Cost per hour of pressure side cleaner (boost pump) vs. electric robot

[Burke_B]

Hello all!

I have read several comments on here about the significant cost of running the boost pump cleaner vs the power consumption of an electric robot so I had been pondering switching out. I attempted to calculate the power consumption cost of running my boost pump and come up with about 8 cents/hour. It is a .75hp and, according to some online sources, that equals about .56 kWh. Not counting my service availability charge, my electric rate is 14.4 cents per kWh. Does 8 cents/hour to run my boost pump sound about right or am I missing something?

Thanks!

 

[mknauss]

You have to have the main pump running too, but if that is normally done when cleaning, that is not additive.

For those with VS pumps, they may have to run at a higher RPM to feed the booster pump.

 

[Burke_B]

You have to have the main pump running too, but if that is normally done when cleaning, that is not additive.

Thanks @mknauss ! Likely a rookie mistake here but I have run my boost pump cleaner without also running my main pump. Is that problematic? Have I possibly damaged something?

 

[mknauss]

The booster pump must have the main pump running to feed it. They are to boost the pressure, not create the flow by themselves.

 

[Burke_B]

The booster pump must have the main pump running to feed it. They are to boost the pressure, not create the flow by themselves.

Thanks @mknauss !

I understand what you are saying (that makes sense since it is called a boost pump) and I am not trying to dispute what you are saying but it does work enough to move the 3900 whether the main is on or not. Admittedly, I haven't really attempted to compare whether it works any better with the main running. Since "inheriting" it with the purchase of the house/pool, I have thought it wasn't working 100% because the tail doesn't sweep and the wheel revolutions are a bit lower than they should be but it does still pick stuff up. The fact that I don't believe it is operating at 100% is another reason I have been considering my replacement options (to include a robot). I will only run it when the main is on from now on.

With that, the price per hour to run it, even with the main running, still seems fairly negligible in the decision to replace it unless my calculation is way off. Especially, if I only run it when my main is already running for filtration. Am I missing something in my cost comparison calculation?

 

[mknauss]

Your calculation looks correct.

Electricity savings is not the main driver of getting a robot. Improved cleaning and no hoses in the pool are the main ones.

 

[DrewLG]

I attempted to calculate the power consumption cost of running my boost pump and come up with about 8 cents/hour. It is a .75hp and, according to some online sources, that equals about .56 kWh. Not counting my service availability charge, my electric rate is 14.4 cents per kWh. Does 8 cents/hour to run my boost pump sound about right or am I missing something?

No, it costs more than that. The 0.75HP specification is what the motor puts OUT, but what you pay for is the electricity that goes IN to the motor to produce that output.

If you select the Specifications tab on Pentair's booster pump page, you'll see their 0.75HP pump's power consumption: 13 amps at 115V (or 6.5 amps at 230V) = 1495VA, so around 1500 watts at full load.

Add the probably 200 watts that your main filter pump draws, and you're at 1.7kW, or around 10 times what a robot uses.

An hour at 1.7kW costs you $0.25. It costs me $0.58, which is why I'm getting a robot ASAP. Cleaning 2 hours a day, I'll break even on the cost of the robot after only 2 years -- and that's assuming that my booster pump and pressure-side cleaner cost nothing and never have to be repaired or replaced.

 

[Burke_B]

Thanks @DrewLG ! I figured I was likely missing something in my calculation. For me, it doesn't make a big difference though. I am currently only running my cleaner probably 4-6 hours a week.

I think for me, it comes down to whether I want a robot for the reasons @mknauss states.

 

[Vandergraff]

No, it costs more than that. The 0.75HP specification is what the motor puts OUT, but what you pay for is the electricity that goes IN to the motor to produce that output.

If you select the Specifications tab on Pentair's booster pump page, you'll see their 0.75HP pump's power consumption: 13 amps at 115V (or 6.5 amps at 230V) = 1495VA, so around 1500 watts at full load.

Add the probably 200 watts that your main filter pump draws, and you're at 1.7kW, or around 10 times what a robot uses.

An hour at 1.7kW costs you $0.25. It costs me $0.58, which is why I'm getting a robot ASAP. Cleaning 2 hours a day, I'll break even on the cost of the robot after only 2 years -- and that's assuming that my booster pump and pressure-side cleaner cost nothing and never have to be repaired or replaced.

