Understanding Glow worm display

31 Dec 2003
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United Kingdom
I have recently moved to a new build house which has a Glow worm Energy7 18S -A boiler and Neostat room stats connected to a Neostat hub; there is a hot water cylinder on the frst floor.

The boiler supplies underfloor heating on the ground floor, radiators on the first floor and hot water. Currently the Neostat hub is set to provide hot water; the rads are OFF and the underfloor heating is on frost mode so should not be drawing any hot water.

I have noticed that the boiler fires occasionally even when the hot water is OFF. I believe for combi boilers there is a pre-heat option which causes the boiler to run intermittently so that hot water is quickly available. I also believe it's possible to disable pre-heat (to save gas) but there doesn't seem to be an option on my boiler to select this? I have tried pressing and holding the + and - buttons but there's no option available. Why is this not available; is there another way to disable the pre-heat option or, if pre-heat is not available on non-combi boilers does the occasional running of the boiler indicate a fault?

If I press and hold the + and - buttons together for approximately 10 seconds the display cycles through 3 icons - a) boiler pressure b) temperature (this varies slightly each time the buttons are pressed) currently showing 34° and c) the number 5.30. To what does the number 5.30 refer?

The boiler is currently displaying the rad icon only, which seem strange since only hot water is programmed to run, however this doesn't seem to have affected the operation of the system i.e. we are only getting hot water - the underfloor and rads are OFF. Should I change the boiler option to show only the hot water icon or won't it make any difference?

Thanks for any advice.
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You don’t have a combi boiler, you have a system boiler, so no pre-heat function. What you might have is a faulty motorised valve or a link left in at the boiler. S.30 is a status code which means the room thermostat is blocking, so this isn’t calling for heat. Is the boiler definitely firing up?
Thanks for the feedback. I'm pretty sure the boiler is firing up - my wife told me she heard it!

I believe the system is under warranty so I'll get the S.30 status code checked out.


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