Gas boiler will heat Rads but not water

Hi all

i have a Sime gas boiler, same as in this link : [broken link removed]

the boiler does not work when the timer is set for the water, or even if i hit the boost/advance buttons on the control box on the wall.

However if i hit boost/advance for the radiators either upstairs or down stairs it will start no problem.

if i start the rads, and hit the button for the water, and then turn off the rads, it will shut down. looks like it's just the water heating part that does not want to work. i turned the power off at the wall to try and re-set it but that didn't work

its 4/5 years old and was serviced by a Board Gais service engineer 2 months ago..

Anyone know any fix, or just a case of calling someone out to look at it ?

Assuming this switch normally worked to give you hot water without rads heating, then either the timeclock, cylinder stat or motorised valve actuator has gone faulty (90% says the valve)

Had the same problem last year - it was the timeclock (sunvic I think).

DGOBS said:

Assuming this switch normally worked to give you hot water without rads heating, then either the timeclock, cylinder stat or motorised valve actuator has gone faulty (90% says the valve)

Click to expand...

yep, was the motorised valve...

scuby said:

yep, was the motorised valve...

Click to expand...

Scuby,

I've just started a very similar thread to your...must be going blind, didn't see it.

When you say it was the motorised valve,is this the valve which is situated on the pipe going into the water tank? (It opens and closes to allow the water to heat to a certain temperature before the rads get the benefit?)

I presume a plumber had to replace?

Thanks