System boiler - can't repressurise it!

Worked fine for 4 years. It's a system boiler with 3 port valve "Y" plan. DHW via Heat Store. Fault: pressure gauge on zero. Obviously system has leaked and suspected PRV as no other signs of leaks on system. PRV operated manually and allows water through but in "closed" position I had to "wobble" it to get it to seal. All straightforward you might say - replace PRV. BUT - With the PRV properly closed off, I can only get a small dribble of water to enter the boiler via the filling loop - pressure gauge barely off zero before flow stops. Approx. 3 bar pressure at filling loop connector. Can't think of a reason for this - can anyone?

Thanks for any thoughts!

diymostthings

 

Thanks for that Tom - mains pressure is 3 bar but just on 2 bar at the filling loop (I fitted a pressure reducer with gauge on installation) and water p----es out when connection to boiler return is loosened. The gauge is connected by thin flexible plastic pipe to the PRV manifold and I wondered if this could be blocked. i.e.boiler up to pressure but gauge stuck on zero. But the boiler won't fire so some electronic gizmo thinks its low pressure - so I assume it is! The digital readout says "0" - i.e. normal standby mode - no Error E codes at all! Its a Remeha (now Baxi) Avanta Plus System.

I sense another drain-down coming on and 15 quid for the Sentinel. Will check for blockages as you suggest but can't help thinking the original problem (no pressure) has something to do with the fact I can't re-pressurise.

Thanks for you input as always Tom

diymostthings

 

Thanks for that DA - well it has got a whole host of error codes - and a facilty for looking back at the last 15 stored errors codes! Low system pressure is one of them. But I can't get any error codes to show - it just sits there reading "zero" (all hunky dory and awaiting a heat call) But doesn't fire on heat demand. Yes the gauge is simply mechanical but the connecting pipe can't be checked/removed without a partial drain-down. Still very puzzled about the original fault though- surely this lot must all be linked somehow?

We have an immersion in the heat store and CH not needed so not desperate at the mo.

diymostthings

 

Dear respondants - I have sorted the problem and I confess to being a complete plonker. DA is absolutely right - the boiler is actually up to working pressure (although I don't know what it is as the gauge must be faulty). The boiler DOES fire fine - my check with the room thermostat to demand heat didn't work AS I HAD THE CH OFF AT THE PRGORAMMER. DHW demand didn't fire it as the Immersion had the heat store water up to temperature. Will send off for a new gauge and pipe (under warranty still).

Very sorry to have wasted your time - quite expect to be ceremoniously stripped of my gas grips and mole wrench and drummed off the forum.

diymostthings

 

House pressure is isolated from the system by the filling loop (and the loop is reduced to about 2 bar by a reducing valve and gauge) which is removed from the system (as required by the water co. rules) after filling. I think the connecting pipe to the gauge has become blocked - apparantly they are tiny bores and can be cleaned with a pin!

Many thanks Tom and apologies again

diymostthings

 

While you are rolling about on the floor laughing DA, can you see if you can spot the screw I dropped - you know the one - it holds the front casing on....

BAD DAY!!!

diymostthings

 

Hmmm..wise words. Didn't feel much like a good day this morning though. Good news now is that Baxi are mailing me a new gauge and connector under warranty. Good service!

diymostthings