Worcester Greenstar 28i Junior. HW goes Cold

[Stuckinarut]

Could be the diverter/stepper motor, blocked plate heat exchanger, et al.

 

[MattyL88]

When it goes cold, I check the boiler and the green burner light is no longer lit. So on that basis I ruled out diverter motor and heat exchanger. It's makes noises as though it's trying to relight. It's just had a service and new electrodes but still doing it.

 

[terryplumb]

Does the shower go cold when only using the fixed head ,or same issue with hand held one ? If you remove the fixed head ,and just have open ended pipe ,does water still go cold ?

Pity you didn't answer the question above ,might have been able to save you buying a new shower.
How about answering now ?

 

[MattyL88]

The trouble is it takes ages to check and repeat and seems internittant so not confident if it doesnt run cold. Difficult to find time with work and then kids in bed from 7. The shower had done 9 years of service. Also none of the parts were available for it.

I was confident it was the shower as its never done it through the taps. It seemed better on smaller handheld shower head but not confident due to intermittant nature of it.

What if it does it through both shower heads? Then what?

What if its only the large shower head?

 

[terryplumb]

Did you fit the new shower or a plumber ?
Did shower heads get replaced or just the shower valve ?

 

[MattyL88]

I fitted it. It was just the shower valve.

 

[terryplumb]

Take the fixed showerhead off ,it takes 5 minutes.
If problem is the same with the unrestricted flow it's a boiler issue.

 

[MattyL88]

Had a shower. I estimate it went cold after about 8-10 minutes. Jumped out and left it running. It restarted by itself after about 3 minutes at which point I switched it over to to the shower hose end with head not attached. Left it running 10-15 minutes and boiler stayed running with hot water.

 

[MattyL88]

Just to add...when I replumbed the new shower I changed the crappy isolaters that were in the hot water feed from the boiler to full bore isolaters.

 

[terryplumb]

Had a shower. I estimate it went cold after about 8-10 minutes. Jumped out and left it running. It restarted by itself after about 3 minutes at which point I switched it over to to the shower hose end with head not attached. Left it running 10-15 minutes and boiler stayed running with hot water.

Inconclusive really. If you only use the shower hose with it's shower head attached, ( and I assume no water flows out the fixed head in that setting) does water run cold whilst showering in that mode ?

 

[MattyL88]

Well after having changed the shower and the problem still occurring in much the same way. It would suggest that it's the boiler or at least an interaction with the boiler when flow is reduced slightly like during a shower.

That doesn't seem like a huge leap to make. The only bits that weren't changed with the shower is basically a hollow pipe to a shower head that has just had its silicone nozzles cleaned.

Boiler will eventually fire back up after a few relay clicks later.

Wonder if it's the turbine on the way out or something?

 

[terryplumb]

Very possible. I assume the answer to my last question is yes it does run cold when only the showerhead attached to Flexi is used .
Call an engineer.