how can i fix Vaillant combi not sure on model?

Oh dear... Well I presume it's one of the older combi's (Such as a SIME) with a metal PCB box on the bottom left hand side...

Obviously check all the fuses, including the 3Amp main fuse as this can sometimes get blown on these models even with the quick-blow protection.

If that doesn't solve the problem you'll need to get the board replaced... Now depending on what model you have will determine the board as there were several variants for some of the models, with Hybrids being the most common to get hold of.

You really do need to identify the appliance though before you go any further...

Newer appliances have a databadge located on the rear of the black drop down electrical panel, brand new appliances are also marked here but the panel is grey... Older appliances such as the SIMEs can normally be identified from the top line of text located in the inside of the bottom metal door above the lighting instructions... Once you've got this info... Post back, along with whether or not you have any lights coming on at all or whether or not the appliance is making any noises or doing "anything"....

GasAid.co.uk
December 2006