Can someone explain how these storage heaters were wired via the contactor?

[loz2754]

There are only 4 poles in the contactor, with one pole for each circuit. There are 7 off peak circuits (that I can see). Hence the 3 individual relays, one each for the other 3 circuits. There were probably originally 7 of the relays, or 2 of the 4 pole contactors.
You can think of a contactor as a relay with the ability to switch higher current loads.

 

[snowhead]

but I still don’t understand the role of the relays in this configuration- Why are they there when it could just be the contactor, with the load of the contactor supplying the power to the MCB’s during E7 hours?

As shown in the Electratec link Oscar21 posted (#21) they were originally all single relays across the top, total number would depend on how many heaters installed, 1 for each heater, 1 for the Top immersion heater and 1 for the bottom immersion heater.
The relays are used as the Electec controller cannot switch the heater loads, it just uses a control signal for the relays.

Sometime in the past some relays have failed and have been replaced by a 4 pole contactor, (effectively 4 relays in one) probably cheaper or happened to be in the van.

 

[oscar21]

What usually happens is either the control panel or the brainbox goes kaput, you cant get the spares for them so they need adapting. As you can see the 3 original relays that are left are 2 x immersion ones and one bedroom heater, these will no longer be in use and I think the OP said the immersions are just on a switch now so the relays will have been bypassed, he also said one of the bedroom heaters was now a panel heater so that relay will have been bypassed as well. In fact you can see there aren't any 24V contol inputs to the A1&A2 contacts on the relays anymore.

Whats left is 4 storage heaters (if all 4 ways are in use) but these still need some kind of control so 4 of the relays have been removed and replaced with a 4 pole contactor controlled by a time-clock elsewhere or even the meter itself.

Edit : its 3 storage heaters still in use, you can tell by the labeling.

 

[snowhead]

Thought this was sounding a bit familiar.
A thread on the same subject from 2021,,
There's a link to the manual, but no diagrams, in my post #2

What is the purpose of the multi9 contactors

Hi, Last week I went to a property where the owners had just moved in. They wanted advice about various electrical things including a large DB filled with these multi9 TL contactors. Does anyone know what they are for and is it easy to remove them to change the board for a more conventional system?

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