Kilowatt per Hour Formula

[whodunit]

We are trying to figure out what we are spending on watering several head of livestock. It seems I have com across a formula for this in the past. Does anyone have one that might work?

We have a 1/2 HP pump and I think DW said it is 230 watts.

Thanks in advance!!!

[sgl42]

google does unit conversions. type in "1/2 horsepower in watts" and it tells you:
(1/2) horsepower = 372.849936 watts
(which is of course 0.372 kilowatts.

i believe you want "kilowatt hours", not kilowatts per hour.

if you run the pump for one hour, you would use 0.372 kilowatt hours.

so, figure out how many hours a day (or week, or month) the pump runs, and multiply it by 0.372 kilowatts, and you'll get the kilowatt hours used by the pump for that time period.

multilply that by the electricity rate you pay per kilowatt hour, and you'll have the cost.

--sgl

[Yvonne's hubby]

Originally Posted by whodunit

We are trying to figure out what we are spending on watering several head of livestock. It seems I have com across a formula for this in the past. Does anyone have one that might work?

We have a 1/2 HP pump and I think DW said it is 230 watts.

Thanks in advance!!!

One horsepower equals pretty close to 750 watts. I would just figure up the hours the pump runs per day average, divide by two then multiply that by .75 and get pretty close to the amount of kilowatt hours used. Since your pump does not run continuously (or at least it shouldnt) the tricky part will be figuring out exactly how long it runs to water your stock. Unless you are watering a lot of stock, (thousand gallons a day or so) your pump should not be costing more than a few cents a day to operate.

[Windy in Kansas]

One kilowatt hour is 1,000 watts used for 1 hour. If you divide the 1,000 by the 230 watt rating of the motor you get 4.35 which means you could pump water for 4.35 hours before drawing 1 KWH. However thrown into the equation is the fact that water friction takes a little more more power to get the water started moving, and generally electric motors take more power as they first start up. That is why it is better to turn extra faucets on when using a pressure tank system to water a lawn or garden in order to keep the pump running rather than cycling on and off.

KWH is really no mystery once you learn a little. The key is 1,000 watts total for one hour.

If you burn a 100 watt bulb for 10 hours you have used 1 KWH.
If a refrigerator draws 1,000 watts but only runs for 15 minutes each hour it will take 4 hours before it draws 1 KWH.
If 2 range burners draw 1500 watts each for a 3,000 watt draw total they can only be used for 20 minutes before drawing 1 KWH.

The formula works for cumulative hours and watts.

In reality the work we get from electricity for mere pennies is great. Who in their right mind would want to work hard pumping water for over 4 hours when 10¢ would do the work for you?

[whodunit]

I guess it would be better to lay out what I'm trying to figure out.

We rent a place and aside from household use and yard use, we also have three head of livestock that we personally water.

In addition, there are another 10 cows and their calves and four full-grown horses also kept on the property which are all owned by others. They water from the same well with us paying the power bill.

In addition to rent we also pay a pasture fee.

Our electricity bill has more than doubled since we moved from town.

Of course, everything as far as household use of water (dishwasher, baths, etc.), and number of appliances are the same.

We are doing much more cooking using an electric stove, so that has changed.

The biggest difference now is that we didn't have to pump water.

Would having to now pump water more than double our bill?

The landlord believes that the cows are drinking maybe 150 gallons of water a day and maybe another 40 a day for the horses.

If that's true, we are pumping 5700 gallons of water a month for the livestock that is not our own.

Is there a way to figure what it might cost to pump that amount of water?

[SolarGary]

Hi,
If the pump plugs into a regular 120VAC outlet, you could get a Kill-A-Watt meter -- it will tell you exactly how much the pump uses over a day (or week, or month). Its a very handy device to have -- you can use it to track down what is using more power than you think it should. Things like older fridges can be pretty bad.
Newegg.com has the Kill A Watts for $20:
http://www.newegg.com/Product/Produc...ill%20a%20watt

You can also use the utilities power meter to measure power coming into the house over a short period. It measures total power to the house, so if you want to get just how much power one thing uses, you have to try to shut everything else off -- kind of awkward, but can be done -- there is a link in this section to tell you how to do it:
http://www.builditsolar.com/Referenc...ents.htm#Power

The power the pump uses depends on how much head it is working against and how efficient a pump it is -- so, hard to tell just by the water pumped.

Some more ideas on what usually burns a lot of power:
http://www.builditsolar.com/Projects....htm#PowerHogs

What does your electric bill run per month in kilowatt hours (KWH)?

Gary

[Harry Chickpea]

IIRC, rule of thumb for cattle is 2 gallons per 100 lbs per day in hot weather. A thousand pound cow will take 20 gallons per day. A horse might take a little less, but not much. Just ballparking a guess - I'd think the figure is closer to a total of 300 gals per day or about 9,000 gal per month.

