shower not heating up due to pilot light not kicking in

[dmoyes]

Hello everyone i have a problem with my shower/boiler, the vailliant boiler is few years old and the central heating and hot water taps on the sinks work fine but when i turn the shower on the water is hot for 1 minute then goes cold when i have checked the boiler the pilot light and boiler fails to kick in when the shower is turned on so the first minute worth of hot water is just from the boiler then after that the shower is cold but if i run a sink tap simultaneously with the shower the water heats up again. I have a feeling it may be the diaphragm/diverter or a microswitch. Basically it seems that the shower is asking for hot water but not telling the boiler to produce the hot water (but if the shower has no feedback/sensor or switch then i would rule that out) or the shower is requesting hot water and the shower is not seeing this and the pilot light is staying off, please help me!!!!!

[joesdaddy]

What is the water pressure like on the shower

[The Builder]

I can only think it's down to maybe a flow sensor in the boiler. The boiler has no way of knowing if it's the sink or the shower that is "calling". This is just a wild guess, but it surely must be related to the amount of flow being called for ................ boiler engineer needed I think :o(

[dmoyes]

Since we've had the problem the water pressure has dipped to the shower however we have two bar of pressure on the water thankyou it seems like a strange one

[joesdaddy]

sounds like it could be a faulty mixer valve on the shower i

[joesdaddy]

Is there any way you could open the hot water pipe just before it gets to the mixer tap this would test it

[dmoyes]

Okie dokie I shall have a more detailed look in the morning, im on nights now so I shall check a few things and update you tomorrow