Hot water comes ON when heating is demanded

[rdjohn]

Hi, I have an S-plan system with 2-valves, new batteries in the cylinder thermostat and everything well spaced. It has worked well for several years. After being switched off for 2-months I have returned and started having issues. Firstlynthe hot water did not come on. I changed the batteries and rebinded the hot water system.

Currently hot water is not coming on overnight and is coming on when the heating is being demanded. Pressing the relay button to switch off does not prevent it from coming on. On Guided System config the option is for single, or 3-port valve. I have selected single.

Is the relay likely to be faulty and need replacing.

Yesterday, when hot water valve was demanded an error message came up. Hot water did not function.

Thanks

[Somebody]

Could it be the batteries in the CS92 for the hot water probe?

[Richard]

Hi, I have an S-plan system with 2-valves, new batteries in the cylinder thermostat and everything well spaced. It has worked well for several years. After being switched off for 2-months I have returned and started having issues. Firstlynthe hot water did not come on. I changed the batteries and rebinded the hot water system.

Currently hot water is not coming on overnight and is coming on when the heating is being demanded. Pressing the relay button to switch off does not prevent it from coming on. On Guided System config the option is for single, or 3-port valve. I have selected single.

Is the relay likely to be faulty and need replacing.

Yesterday, when hot water valve was demanded an error message came up. Hot water did not function.

Thanks

Pictures of the BDR91 and CS92A installation would be useful. Have you looked at this at all - https://thesmartthermostatshop.co.uk/ev ... elp-guide/

[rdjohn]

I am not sure if my post was read correctly. This is an old system that has functioned correctly for several years.

Having been switched off for a long period, it has developed a fault with the hot water circuit. Firstly, I replaced the batteries in the cylinder sensor and tried to re-bind both elements.

It is still not working, but as of today, I can no longer bind the valve relay. I am now going to buy a replacement.

[Richard]

I am not sure if my post was read correctly. This is an old system that has functioned correctly for several years.

Having been switched off for a long period, it has developed a fault with the hot water circuit. Firstly, I replaced the batteries in the cylinder sensor and tried to re-bind both elements.

It is still not working, but as of today, I can no longer bind the valve relay. I am now going to buy a replacement.

It could well be a faulty BDR91 but hard to diagnose without images (hence I asked for them). If the BDR91's are mounted too close to each other they can cause each other to fail over time. Other things like the motorised zone valves failing can also cause them to fail, so if you are replacing it try and understand what has caused the fault on the previous one.