Boiler Locking Out

[inja]

This seems an odd problem but most likely has an obviose answer!
My system is:boiler a Worcester 9/14, Honeywell mid position valve, Honeywell cylinder stat, Horstmann 2 channel programmer,room stat, all only one year old.
Everything works ok, except, when I run a bath the boiler locks out and has to be reset then every thing ok again until the next bath night!.
Any ideas, all suggestions gratefully accepted and I do have a shower!!.
Thanks

 

[Softus]

Has it been doing this for a year?!

 

[scatmanjohn]

Softus wrote:

Has it been doing this for a year?!

 

[inja]

Thanks for the reply,
No it only started when I turned on the central heating (radiators)