Hello and help with Worcester Greenstar 8000+

[Joolsf]

I had this boiler fitted a few months ago. I've been renovating and the guys came back last week and installed two new radiators. When they'd gone I turned the thermostat off because of the warm weather and I was not living at the property. I've moved in today and turned the thermostat to on but nothing is happening, all that's showing on boiler is the illuminated OK button. Everything is set correctly and pressure is correct. I'm getting hot water and it fires up for that, but not for heating???

Can anyone advise? It shouldn't be batteries as it's a new thermostat. I'd turn it off and on if I knew how! Is there an on/off button?
ps the little blue flame isn't on, it's reflected as the boiler is in a dark cupboard.
Thank you.

 

[Chuck]

The 'little blue flame' on the boiler should come on when the remote thermostat calls for heat and the boiler won't heat the radiators unless it is on. Can you provide photos(s) of the remote thermostat, please? There will normally be one on the wall in the hall or main living area.

It's been warm lately, it's possible that the thermostat has decided the house is warm enough not to need the radiators on.

In my opinion, thermostat batteries should be changed every two years. They may still be working after this period but the risk of damage due to leakage goes up. I also recommend Energizer brand obtained from a reputable source with a high turnover, e.g. a big supermarket not eBay! This brand now offers a 'no-leak guarantee' which, last time I checked, other brands do not:

https://energizer.com/eu/uk/wp-content/uploads/sites/65/2025/01/ENR1209_TermsConditions_V5HIGH.pdf

 

[Joolsf]

The 'little blue flame' on the boiler should come on when the remote thermostat calls for heat and the boiler won't heat the radiators unless it is on. Can you provide photos(s) of the remote thermostat, please? There will normally be one on the wall in the hall or main living area.

It's been warm lately, it's possible that the thermostat has decided the house is warm enough not to need the radiators on.

In my opinion, thermostat batteries should be changed every two years. They may still be working after this period but the risk of damage due to leakage goes up. I also recommend Energizer brand obtained from a reputable source with a high turnover, e.g. a big supermarket not eBay! This brand now offers a 'no-leak guarantee' which, last time I checked, other brands do not:

https://energizer.com/eu/uk/wp-content/uploads/sites/65/2025/01/ENR1209_TermsConditions_V5HIGH.pdf

Hi and thank you, yes I realise that's what should happen but it didn't. However, today I pressed 'advance' and it came on, but still don't know why. Advance to what? I've set times for it come on and go off Mon - Fri and Sat - Sun, but that for Auto mode as far as I'm aware? I thought if you were in 'on' mode it should be on!
The thermostat is a Comfort+ IIRF

 

[Chuck]

There are two 'advance' keys on that model. They have dual uses depending on whether you short- or long- press them.

It's possible that you've put the thermostat into a setup mode and it's waiting for some magic combination of presses to actually start working. It's instructions are available here:

https://www.worcester-bosch.co.uk/support/literature/download/6720892636

Check the key is happy (constant green LED, section 2.2) and then work through section 4 'Using the Control Unit'.

If in doubt, contact the installer. They should have explained how the controls work to you as part of the commissioning / benchmarking process.