What are these relays in the fuse box?

boris1 said:

Hello, can someone explain to me what these are and how they work?
I suspect these are relays that control the electro heaters because the heating dials have an On and Night setting. Or because there is a dial in another part of the house where I assume some kind of schedule can be programmed.
There are just three heater circuits (with their own individual switch) but a a bunch of these relays. Why do you need so many?
Another strange to me occurrence is when I screw a fuse in that is wired to these relays, the heaters are turned off. When I unscrew the fuse (10amp), the heaters are on according to the three black dials.
I'd like to learn about relays if not this specific fuse that seems to be counter-productive.

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Pete999 said:

Have you asked the Electrician supervising your work? or are you, like lots of Trainees just thrown in at the deep end and left to work things out for yourself, when I first started work 100% of my time was spent chasing with a 2 lb lump hammer and a cold chisel, also used as dirt cheap labour, that was until the firm went bust and I was transferred under TUPE to a more suitable employer.

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camerabloke said:

Didn’t know you wore a wig

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Pete999 said:

Have you asked the Electrician supervising your work? or are you, like lots of Trainees just thrown in at the deep end and left to work things out for yourself, when I first started work 100% of my time was spent chasing with a 2 lb lump hammer and a cold chisel, also used as dirt cheap labour, that was until the firm went bust and I was transferred under TUPE to a more suitable employer.

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Lucien Nunes said:

There might be only three separately controllable heating zones but there are as many electrical circuits as there are sets of fuses. Each circuit probably has its own contactor (relay) with the possibility of multiple contactors within any one zone under the control of one programmer, but possible again separate thermostats.

The fuses you mention are probably for the control circuits. The controls might be wired to inhibit the heaters, i.e. the heaters go off when the control circuit is active, but default to on when the circuit is dead. Screw in the fuses and look for why the control system is not correctly controlling the heaters.

You give your location as 'Earth' but presumably this installation is in Finland?

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Lucien Nunes said:

There might be only three separately controllable heating zones but there are as many electrical circuits as there are sets of fuses. Each circuit probably has its own contactor (relay) with the possibility of multiple contactors within any one zone under the control of one programmer, but possible again separate thermostats.

The fuses you mention are probably for the control circuits. The controls might be wired to inhibit the heaters, i.e. the heaters go off when the control circuit is active, but default to on when the circuit is dead. Screw in the fuses and look for why the control system is not correctly controlling the heaters.

You give your location as 'Earth' but presumably this installation is in Finland?

Click to expand...