Massive pump power consumption

[overtheinfinityedge]

I have a 30K gallon inground plaster infinity edge pool that came with a home I purchased a year ago. The pool is currently plumbed with 3 single speed pumps that are about 6 years old. There is no skimmer in the pool (the IE acts as a skimmer)

The infinity edge runs on a 4HP pump that constantly sounds like it is cavitated.

The filter runs on a 1.5hp pump and there is a 3/4HP booster pump for a Polaris cleaner.

Each pump is on a timer. I have the filter pump set to run 6-8 hrs/day, the Polaris runs 3-4 hours/day and the Infinity Edge pump runs 20 minutes twice/day.

My electric bills have been enormous and I have been trying to see what the costs of running the pool pumps are and should be and trying to determine whether replacing the pumps will save me money.

I ran some quick calculations of costs to run based on my schedule and found the following:

Spillover (Infinity Edge) Pump: 230V X 19.4 amps = 4462W/1000 = 4.462 kW x .66 hr/day = 2.945 kWh/day X 30 day/mo X .10 dollars/kWh = $9/mo if running correctly (should run 4.46 kW per hour of running)

Filter Pump: 230V X 10.4 amps /1000 X 8 hr/day X 30 day/mo X .1 dollars/kWh =$57.40/mo (2.4 kW per hour of running)

Booster Pump: 115V X 13 amps /1000 X 4 hr/day X 30 day/mo X .1 dollars/kWh = $17.90/mo (1.5 kW per hour of running)

However, when I read the electric meter before and after running the spillover pump for 20 minutes it shows a burn of 5kWh in 20 minutes!

Not sure what is causing that or how it is happening without killing the circuit breaker but I am wondering if this could be wired incorrectly and is creating a false reading of usage? I think I did the calculations right.

My pool guy is recommending I replace all three pumps with an Intelliflo XF VS pump. I have no idea how to determine if this will even work with my system and I haven't seen him perform any calculations to show me if it would work and more importantly how much it would cost me to run in this configuration if it did work.

Any insights would be greatly appreciated - especially how the spillover pump appears to be burning so much power.

 

[mas985]

Do you have a pump model # for the spillover pump?

However, when I read the electric meter before and after running the spillover pump for 20 minutes it shows a burn of 5kWh in 20 minutes!

Are you taking a meter reading with the pump on vs off? That just doesn't sound right for that pump.


Energy use and flow rate are directly related so if you can get away with lower flow rates, then you can drastically reduce energy use. Unfortunately, an infinity edge usually requires high flow rates to work properly. You can reduce the flow rate but it just won't look the same and may not have the same skimming ability.

The Intelliflo will save ~10% of the energy at the same flow rate of a single speed pump. But again, where you can save energy is when you can reduce the flow rate (RPM) of the pump and the Intelliflo has a lot more flexibility in setting flow rates.

 

[overtheinfinityedge]

It is a Speck Pump model # 21-80/33BS. Yes, I am taking a meter reading with the pump off, then turning it on for 20 minutes then turning it off and taking a reading immediately after.

 

[mas985]

Are you measuring instantaneous power (KW) or cumulative power (KWH)? Some meters will display both. Instantaneous power is a bit more accurate since anything else in the house that is running at the same time is removed from the measurement by subtracting the power with the pump on vs off but that is not the case with cumulative power which will include everything in the house.

 

[overtheinfinityedge]

The meter reads KWh. Without the pump with normal usage of refrigerator, etc I burn about .5-1 KWh and nothing other than that was running during the test and I factored that in - the actual number was 6KWh higher after the 20 minute run of the pump.

Since this is wired 230V I'm wondering if there is some way that it could be wired incorrectly that could lead to this draw of power?

 

[mas985]

An incorrectly wired pump motor will not run, it will just trip the circuit breaker. Can you post a picture of the pump motor label?

 

[overtheinfinityedge]

Picture attached here.

 

[mas985]

For water ever reason, I think the house meter is not giving a good indication of energy use. That pump motor should not draw more than 5 kW.

 

[JamesW]

How many linear feet is the infinity edge?

How many square feet of main drains does the infinity edge pull from?

What size is the suction piping feeding the pump?

Have you measured the actual current draw?

