Help with thermostat wiring

Daniogroove

Hi,

I have a zoned system but I'm having a problem with my downstairs thermostat (zone 1). It doesnt knock off when the temp is reached. The timer panel will show room temp as 24c but stats are set to 20. I put a seperate thermometer ontop of the zone 1 stat and it reaches the same temp displayed on control panel.

I've taking the covers off and have seen the wiring is different. Is that right or is there something simple i can do to? If it is correct is it just a case of recalibrating or replacing the thermostat?

I've included photos. They are Robus stats

Daniogroove

*bump*

brightspark

Does the neon light (between 5&6) turn on and off when the temp controller switches? try turning the stat up and down the full range to see it it switches on/off.

Daniogroove

brightspark wrote: »

Does the neon light (between 5&6) turn on and off when the temp controller switches? try turning the stat up and down the full range to see it it switches on/off.

Thanks for the message.
The downstairs one (zone 1) will click on/off but with zone 2 the light stays on no matter what way it's turned.
If i have only the hot water on, the upstairs stat light will turn off if i turn it up and stay on when i turn it down.

Surely the hot water shouldn't be linked to any room stat?

Thanks

Bruthal

Daniogroove wrote: »

Surely the hot water shouldn't be linked to any room stat?

Thanks

What exactly are the stats switching on and off?

For example, on an oil or gas boiler, they can be each switching on and off a motorized valve, and the valve switches control the boiler. Therefore, the switch wires of the stats are isolated from each other, with the motorized valves acting like relays.

Daniogroove

Bruthal wrote: »

What exactly are the stats switching on and off?

For example, on an oil or gas boiler, they can be each switching on and off a motorized valve, and the valve switches control the boiler. Therefore, the switch wires of the stats are isolated from each other, with the motorized valves acting like relays.

Ya they're controlling two valves alright..
But what would cause the zone 1 stat not to close the valve when it reaches temp? Is it right that they're both wired differently?

Cheers

Bruthal

Daniogroove wrote: »

Ya they're controlling two valves alright..
But what would cause the zone 1 stat not to close the valve when it reaches temp? Is it right that they're both wired differently?

Cheers

They are both wired the same except the neon is reversed, although telling that the supply is into 2, and switch wire to valves from 3, on both is not possible by viewing.

Did this work properly before and suddenly not work, or never worked, or was recently wired and didnt work?

A supply into a stat, and out the other side should be simple. And is simple to test for anyone experienced. Slightly more tricky from remote locations.

Daniogroove

Bruthal wrote: »

They are both wired the same except the neon is reversed, although telling that the supply is into 2, and switch wire to valves from 3, on both is not possible by viewing.

Did this work properly before and suddenly not work, or never worked, or was recently wired and didnt work?

A supply into a stat, and out the other side should be simple. And is simple to test for anyone experienced. Slightly more tricky from remote locations.

Recently wired and never worked properly. I thought first it was one of the valves but can rule that out now.

Bruthal

The way it should be done, assuming a 3 channel timeclock and 3 zones, (2 radiotor circuits and cylinder)

Live out from each timeclock output terminal to each stat common terminal(2).

Switched Live out of each stat terminal (3) to each motorized valve power supply. That`s all there is to the timeclock-stat circuit. Your one has the addition of neons in the stats to indicate call for heat.

The motorized valves have switches in them that are then wired in parallel to the boiler control loop. You will hear them click when the valve is almost fully open after power on, and just as it starts to close after power off.

Daniogroove

Bruthal wrote: »

The way it should be done, assuming a 3 channel timeclock and 3 zones, (2 radiotor circuits and cylinder)

Live out from each timeclock output terminal to each stat common terminal(2).

Switched Live out of each stat terminal (3) to each motorized valve power supply. That`s all there is to the timeclock-stat circuit. Your one has the addition of neons in the stats to indicate call for heat.

The motorized valves have switches in them that are then wired in parallel to the boiler control loop. You will hear them click when the valve is almost fully open after power on, and just as it starts to close after power off.

Legend thanks!

Am i most likely looking at a faulty stat then in zone 1 as the call for heat never seems to stop from that stat regardless of temperature?

Bruthal

Daniogroove wrote: »

Legend thanks!

Am i most likely looking at a faulty stat then in zone 1 as the call for heat never seems to stop from that stat regardless of temperature?

You could test the stat with wire disconnected from terminal 2, with continuity tester from 2 to 3, and see it opens when turn the dial from extreme to extreme.

Usually if you hear them click, they are fine. A stuck closed stat is possible, but I thought you said it behaves different with other zones on or off.

It is not unheard of for wiring mistakes. Heating control circuits seem to baffle more people than none.