Glowworm 30cxi - pressue sensor/reading issues

[wizbongre]

Hi All,

Got up this morning to no hot water. Checked the boiler and it was flashing the red warning light and showing low pressure (0.6bar) This was odd as it was over 1bar at the beginning of the week and I can't find any leaks.

Anyway, tried to fill it with the notoriously carp filler loop and nothing happened. Left it all turned off for a while then tried again, this time it was down to 0.4bar and when opened, I could hear the filler allowing mains water in.

The problem now is that the boiler is working fine again with no red light, however the display is only showing 0.5bar no matter how much water I try to fill it with. You hear the water rushing in and then slowly stopping, as if the pressure has equalised and the system can't take any more. Unfortunately its raining so I can't tell if any is being released via the pressure release overflow out the back wall.

I'm thinking there is something wrong with the pressure sensor/readout but given that it is all working, am I right to think there are two feedback loops at play here? One for showing the pressure and a second which is the actual pressure cutout switch? I'm guessing that the low pressure switch hasn't activated because the boiler is above necessary pressure but the readout isn't showing the actual pressure?

Or is it something else? We do have a dodgy TRV valve that will need replacing in summer as it weeps slightly if it isn't fully open, however that and the area around it is bone dry.

I have no faith in the pressure readout so don't want to do anything or call BG out before I have at least half a clue as to what the actual problem might be! I suspect it needs another (3rd) new filler loop but that shouldn't affect the pressure readout?

Could the pressure sensor just need a good clean?

All suggestions welcome.

 

[Ihavenojob]

The pressure sensors on these & vaillants fail for fun. An easy way to check is to drain the boiler, it should then read zero , but if faulty will still display a reading. Easy enough for BG to fix first time.

 

[wizbongre]

fail for fun

Ha, indeed! Drain the full system or isolate the boiler and drain that?

 

[Ihavenojob]

Just release the pressure from the boiler, you should get zero pressure.

 

[wizbongre]

BG came out yesterday as the boiler completely gave up the night before with a low pressure warning and no amount of filling would resolve it. The pressure sensor was filthy and needed cleaning to resolve the errant pressure reading, but also it was identified the pressure release valve was weeping, leading to the original loss of pressure. PRV has just been replaced and its all working fine again apparently, however I'm a bit concerned at the apparent dirt and grit in the system leading to the problem. BG haven't commented on this at all and unfortunately I wasn't home to question them.

Anyway, looks like a drain, flush and refill is on the cards, probably with the addition of a MagnaClean or similar and some monitoring for the next 6-12months. The system definitely has had inhibitor in it so I need to get to the source of the muck.

 

[Agile]

The BG engineer was seriously lacking!

He should have told you that you needed a power flush and try to get you to have a quote so that he can earn his commission payment!

Maybe he was having a bad day?