Shower cutting out boiler

Hi 

The problem I have is I accidentally damaged a pipe that takes cold water to the combi boiler. I replaced the pipe but now the shower isn't as hot as and the boiler cuts out after 3 minutes. 

The hot water taps work ok and the ccentral heating works too.

If the taps are running the shower will be liuke warm.

If the central heating is switched on the shower will be ok.

But as soon as the tap or heating is switched off the boiler stops heating.

It won't run for long than 3 minutes on it's own.

hello Slug, welcome to the forum. Is the shower an electric shower or a mixer shower, and do you have any additional storage tanks for hot/cold water? ie. (a) Electric = cold water only feed + electric supply to heat the water for the shower, or (b) Mixer = cold AND hot feed from boiler (or tanks) but NO electric supply, {unless for a pump for a 'Power Shower'}? Need to know this to make a better understanding of your symptoms. e.g. a bog-standard mixer shower direct fed from boiler, will be cooler when the hot tap is running as the boiler has to try and heat more water faster.

Doc H.

Is the boiler system up to pressure? Mine won’t operate below 0.7 bar. 

air in system?

Thanks it's a 24i worsted combi boiler.

The shower is themostatic and fed from the boiler.

The pressure is just over 1.5 bar.

The boiler runs with 2 taps and the shower running, but as so as i turn off the taps and the show runs alone it stops.

binky said:

air in system?

Click to expand...

I was thinking maybe I'm not sure how to balance it to fix this.

When you read the pressure is that whilst system is hot or when it’s cold? 

It really needs to be read when stone cold. 

What is is the flow of water like at the shower? 

1.5 bar cold 

The flow seems a little slow

If you leave the shower running does the boiler cut back in? 

Usually a boiler will cut out when the heat is not being dissipated quick enough. It will then come back on when the heat is gone.  

Sharpend said:

If you leave the shower running does the boiler cut back in? 

Usually a boiler will cut out when the heat is not being dissipated quick enough. It will then come back on when the heat is gone.  

Click to expand...

I'll try that but I don't think it was going to kick back in.

I'm not a great believer in coincidence so trying to think of a cause/effect link.  

Did you run the boiler with no cold supply? I wonder if you could have damaged a temperature sensor on the DHW output side of it?