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If I just wanted to run the well pump, keep the central heating system going, and keep my computers running, about what would be the smallest generator I would need?
(P.S. I won't need to run a refrigerator, TV)
I'd be able to figure this all out myself, except I have no idea what demand a well pump would put on the generator.
If I just wanted to run the well pump, keep the central heating system going, and keep my computers running, about what would be the smallest generator I would need?
(P.S. I won't need to run a refrigerator, TV)
I'd be able to figure this all out myself, except I have no idea what demand a well pump would put on the generator.
3500-5500Kw should run most any house. No electric heat.
I run a 4000W generator that can take a high surge load, (6800W I believe). The problem with a well pump isn't running it, the problem is starting it. An electric motor tied to a pump demands a lot of juice on start-up. I went with fairly low wattage to conserve fuel but high surge capability for start up of things like the furnace and well pump.
With my 4000 watter we can run the well pump, furnace (with 3 zones), refrigerator, television and a couple of light. That's about as far as I will push it.
Depends a WHOLE lot on the size of your well pump. The deeper the well, the bigger the pump, the bigger the genset.
You might be surprised at how little a difference that makes. A huge submersible pump is a1 1/2 HP which is 3 times the size of most. Those 1.5 HP wells draw less than 2000 watts, take the inrush amps at start-up and a 5000 watt genset would be more than big enough. Most 1/2 HP pumps only draw between 550-700 watts.
I have a 5000 watt that runs my well pump, fridge, tv, pellet stove and one light. I do have to unplug something if I run a microwave or toaster oven tho.
I agree with everybody else. The well pump is the beast that the generator has to be sized for. That said, I think most 4KW gen sets will have the surge capability to start any typical residential 240V well pump (unless all the lights are already on in the house, along with the air conditioner. )
After I kept my power during Irene, I loaned my generator to my sister after they lost their power. My generator is only a 3KW model that fits onto my Troy Bilt tiller and just for kicks, I tried turning on their 240V, 1HP pool filter pump, and it started and ran, though it didn't start quite as quickly as when on the grid.
Hopefully, your well pump is a 240 V model as most small 120/240 generators don't have their full wattage available for a single 120V load. This means that a 240V load will actually load a generator more evenly than if that same wattage load is only 120 V. The actual alternator on generators is actually made of two, 120 V generator coils that are 180 degrees out of phase, with a center tied neutral, set up this way to mimic the service we usually get from the transformer mounted on the pole outside our houses. The thing is, I don't think many of these gen sets have the capability of pulling their full rated power off of only one coil. The full rated power is only available to a load using both coils, i.e., a 240V load connected up to a panel being powered by the generator's 4 prong, 120/240V outlet. Happily, most pump motors in the 1/2 to 1 1/2 hp size we are talking about here are dual voltage and can be set for running on L1-L2 at 240 V or on L1 and a neutral at 120V, but twice the amperage of the 240 V option. You want to check that your motor is set for 240V operation. Keeping in mind that my 3KW unit started a 1HP pump wired at 240V, I would say that almost any 4KW generator should run your smaller pump motor. Actually, a 3.5 KW unit would probably be okay too.
Once one starts talking about larger generators, say 5 to 6 KW and up, there is so much power for just about any 120V load that even if we're only using 1/2 of the generator, that still leaves a lot of reserve power. The only issue, as I say, is with a fairly small 120/240V gen set, being contemplated to power a fairly large, single 120V load.
Side note: I actually wired something called an auto-transformer into the cord of my generator. I used an Outback Power Systems X-240 auto-transformer in a small, metal cabinet and paralleled it across the L1/L2 and neutral wires coming from the generator. What this transformer does is make sure than any imbalance in the loads coming from my power panel between L1 and L2 (the black and red wires) is shared evenly between the two 120V sides of my generator. This helps my admittedly small, 120/240V generator run almost everything it can run much better. *Some* higher quality home generators have auto-transformers built in (they'll say something like "full power from every outlet" if they do), but most don't as auto transformers, like all transformers, are pretty heavy. My X-240 in it's cabinet is probably 30 lbs. minimum. Again, the larger generators have so much capacity, in each 120V side of their coil, that this using-half-the-generator issue isn't really an issue to begin with.
This auto-transformer, however, would not have helped my 3KW genny run a 240 V load as there is no benefit to such a transformer at 240V.
I use a 5500 watt generator. Runs the well and some other items, but not at the same time (I have to switch from 220 to 120).
I picked mine up at Pep Boys for just under $400 bucks so I can't complain.
It's a Wen Power Pro 5500 and all I ever had to do was change the brushes. I now have a very good supply of them on hand though.
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