I have a profile 50e boiler,it uses an external time clock also made
by potterton and there is a romm and tank stat as well as 2 honeywell
2port vavles

Even with the programmer and room stat removed the boiler still runs
and the rads get hot, the only way of shutting down the boiler is by
adj the boiler stat to low or switching it off.

I am thinking that there is eithera fault on the 2 port valve or there
is a fault with the boiler.

can anyone help please.

simon