ESWA Ceiling heating thermostat - replacement - wiring question

[andiron]

Hi all,

house came with this old fancy type of heating and one thermostat stopped working.

I had a spare one of these:

https://www.amazon.co.uk/dp/B00QGKSTD8/ref=pe_27063361_487055811_TE_dp_1

that simply takes three wires - red, black and yellow/green.

But the existing one has 6 wires:
a) one set of red and black
b) one set of red, black and yellow/green
c) random grey wire

Does anyone have any idea how to connect it - or even if it's possible? I can provide photos if needed.

Also, what are these sets? Is one red/black connection to ceiling heating, one red/black power supply?

Thank you

 

[stem]

Unfortunately, just telling us the colours and numbers of wires doesn't really help. The colours and method of installation would have been chosen by the original installer according to their own personal preferences.

To assist we would need either to know what the other end of each of the wires you mention are connected to, or a photo of the terminal wiring diagram for the existing thermostat showing which wires are in which terminal, often the method of installation chosen can be worked out from this information. The make & model of the existing thermostat may also help. Because it's a ESWA system it doesn't mean it's fitted with a ESWA thermostat. Also, the current consumption is important, some thermostats are designed for gas boilers and can't handle the current consumption required by electric heating systems, unless wired via a relay.

 

[andiron]

@stem , thank you, you totally right, here is the picture with diagram (the one made in West Germany is the old one , the other one the new one).
Also a photo of existing wiring.

 

[stem]

The thermostats are not compatible. The existing thermostat has a timed switched input to terminal 5 to provide what I believe is a setback function (S.B.) these would appear to be the grey wires you mention. If I'm correct, this function drops the set temperature by a few degrees when selected, so tends to be used at night time to maintain a lower temperature than during the day.

.....having said that, terminal 6 according to the wiring diagram should provide the Neutral for the setback.

However, in your case terminal 6 (far left) is connected to the live by the link between terminals 6 and 1.....

.....in which case, it means that the setback connections are both 'live' rendering it inoperative. Can you shed any light on this?

Setback aside, the new thermostat has the same rating of 16A and the basic switching function (on/off) is there, so it might be possible to use it as a basic thermostat without the setback.

So, unfortunately I can't really give definitive assistance here and you may have to get someone in who can examine the installation in more detail. My thoughts are below, but it really needs someone to physically check my assumptions are correct.

Discounting the setback facility:

The new ESI thermostat terminal 1 corresponds to terminal 1 of the old Eberle thermostat (live)
The new ESI thermostat terminal 3 corresponds to terminal 2 of the old Eberle thermostat (switched live or call for heat)

The other wires would probably need to remain connected together as they are, but not to the thermostat.

 

[ericmark]

Personally I would use a battery powered programmable thermostat, so only wires 1 and 2 are used that went to old thermostat.

 

[andiron]

@stem "If I'm correct, this function drops the set temperature by a few degrees when selected, so tends to be used at night time to maintain a lower temperature than during the day."
That's correct, there is a switch downstairs that we were told it kind of does this - switched between LOW/HIGH I believe it adds "5*C" to the thermostat so 1 at Low is 16*C, 1 at High is 21*C, more or less like that.

I'm totally happy to ignore the above - not much use of it really.

Ok I will try your suggestions and if there is no luck - I'll get someone to have a look at it.

 

[stem]

That sounds about right, the setback has been wired to a manual switch instead of a timeswitch. If you leave the two grey wires connected together, the LOW/HIGH switch will still work with the other thermostats (assuming that they are connected correctly), but not the new ESI one.

The two red wires in 6 and 1 would go to ESI 1
The red wire in 2 would go to ESI 3

The two earths should remain connected together
The two grey wires now in 5 should remain connected together
The two black neutrals now in 4 should remain connected together

 

[andiron]

@stem , thank you - that all worked!

Can't really tell about LOW/HIGH as I never fully understood how it works, but the basic thermostat does what it supposed to do.