I have a pilot light, but the burners will not light when turning the water (hot tap) on. I cleaned out the jets and after some hours, it suddenly worked.... but alas, only for one day.... now we have no hot water again.... the boiler is in a mobile home and is around 25 years old, but only gets used in the summer months. It has been fine up to our arriving this year...

model is Valliant sink-heater MAG125/7

Hazel, August 2009

You say you are in a mobile home, are you using LPG (Propane) if so, the problem may be caused by the main injector. LPG is 4x more powerful than natural gas so the injector is 4x smaller. Take out the main burner so you can see the gas injector, the actual hole will almost be invisible so a replacement is recommended. As a stop-gap a fine wire can be used to clear the aperture. One of those sewing needle threaders is about the sme size and sturdy enough.

Townteck, August 2009