Tempest Unvented Cylinder - Immersion Heater?

justinjustice

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 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 it have switched on the power for the immersion within the cylinder for the past 4 hrs and since them the boiler remains on.
The boiler gas light is on however it doesn't actually go into full mode just humms constantly.
Is this normal as I assumed with the immersion it simply required electricity and nothing else?

fred246

We have a similar size Megaflo. It is normally cheaper to heat anything with gas rather than electricity. The only way I can imagine electricity would be cheaper is if you have a timer on the immersion heater and economy 7 electricity. If it is only on for an hour each day you will be OK except if you have a houseful of people all wanting showers or baths eg at Christmas. There is a thermostat in the cylinder. The boiler should only be on when the temperature of the water is below the set level AND the timer is set to be on. In your case only ever on during that one hour period. Your boiler will be on if you need hot water OR central heating. The radiators may be demanding heat which is keeping your boiler on.

AndyPK

You would need to turn the boiler off somehow.

Anyway gas is cheaper.

Maybe try the immersion in the evening. If you can hear a quiet kettle sounds it is working