Glow worm compact boiler, shower running hot and cold

[MPEJ]

i have just moved into a new house in need of renovation.
I removed a radiator yesterday and represurised the system afterwards.
I woke up this morning to find the pressure dial at over 3.5 and the pressure release pipe outside dripping.
I shut the water off and the boiler down and bled a radiator to drop the pressure.

I then put the water back on and the the boiler before taking a shower only for it to run hot then cold continually.

Boiler is a glow worm compact (no model number evident).

There is no more dripping from the pressure release pipe.

Is this a simple part replacement fix?

I bought the house after a divorce and I’m super skint so I can’t really afford to get someone in.

Thanks in advance.

 

[terryplumb]

Your post is a bit vague so can you clarify a few things please. Firstly ,after your shower went cold ,did it remain so or were you getting varying temperatures ,like hot / cold / hot / cold? The fact that you removed a radiator is highly unlikely to effect your shower afterwards. The excessive pressure in system is possibly because you did not fully close the filling loop when you repressurised ,after removing the rad. Is the pressure now stable ,and what does gauge read ? What exactly is your shower , thermostatic or manual mixer or combined bath filler / shower? Or is it electric ? Is your central heating working OK ? The more accurate answers you provide to all questions will enable a much clearer picture and will help to nail down your issues. Regards terry

 

[MPEJ]

Thanks.
Shower kept alternating hot then cold.
It’s a thermostatic mixer shower running off the combi boiler feed.
Shower was installed two months ago.

Central heating appears to be running ok.

Pressure now sits at 1.5, pressure loop is now closed. Yes I believe this was the initial cause of the pressure issue.

 

[terryplumb]

Thanks ,and if you turn on ,and let run ,for a few minutes any hot water tap, does the temperature stay constant at the tap ? Or does the temp cycle hot and cold same as shower ? If its the same as shower then the boiler is at fault. If the tap temp is stable it points to a problem with the shower.

 

[MPEJ]

Just tried it with the bathroom tap, yes the problem is present in the taps too.
It got very hot (hotter than usual) then cooled down again then started to rise.

 

[terryplumb]

Looks like your gonna need an engineer to visit mp as the boiler controls are not stabilising the dhw temp . needs investigating to establish what's failed and needs replacing.