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-   -   Portable Generator for 2 Sump Pumps (http://www.diychatroom.com/f18/portable-generator-2-sump-pumps-153253/)

ed3120 08-10-2012 02:55 PM

Portable Generator for 2 Sump Pumps
 
I want to purchase a portable generator to run the 2 sump pumps in my house in the event of a power outage. One is in the front of my house and one is in the back. (I do not have a french drain, so they aren't pulling from the same water source.) I do not plan to run anything else.

I'm not sure if the sump pumps are 1/3 or 1/2 HP, but I used an inline amp meter and I know that one pump pulls a continuous draw of 12 amps, while the other pulls a continuous 10 amps.

I'm looking to size out a generator, but I'm having trouble doing so due to the starting amp draw. (I don't know what the draw is, as I didn't install these pumps and I can't find any model numbers on them.)

22 amps yields somewhere around 2600 watts when both are running at the same time. A small, 3000 watt generator would be able to handle that continuous wattage. The startup wattage draw is more confusing to me, because what happens if the two pumps start at the same time? I do not know the odds of that happening and I don't know if the startup draw would pull for 1 second or 1 millisecond. (The shorter the startup time, the less likely that the 2 would overlap.)

During a storm, my pumps will usually run for about 10-15 seconds and then turn off for a few minutes.

joecaption 08-10-2012 03:04 PM

A lot of money to run just two pumps.
Far more worth while figuring out why the waters getting in and fixing that.

Working gutters, grade running away from the house, no mulch piled up againt the house, no flower beds forming ponds up againt the house.
Installing a french drain outside can go a long way to getting rid of the problum.

ed3120 08-10-2012 03:38 PM

My gutters are new (and cleaned), my ground is sloped away from the house for the first 3 feet. I also have a thick layer of plastic on an angle away from the house running under the soil. No mulch or flowers. The first 18 inches is sloped dirt, the next 18 inches is a rock bed to move the water.

I just don't have a french drain. The water isn't a problem until I get into a hurricane or heavy storm situation and I lose power.

bobelectric 08-10-2012 03:49 PM

You need a generator panel. I've hooked up Sump pumps with a car type battery back up.

stickboy1375 08-10-2012 04:07 PM

Quote:

Originally Posted by bobelectric (Post 985686)
You need a generator panel. .

Why? Just run extension cords to each pump...

mpoulton 08-10-2012 04:59 PM

A 3kW generator will probably handle both pumps. The only way to know for sure is to actually test it, though.

bobelectric 08-10-2012 05:02 PM

True. I made a patch panel for my genny for extension cords.

stickboy1375 08-10-2012 05:04 PM

Quote:

Originally Posted by bobelectric (Post 985747)
True. I made a patch panel for my genny for extension cords.

The OP's intent was only two appliances, so it only made sense to keep it simple.

andrew79 08-10-2012 05:40 PM

Most gennys these days are built to handle an initial inrush. So your 3000w gen may handle 4500w on startup. Check the data sheet for the genny your purchasing.

dmxtothemax 08-10-2012 07:32 PM

Quote:

Originally Posted by ed3120 (Post 985650)
I want to purchase a portable generator to run the 2 sump pumps in my house in the event of a power outage. One is in the front of my house and one is in the back. (I do not have a french drain, so they aren't pulling from the same water source.) I do not plan to run anything else.

I'm not sure if the sump pumps are 1/3 or 1/2 HP, but I used an inline amp meter and I know that one pump pulls a continuous draw of 12 amps, while the other pulls a continuous 10 amps.

I'm looking to size out a generator, but I'm having trouble doing so due to the starting amp draw. (I don't know what the draw is, as I didn't install these pumps and I can't find any model numbers on them.)

22 amps yields somewhere around 2600 watts when both are running at the same time. A small, 3000 watt generator would be able to handle that continuous wattage. The startup wattage draw is more confusing to me, because what happens if the two pumps start at the same time? I do not know the odds of that happening and I don't know if the startup draw would pull for 1 second or 1 millisecond. (The shorter the startup time, the less likely that the 2 would overlap.)

During a storm, my pumps will usually run for about 10-15 seconds and then turn off for a few minutes.

A 3Kva genny will supply the running current ok !
But what about the starting current ?
Some gennys can handle overloads if they are breif !
But not all modern ones will be so happy.
The older ones cope pretty well.

So what genny are you going to use ?
Can it handle the starting current ?
If not, you will have to go with probably a 5Kva minimum.

micromind 08-10-2012 10:37 PM

Provided the 3KW gen in question is an actual mechanical unit coupled to an engine (and not one of those new-fangled electronic inverter types), it'll very likely start both pumps at the same time.

Sump pumps start fairly easily and even though the starting current surge is huge, it lasts only a short time.

A 3KW gen will produce more like 8KW for a half-second or so, the main limitation here is the inertia of the engine and gen rotor.


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