plumbing help needed

crawford2110

I recently changed the radiator in the bathroom and ever since, when the heating is on and a hot tap is used, when the tap is turned off the heating goes off?
the radiator may have been pure coincidence but if not i did it like this:
turned boiler to water only, drained radiators from downstairs drain valve, swapped bathroom radiator and did all relevant pipework, refilled system (fill, bleed, fill, bleed, fill), switched boiler back to heating and water, then tested for leaks/operation.
any ideas as to what problem is and if it is something a competent diyer could tackle.

gas4you

Presumably you have a combi? What make and model is it?

crawford2110

sorry, its a chaffoteaux brittony 80

gas4you

How long does the heating go off for after the tap is turned off? All the time?

crawford2110

the heating goes off as soon as the tap is shut off, every time a hot tap is used. i need to reset the boiler manualy (via the reset button on front of boiler) to get heating back on.

gas4you

It sounds as if it may be going to overheat after the tap is turned off. This could possibly be a lack of flow or a diverter valve problem

crawford2110

diverter valve was a problem about six-eight months ago and was replaced then so hopefully this isnt the problem. the new radiator has been fitted with trv valves. the valve that adjusts pressure was fitted to the same pipe that the old pressure valve was on with the trv on the other pipe. I assume (possibly wrongly now)that this is the correct way round. pressure valve is fully open

crawford2110

the pressure valve is fitted to the pipe that feeds the hot water into the radiator (as was the old radiator) and the trv is fitted to the other pipe.

gas4you

Quite often a divereter valve cause problems due to muck in the system. Fitting this new rad could have stirred it up again.

As it is still so new, get the engineer back who fitted it to check it again under warranty.