Help - low pressure indicator on Ariston EuroCombi a/23 MFFI

I've drained the CH system and replaced the manual valves with thermostatic ones. However after filling the system back up again and bleeding the radiators the pump cuts out after aprox 30 seconds and the insufficient system pressure LED comes on and the pump turns off.

The automatic air release valve on the pump is open but there sounds like there is air in the boiler. The boiler is probably at the highest point in the whole CH system.

I can't figure out what's wrong.

Please help, I'm freezing

What pressure does the gauge show?

Have you bled the pump? Look in FAQ.

Tony

Agile said:

What pressure does the gauge show?

Have you bled the pump? Look in FAQ.

Tony

Click to expand...

Pressure was at 1, 1.25 and 1.5 bar (tried it at several levels)

Yup, bled the pump.

UPDATE: All sorted.

I followed a recommendation to put the pressure up to 2.5 bar and flip the boiler back and forth between heating and test modes to keep the pump going. And it only went and worked!

Tested the HW tap and it was good, so I bled the radiator to get the system pressure back to just over 1 bar and am now enjoying a rapidly warming house and (more importantly) a happy g/f!

Seems there may have been an air lock in the small control pipes of the boiler and that was just the job to move it!

I'm no expert but could this be something for the FAQ?

I expect it was air in the boiler itself.

It relies on expelling air from an auto air vent and that is at the base not the top.

It clears best if run alternately on CH and DHW for a few seconds each.

Tony

Agile said:

I expect it was air in the boiler itself.

It relies on expelling air from an auto air vent and that is at the base not the top.

It clears best if run alternately on CH and DHW for a few seconds each.

Tony

Click to expand...

Ahh cheers for the explanation, it's always nice to know the logic behind things like this. I'm totally at ease with massive server farms yet the plumbing in my house is like some arcane black magic to me!