(amps x voltage) ÷1000 = kw

[MrsRenovator]

Hello

Bear with me, I'm just a housewife of very little brain. But I thought that (amps x voltage) ÷1000 = kw. My fridge freezer says it's 1.4amp. Since it's a Liebherr brand I've multiplied that by 230v. I've got my own kind of logic. That gives me 0.322kw. Have I gone wrong right at the beginning? The fridge label says it's 186w. How can that be?

I'm wondering, because if I multiply 0.332 by 24 hrs, then by 15p a kw/h unit and then by 365 days, I get an annual cost of £423. But when I Google 'How much does it cost to run a fridge freezer?' all the answers are under £100.
So where am I going wrong in my calculations? Should I have stayed in school beyond the age of 16?

Can you please explain what I am obviously not understanding?

Thank you.

Mrs Renovator

 

[sparkymarka]

Probably because the fridge motor does not run 24/7

 

[MrsRenovator]

Ah yes, that's true. So how do they calculate how many kw/h it uses annually?

And why is there a discrepancy between my calculations of kw and the label on the fridge?

 

[big-all]

186w is the power to run the fridge excluding momentary surges
now the fridge may run for 5 mins every hour up to perhaps 20 mins every hour
internal temperature required and contents along with external temperature and how often the door is opened and closed and how often warm things are added will effect the amount off power consumed
and iff we assume its 12p per kwh 5 mins will cost 1p 10 mins 2p ect
but as your fridge is around 1/5 off that consumption it will cost you about 2p for every full hour the motor is running
if we assume it runs for say 15 mins every hour on average thats 1/2p an hour 12p a [kw unit] per day or 365 kw units a year or about £44 a year with the assumption i have made for simplicity in my example

 

[MrsRenovator]

Thank you. Interesting answer. I didn't realise that the motor is running so little in general use. I'd thought the low ampage was what it must be drawing constantly to keep it running. And that maybe it used even more for when it needed to reduce the temperature further.

So losing internal space in my fridge freezer due to the thick insulation in its walls really does make a difference.

These are the kind of things that I think of at 3am!

Thank you for taking the time to explain.

 

[winston1]

Hello

Bear with me, I'm just a housewife of very little brain. But I thought that (amps x voltage) ÷1000 = kw.

Your formula is wrong, or at least it only applies to DC.

(Amps x voltage x power factor) ÷1000= kW. The power factor of a fridge is less than 1.

 

[JohnD]

your formula is good enough for the question you asked.

 

[winston1]

your formula is good enough for the question you asked.

I disagree. 0.332kW as against 186w is a big error. It implies a power factor of 0.57.

 

[JohnD]

regardless of the exact PF

This is the answer.

Probably because the fridge motor does not run 24/7