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Author Topic: How do I know what size generator I need to run my well?  (Read 44789 times)

cowboy

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How do I know what size generator I need to run my well?
« on: March 03, 2011, 07:38:08 PM »
I don't know exactly what size generator it will take to run my water well.     It says that the pump is 1.5hp.     I bet one of you guys out there can tell me how to determine minimum requirements.     I don't want to use the minimum, but I would sure like to know what it is.

Thanks in advance,
Cowboy

mike90045

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Re: How do I know what size generator I need to run my well?
« Reply #1 on: March 03, 2011, 08:20:25 PM »
I hope you don't really need that large of a pump.   from my experience , you will consume about 3,000w keeping it running, and about 5-10X that to start it.

When it needs replacing, consider your actual lift and volume needs, you may be able to get by with much less of a pump.

Thob

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Re: How do I know what size generator I need to run my well?
« Reply #2 on: March 03, 2011, 08:46:18 PM »
We'd really need a little more information to help with this.  What kind of pump is it?  Submersible pump or topside centrifugal?  1 or 3 phase?  If it's a 1 phase submersible, is it two wire or three wire?  The starting needs vary quite a bit depending on what type pump you're using.  Submersible pumps are one of the most difficult loads to start, they typically have a full column of water from the pump to the surface to start against.  The two-wire single phase pumps are typically even worse.

Then there's the question of what kind of generator - a Lister type setup with huge flywheels and a well-built permanent magnet alternator will start a much bigger load than a big-box-store high RPM engine with a poorly regulated generator head, even if both are rated with the same HP engine.

Unfortunately, there's no magic formula that will really tell you if it will work.  Various people have widely different "rules of thumb".  Whatever you get, try it before the power goes out and it's crunch time!
Witte 98RC Gas burner - Kubota D600 w/ST7.5KW head.
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xyzer

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Re: How do I know what size generator I need to run my well?
« Reply #3 on: March 03, 2011, 09:13:52 PM »
For what it is worth......my 6/1 with a st-5 will start a 1-1/2 centrifugal no problem and run it days on end. Our home water supply 1-hp submersible starts no problem. I would bet 1-1/2hp submersible would be my limit. I learned from a power outage years ago before my generator phase that keeping the wife happy when the power is out it is a tossup between water and heat! No one is happy if they are warm and can't flush the toilets! Do you think I really care if it uses .25gal/hr or.30 .........nope! I want water no matter what I have in the hole!
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cowboy

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Re: How do I know what size generator I need to run my well?
« Reply #4 on: March 03, 2011, 09:22:11 PM »
Since the pump is not visible, I guess that makes it a submersible pump?     It's single phase, 220 volt and the well is about 425 feet deep.   I have a Lovson 6/1 that I want to put a PMG head on,  but have not been able to find one.    Utterpower has them on backorder.     I will buy one as soon as they are available.    For the time being I was thinking about getting a 5KW ST type head, but don't want to waste the money if it won't run the well.   The well and refrigerator/freezers are my ONLY mission essential concerns.   I wish I knew more about the well, but it was here when I bought the property and I haven't had any problems with it.     Well,   except fire ants getting into the contacts and stopping them from working.    After blowing them out with the air hose it was back in operation.

xyzer

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Re: How do I know what size generator I need to run my well?
« Reply #5 on: March 03, 2011, 10:33:52 PM »
An st-5 is a bit larger than what a 6/1 can sustain. On average on a good day a 6/1 will put out 3500 watts continuously. I don't think you will hurt a 4000 watt head with a 6/1. The 5000 watt will deal with start up a bit better. I'm sure you could run a 1-1/2hp submersible .......but will it start it?
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BigGreen

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Re: How do I know what size generator I need to run my well?
« Reply #6 on: March 03, 2011, 11:29:56 PM »
Cowboy
How much are you planning on paying for this ST-5? If you pay fair price and you realize it doesn't work for you I'll buy it off of you. I was thinking on buying one to play around with and I'll help you out here if needed. Keep in mind you may or may not need to buy a different bushing if you get a different head later. I'm south of Houston.

PM me if interested and when you have details
Dave
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LowGear

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Re: How do I know what size generator I need to run my well?
« Reply #7 on: March 04, 2011, 02:59:03 AM »
Its too bad the submersibles don't have a pressure bleed off like air compressors.

They still need to know if you've got two wires going down the hole as opposed to three.  Your pump control box is a good and hopefully easy place to check.

