Calculating heater running cost

danrv

Hi
I’m trying to work out how much one of my convector heaters cost to run per hour. I have them set on 750w but they cycle on and off. 
I did check how long one was on for in one hour and it worked out at 40mins 23s. Another time when slightly milder it was 21mins.

It’s easy to calculate say a 1kw appliance on for an hour but it’s 750w on for the above durations.
Unit rates are 12.969p off peak, 20.408p peak.
I realize that the duration they’re active changes depending on thermostat setting and temperature but would like to get some idea.
Any help appreciated.

Gerry1

It's simple pro-rata, e.g. for 21 minutes peak rate it's 21/60 of an hour multiplied by 750/1000 kWh multiplied by 20.408p = 5.36p.  Plus 5% VAT if not already included.

danrv

Gerry1 said:

It's simple pro-rata, e.g. for 21 minutes peak rate it's 21/60 of an hour multiplied by 750/1000 kWh multiplied by 20.408p = 5.36p.  Plus 5% VAT if not already included.

That’s great, thanks.
Just couldn’t get my head around it. 
Maths not my strong point.

Gerry1

danrv said:

Gerry1 said:

It's simple pro-rata, e.g. for 21 minutes peak rate it's 21/60 of an hour multiplied by 750/1000 kWh multiplied by 20.408p = 5.36p.  Plus 5% VAT if not already included.

Maths not my strong point. 

That's because your brain is in suspended animation because of the cold...