Boiler in question looks like this: [https://www.wolseley.co.uk/product/baxi-assure-ng-boiler-25kw/](https://www.wolseley.co.uk/product/baxi-assure-ng-boiler-25kw/)  
  
I had a problem with my boiler mid June 2026, it was installed in 2019 and was still under warranty and I couldn't get Baxi out until July 14th or so.

So... after almost a month of tanking cold showers and channelling my inner Wim Hof the boiler turned out to have two problems.

1) The most obvious being the fact that analog pressure sensor had leaked, it had leaked out the entire contents of the system onto the floor in the cupboard.

2) In the PCB below the white components in the top left had blown, black on the board, black on the component so burnt out, thankfully whatever failsafe there is kicked in, or there was nothing else to burn. I don't think this was caused by the leak, because the leak was from the plastic housing which sits outside the boiler in the bottom right.

So, I guess it's quite likely I had two separate problems at the same time?  


[It was the white device in the top right which has totally burnt out, causing there to be no screen, etc, yet there was still some power to the screen as you could see it flash up it's model number or firmware version when the boiler first went on.](https://preview.redd.it/i5r2ti83lwoh1.png?width=800&format=png&auto=webp&s=abaf4f3ef5d85352b02ef79ef7e16927c2c0f7be)

The guy from Baxi changed the pressure sensor and PCB - didn't take long, standard swap out with no issues.

He drained the system fully and refilled it - all seemed to be well (mind you, I only used it maybe twice).

\------------------

Since then it's been giving me spells of hot and cold water, and if the number in the middle of the panel is the water temperature it seems to be reading incorrectly, suggesting that it's getting to 92 degrees and then dropping back down to 60 and repeating, and within a minute it'll throw either error 110 or 125.

I CAN use it if I keep the tap water temperature on the really low side, so that when it over-reads the temperature it doesn't hit some sort of cap and cycle (or it at least takes longer) but the water is likely about 35 degrees, it feels pretty cold and then it'll drop down to being normal cold tap water temperature, and I have to turn the boiler twisty thing past the hot cap, into the point of maxing out the max temperature the shower can do to get anything usable and the flow is awful, think of the worst electric shower you've ever seen x5 - and this is obviously gas and is usually super powerful.

During this time you can see the analog pressure gauge needle having what looks like a seizure between about 1.5 and 2 bar.

Once the boiler stops firing you can sometimes hear what sounds like something falling inside the piping (almost like some of the water is airlocked and when the boiler is off it's falling back down). I water-cool my PC's and I've heard similar sounds from that sort of equipment before, but this sounds much louder, almost to the point I'm wondering if there's something IN the system.

I've bleed all of the radiators - there is NO air coming out of them at all. There are only 3 radiators in the property and all that comes out of them is water, not even a slight hiss of air at all.

I've run it's aeration procedure (312) code multiple times to no effect.

As I'm not allowed to take the cover off - are there any other options before calling Baxi out again? Am I allowed to totally drain and refill using the valves on the bottom of the boiler?

 I have a video of what the boiler is doing, sadly the noise in it isn't it's usually banging, it's just a minor bump :-/ but hopefully you get the idea.

Excuse the mess from the pressure gauge, I wanted to leave it in place for next time they come so they can see what was happening.

Here is a link to the video - it was a large file so had to upload it elsewhere.

[https://streamable.com/napv1g](https://streamable.com/napv1g)

Baxi combi boiler - recently had its circuit board replaced