Immersion heater thermostat setting

wingzero

Hi - I'd like a bit of advice on how I should set my thermostat up in order to save a bit of money and have hot water when I need to. I've currently set it up as that, the pushed in tabs is when it will turn on.

Set up: 2 bedroom flat, no central heating, electric immersion heater tank for hot water only. I've attached a picture of the thermostat that's there. 

Me: I live alone renting this flat privately, have 1 maybe 2 tepid showers (not at the "there be dragons" setting) a day, do the dishes myself with warm water. 

Energy supplier: Shell Economy 7. I have no idea at which times the electricity rate is cheaper so any advice on how to find this one out would be appreciated. 

TIA

theoretica

I would try removing the evening heating entirely - if your tank is reasonably insulated you should still have warm enough water. 

Alnat1

We heat our tank for 40 minutes a day, gives 2 showers, hubby's shave and some for washing up/hand washing etc. If either of us fancies a bath we manually put it on for 15 minutes.

wingzero

theoretica said:

I would try removing the evening heating entirely - if your tank is reasonably insulated you should still have warm enough water. 

it's not insulated at all. it's just a metal tin in a storage cupboard. 

theoretica

wingzero said:

theoretica said:

I would try removing the evening heating entirely - if your tank is reasonably insulated you should still have warm enough water. 

it's not insulated at all. it's just a metal tin in a storage cupboard. 

And hot as a radiator to touch?  Or insulation under a metal cover?  If it is acting like a radiator I suggest getting that changed!

wingzero

theoretica said:

wingzero said:

theoretica said:

I would try removing the evening heating entirely - if your tank is reasonably insulated you should still have warm enough water. 

it's not insulated at all. it's just a metal tin in a storage cupboard. 

And hot as a radiator to touch?  Or insulation under a metal cover?  If it is acting like a radiator I suggest getting that changed!

no it isn't hot or warm at all to the touch. insulated under the metal cover as I've just had a look. 

Alnat1

Try reducing the time it's on for bit by bit. Leave around 3 days between each reduction as the tank will take a few days to adjust if well insulated. When you get to the day when you run out of hot water, you'll know you've gone too far 

Rodders53

Timer and thermostat are two separate devices...  OP describes a mechanical timer...

T'stat often in the metal element cover (or under another cover on the tank)... that should be set to as warm a temperature as you want.  Some say it needs to be 60C+ to cater for Legionella sterilisation... but that's debatable in domestic installs, so 50C may be acceptable.
Lower water temperature means less electric will be consumed to reach set temperature.  It may not always translate to lower overall energy used as more hot will be needed to mix with cold water for showers.

How much water the tank holds /is used daily and kW rating of the immersion element determines the time taken to reheat and make up for losses... Too short a time and the water will never get to the temperature set by the thermostat.  The thermostat will stop any further heating (and electric consumed) once the set temperature is reached.  {It will switch on again if enough water is drawn of or heat lost from the cylinder.} 
Many cylinders lose a kWh-worth or two over 24 hours.