vaillant ecotec plus 630 hot water issue

[JPH44]

I have a vaillant ecotec plus 630 boiler.

The hot water is not working correctly.

Sometimes HW will come on when programmed but not always.

HW does come on when the heating and hot water are both programmed to be on.

HW is now coming on when the Heating is on but HW should be off.

I can hear the HW honeywell switch/actuator moving on and off when programmed to.

I have not checked the cylinder thermostat (as the HW sometimes works that did not seem to be the issue but maybe I am wrong).

Any ideas what I should check and what the problem is?

 

[lightning]

Faulty 3 port or 3 port valve

 

[JPH44]

Thank-you. Is there a way to check that?

 

[CBW]

Is there a way to check that?

Can be checked with a multimeter, but very likely, given the symptoms.

 

[JPH44]

cheers

 

[JPH44]

Just to check the 3 port valve is the valve the actuator controls and so not a boiler issue but the pipework?

 

[DP]

Just to check the 3 port valve is the valve the actuator controls and so not a boiler issue but the pipework?

How can the boiler be faulty when heating is working. Boiler just heats the water when demand is applied

what size of house do you have and what is the cylinder ( open vented or unvented). That is a BIG boiler

 

[JPH44]

It's an unvented cylinder and a reasonably large house. As you ask, I was under the impression that boilers have diverter valves (which is the first thing that comes up as a problem when a google search for hot water only when heating on) but seems relevant only for combi boilers.