# Appliance Output per Hour

Discussion in 'Electronic Basics' started by ldbk, Dec 20, 2006.

1. ### ldbkGuest

Hi there- I'm hoping someone can help me. I'm thinking of purchasing
a space heater with the following ratings

Amps - 12.6
Watts - 1500

I'm trying to find out the kw/hr it puts out. I'm assuming the kw are
1.5? When an appliance lists watts is it watts per hour? I'm not sure
how I get that watts or kw/hr. Bottom line I'm trying to obtain an
estimated cost per month of running this appliance 3 hrs/day, 7
days/week. If someone can help me understand how to get to the kw/hr
I'd really appreciate it!

2. ### John LarkinGuest

1500 watts is 1.5 kw. So every hour it uses 1.5 kwh (that's
dimensionally kwh, kilowatts * hours, not kw/hr). If electricity costs
you 10 cents per kwh, the heater will cost 15 cents per hour to run.

Check your electric bill to see your local cost per kwh.

Newspapers commonly refer to energy in kw/hr, because they all
graduated from journalism school.

John

3. ### Michael A. TerrellGuest

They don't graduate, they run out of money. Then the school gives
them a diploma to free up the seat for another paying customer.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

4. ### John FieldsGuest

---
Yes. 'kilo' means "times 1000", so 1.5 kilowatts = 1.5kw * 1000 =
1500 watts.
---
---
Watts is the amount of work done in moving one coulomb's worth of
charge from one place to another in one second, i.e, 1 watt = 1
coulomb per second. So, a 1500 watt toaster burns 1500 coulombs per
second every second it's on.
---
---
Energy is measured in watt-hours, not kilowatts per hour, so to get
how much energy you use you multiply the number of watts it uses
times how long it's been on, and then multiply that by your utility
company's rate.

For example, your appliance uses 1500 watts, (1.5kw) so if your
utility charges 10 cents per kilowatt hour, you'll be charged 15
cents for every hour your appliance is on. 3 hours a day every day
comes out to 90 hours for 30 day months, so at 15 cents per hour
it'll cost you \$13.50 a month to run the appliance.

6. ### ldbkGuest

Thank you! No more "/" in kwh. I did not graduate from journalism
school. :^)

7. ### GarethGuest

Does this heater have a thermostat? If it does, it could cost a bit
less since it may not actually be running all the time. Depends how
cold it is and how well insulated the room is.

Gareth

PS if you really want to look like you know what you are talking about,
it should be a capital W in kWh because watts are named after a person
(James Watt)

--

8. ### John LarkinGuest

Sorry, but I don't care how I look.

John

9. ### Roger DewhurstGuest

The watt or kilowatt is a measure of energy at an instant of time. Watt
seconds, or joules, or kilowatt hours are a measure of power or work. You
pay for power, not for energy. There is no such unit as kilowatts per hour!

R

10. ### Roger DewhurstGuest

Get yourself a copy of "Dictionary of Quantities and Units" by J B Drazil
(Pub = Leonard Hill, ISBN = 0 24944092). It is invaluable for this sort of
problem.

R

11. ### John LarkinGuest

You can't measure energy at an instant in time. Well, maybe potential
energy. Energy is a time integral.
Joules or kwh are measures of energy, not power. And you pay for
energy, not for power.
Kilowatts per hour is a legitimate engineering unit, but it's not
energy.

John

12. ### jasenGuest

you've got work and power swapped round.

It's only called a "power bill" colloquially,

Bye.
Jasen

13. ### GarethGuest

John,

I meant that for the OP's information. I wasn't intending to criticise
your post, and I'm sorry if I gave that impression.

I know that you know what you are talking about.

Gareth