Calculating watts used with a Hour Meter?


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Old 12-06-07, 07:13 PM
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Calculating watts used with a Hour Meter?

First off- Please move if there is a better section to post my question in. Thanks

All right I'm sharing a well with my neighbor. The electricity is coming from my house. They have been paying me $15 a month. Everyone keeps saying that that's not enough money to cover it, so I had a hour meter (230 volts) laying around so I hooked it up. I can't quite figure out how to calculate power used? My pump and my pressure tank are using power at the same time. My pressure tank is 230 volts and I still have to find out what type of pump I have. This may be a stupid question but if I have a 100 watt light bulb turned on- how many watts a hour is it using? Does that mean it consumes 100 watts per hour? Any help would be great- Thanks
 
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Old 12-07-07, 01:39 AM
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Ok easier question first:

Originally Posted by buzzharley
if I have a 100 watt light bulb turned on- how many watts a hour is it using? Does that mean it consumes 100 watts per hour?
"Watts" and "Watt-Hours" are two different measurements. You pay for energy used (Watt-Hours), not Watts.

A 100W light bulb is using 100 watts at all times, at any instantaneous moment. If you leave it running for 1 hour you have consumed 100 watt-hours (100W x 1hr). For 8 hours of use you would be charged for 800 watt-hours. One minue of use would be 1.67 watt-hours. Just multiply watts x hours. That itself is pretty simple.

What is not so simple in your case is measuring the energy used by these two independent devices, given you only have one hour meter and nothing to measure current.

Where exactly did you connect the hour meter? I'm not a well guy, but can I assume that the pump and pressure tank can kick on and off at slightly different times? The problem right there is you'll know how many hours either or both were running, but this is not terribly helpful unless they are both exactly syncronized. Can't imagine they would be.

Even if they were, you then have the problem of measuring the wattage of each device. I think if you used the nameplate rating you would be seriously overestimating the real-life normal current draw.

What I would probably do, if buying anything is out of the question, is to use your kilowatt-hour meter that's on your house to run some tests, although this is not exactly a quick process and is very inconvenient as you cannot use any other electricity. You could then further assume that the running time of the pump and pressure tank are directly proportional to one another. If you connect the hour meter to your tank only (or pump only), your kilowatt-hour meter tests could tell you for example that for every 'x' minutes that the pressure tank is running you'll use about 'y' watt-hours of energy.

This would still be a severe estimate but it's about the best I can think of given the equipment at hand. All under the assumption that you do not wish to buy additional measuring devices.
 
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Old 12-07-07, 03:11 AM
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The hour meter is going to tell you how long the pump or tank runs in a given period. Give it a week on each device to get a good average.

You know the voltage. Amps x volts = watts. You can use a clamp-on amp meter to see how much current each device uses when it's on.

Divide the wattage figure by 1000. Multiply that times the cost of a kilowatt hour. Multiply that times the number of hours the system is on in a week. Multiply that times 4.3 to get the monthly cost. Divide by 2 for the neighbor's monthly charge.

Side note: The cost of a kilowatt hour in my area is hard to figure. There are delivery charges, generating charges, distribution charges, base charges, fees, taxes, and all kinds of other nickels and dimes. I just divide the monthly bill by the total used to get the "real" cost.
 
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Old 12-07-07, 07:22 AM
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I'm including a link to pictures of my setup- The pictures don't include the hour meter hooked up. The 2 wires from the meter are connected to line 1 and line 2. Now thinking about it- I think it's only giving me hours used for my well pump, and not my pressure tank?

Here's how the power is hooked up-
Breaker Box-
to pressure tank-
then out to control box- Line 1 and line 2-
then out to well pump (R,Y,B)

I'm now thinking that I would need to connect the meter right after the breaker box before it reaches the pressure tank in order to get both devices?

I can spend some money if there is a not too expensive electric meter out there.





 
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Old 12-07-07, 12:17 PM
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I don't understand your setup. I have never seen a pressure tank that used power. they have a switch that turns on the pump but don't use any power.
Is there two pumps, one for you one for your neighbour? Is there one pump and the neighbour gets his water from your house? Is there one pump and it pumps water direct to you and the neighbour?
You can buy different version of Kilowatt measuring devices. Instead of measuing time and amps just measure the actual power used.
 
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Old 12-07-07, 01:26 PM
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Pressure tanks do not use any power. There is only a pressure switch which trips a contact to send power to the well. The well is the only thing that uses power.
 
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Old 12-07-07, 01:55 PM
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It looks like you could use some new wiring at your pressure tank. There are lots of "whole house" watthour meters out there. They are designed to measure the whole house, but you could use them for a single circuit. An example can be found at http://www.theenergydetective.com/index.html
 
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Old 12-07-07, 04:23 PM
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Now I'm confused? In the 2nd picture at the bottom of the pressure tank there is a square D device (pumptrol) which I thought needed power, but I guess it's just a gauge switch. Is the pumptrol just telling the pump in my well to pump when it goes below the set psi? If so then I guess I only have the pump that needs power.
 
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Old 12-07-07, 04:43 PM
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Square D pumptrol is a pressure switch. It turns on the pump at low pressure and off when it reaches full pressure. Usually something like 2-40 or 30-50.
 
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Old 12-08-07, 06:21 AM
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FWIW, just off the top of my head I think $15/mo probably covers it. We are on well and have a two pump system + CH&A + electric WH + range + pool and average between $150-175 bill each month. I seriously doubt that my two pumps make up 10% of my total consumption.

Who is "everyone"?
 
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Old 12-08-07, 06:50 PM
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Are you irrigating with this water? If so, it could be using a lot of power in the summer. Is sharing a well even allowed by code? I think I would put in a water meter and charge by the cubic foot.
 
 

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