cannot refill system?

I HAVE A GLOW-WORM 30CI BOILER ABOUT 2 YEARS OLD - BEEN HAVING PROBLEMS WITH PRESSURE FALLING WITHIN A MINUTE OF SWITCHING OFF ITS ZERO - HAVE TO ADD PRESSURE AND BLEED RADS SEVERAL TIMES TO GET IT TO HOLD ITS OWN AND THEN IT WORKS FINE THE REST OF THE DAY - HAVE NEVER SEEN THE OVERFLOW DRIP ONCE -
ANYWAY - NOW I HAVE A NEW PROBLEM, THE FILLER LOOP WILL NOT LET ANY WATER INTO THE BOILER - IT IS TURNING THE NUT AND WILL TIGHTEN UP AGAIN BUT WILL JUST NOT LET ANY WATER IN? - CAN ANYBODY HELP? MANY THANKS

could be its blocked boiler side due to black oxide due to constant filling either renew or try to unblock filling loop or fit extyernal one but you will have to adress loss of pressure problem sounds like a leak on your system can easily be proved by isolating flow and return valves leaving it a day or so then open them if pressure drops lak syst. side of boiler p.s turn off central heating demand dhw can be left on.

1.Glowworm have now upgraded filling loop due to let-by problems.2.water pressure problems,When heating has reached temp check pressure gauge has not gone upto 3 bar.otherwise you have a leak on the system somewhere

boilersmart said:

1.Glowworm have now upgraded filling loop due to let-by problems.2.water pressure problems,When heating has reached temp check pressure gauge has not gone upto 3 bar.otherwise you have a leak on the system somewhere

Click to expand...

many thanks
can you let me know exactly what part i am after, what to ask for? how will i know if its the upgraded one?

am i to then run boiler and not drain rad a few times to let pressure build and then if it reaches 3 bar i have a problem with leaking system?? sorry could you be so kind to explain more exactly what to do as i am still a bit unsure - many many thanks

The boiler will require a service call.
1. A new blow off is required.
Any dirt on the seating on these blow offs and the leak.
2. The new filling loops have a double non return valve.
Have an external one fit it will prob be cheaper.
3 When drained ask CORGI man To check expansion vessel and also check the flexible hose connected exp/vessel to boiler for blockages.
4. Also check under pressure sensor for dirt.
I would then suggest if dirt is found in the boiler that the system is power flushed otherwise you will get the same probs again next year.