Central heating thermostat

[littlespark]

We can only guess at what all the wires are.

The fact that it’s in a pattress and not a proper joint box… we have no clue what diagram the installer was following.

 

[freddo]

We can only guess at what all the wires are.

Looking at what terminals the valve is connected to greatly reduces the number of unknowns.
Terminals from left to right: Hot water on from timer to cyl stat, Hot water off from programmer and cyl stat, Boiler call for heat, Heating on from programmer to room stat, Heating call from room stat, Neutral. The last one could be permanent live or pump overrun from boiler. The block on its own earth.

 

[timhoward]

We can only guess at what all the wires are.

But it's much more fun this way! In fact Danfoss 3 port zone valve wiring is a known entity and has stayed the same luckily even for 30+ years!
As per @freddo 's comments:
Grey is Hot Water Off
Brown/White is Heating On
Blue is Neutral
and Orange is the output signal to ask the boiler to fire up.





So with 100% certainty we can say that with the Heating set to ON and stat all the way up then 2 and 3 should measure 230v to Neutral (marked)
I agree with Brian and Freddo that 1 is the controller asking for heat. So this should also measure 230v to Neutral.
Obviously this needs doing very carefully.
That will quickly reveal what is going on.

 

[buzzlightyear]

1) when you call for heat does the boiler kick in when the time clocks on.
Does the boiler kick in when you
Turn the stat on
2) does the stat on the cylinder call for hot water
3) does the hot water comes in.
Zone valve work from the time clock
Does the valve move.
Is it a two chanel time clock.

 

[Alan Stirrup]

But it's much more fun this way! In fact Danfoss 3 port zone valve wiring is a known entity and has stayed the same luckily even for 30+ years!
As per @freddo 's comments:
Grey is Hot Water Off
Brown/White is Heating On
Blue is Neutral
and Orange is the output signal to ask the boiler to fire up.


View attachment 105004


So with 100% certainty we can say that with the Heating set to ON and stat all the way up then 2 and 3 should measure 230v to Neutral (marked)
I agree with Brian and Freddo that 1 is the controller asking for heat. So this should also measure 230v to Neutral.
Obviously this needs doing very carefully.
That will quickly reveal what is going on.

Fantastic, thanks Tim I'll check this tomorrow. Thanks Buzz I'll reply to your helpful questions tomorrow too.

 

[Alan Stirrup]

I'll test the wires later today when I get home from work but I have a quick question to ask. Would the wiring on my thermostat accommodate one of these digital/programmable units such as this?

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[buzzlightyear]

Before you start ordering some thing
That might not be compatible. With the system, for a replacement dryton stat.

 

[brianmoooore]

Would the wiring on my thermostat accommodate one of these digital/programmable units such as these

It looks like you may have the neutral present at the stat, that some installations lack, but in my experience of 'stats similar, but not identical, to the one in the link, it might need a permanent live to preserve its programming, which will need the 'stat wiring to be arranged so that is is before the programmer instead of after.
The one's I have in one of my properties will default to their 'off' position if their power is interrupted.

Edit: Also worth noting that there are two types of these kinds of 'stats. Ones with the temperature sensor built in, and ones where they connect to a remote temperature sensor on a 2m or so lead.

 

[Alan Stirrup]

It looks like you may have the neutral present at the stat, that some installations lack, but in my experience of 'stats similar, but not identical, to the one in the link, it might need a permanent live to preserve its programming, which will need the 'stat wiring to be arranged so that is is before the programmer instead of after.
The one's I have in one of my properties will default to their 'off' position if their power is interrupted.

Edit: Also worth noting that there are two types of these kinds of 'stats. Ones with the temperature sensor built in, and ones where they connect to a remote temperature sensor on a 2m or so lead.

Is that the blue wire for neutral, Brian, I don't think that's connected at the junction box.

 

[Alan Stirrup]

So 1&3 are pulling 244 & 245 volts respectively but number 2 is dead, do we have a culprit?