Well Pump Draw

[kbs2244]

How can I find out how much power my well pump uses?
Other than pulling it up and reading the label?

I know how to determine the time per day it runs, but how much juice during that time?

I, and the county and state, have no documentation.
The well was dug before that documentation was required.

I know it is a 220 install, but that is all.

 

[Milton Shaw]

Use a clamp on amp meter and read the amps as it runs. Simple math. One easy way to see how much it runs is to wire a dial clock in parallel with pump. Set it to 12:00 and after 12 hours/ 24 hours etc see how much time the clock has moved. Most digital clock would be resetting to zero every time it came on. Then amp x volts x time gives you a figure of watts used and find rate and work out how much its costing to run.

 

[Norcal]

There should be a data plate on the motor controller box, ** amperes @ 230V, for example a non-working pump (worn out impellers) in a well on the property is a 1 1/2 HP rated at 11.6A @ 230V. Do not use "220V" in the calcs unless the data plate says it.

 

[Joe92GT]

There should be a data plate on the motor controller box, ** amperes @ 230V, for example a non-working pump (worn out impellers) in a well on the property is a 1 1/2 HP rated at 11.6A @ 230V. Do not use "220V" in the calcs unless the data plate says it.

If you want to be accurate, the voltage that should be used for the calculation is the voltage that the pump is getting. Not the name plate, not the theoretical, but the actual voltage supplied to the pump.

A clamp on amp meter is the easiest way of getting the current used by the pump, multiplied by the actual voltage is a really close number to the KW used.

I measured a well pump for a friend of mine with a power logger, don't know any of the details other than he is on top of a mountain so the pump is rather large. It ran at just under 4kw.

Where are you located?

 

[kbs2244]

I am in north east Illinois.

It is a submersible pump with the pressure tank in the basement.

There is a disconnect switch right by the tank.
EMT from the panel to the switch.
What I call “BX” from the switch to the pressure switch.
And flex, black, plastic from the pressure switch through the foundation and out to the well.

Where would I put the clamp on?
I have never used one.
Do I need exposed wires or will it read through the EMT or BX?

I am not so much concerned with cost to run as with power needed to run it.
I am thinking of a battery bank and inverter for back up water supply.
So I need to know how big a battery bank and how big of an inverter.
I will use PV to charge the batteries.

Our power is pretty good here, but we did have a lighting strike that blew out one of those car sized transformers last summer. It took 3 days to get the power back.
We did OK with everything but water.
You need water to flush the toilet!

I know they make ac/dc pumps, but they are pricey and there is nothing wrong with the one I have.
And since I would need the batteries anyway I am expecting an inverter to be less expensive.

 

[larry_g]

In your case I would look at the fuses that protect the circuit. If they are 15A then assume that is the max you will pull. If the pump is fused with odd fuses then they are matchec to t he pump and would be a good clue to the HP. Most likely you will have a 1hp pump or less. You should have a control box there some where that would have the specifications for the pump capabilities it will handle. Use the max number that is listed in the control box. Nothing rocket science here. If you size your backup for worst case your good.

lg
no neat sig line

 

[Joe92GT]

I'm thinking a well pump would need a very large battery bank to be of any use during a power outage.

Assuming only 15A at 240V, would mean 300A at 12V, plus inefficiencies in the inverter.

Wouldn't it be cheaper and easier to get a small generator?

 

[kbs2244]

Joe...

That is the home work I am doing.
Before I can do anything, I need to know the load.

Larry...

That is a good idea.
The CB will be for worst case, so if I use them I will be safe.
Most likely oversized, but safe.

Thanks guys

 

[VHF]

Where would I put the clamp on?
I have never used one.
Do I need exposed wires or will it read through the EMT or BX?

You need to put the clamp around a single conductor. It can be anywhere in the circuit as long as you get the clamp around a single wire. It won't read through EMT or BX, and even with Romex the two conductors would "cancel out". You might be able to access a single conductor if you take the cover off the pressure swtich.

So I need to know how big a battery bank and how big of an inverter.

My submersable well pump has a 7A running current but an inrush of 37A! It is feed by a 15A double breaker.

The challenge will be a large enough inverter that can supply the inrush current needed to start the pump! I would guess you would need at least a 240VAC 3,500W inverter. The technology has been improving, so there may be some options.

I know they make ac/dc pumps, but they are pricey and there is nothing wrong with the one I have.
And since I would need the batteries anyway I am expecting an inverter to be less expensive.

Going to a DC pump (perhaps a variable speed soft-start model) might be less expensive than the inverter! What about keeping your existing pump and adding a second DC pump just for backup?

I like the idea of photovoltaic power, but strictly for backup purposes a propane or nautral gas fired generator might be the most practical way to go. I have a 10KW Generac on propane which can run my well pump, fridge, sump pump, furnace blower, microwave, and some lights.

 

[kbs2244]

37A going down to 7A !
That is the kind of info I was looking for.
Do you think that is typical?
Mine is two 15A breakers as well.

The second DC pump may be an idea.
How would you do it in a submerged set up?
Would one be a pass through?
Does anyone know of a supplier?
I have a 4 inch caseing.

You would have to pull and re-install, but it may be worth it.

I like the battery idea for the lack of noise and PV for the lack of fuel storage.
By it’s very nature a well pump is an intermittent and unpredictable load.
But dollars do play an important part in this.

What about going to an all DC set up?
PVs to batteries to pump?
Do any of the alt energy guys do this with decent pressure and volume?

