Pressure drop confusion

My own system chaps.

Atag IC Economiser 35 (combi).
Low Pressure warnings via the app early part of this year and into the summer (when no demand for CH).
Air side of EV zero'd so regenerated properly.
Repressurised system and @10 days later got low pressure notifications again.
Repressurised and isolated boiler from system at F&R valves.
Been that way for over a month and no notifications/drop.
Opened it back up to the system today (as it's now getting a bit chilly) and expected the A6 parameter to drop like a rock (thought I'd even hear the differential equalise) but no... Didn't budge a decimal!
So, now heating's on and I'm waiting for a 118 code to manifest on the app

Back to thinking it's an expansion issue and to get Atag out on that basis.

Thoughts, opines and general chucking of suggestions sought from the brethren

dirty or faulty pressure sensor, usually I put the heating on and watch A06 and see if it varies a lot, if it drops below 0.7bar the boiler will lock out for 7 minutes , real pain but great boilers, the pressure sensors are very sensitive though

Seems to be jumping between 1.7 and 1.8 with heating on... (Love that smell of heated dust when the rads have been off a while )

Thanks for the nod about the sensors

No low pressure notifications thus far and it's been performing daily routines with CH and DHW, as and when needed, including weather compensation.

Weird!

dilalio said:

Seems to be jumping between 1.7 and 1.8 with heating on

Click to expand...

That is totally normal,

Page 74 on this tells you what codes it has been getting
https://atagheating.co.uk/wp-conten...ICING-INSTRUCTIONS-iC-RANGE-BOILERS-v0319.pdf