Sump pump soft start question

[kanelr]

Hi. Our system current;ly is supporting a 120V residential sump pump, which cycles relatively frequently, perhaps hourly in wetter weather. The draw is 30+ amps. the inverter supports 40. I need to load more onto the system to get best use, yet have to duck around the startup surges to avoid co-incidental loads causing a trip. Load wise here we have lights and motors (other than tv/pc's). Do I buy /create a soft start for the sump pump, or are there other strategies. I suppose there could be a software solution, but with what kind of interface? Attached is a shot of the trends- you can see the regular draw of the sump pump, it is stormy now. On the readout I don't really see as dramatic hard start followed by a lower draw though.....thought I would. Pump runs about 50 seconds per cycle. Here's an edit- wondering if the Zoeller pump is drawing more than it is supposed to.

 

[sunshine_eggo]

A pump is likely to draw about 5X the rated run current.

I would measure the actual surge with a clamp AC ammeter with an INRUSH function and then make a decision.

 

[RCinFLA]

Water pumps usually have a centrifugal start up switch that kicks in a large mfd value start capacitor (black plastic cased electrolytic non-polarized capacitor) only during startup. Once motor is up to speed the centrifugal switch disconnects the starter capacitor. The large start capacitor provides near 90 degree current phase shift to starter winding giving motor greater startup torque during the spin up period.

They also don't bother with a lower value Run capacitor. This results in poorer run power factor on pump motors meaning more run current load on battery powered inverter or generator.

Just a 'light dimmer' type softstarter may help. All it does is use a triac to control effective startup voltage ramp up. There are adjustments for initial AC voltage at beginning of startup and rate of voltage ramp up. You have to tweak the two adjustments until you get a reliable startup of pump with the minimum startup surge current. These softstarters typically do not bypass their triac so the run current always flows through triac which has about 1.5-2 volts drop requiring a large heat sink for triac.

These are different than what many call a softstarter like MicroAir Easy Start units which are actually a combination of softstart voltage ramp and a large value start capacitor. They are really a combo soft start voltage ramp along with a hard start capacitor. Easystart will not work with a water pump unless significantly modified. The modifications would be to remove original motor start capacity and wire in Easystart's start capacitor which must be of the correct value, similar to pump's original start capacitor.

Water pumps have a high initial mechanical load compared to an air conditioner compressor motor so the start capacitor is absolutely necessary to get them spun up.

 

[DIYrich]

Buy a battery sump pump like basement watchdog. Now you have a plan C if grid down and inverter batteries are drained.

 

[Warpspeed]

I doubt if you can do very much about the pump itself.
As RC says, any kind of induction motor has a relatively high starting current, and pumps and compressor loads are particularly bad when starting up under load.
If you wish to keep the existing pump, the only way I can see, is fitting a second inverter just for the pump.
The alternative is finding a dc pump motor and powering it directly from the battery, bypassing the inverter altogether.

 

[efficientPV]

You have too big a pump or too small a sump. My parents had a big pump that cycled a lot. Sometime later they found out that water main had a leak The pump went bad and I kept the float switch. Just hooked that up to a Little Giant pump of much lower capacity. It ran longer, but did the job. It pretty much stopped a year later when the leak was fixed. 50 seconds is much too short to run the pump.

 

[DIYrich]

You have too big a pump or too small a sump. My parents had a big pump that cycled a lot. Sometime later they found out that water main had a leak The pump went bad and I kept the float switch. Just hooked that up to a Little Giant pump of much lower capacity. It ran longer, but did the job. It pretty much stopped a year later when the leak was fixed. 50 seconds is much too short to run the pump.

If the pump is running hourly in wet weather, he doesn't have much of a water problem. I can see any pump emptying a sump (that is slowly refilling) in 50 seconds or less.

 

[Shimmy]

If the pump is running hourly in wet weather, he doesn't have much of a water problem. I can see any pump emptying a sump (that is slowly refilling) in 50 seconds or less.

Which would then mean too small of a sump. The ideal solution is a pony pump which might only be 0.5-1.0 gpm plus the main pump at a higher float.

A 12V automatic bilge pump might do the job of the lift is less than 6 feet.

 

[efficientPV]

Well, you won't likely change the size of the sump. A more than adequate pump for the job would only draw 3A @120V. At my camp I have a cheap 12V boat bilge pump and that only draws 3A with a head of about 6 feet. A head of 10-12 feet would be easy for a 3A 120V pump. So what if it runs 10 minutes. Solves the problem.

 

[efficientPV]

Your pump is so big, you could wire a smaller second pump in series with it and not have to mess with the float switch. Just ge an AC cord, outlet box and outlet. Break the jumper bars and put them in series with the one connected to hot going to the bigger pump with the float switch. Then everything is intact for when the great flood comes.

 

[kanelr]

Buy a battery sump pump like basement watchdog. Now you have a plan C if grid down and inverter batteries are drained.

Actually there is another plan C available that uses your city water pressure to run a secondary impeller. Nice solution lotza water...also emp proof haha

 

[kanelr]

All great inputs. I've long ago tied off the Zoeller float to "on" and use an electronic float near the top of the crock. It has an adjustable run timer so I have the surge per gallon ratio maximized. It also has a zero current alarm. The head is about 11, backcheck top and bottom makes it dead quiet.

Which would then mean too small of a sump. The ideal solution is a pony pump which might only be 0.5-1.0 gpm plus the main pump at a higher float.

A 12V automatic bilge pump might do the job of the lift is less than 6 feet.

Well, the sump crock is the bigger one from the supply house, I suppose 30 gallon. Head (lift) is about 11'. I had expected to have a bad time using a standard 120V pump, but it's been fine, so I stop the surge (in 15 days or less i promise) all is ok. And nice input, RC THX

 

[kanelr]

Is this too much to hope for? found on Green Acres.........

that's "closes" in english

 

[DIYrich]

You can hope all you want. Much easier to buy the right equipment.

 

[efficientPV]

Little Giant $49 6.5A starting @120V 1,000GPH at 10 foot head

https://www.amazon.com/Little-Giant-5-MSP-10-115-Volt-Aluminum/dp/B000LGA666/ref=asc_df_B000LGA666?tag=bingshoppinga-20&linkCode=df0&hvadid=80333120120471&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583932699011467&th=1

The little giant I used I used was even smaller but onlt 7 foot.

 

[kanelr]

intriguing. In my traditional building trades experience sump pumps worth risking your basement on are in the 225.00+ range (2023 dollars). i could use one as our primary and leave the older less efficient one near the top of the crock as an always-on backup. The Zoellers' pump so fast there would still be time to stay ahead of inflow.

 

[DIYrich]

intriguing. In my traditional building trades experience sump pumps worth risking your basement on are in the 225.00+ range (2023 dollars). i could use one as our primary and leave the older less efficient one near the top of the crock as an always-on backup. The Zoellers' pump so fast there would still be time to stay ahead of inflow.

Need to provide for a regular test of the backup. You don't want to find out it is not working when you need it.

 

[MiSh]

Need to provide for a regular test of the backup. You don't want to find out it is not working when you need it.

Very true. Your battery backup pump should discharge the same rate, or very close to the same rate as your main pump. What some people have noted is when the power goes out and the backup pump is needed, it gets overwhelmed because it's too small and can't keep up with the water flow that the main pump could. The backup sump pump companies don't really tell you this.