Casey
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Thob

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Re: How do I know what size generator I need to run my well?
« Reply #8 on: March 04, 2011, 03:10:23 AM »
The folks at Central Georgia Generator have PM gen heads, apparently in stock:

http://cgi.ebay.com/6-5-KW-Rare-Earth-Permanent-Magnet-Generator-Alternator-/160499729388?pt=BI_Generators&hash=item255e8783ec

I don't know these folks or this particular generator; other people on the discussion boards seem to think highly of these folks.  It would be worth a phone call to them and discuss your well pump, etc.  Web site:

www.centralgagenerator.com

They also carry the ST (and other style) gen heads.  Their advice is surely worth more than my opinions.
Witte 98RC Gas burner - Kubota D600 w/ST7.5KW head.
I'm not afraid to take anything apart.
I am sometimes afraid I'm not going to get it back together.

Thob

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Re: How do I know what size generator I need to run my well?
« Reply #9 on: March 04, 2011, 03:14:18 AM »
Oh - and put me down 2nd in line behind big green if you buy an ST-5 and then decide to sell it.  I'm planning on buying one - sometime in the next 6 months?
Witte 98RC Gas burner - Kubota D600 w/ST7.5KW head.
I'm not afraid to take anything apart.
I am sometimes afraid I'm not going to get it back together.

cowboy

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Re: How do I know what size generator I need to run my well?
« Reply #10 on: March 06, 2011, 12:51:07 AM »
I called a popular well drilling and service company in my town and asked them about generator size.     I told them I had 425ft well with a 1.5hp pump and they said "take 13 amps x220 volts=2860 watts,   add about 25% for start up, about 750 watts, for a total of 3612 watts minimum for generator size".    They said "minimum, bigger is better".     There are 4 wires going down into my well, marked red, green, black and ground.      I'm hoping all that is correct,   but they are supposed to be the experts!    So I guess a 3KW ST head won't do it, but a 4 or 5KW would?

bschwartz

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Re: How do I know what size generator I need to run my well?
« Reply #11 on: March 06, 2011, 05:01:14 AM »
I'd go with the PMG from Tom (Central Georgia Generator) if you can afford it.  It is more efficient, and will put out a few hundred more watts than the ST-5 at the same engine output.  If your budget can't afford the PMG, then get the ST-5.  When you called the well drilling place, did you happen to mention 250 lbs. of flywheels on your engine?  ;D ;D ;D  It helps a bunch for heavy surge start loads.

The engine will probably slow down a bit upon startup, buy should recover to run the load.

425ft!!!!! Holy Cow!!!!!
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deeiche

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Re: How do I know what size generator I need to run my well?
« Reply #12 on: March 06, 2011, 04:00:10 PM »
SNIP

425ft!!!!! Holy Cow!!!!!
425 isn't that deep, in the mountains east of Albuquerque people regularly go down 500'.  My well was 450' and I was lucky to get 200 gal/day.

toydiesel01

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Re: How do I know what size generator I need to run my well?
« Reply #13 on: March 06, 2011, 05:58:31 PM »
red green black and ground  ??   red , black is ok but the green is used  for the ground on a legal install
what color is the ground wire then?
in the pump controll box where does the green wire attach?
what are the numbers of the pump box what voltage what ampre's need more info

cowboy

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Re: How do I know what size generator I need to run my well?
« Reply #14 on: March 06, 2011, 08:08:34 PM »
Oops!   Sorry,  I should proof read my posts better.    From my service panel there is a white, black and bare copper wire running to a small box with contact points.   From there a white, black and bare copper wire goes to the well control box.    The bare wire grounds to a bolt in the case and the white wire goes to a panel and connects to a poll marked L1.   The black goes to a poll L2 on the panel.    The next polls are marked Yellow, Black and Red.   These 3 wires connected here are all actually yellow, but one has a red stripe, the one on the black poll has some writing on it but I can't make it out, one is just yellow.   They join a 4th yellow wire with a green stripe that is grounded to a bolt in the case just like the bare copper wire.   All 4 wires then go down a pipe to what I assume must lead to the submersible well pump.   There is also a run capacitor and a start capacitor in the control box.   These things are WAY more complicated than I thought.    I hope I never have to figure this stuff out by myself.     I wonder if I should take a class or something on wells and making them work.   Maybe I should stick with the figures the well company gave me about generator size and be happy there is water coming out of the faucet.   At one time I thought I knew a little bit about how this well worked,    Now I'm not so sure!  I hope I covered it all this time.