As for figuring how much it costs to pump that, you have to do a bit of field work. The simplest way is to go to your breaker box, cut off every circuit except for the pump, walk up to the electric meter and read it, then run the pump until you have 1000 gallons of water. Go back and read the meter again, subtract the first reading from the second, and get the number of KWH. This figure will vary depending on the depth of the well, the resistance of the pipe, the efficiency of the motor, and a few other minor factors.

Cutting to the chase, my best guess is that you are paying no more than $10/month for pumping. I base that on my figures using 3 ganged 1/2 hp pumps to get water over 800 lineal feet and up 120 vertical lift feet to my garden. That runs me about 70 cents per 1,000 gallons, and I'm sure you are paying less than that.

Your electric stove is likely to be a big consumer of electricity -especially if you are canning-, any air conditioning is another factor, and water heating is a third factor. You could have different power rates as well. Speaking of wells, do you have a well for your own drinking purposes? That is another $5 to $10 right there.

[whodunit]

The last bill was 1545 KWH with us paying just over 7 cents per for the first 600, and just over 8 cents per for anything over that.

The bill before that was even more (1771). DW believes we accidentally left a hose running or something that month.

The highest full month, in town bill (during which we did not have to pump water) was 1000 KWH and the lowest was 760.

That house had a radiator system that used electricity or oil, but I think always some electricity to pump the water. We used oil, but the high months of 1000 may have been times we ran out of oil and had to switch over to electricity until we had more delivered.

Like I said we haven't added appliances (we even reduced one computer) and we are basically using the same amount of water running the household (possible exception of maybe one more load of dishes a day). We laos haven't had to use the electric heat here for the last two months and we don't use A/C.

[Windy in Kansas]

My well puts out 35 gallons per minute so would take 163 minutes to pump 5700 gallons per month. The pump doesn't draw 1000 watts but even if it did 2.71 hours of pumping at 10¢ per KWH would cost an extra 27¢ per months.

In my opinion look elsewhere. Using electricity to produce heat for cooking would be the culprit in my opinion.

[MELOC]

electric water heater with a bad element or thermostat?

[ca2devri]

I really doubt pumping 150 gallons a day is going to add up to any significant kwHr amount. We have a pool with a 1HP pump that runs 12 hrs a day. Now that does add up to significant power, but for your pump, I bet it's on less than 5% of the time to get your water to the cows.

As already suggested, get the power meter and start plugging it in to the probable offenders. We moved to the country a few years ago and had the same thing (a jump in electricity usage). For us the biggest difference was electric water heater and cooking instead of gas. Check your refrigerator and freezer (if they're old they can be a big sink of electricity). You're well pump is probably high HP as well, but again likely only on a small % of the time so very doubtful it's a big deal. The electric water heater temp could be turned down and that helps. We replaced all often-used lights with compact florescent. I swear the lights are turning themselves on all the time though because I must switch them off 20 times a day (Note: I have 2 young kids and a wife)!

[whodunit]

We have increased using the electric stove since we have lived here since we are making dairy products.

I think we use cold water for most laundry and the kids share a bath. DW and I take a shower each and probably tend to be longer than needed.

The stock tank that the cows use has a float to keep it filled. The landlord wondered if we instead manually filled it as needed that it might cut back on the pump power usage since initially starting the pump draws the most power.

But, DW says the pump kicks on and off all day and I agree. I can turn on a hose and hear the pump immediately kick on. Could it be that the pressure tank is too small and it's trying to keep up the water level?

We don't want to be difficult about things with the landlord, but even if the cost of watering other livestock is minimal, should we be paying for it? We already pay extra "rent" for use of the pasture.

Of course, my concern is that the landlord has been good to us. He has allowed us to run our cow with his outside of our pasture. He has also offered use of a bull to breed our milk cow. Now the latest is that he has offered a "bummer" calf to us that if we raise, we can have half the meat. We think it would be a great project for our kids.

If the water issue isn't costing us any significant amount, I think it's being petty for us to worry about it. Much of this is the just the shock of seeing our power bill double and not knowing why.

[TurnerHill]

If the pump is kicking on all the time, you have a water leak somewhere.

I agree with the other posters. Moving that amount of water should be extremely inexpensive.

I'm afraid you will find it is your own usage, not the neighbor's stock, that is the problem.

[Windy in Kansas]

Originally Posted by whodunit

We have increased using the electric stove since we have lived here since we are making dairy products.

Could it be that the pressure tank is too small and it's trying to keep up the water level?

Indeed cycling would cost more than if the pressure tank were the largest available. I never really understood why smaller ones were even made, but I suppose for many systems they are better for initial cost and if enough faucets are opened for outdoor watering the pump will remain on anyway.

I still blame the range. Next time you get ready to heat dairy write down the meter reading and then read it again after your normal usage for the heating. You may wish to record the actual time as well to get a truer KWH handle.

