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Tempest 250I Unvented Cylinder and Running via Immersion Heater?

Postby chris101 » Wed May 29, 2019 11:24 pm

Evening all,

We have had a Tempest 250l unvented cylinder for just under a year which runs in connection with a boiler.
It is scheduled to come one once a day (6am) for 1hr via a Nest thermostat and it provides the house with hot water for the rest of the day.

I have read on some forums it may be cheaper to run via immersion if kept on 24hrs.

Cannot see how that is possible but I wanted to test the immersion as a backup.
I currently have the immersion switched on which is within the cylinder for the past 5 hrs and since then the boiler remains on.
The boiler gas light is on however it doesn't actually go into full mode just humms constantly and from time to time comes on fully to heat up.
Is this normal? as I assumed with the immersion simply required electricity and nothing else?

The thermostat is set on the cylinder to near max and the time on the boiler is set to continuous, which has always been the case for both.
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