No hot water from Vaillant TurboMax plus 837Eand Error code F.28 showing. I can get it going if I hold down the pilot light reset button after a few goes. Am I right to assumr this is a pilot problem? Does anyone have a link to a manual for this boiler or point me to where I can order one. I certainly need to do a quick service/brush up to it so will need to take apart.

Mike, July 2010

There is no 'pilot light' it is an automatic ignition. F.28 indicates failure on ignition ie: no gas. First check you have gas and it is turned on (at the meter), once you have established this, there could be a variety of causes.
Gas valve.
Burner partial blockage (lights but fails to establish flame).
Lack of water pressure has also been known to cause this fault.

I can only advise you that (before you go 'fiddling' with gas appliances), you MUST be deemed to be competent to do so, especially when playing with gas components.

By your initial post asking about pilot lights, I can only assume you are not. Therefore, don't attempt repair yourself.

Carefree, July 2010