Faema Legend heating element regulation

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Northernguy
Posts: 3
Joined: 4 years ago

#1: Post by Northernguy »

Hi, can anybody explain to me how the heating elements in my Faema E61 Legend S1 is controlled? (Not thinking about overall/thermosyphon temperature regulation, but the on/off of the heating elements themselves.

I have three-phase delta connection.

After replacing the heating element since I believed 2 of the cores were malfunctioning, I get the same as before - only one is working. It works ok, but of course heating the machine takes some time. After replacing, still only one element is functional. (Yes I should have checked/ohm'ed them before, but after 15+ years I took it for granted that they were broken when they stopped working).

Also, after the replacement, the hysteresis around the correct setpoint (1 bar pressure in the boiler) seems to have changed, now the heating element is swithcing on and off more frequently (a couple of times a minute) than before. The leads to a very precise temperature/pressure regulation, but it's odd and I'd like to understand it.

Is it the temperature gauge/pressure switch in the center of the elements themselves that switches it on/off? In that case, there was quite some scaling on the old elements, so I guess the temperature response may be quicker of both elements and sensor, and this might explain the phenomenon.

Any thoughts?

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ira
Team HB
Posts: 5491
Joined: 16 years ago

#2: Post by ira »

If only one element of the three is on, then it's likely one of the phases is missing. If you have a meter and know how to test, look at the inputs and outputs to the big relay or the Siri pressurestat. On mine, the Siri controls a big relay. Check the voltage between all three wires, 1-2, 2-3 and 1-3. they should all be the same on the in and the out of whatever controls the power to the elements.

Northernguy (original poster)
Posts: 3
Joined: 4 years ago

#3: Post by Northernguy (original poster) »

I guess it's a phase issue as you say, but I'm no good with three-phase. I've got 230V between all phases, all the way from input to the relay, and on the "input" side of the element. Over the elements, only the upper one shows 230V, the two others are "crossed", that is 230V between no. 2 and 3 and vice versa.



ira
Team HB
Posts: 5491
Joined: 16 years ago

#4: Post by ira »

So before we get to far, can you show me the wires coming off the relay that go to the element. I would assume 3 terminals, each one having 2 wires of the same color, with different color per terminal?

If that's the case, than each terminal of each element should have one wire and each terminal of each element should have a different colored wire So:

element one: red and blue
element two: blue and brown
element three: brown and red

I'm assuming that at the relay you have 230 across each of those three color pairs we connected to the 3 individual elements:

I can't think of a good reason there should be additional connections to those wires unless there is a light that indicated heater on and then I'd assume there will be two small wires going to that light from any two of the three terminals on the relay.

ira
Team HB
Posts: 5491
Joined: 16 years ago

#5: Post by ira »

In this application, you can look at 3 phase as if it was 3 single phase 230V supplies. You want to connect one of the three 230V supplies to each heating element. Not because it won't work if you connected them all to one, but because if you have 3 phase the more even your usage, the less you pay and you can use smaller wire because each wire only carries 1/3 of the load. So if you consider each element separately and make sure each one is powered by a different pair of the three you should have it working in no time.