New to gas - Help!

[Foxyboy43]

Soooo just in time for oil to go through the roof Chez FB has converted to gas central heating. Lady FB is ecstatic as she was “cooking on gas” until she moved to NI only 33 years ago - and still grumbles about it - imagine!
The question is about “efficiency” - apparently the new wonder Bosch Worcester boiler can heat 18 radiators give or take but chez FB has only 13 - the toob suggests this requires the boiler to run at c.66% efficiency to save gas but I am not sure if this is correct.
Soooo - any SD chaps with an ology in gas heating who could comment or proffer advice please? There's a conspicuous absence of manual or guidance on the boiler and the fitter has been as much use as a chocolate fireguard!
Much obliged chaps.

 

[Rob-E]

Adjusting your boiler temp to 60 degrees should save you about 12% a year on heating without making your house noticeably colder.

 

[Stevie/P]

We’ve the Worcester Bosch green star I find that setting the heating flow temperature 56C is perfect for our central heating in saying that we have a very efficient insulated home 60 C would be a good start point you can then adjust as required

 

[Foxyboy43]

Adjusting your boiler temp to 60 degrees should save you about 12% a year on heating without making your house noticeably colder.

Thank you and forgive the dumb question - do you mean radiator temperature - the Bosch has Rads and HW settings, currently I have the rads at 70.

 

[Rob-E]

I believe both.