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Sump pump backup

photod

Nov 7, 2008
3
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Nov 7, 2008
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I would like to use my existing sump pump and back it up without
Having to buy another pump.
Does any one how that can be done?
Thank you
Photod
 

Bluejets

Oct 5, 2014
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Oct 5, 2014
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Does not make sense.
Can you try to explain what it is you are expecting to do?
 

Tha fios agaibh

Aug 11, 2014
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Aug 11, 2014
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Photod, The reason it's usually not done is because its not practical. But yes, it could be done.

Standard household Sump motors take a lot of energy to start-up because of their inductive nature. Usually about 2 or 3 times the normal running current. So the motor probably needs at least 8 or 9 amps at 120vac to start.

You could use a battery bank and a 1000w (or larger) power inverter for the back-up supply that would switch on-line and at the same time disconnect the household circuit (for safety) via a relay or contactor that would work like a transfer switch.

In other words you'd be using a DC to AC inverter similar to how a standby generator works, but only to supply the Sump pump.
Of course you'd also need to charge and maintain the batteries so they are ready in the event of a power loss.

Most people opt for a DC sump back-up or better yet, a water powered back-up pump.
 

photod

Nov 7, 2008
3
Joined
Nov 7, 2008
Messages
3
Photod, The reason it's usually not done is because its not practical. But yes, it could be done.

Standard household Sump motors take a lot of energy to start-up because of their inductive nature. Usually about 2 or 3 times the normal running current. So the motor probably needs at least 8 or 9 amps at 120vac to start.

You could use a battery bank and a 1000w (or larger) power inverter for the back-up supply that would switch on-line and at the same time disconnect the household circuit (for safety) via a relay or contactor that would work like a transfer switch.

In other words you'd be using a DC to AC inverter similar to how a standby generator works, but only to supply the Sump pump.
Of course you'd also need to charge and maintain the batteries so they are ready in the event of a power loss.

Most people opt for a DC sump back-up or better yet, a water powered back-up pump.
Thank you for the information
Photod
 

dave9

Mar 5, 2017
1,188
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Mar 5, 2017
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1,188
One of the more common problems with sump pump failure (besides the AC mains being off) is the pump itself has an on/off switch failure.

This makes it useful to have a 2nd pump as a redundant measure and that pump being DC, battery powered, kills two birds with one stone.

The weak link in that scenario, in my experience has been the SLA battery charger. The contemporary highly efficient (and consumer grade, cost effective) SMP PSU designs in those, save you money on your electric bill but have more possible faults. I suppose the bottom line is nothing lasts forever or is cheap if it's good.

Considering my flood damage losses if there were a fault, I didn't think for a second about an inverter for AC loss instead of a redundant, second DC powered pump. Plus, consider that if the 2nd redundant pump is mounted higher than the primary AC pump, if there isn't a failure it won't ever be submerged so won't ever run, so its lifespan will be much higher as a result, BUT as with all mechanical things, it is a good idea to manually trigger a backup pump to spin the motor a few revs, to verify that it works and not let various aging factors cause it to seize.
 
Last edited:

BobK

Jan 5, 2010
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Just FYI, this forum is for homework, as in problems you are assigned in a class, not for work being done on your home.

Bob
 
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