Vaillant Combi Boiler

[Wainscotting]

sensor. Much appreciated.

[Wainscotting]

Update - The cold water section diaphragm seems to work ok. When drawing water the pin lifts straight away and the microswitch contact is made. Are you referring to the actual flow switch? The one that has two microswitches? There is a metal lever that rises and falls depending on whether you are using hot water. When the lever is in the down position it makes the right hand microswitch and the boiler comes on for water. When water is turned off the lever reverses it's action and moves away from one switch and makes the other. It seems to take about 2-3 mins to move from radiators position to hot water. Can the flow switch be refurbished or does it have to be replaced as a unit?

[Ed Sirett]

I'm less familiar with Sines than other Vaillant combis. I'm fairly sure that the switches should go back and forth between the modes in a second or two. I know that 242s have a three position diverter valve unit which has CH-neutral-DHW positions. However they are indrectly servo operated by pump pressure.

You'll have to ask at a heating spares shops if they have a 'service kit' for the unit. A new unit which sounds like its a DHW flow + diveter valve unit is likely to be pushing £100. Incidently I notice that the cheaper the boiler the more expensive the spare. This part is £140 for an Alpha, and £110 for a Pott. Lynx. A possible cause of failure is spindles getting sticky on the O-ring glands, or a load of gunk in the primary circuit part preventing free movement of the valve.

[Wainscotting]

microswitches?

before I think about buying another.