Zone valves & burner light?

[Jurgenjay]

Hi all,

For my boiler worcester bosch greenstar 30Kw Ri Compact, I noticed that, within programmer set time, for heating, if the house temperature has reached set temperature say19°C, the zone valve for heating will close, the boiler's a burner light (green) will be off, and blue light is off too.

For hot water, even if the hot water timber is on for a long time, i.e. the cylinder hot water should be filled and full, but the zone valve for hot water is still open, the a burner light (green) is off for a while, then on for a while, just off/on periodically, the blue light is always on.

I understand the above when temperature reaches set °C then: heating's zone valve closed+ burner light off+ blue light off.
But I am not sure when hot water is full in cylinder then should this be correct that: hot water zone valve still open + burner light off/on periodically+ blue light on??

Thank you!

 

[SJB060685]

Could be a dodgy cylinder stat keeping the valve open or the valve could be stuck. A multimeter will give you the answer.

 

[Jurgenjay]

Could be a dodgy cylinder stat keeping the valve open or the valve could be stuck. A multimeter will give you the answer.

The hot water valve indeed will be closed when the timber is off, say if we set the hot water 5-9pm, by 9pm when timber set time is off, the valve for hot water does close.
But, say by 7pm, after two hours hot water is on, the hot water in cylinder should be full, but the burner light is off, then on, then off/on from time to time, the blue light is on all the time.
I thought it should be like heating that once reach the set temperature, the zone valve closed, burner light off, and blue light off.
But hot water is not the case.

 

[SJB060685]

Can comment on the boiler as I’m an oil burner technician by trade, not gas. How the zone valve behaves is the same in either case though. I imagine from what you’ve said the cylinder stat is playing up but without a multimeter one could say for sure.

 

[Jurgenjay]

Can comment on the boiler as I’m an oil burner technician by trade, not gas. How the zone valve behaves is the same in either case though. I imagine from what you’ve said the cylinder stat is playing up but without a multimeter one could say for sure.

Thank you!
So you believe that both zone valves for heating and hot water should be closed once reach temperature or hot water is full, and burner light(green) should be off+ blue light should be off?

 

[SJB060685]

Yes when both CH and HW are satisfied their respective valves should spring return to closed positions and cut the power to the boiler.

 

[Jurgenjay]

Yes when both CH and HW are satisfied their respective valves should spring return to closed positions and cut the power to the boiler.

Yes, logically, they should be like that! Now only heating part is like that, hot water is not.
But, when the timer set time is up, both valves do close---so the valves follow the programmer.
When it is within set time, even if long time enough, the hot water valve never close, the burner light off/on periodically, and blue light always on.
"Could be a dodgy cylinder stat keeping the valve open"===This sounds possible, as the hot water valve does follow timber, just not close within timber set time. Cylinder stat is the small white box on the cylinder, right? (see attached photo)
"A multimeter will give you the answer."===Where to check with multimeter, the cylinder stat? (attached photo)

Thanks!