Horsepower Ratings vs. Actual Consumption

I am trying to make some sense on how Hayward and Pentair rate their pumps.
I've called both of their tech support lines, and neither of them were able to give me satisfactory answers.

I've measured the draw on a 1.5 HP Super Pump - They say it is 1.5HP, but Consumption is actually 9.3amps at 230v. This equals 2139 watts divided by 746w/hp
= 2.86hp

For their Tristar 1.5hp - It's rated 1.5hp * 1.6 Service Factor = 2.4hp - But it gets worse, they claim 10.2amps at 230v = 2346w = 3.14hp

As for Pentair, they advertise 1.5hp full rated and 2.0hp up rated pumps. Apparently those pumps are identical, and all they did was change the service factors on the labels. Is it me or is this really deceptive???

Then they have the gall to recommend that I spend 1500$ on an intelliflow, when it seems that those pumps are only useful for people who want to turn various features on or off... It seems that the best way to save money would be to get the smallest pump possible that meets filtration requirements of turning the water over at least once every 12 hours then let that pump run all the time???

Am I missing something?

Yes, you are missing something, it is called efficiency.

The rating of the motor is the output power (aka brake HP) delivered by the motor shaft, not the input power (aka electrical HP or input Watts). Here are just a few definitions:

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Motor Nameplate Definitions

Nameplate HP (NPHP) - This is the HP rating on the motor nameplate but is pretty much meaningless without the service factor.

Full Rated HP (FRHP) - Similar to nameplate HP and sometimes used when the pump is full rated.

Up Rated HP (URHP) - Similar to nameplate HP and sometimes used when the pump is max rated or up rated.

Nameplate KW = NPHP * 0.7457 - This is the KW rating and is similar to the nameplate HP and is generally used outside the US. Note that this is not the input power to the motor only the rating for the output power of the motor.

Service Factor - This is an overload rating for motors which states that the motor can be safely operated over the NPHP by the service factor for short periods of time. However, for pumps, this overload rating is typically used as the maximum load that a motor would need to deliver to the wet end. Because the load on a pump does not rapidly change over time, the service factor load is often used as the maximum design point for the pump.

Total HP (THP) or Service Factor HP (SFHP) = NPHP * Service Factor. This is the maximum load that can be safely driven by the motor and must always be greater than the maximum load from the impeller. A motor can be driven above the THP but will likely fail in a short period of time.

Electrical Horsepower (EHP) = Input Watts / 745.7 = Volts * Amps * Power Factor / 745.7 - Electrical power input delivered to the motor.

Brake Horsepower (BHP) = EHP * Motor Efficiency - Power delivered by the motor shaft to the impeller. This is not the same as THP or SFHP. BHP is a function of the load on the motor shaft and will change with Head, GPM and RPM.

Hydraulic HP (HHP) = BHP * Pumping Efficiency = Head (ft) * GPM / 3960 - Power delivered to the water. Sometimes called water HP (WHP) or pumping HP (PHP).

Motor Power Efficiency = BHP / EHP - I2R, magnetic and mechanical losses in the motor only.

Pumping Power Efficiency = HHP / BHP - Recirculation and internal friction losses in the wet end only.

Total Pump Power Efficiency = Motor Efficiency * Pumping Efficiency = HHP / EHP (note this is why total pump efficiency approaches 50%).

Energy Factor - Gallons/watt-hr = GPM * 60 / Watt-hr; A CEC definition used to measure a pump's true pumping efficiency.

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Thanks for the explanation.

Shouldn't they be selling pumps based on how much they will cost to operate - IE - consumption in KW/h? We all pay for watts, so it would make more sense to get electrical input and energy factor or a total pump power efficiency curve since wattage varies with the the amount of head.

It makes NO sense that people walk into a store and 5 different 1hp pumps will have 5 different actual input watts ranging from 746 to 2000+

This rating difference can mean $500+/yr in actual operation costs.

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Originally Posted by gpnyv

Shouldn't they be selling pumps based on how much they will cost to operate - IE - consumption in KW/h?

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Until recently, that hasn't been a priority. The California Energy Commission now requires manufactures that sell pumps in California to measure their pumps and they now publish a database located here. The database has the flow rate and energy use for many pumps on three different plumbing systems.

The three plumbing conditions included in the database are:

• Curve-A which represents fairly restrictive plumbing typical of an AG pool or an IG pool with 1.5" pipe size.
• Curve-B which represents extremely high head loss conditions. Not many pools would fall in this category.
• Curve-C which represents less restrictive plumbing typical of pools using 2" pipe size.

So if you are so inclined, you can download the database in spreadsheet form and see what each of the pumps draw in terms of energy. But keep in mind, that a pump on your pool plumbing may draw more or less than that shown in the table.

However, if you are just interested in getting the most energy efficient pump, I can certainly help in that area. Generally, speaking, the smaller the pump, the less energy it will consume so just sticking with that will save energy. Second, a two speed or variable speed pump will reduce energy even further. But which is more cost effective depends on three primary factors:

Size of the pool
Run time of the pump (i.e. # turnovers per day, should be no more than 1/day)
Cost of electricity

Your plumbing setup has some influence as well such as pipe size and distance from the pool but these are secondary factors.

So if I can get some details on your setup and what you pay for electricity, I can help further.

Thanks for the information and the california energy comission link. It was very interesting.

I had the Hayward Super Pumps in 1hp, 1.5hp, and 2.0hp, as well as the hayward Tristar 1hp tested for flow vs. Amp draw.
The 1.0 hp Super pump was drawing 1600 watts at about 50ft of Head flow rate, the 1.5hp -2040 watts at 50ft of head, and the 2.0 hp 2400 watts at 50ft. The 1.0hp Tristar was Drawing around 1750w. THis was all on the same setup and using a valve and flow meter to vary restriction in the piping.
The 1.0hp tristar flowed more than the 2.0hp Super Pump for much less energy, but all of the pumps, regardless of the Hayward HP ratings consumed a lot more wattage than their nameplates.

Who did you have test the pumps because those numbers do not look correct?

Tested them in the lab at one of my clients. They make heat pumps, so the equipment is quite precise. The wattages above are rough averages of what we datalogged. We reduced flow to several GPM increments and kept datalogs of the amperage draws for each of the pumps.

The CEC measurements for the Superpump are well below what you measured so something is wrong. Are you sure the pumps weren't Super IIs instead of the Superpump? There is a big difference between the two.

The full rate 1 HP Tristar is within operating limits so that one I believe.