wierd central heating problem, help please !! All aspects of plumbing questions and answers, help, tips and information

[oldwelshman]

Hi all, hope some one can help me.
I have recently heard the water "hammer" in my house get worse, even at night!!!
This should not happen as heating is programmed to be off then.
I checked rads and they were hot even though controller was off!!
I switched controller from auto to off and same thing is happenng, some how heating is on with controller off !!!!
Any ideas

[jondeau]

Water hammer is rarely anything to do with central heating....more of a mains water problem.

Your heating system has a problem with the electrical controls/wiring and needs an experienced electrician or heating engineer to sort it out.

[oldwelshman]

Ah ok, appologies, maybe hammer was the wrong expression, it is more of a creaking noise due to the heat expanding the pipes not the regular banging caused by high pressure water going round bends of loose pipes :lol:
I am experienced wiring, graduated in electronics :lol: Checked the controller wiring, still ok.
Checked the Vaillant manual but it only shows the controller wires going to terminal connector of the main circuit board in the boiler, but there is no schematic of the board itself :cry:
I power cycled the boiler yesterday and it has been ok since but suspect there may be a problem with the main board :cry:

[oldwelshman]

getting closer to resolving I think.
I discovered the radiators only get hot when I turm on the hot water.
Boiler display shows 5 which is for DHW ( 4 is for CH).
I cheacked the manual and for CH and DHW it says to operate them and check position of the diverter actuator.
Fow heating the divertor moves down, then back to centre when off.
For water it stays centre. I feel the heating pipes and they get hot!!!
Am I right in thinking for hot water only the actuator of the divertor should be in top position not allowing flow to heating? Looks like that in the pic in the manual.

[jondeau]

These things vary considerably from boiler to boiler.........and being that my typing finger is almost worn out........I'm going to generalise.

You have a problem with the divertor valve.......could just be dirt on a valve seating......could be several other things.....

Not really a DIY job........

[oldwelshman]

Just to let you know it was the divertor valve.
Bought a new one for £22 and fitted in 10 minutes :D