[Dave Anderson]

Hey Nathan, just for the giggles perhaps you could input the data you have here and see if the reality and the science match... Would do it myself but am awaiting my equipment/heater order to arrive in the next few weeks....

https://www.oemheaters.com/topic/immersion-wattage

Cheers Dave.

[Dry Clean]

You prob already know lol. That i have a 1kw 27inch immersion heater in my tank.
(I ordered a 2kw one and only recently i had to check something and found it to be a 1kw) but i get my water into the 60 degree marks. My tank is insulated and it holds the temp nicely all day. So done a quick vid to show that, taking the temp of what water ive got left in van at 6pm ish.
As i know u said more for not freezing over night, but everytime i open van doors im hit with the heat contain within. Infact when im travelling between jobs or on way to work i turn the air vent on (already installed b4 i bought the van) to try n help disperse the heat.

https://youtu.be/aDKzwvOAkHk

Have you had your first actual electric meter read yet Nathan?

I did and i was shocked!!
I phoned them to see what rates im on per hour, expecting cheaper at off peak!  I wasnt, i was on a flat rate of 16p per kw day or night. So i got that swapped asap! They had to swap the meter reading machine so it recorded day n night usage and now im on 15 day and from 11pm (till 7am) only 8p. 
I stick it on either at 8 or 9pm till 8am. so thats either (from 8pm -11p plus 7am -8am    then 11pm till 7am) 60p + 64p =£1,24 per night or (from 9pm) 45p + 64 = £1.09 per night so not gonna break the bank at that rate. Plus a penny cheaper during the day

So pending how long i run the heater and if it is as it should be, a 1kw its between £1.10 - £1:50 (if i run it longer than above, so giving some scope)
 On average about 4 days a week. At mo running a little late due to van breaking down and some other circumstances. So ive a wk n half left to get 3 wks work done. Easily do it, but means im mon to fri at the mo

Give me strength (roll eyes) Its impossible for it to be 1kw, do you not have youngsters ? if so ask them to explain it to you, this is basic 11+ physics.

[Dry Clean]

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwj56r6T65PVAhWsJ8AKHRwmBTsQFggpMAE&url=http%3A%2F%2Fprocessheatingservices.com%2Fwater-heating-time-calculator%2F&usg=AFQjCNGV4qZovPM5YjDIY4ILPUYIhW0LYA

[Dry Clean]

1kw heating 500ltrs by 30degrees from starting temp will take just under 17.5 hours, this is fact and if your readings are different
then you have a stronger heater or your not heating 500lts.