[SolarGary]

Originally Posted by whodunit

The last bill was 1545 KWH with us paying just over 7 cents per for the first 600, and just over 8 cents per for anything over that.

The bill before that was even more (1771). DW believes we accidentally left a hose running or something that month.

The highest full month, in town bill (during which we did not have to pump water) was 1000 KWH and the lowest was 760.

That house had a radiator system that used electricity or oil, but I think always some electricity to pump the water. We used oil, but the high months of 1000 may have been times we ran out of oil and had to switch over to electricity until we had more delivered.

Like I said we haven't added appliances (we even reduced one computer) and we are basically using the same amount of water running the household (possible exception of maybe one more load of dishes a day). We laos haven't had to use the electric heat here for the last two months and we don't use A/C.

1500+ KWH a month is a lot of electricity. The US family average is a bit under 1000 KWH per month. If the pump is hooked up right and is working correctly, it does not seem likely that its accounting for nearly that much difference.
It does sound like your pressure tank might be water logged -- this makes the pump cycle more, which is not good for it. I don't think that it would increase the electricity used a whole lot. Some tanks let you add air, and that might fix the problem. But if its the type with a rubber diaphragm and the diaphragm is broken, the tank probably needs to be replaced.

I think you need to systematically look at everything that uses electricity in the house -- I think you will find one or more things that are using a lot. The Kill A Watt meter is a big help in this, and, if it gets you down closer to normal usage, it would pay its cost back in half a month.

Working systematically on finding where the power is going, and then trying to cut it back is pretty effective for most people -- we cut our bill from right around 1000 KWH a month to right around 500 KWH a month with a few changes.
http://www.builditsolar.com/Referenc...nservation.htm
I think you probably have more going on than the pump.


Gary

[Harry Chickpea]

First of all, you have a great landlord. I think you are putting this in good perspective.

The momentary start-up surge of a motor or pump is insignificant, other than to force the use of properly sized wiring. The pump going on and off will wear out the pump faster, but not have any major effect on the bills (major being doubling the usage or anything on that order).

Making dairy products - like scalding milk for yogurt or other stuff? How many gallons? Boiling water to reduce a sauce takes a lot of energy. Just heating to 180 doesn't take as much but if you have a lot of milk, it could be an issue.

The typical cautions apply. A dripping hot water faucet or TPI valve can mean a lot of wasted hot water. A refrigerator that isn't sealed or has an inefficient compressor can use a lot of power. Hunt around for anything where there is electricity and heat. If wiring is hot, you have a problem.

[raymilosh]

if your pump turns on and off every time the water is turned on, the bladder tank is likely the culprit. It is bad for the pump and will use more electricity. Your increased power useage is prolly the range and/or the water heater adn you could check everything like Gary and the others have already said.

Basically, I agree with everything Gary and Harry and everyone else has said.

[whodunit]

We are a family of six with all the kids being under 9. They are all girls, and one is a toddler, so that means lots of dirty clothes. I'm not sure how many loads DW does a day.

I handle most of the dishes and we easily do three to four loads a day. They are usually to full capacity with more dishes awaiting the next load.

The extra stove usage now is basically heating milk to make cheese. It doesn't involve high temperatures, but it's on at low settings for up to an hour getting the cheese to the right temperature.

We have three refrigerators, one full-size deep freeze and one small freezer. All are less than 10 years old. I don't know the age of the stove and water heater, but I would guess it came with the house which is a manufactured built in 1994, I think.

The pump doesn't seem to just run without usage. It kicks on when someone takes a shower, a hose is turned on, the dishwasher is running or whatever. I've never heard it on for no reason.

We don't have different KWH costs with our company. It's a penny more expensive over 600 KWH.

All our lights have CFBs (at least the ones which are used constantly). We have been shutting off the computer monitor at night, but we don't shut the computer down.

We do have a couple clock radios and a phone system that are always on.

We don't have any security lights on all night or anything like that.

We have practiced "yellow mellow" in the past but with the hotter temps I'm hesitant to let then toilets stand too long between flushing.

[Yvonne's hubby]

If your well pump is indeed a half horse, and ran constantly, it will use .75 kilowatt hours every two hours which is 8kwhs per day, times 30 days is 240 kwhs per month. This would certainly NOT run your usage into the 1500 kwhs per month category. Assuming it actually runs two hours a day, which would be a lot, even with your stock demands, you are prolly using in the range of 20 kwhs a month. A single stove burner on for one hour a day would use 4 times the amount of the pump running 2 hours. Heating or cooling anything is going to be your major factors in your power consumption.

[TurnerHill]

Originally Posted by whodunit

We have practiced "yellow mellow" in the past but with the hotter temps I'm hesitant to let then toilets stand too long between flushing.

Man, do you know what the cost of pumping a gallon and a half of water is?

Flush the toilet.