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Energy audit question: Shallow Well Jet Pump

rjpear

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Hi Folks. In starting an energy audit i started with the most important (and problematic ) part of my needs..and that is my water well pump. It is a Shallow Well Jet Pump with the following Specs: 115/230v 3/4hp 8.0/4.0 Amps ..per the label. How would you calculate the pumps needs if it is generally random usage for 30 seconds or so? It is part of a pressure tank system so only kicks on when the pressure is dropped past a certain level.

Thanks..
 
Heh... I guess "it depends" is not a great answer. Lets say 2x an hour on average. I figure after 10 PM it may kick on only 1 or 2 times all night/AM due to no usage.
 
115/230v 3/4hp 8.0/4.0 Amps
Lets do some math!

I will go with runs 30 per day. Thats 15 minutes.
.25 h x 120V x 8A = 240Wh per day

For a 24V bank thats 240Wh / 25.6V = 9.37Ah

The tricky bit will be the surge current which can be 10x the 8A run current.
 
Ok..thanks.. so I had a "light bulb" moment when looking at your math. Since I am at 120V I have to use the Higher Amps (8) but if it was run at 220 then would it only use 4 amps? And does this kinda play into the more efficiency of a 48 volt vs 24 volt system.?
Math can be fun! ;-)
 
Ok..thanks.. so I had a "light bulb" moment when looking at your math. Since I am at 120V I have to use the Higher Amps (8) but if it was run at 220 then would it only use 4 amps? And does this kinda play into the more efficiency of a 48 volt vs 24 volt system.?
Math can be fun! ;-)
Yes, lower amps, same watts though. Startup watts are still 10 times running watts, so 2500W to start, 240 to run…
 
Since I am at 120V I have to use the Higher Amps (8) but if it was run at 220 then would it only use 4 amps? And does this kinda play into the more efficiency of a 48 volt vs 24 volt system.?
The power use is pretty much the same, especially when just doing the math (real world has to be different)
4A x 240V = 960W
8A x 120V = 960W

Lets say you have 16 100Ah LiFePO4 cells at 3.2V

24V battery bank (either 2P8S or 8S2P) = 16 x 3.2V x 100Ah = 5120Wh
48v battery (16S) = 16 x 3.2V x 100Ah = 5120Wh
 
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Or how you might be expecting to see the numbers:

Also assuming your battery bank is made up of 16 3.2V 100Ah LiFePO4 cells...
And will use 25.6V for the "24V battery" since its correct (8 x 3.2V):
25.6V x 200Ah = 5120Wh

And will use 51.2V for the "48V battery" since its correct (16 x 3.2V):
51.2V x 100Ah = 5120Wh
 
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Maybe a energy audit should look at the efficiency (power & labor) of shallow well jet pumps compared to submersibles.
From my farm experience, 20 - 30ft down , the arrival of submersibles meant the end of the jets.
We also realised that pumping into a overhead tank for a few hours with a smaller pump was a lot better than constantly stop starting a larger pump and also avoided the starting requirements needed for larger pumps.
The arrival of cheap pumps from China made the decision easier!
 
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Maybe a energy audit should look at the efficiency (power & labor) of shallow well jet pumps compared to submersibles.
From my farm experience, 20 - 30ft down , the arrival of submersibles meant the end of the jets.
We also realised that pumping into a overhead tank for a few hours with a smaller pump was a lot better than constantly stop starting a larger pump and also avoided the starting requirements needed for larger pumps.
The arrival of cheap pumps from China made the decision easier!
I agree..but I don't have access to the well head at this point (under a Cement foundation of an addition). So it's a new WELL and then the new pumps. Plus the Jet is noisy!
 
Maybe a energy audit should look at the efficiency (power & labor) of shallow well jet pumps compared to submersibles.
From my farm experience, 20 - 30ft down , the arrival of submersibles meant the end of the jets.
We also realised that pumping into a overhead tank for a few hours with a smaller pump was a lot better than constantly stop starting a larger pump and also avoided the starting requirements needed for larger pumps.
The arrival of cheap pumps from China made the decision easier!
This aligns with what I'm thinking. I am in the humid east, and although my well is called a deep well it's usually much less than 100 feet to the top of the water column.
 
Hi Folks. In starting an energy audit i started with the most important (and problematic ) part of my needs..and that is my water well pump. It is a Shallow Well Jet Pump with the following Specs: 115/230v 3/4hp 8.0/4.0 Amps ..per the label. How would you calculate the pumps needs if it is generally random usage for 30 seconds or so? It is part of a pressure tank system so only kicks on when the pressure is dropped past a certain level.

Thanks..
We have a 1 hp shallow well pump thats setup to cut on at 20 psi and off at 40 psi. Its measured inrush current is 13.5A and running current is 3.5A. Those are measured values. The label reads 6A. Forgot to mention, the voltage here is 230vac. So its powered with 5kw inverter. No problems. Also run LED lights throughout the house as well as three electric fans. No A/C. Guess you would have to measure the average on time durations in a 24 hour day to get an answer to your question.
 
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