boiler will not fire on demand

[spyder53]

Hi, i have a Firebird 90 combi boiler, been having problems with no hot water and complete loss of water pressure, have just replaced the plate to plate and fitted a new blender valve, this has solved the pressure problem as the exchanger was completely fured up, the problem is the boiler will not fire on hot water demand, the ch side is ok boiler fires no problem, i have checked the impeller on pump and it seems to turn freely with a screw driver through the hole, so im at a loss as to what else it could be, can anyone help

 

[Gasop]

Very likely to be a problem with the flow switch.

Check it out with a multimeter or continuity meter to see if it
switches when tap running.

 

[spyder53]

ok will do, am i right in saying that ill have to drain down boiler to replace flow switch

 

[Gasop]

ok will do, am i right in saying that ill have to drain down boiler to replace flow switch

You won't need to drain down. Just isolate mains inlet.
(open hot tap to relieve pressure)

 

[spyder53]

Hi that's good news I'll do that tomorrow if I can get a replacement flow valve, and maybe I'll get some hot water at last. many thanks.
Rich

 

[spyder53]

By the way what is the best way to add inhibitor into the ch system as it all had to be drained yesterday for the plate exchanger to be fitted and was'ent done at the time