Combi boiler won't start after bleeding rads

28 Apr 2021
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United Kingdom
So I just had the heating system drained by a plumber to replace a UFH mixer valve, he filled it back up and left in a hurry. I ran the heating to see if it worked OK and noticed all the radiators upstairs were only half full. I turned the heating off and bled them. I tried running the heating again but it wouldn't start up, it kicked in then stopped. I looked at the digital pressure which was about 1.2, but when I took the cover off the boiler, the analogue dial was almost at its minimum (it doesn't have any numbers on it unhelpfully). So I added water to the system from the filling loop until the analogue dial was in the middle of its range. This took the digital readout to about 2 bar. The boiler still wouldn't start up, I thought maybe it was too high pressure , so I drained about 3-4 litres out until the pressure was 1.4 on the digital readout and whatever the minimum value is on the analogue dial. It still won't start up!
I seem to remember it was running OK a few months ago at about 1.5 bar on the digital. At this point I don't know whether to trust the analogue dial or the digital meter, so I don't know if its too high pressure or too low pressure! or maybe some other issue?

Edit: its a Glow Worm Ultimate 30C


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Get the Plumber back, if he's worked on the system and caused the issue, he is liable for sorting it out.
Difficult as he’s a subcontractor for an insurance company. It takes weeks or months to arrange anything through their chain of command and they won’t give out subcontractors numbers.

At this point I’d rather fix this myself , The plumbers they’ve sent just seem to leave me with more problems
set the boiler to around 1.5 Bar and then press in the little reset button on the facia and it should come on
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Have you left one of the filling loop taps turned the wrong way? I think on some boilers this will stop the flow round the central heating system.
set the boiler to around 1.5 Bar and then press in the little reset button on the facia and it should come on
Nothing! I don't really understand why the analogue dial is at its minimum value when the digital says 1.5 bar. Could one of them be faulty?
What is the make and model of the boiler ? looks like a Glow worm in your pics but not really sure
If your pipe slinger didn't bleed the rads properly it's good odds he didn't bleed any air out of the boiler. Have a look at your boiler manual, see if there is a bleed valve that can be accessed without removing any room sealed elements.

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