom. That should give me 220V across the top and bottom terminals.

just to be safe, I connected the top red,black and white wires. I had the other sides dangling not touching
anything. I turned on the power and measured the voltage. I found that the voltages on 4 wires were the same
and 2 wires were the other voltage, ...that does not seem to make sense.

...could it be that someone deactivated one of the heaters to reduce power consumption
by making similar voltages on both leads? I would think you would just disconnect the wires and cover them up. Or is something broken from when the heater blew?

2. Checking with the power off, my power switch is jammed up and one of the switched to turn on
the pump (for the left group).
After a lot of force I got the power switch to turn. Clockwise is not too bad but counter clockwise there
is nasty sound and feel of broken bearing or fingers in the switch. Not sure. Could this be be due to arcing?
or sitting around? Is there a way to lubricate the switch that could help? I put some oil on the shaft and tilted
the machine so it would dribble in. ...maybe got oil on contacts. I could spray contact cleaner in there to clean that out. ... Maybe I made a mess of that.

3. My pump did not turn on when the level went low. I will need to fix that next. Looking at the float and
switch, all looks good. maybe it jammed up. I will need to look at that carefully.

Thanks

About heater wiring: if you have single phase mains, connect the three elements in parallel. To be sure of leads (a pair for each element) use an ohm-meter. If you have 3 phases mains, connect each element to each phase (so the need to have red, white, black wires). In case of single phase, check wiring: you will see that red, white and black wires are wired together somewhere.
The two columns of terminals on the heater will be connected a pair for each color; one element has 1 terminal in one column and the other at the same height on the other column.
If you have already done this kind on wiring and 2 elements has 220V, and the other a lower voltage, there is something wrong.
Don't know about dangling wires.

To reduce consumption you can try to connect two out of three elements and check recovery time after steam and boiler refill; if your M20 has two groups (I suppose ~ 10/11 litres boiler) and your heater drains 4KW with 3 elements connected (~ 1.3KW / element), you can safely use only 2 elements (2.6KW; Faema E61 2 groups drains 2.7KW, Vibiemme 2 groups drains 3 KW). For very low volume productions, like home service, you can also try 1 element only.

About power switch: if it doesn't turn on/off with a (very) small force, consider to replace it.

Thanks

Yes I have single phase 220VAC. I expected one set of red,black,white to be shorted together and the
other set shorted together. I would then measure 220VAC between them. That is not what I get.
4 are shorted together. Something must be broken.

Also now I see my pump motor does not turn on. It jerks when I flip the switch to turn it on but it
does not produce pressure. Does not sound like it is spinning.

I would then measure 220VAC between them. That is not what I get.
4 are shorted together.

Had someone modified the original circuit before? Perhaps trying to turn 3-phase to 1-phase.

I see my pump motor does not turn on. It jerks when I flip the switch

Check motor wiring; I should do the following: unwire motor and connect it to 220V with a temporary external switch, check if it runs normally (for a short time, is the pump empty?). If it don't, turn off immediately and check the start-up capacitor; best of all take the motor off and carry it to a technician.