Now I am going beyond flushing the toilets with the power out, but maybe….
However, I do have a post-Menopausal wife who really likes her dishwasher, washing machine, water softener, etc, etc, etc…

 

[Charles (in GA)]

Open the circuit panel and find the breaker for the well pump. If the wires have enough space to clamp the amp meter around it (carefully, don't let your fingers touch anything hot) you could have your wife run water till it cycles on while you hold and watch the meter. They work best if the wires are in the middle of the loop made by the clamp. Some meters have huge clamps, some have small ones. I have a digital one with a small clamp (intended for automotive but works on AC also) and a analog one I really like (Sperry) with a larger clamp.

If you are going to be playing with current and especially DC, I'd suggest you invest in a decent amp clamp meter that works on DC and AC. You will find it useful. Generally they also come with leads and have multi-meter features also, so its not a loss to buy it.

Charles

 

[kbs2244]

Thanks Charles.
I don't know if I will have enough use for one to buy one.
I do know a couple electricians and expect they have one.
Maybe it is time for some back scratching.

I am going to look into the surge rating on some inverters.
And the pressure/volume ratings of some DC pumps.

And maybe some way to auto start one of those super quiet Honda generators so it will come on when I need water and shut off when the tank is full.

So many options.... so much time.

 

[Charles (in GA)]

The generators have a load sensor, when there is a draw, it revs up to proper speed and when the load ceases, it drops to an idle. Provides somewhat of a soft start for the well pump but it works. We use a 5000w Dayton on a 5 hp deep well where I live and it works OK doing this. Saves on gas. You can let it run when you are up and using water. It would never be able to auto start and rev up and then run the pump properly...... I don't think.... I think you would have problems.......... You want the motor to stay warm anyhow, if you plan on using it in the winter.......... Somehow, I think you are really overthinking this.

Also suggest spending the money to get the largest Bladder pressure tank they make (115 gal I think) as this gives you something like 30 gals of water you can draw before the pump cycles (gals of draw down vary somewhat with pump on/off pressure). Its good for the pump, as there are fewer starts on the pump. Pumps like to run, not start and stop all the time.

119 gal tank on a 30/50 system gives you 40.5 gals draw down and 40/60 system you get 35.1 gal draw down. Draw down is the number of gallons you get from the peak pressure when the pump has just shut off, to the point where the pressure switch kicks it back on again. You need the bladder pressure set properly for your pump pressure switch, the bladder pressure needs to be about two pounds below the low pressure of the switch (pump kick on pressure) (bladder tank)

http://www.inspectapedia.com/water/Water_Tank_Bladder_Adjust.htm

http://www.inspectapedia.com/water/watertank.htm

Charles

 

[VHF]

The second DC pump may be an idea.
How would you do it in a submerged set up?
Would one be a pass through?
Does anyone know of a supplier?
I have a 4 inch caseing.

You can probably drop a DC submersible pump down your 4" casing in addition to your existing pump--the pump body needs to be slim enough to fit in the casing along with the pipe/wires from your existing pump. It would sit higher in the well than your existing pump (which should be at least 30' below the static water level.)

Most submersible pump installations use what is called a pitless adaptor for the water pipe to go through the side of the well casing below grade (below frost level.) You could use a second pitless adapter for the second pump.

What about going to an all DC set up?
PVs to batteries to pump?
Do any of the alt energy guys do this with decent pressure and volume?

That's a good question, I'm not sure if the DC pumps are able to push the water up 200-300' (how deep is your well, anyway?) and then pressurize it to 40-60psi.

In fact, as was touched on earlier a 12V DC pump capable of the same pressure and volume output would require some pretty heavy wires running down into the well... I suspect most low voltage DC pumps have a much more limited output.

Some off-grid setups use a DC pump powered directly by PV panels to pump water into a non-pressurized storage tank (say 1200 gallons) when the sun is shining, then use a battery-powered 12V pump to provide pressure to the house. SHURflo is a popular brand of DC pumps (used a lot in RVs and boats.) The cheap ones are noisy and have limited flow, but the better (i.e. more expensive) ones would be suitable for household use.

 

[VHF]

If you haven't looked at HomePower Magazine yet, you'll find a lot of ads for inverters, batteries, PV (photovoltaic) panels, etc. Plus articles on actual off-grid and grid-intertied PV systems. I would imagine there would be some resources there that would help you answer your original question of whether it is feasable to run your existing well pump off of an inverter.

Sounds like what you really want might be a grid-intertied PV system with battery backup.

 

[Charles (in GA)]

You can probably drop a DC submersible pump down your 4" casing in addition to your existing pump--the pump body needs to be slim enough to fit in the casing along with the pipe/wires from your existing pump. It would sit higher in the well than your existing pump (which should be at least 30' below the static water level.)

Most submersible pump installations use what is called a pitless adaptor for the water pipe to go through the side of the well casing below grade (below frost level.) You could use a second pitless adapter for the second pump.

A rather impossible statement. If you have ever seen a deep well pump, it is two to three feet tall and about 3-1/2 in diameter. Some are larger for larger casings. It just barely slides down the 4" casing. Its not like you can drop it down the well next to the one that is there, or down the well even next to the pipe that is already there. In addition, you usually find torque adapters on the pipe. Cone shaped rubber things that are clamped to the pipe and fit rather tightly to the wall of the casing, to keep the pipe from twisting when the pump starts and stops. Simply put, you ain't getting but one pump and one pipe down a 4" casing deep well.

Charles