Halstead ace - not behaving!

[joolsE301]

Hi I am hoping that someone might be able to help me out. I have a halsted ace boiler that has decided to misbehave. The problem is as follows.

The boiler starts to fire as normal, the lights on the front indicate a demand for hot waster or central heating, the pump fan and burner kick in but shortly after (6 seconds) the power light starts flashing and the system ceases to function. Having read through a bunch of articles and the fultfinding procedure in the hand book I know that this indictes the primary flow switch. So with this knowledge I have replaced the flow switch diaphragm and whilst I was there did an inner service kit in the diverter valve (which i suspected to have leaking seals). The boiler was also losing pressure and after invertigating I found the auto air vent to be leaking so I replaced that aswell.

So after all my attempts to replace and repair things that could be wrong, the primary flow switch still doesn't actuate, despite the pump runnung. I don't think this is a pcb problem as when the micro switch it operated manually the boiler is very happy. The system also still appears to be loosing pressure. Just can't get the thing to operate noramlly.

any advicde would be greatly appreciated.

cheers jools

 

[kevplumb]

The system also still appears to be loosing pressure. Just can't get the thing to operate noramlly.

check the prv pipe outside

flashing led also indicates low system pressure

 

[joolsE301]

Thanks kev,

The PRV was my first port of call and I forgot to mention that I replaced it about 2 weeks ago as the old one was leaking at about 2 bar. I am constantly topping up the pressure to a minimum of 1 bar.