 

[overtheinfinityedge]

The infinity edge is approximately 30 feet across (the edge itself is a semi circle) and feeds into a catch basin that is approx 35x4' and sits below the edge by about 10' (to the bottom of the basin). There are two 4" check valves located in the floor of the catch basin that go up to the pump which has a 4" line running in and out of it. There were originally four 4" check valves in the basin but two are capped. There is another air break check valve in line after the pump (on the return) that I had installed to prevent back siphon if a check valve in the catch basin goes bad. (that happened when I first moved in).

The filtration system does not connect to the catch basin or the plumbing to the spillover pump. I have not measured the current draw. Attached are some photos. The first is the configuration for the spillover pump. The second is the whole system and the 3rd is one of the check valves used in the bottom of the basin.

 

[JamesW]

30 feet is about a medium length weir for an Infinity Edge. Some things to consider:

1) How flat, level and smooth the weir is. If the weir is not perfectly flat, level and smooth, it takes more water flow to get the desired effect.

2) How much "Lift" you want to get the desired effect. Lift is how high the surface of the water is above the weir edge.

I'm not sure that I understand what suction intakes you have in the catch basin. Do you just have 2 open holes with check valves? Usually, there are grated main drains to help strain out debris to prevent clogging the lines. If there are just two 4" intakes with no grates, then the lines might be clogged.

If there is not enough open surface area, the intakes would be a safety hazard if anyone were to get in the basin while the pump is running. Kids sometimes find the basin fun to play in. They should not be allowed to play in the basin.

I wouldn't have the check valves on the suction side of the pump. I would put one, or two, check valves after the pump.

To get a better idea of what is happening with the pump. I would put a vacuum gauge on the suction side and a pressure gauge on the pressure side of the pump. A flow meter might also be a good idea.

If you could measure the actual current draw, that would help figure out how much power the pump uses.

Does the pump seem to provide sufficient flow for the weir wall? Your description of the pump sounding like it's cavitating raises the concern that the pump is not getting sufficient water flow.

Do the intakes in the catch basin cause a whirlpool effect that sucks in air?

Why are two of the check valves in the basin capped?

It's hard to tell for sure, but the check valve does not look like it's 4". Are you sure that it's 4 inch?

 

[overtheinfinityedge]

The check valves are 4". They are covered by grates in the bottom of the catch basin. The catch basin is filled to about 3 feet deep so there is no air getting to the valves. The water flow is more than sufficient so the lines aren't clogged. The other two are capped because I was told I didn't need them and it was just another possible failure point. It works well with the two lines going up to the pump.

I guess I'm thinking it might not be worth it to go through all this diagnosis and just bite the bullet and replumb the system to run on a single variable speed pump like the Intelliflo XF?

 

[mas985]

The performance is not going to be the same for the Intelliflo XF and your current Speck pump. The Speck is a high flow, low head pump designed specifically for this type of application. While the Intelliflo is a high head pump designed for a wider range of applications but will not have as much flow rate as the Speck for this specific application. If you go with the Intelliflo, the infinity edge will not be as thick over the edge and as dynamic as it is now but it will use less energy.

 

[overtheinfinityedge]

Are there other pumps that I could consider? The flow with the current pump is very strong over the edge so I don't think I need as much HP as I have to have a decent effect. That said, I want to reduce power consumption. I have the system only running 20 mins/ twice a day on the spillover and that is mainly for the skimmer functionality. What about using an Ecopump for the general filtration ? They only pull 1.4amps per their spec?

 

[mas985]

Using a VS or a two speed for the general filtration would definitely help as that seems to be the majority of the energy use. Also, you could change to a cleaner that doesn't require a booster pump and that would help too. But another way to cut energy use is to simply run your pump less. I doubt you actually need 8 hours of run time for the current filtration pump. 4 hours is probably more than enough.

At $0.10/kwh, it is going take many months to payback the cost of a two speed let alone a VS pump. For example:

Your current pump costs about $57 per month and you can save half of that by reducing run time to 4 hours. If you went with a two speed pump, you could probably reduce the cost to about $6/mo which would be saving you about $22/month. A two speed would cost close to $500 so you would need about 23 months of run time to pay for the two speed. A VS is close to $900 but low speed run costs are even less than the two speed (~$3/month) for a savings of around $25/month so it would take close to 36 months for a payback.