Worcester Bosch maximum flow temperature.

[bruce_miranda]

I did suggest this to be the case several posts ago. So am not surprised this was the issue.

[G4RHL]

Hopefully you got this sorted already, I have a similar boiler albeit British Gas branded. There is an installer menu that allows you to cap the boiler output. I think the Max is 88c for Central heating but it can be set to less. If you search for the installer manual it will tell you how to access the menu and check the setting. I did it a few nights ago.

88c seems far too high. 70c should be fine. Also reduce the kW power of the boiler for the central heating side. Mine is set to 6.4kW. No problems.

[spence189]

88c seems far too high. 70c should be fine. Also reduce the kW power of the boiler for the central heating side. Mine is set to 6.4kW. No problems.

I'm not the OP and don't know if this is the issue but was just adding to your previous point on the off chance the OP hadn't found the installer manual yet

[bruce_miranda]

Any chance you can show how to get to the installer menu

[spence189]

Any chance you can show how to get to the installer menu

Ok, apologies.... I read the model wrong in the OP. My bad! Just double checked the service guide for the correct boiler and it's clearly very different.

[Johntheo]

Good point, but no, the clip-on thermometers are reasonably accurate.

What is your measured return temperature with a measured flow temperature of 60C.

[chrisgare]

Running at full bore this morning, with the outside temperature at zero degrees, it's 40 degrees.

[Johntheo]

If you are replying to my post, then a room temp of 20C with flow/return temps of 60C/40C, the rads will emit 51.5% of their rated output and if the room temp is/was 15C will emit 62.9% of their rated output.