Worcester Greenstar 28i Junior. HW goes Cold

[MattyL88]

I have a Worcester Bosch 28i. The last couple of days I have been in the shower for a few mins then suddenly lose hot water. When I jump out and take a look at the boiler there are no errors but burner light is out.

I have been turning boiler off and on so I can continue my shower but will run cold again within minutes.

Central heating seems fine.

Any ideas? Thanks in advance.

 

[terryplumb]

If you run a hot water tap on fully, let it run for a few minutes ,what's the result ?

 

[MattyL88]

Just tried to get the boiler to drop out. Had a shower until it dropped out (dropped out after 5 mins). Turned it off and back on and ran just hot water tap and it didn't drop out this time (about 10 mins).

Not sure what this means?...if anything? Thanks.

 

[ericmark]

I found with mothers boiler, if set Eco on, it needs taps on nearly full bore to activate boiler, and with Eco off, with a shower it would get hot then go cold, and then hot again, as the reservoir runs out, so always used Eco on.

So if the shower is not turned full on, or shower head blocked a little, then you can get what you describe, you simply not using enough water for the boiler to be able to run.

 

[terryplumb]

Do a trial today. Run hot taps for several minutes ( do this several times over the course of the day),and then run the shower.
If boiler works fine every time taps run , but doesn't using the shower that would point towards an issue with the shower.
Is your hot water temperature excessively hot ?

 

[MattyL88]

From memory it's always been able to put out HOT water (uncomfortable to put hands under hot tap) What is excessive?

I will experiment today, running hot water from tap for prolonged periods and report back. What does it mean if its just the shower that after 5 mins makes the boiler burner led go off?

 

[Stuckinarut]

What does it mean if its just the shower that after 5 mins makes the boiler burner led go off?

Likely the mixer could have failed, letting cold water push the hot out of the way.

 

[terryplumb]

Some thermostatic shower valves shut down if temperature is outside of its operating parameters, some merely close the hot water flow and go cold ,hence the boiler closes down.
If you let the shower run cold for a while ,does it then go hot again ?