No hot water from shower

[JMacgreg]

Hi, I'm installing a shower in an upstairs bathroom. The household boiler is a Potterton Performa HE condensing combi-boiler. During testing of the shower, I was unable to get a flow of hot water. Hot water is available however from the kitchen tap downstairs although it takes ages to come through. I've noticed that when the shower is turned on, the boiler does not fire up. Could someone tell me why the shower might not be working.

 

[exedon2]

Picture of shower valve would be useful.
Are you certain you have installed it in correct orientation? Ie hot on left?
Are inlet filter washers clean?
Is there any flow through shower at all?

 

[JMacgreg]

Hi, I'm certain the hot & cold connections are the right way round. I followed the installation instructions to the letter.

During testing, I isolated the cold water feed and ran just the hot feed through the shower valve and hand spray but it didn't get hot. I noticed that whilst I was doing this the boiler didn't start up, hence no hot water from the shower.

 

[JMacgreg]

Just to be clear. I get water flow through the shower, just no hot water. I was wondering if there is insufficient water flow through the shower to fire up the boiler.