I also live in the Santa Cruz Mountains - so electrical cost per kWh is the same

The reason I was searching this thread was exactly this issue. I also use a Polaris 280 which I run for 1hr a day and when I got my electrical bill this week I decided to look online at the daily usage patterns. The hour during which the Polaris is running is always over 7kW compared to the daily average of 1.375kW per hour. Now there is also a hot tub running about the same time in the morning - but that also runs during the afternoon and the usage then is never more than around 2.5kW per hour. So it seems that the Polaris Booster pump may be using more than the spec sheet would indicate?

I have other pumps (well pump and a pressure pump for house water pressure) but these run randomly during the day and their power usage will average out over the day. My main filter pump is an Intelliflo variable speed pump which also pumps water through the pool solar hot water panels. The Suntouch controller reports this as using 433W when solar is running (for 8 hours a day)

Now if the Polaris pump really was drawing more then 1500W it would of course also draw more than the 6.5 Amps from 230V - which does seem unlikely (?) The Polaris PB4-60 manual does require a 15 Amp circuit for 230V (but I am sure that is over specified to give some headroom).

I am now intrigued by this spike in power usage at the same time as the booster pump is running. Especially as, as quickly as we can reduce power usage local power company seems to be increasing the charge per kWh...

I think I will alter the timing of the hot tub in the morning to see how much difference that makes (but as above it also runs in the afternoon without a similar spike in power usage).

I do like the simplicity of leaving the Polaris to do its own thing and its been fairly reliable. In 20 years I have had to replace the Polaris unit once and the Booster pump once. I did also look at the newer Polaris booster pump PB4SQ which claims better efficiency at 4.5A at 230V (so ~1kW) but the online reviews for this are awful with many reported leaky pumps and drained pools.

 

[DrewLG]

I also live in the Santa Cruz Mountains - so electrical cost per kWh is the same

The reason I was searching this thread was exactly this issue. I also use a Polaris 280 which I run for 1hr a day and when I got my electrical bill this week I decided to look online at the daily usage patterns. The hour during which the Polaris is running is always over 7kW compared to the daily average of 1.375kW per hour. Now there is also a hot tub running about the same time in the morning - but that also runs during the afternoon and the usage then is never more than around 2.5kW per hour. So it seems that the Polaris Booster pump may be using more than the spec sheet would indicate?

Howdy, neighbor.

So 4.5kW for the filter pump + booster pump? It's possible, I guess, although it does seem like an awful lot of power. I've read that it wasn't uncommon for filter pumps to be set to run at maximum speed whenever the booster pump was running -- is yours set that way?

 

[pjt]

Gathered some power data on my robot today. It uses 85 W of electricity, which equates to one penny per hour to operate:

Robot Power Consumption Data (Operating and Standby)

Since we are a community that likes measuring things, I connected my Kill A Watt to my robot (Warrior SE) and ran a two hour cleaning cycle. Total consumption was 0.17 kWh, so the average power consumption while operating is 85 W. Using TX electricity rates, a two hour cycle costs two cents...

www.troublefreepool.com

 

[ajw22]

Howdy, neighbor.
I've read that it wasn't uncommon for filter pumps to be set to run at maximum speed whenever the booster pump was running -- is yours set that way?

The main pump only needs to put out maybe 40 gpm for the booster pump. On my IntelliFlo VSF pump 40 gpm is about 2400 RPM and 900 watts. Plus the 1500 watts for the booster pump and with a VS pump you should not use more then 2,500 watts/hour during the cleaning.

At my 0.18/kwh electrical rate for a 3 hour cleaning cycle it costs me about 1.35/day for the pool cleaning my Polaris 380 does.

 

[SDor]

I have had a PBSQ4 for 7-ish years, and I'm very happy with it. 0 problems, no odd noises or leaks. It's quiet and lives up to its 30% improved efficiency. When I bought it, there were no reviews, but a lot of bad reviews for standard booster pumps so it seemed worth a try.

Obviously, a robot is the energy efficiency king, but I would not necessarily discount the PBSQ4 because of some bad on-line reviews. Unhappy owners are far more likely to post reviews than happy ones. If my neighbors are representative of common pool owners, I'd say most pool owners have no clue what booster pump they own.

 

[ajw22]

Unhappy owners are far more likely to post reviews than happy ones. If my neighbors are representative of common pool owners, I'd say most pool owners have no clue what booster pump they own.

The PB4SQ has leak issues. It may just be a bad batch so it is a roll of the dice if you get a good one or a lemon.

Google search results

www.troublefreepool.com

 

[Vandergraff]

The main pump only needs to put out maybe 40 gpm for the booster pump. On my IntelliFlo VSF pump 40 gpm is about 2400 RPM and 900 watts. Plus the 1500 watts for the booster pump and with a VS pump you should not use more then 2,500 watts/hour during the cleaning.

At my 0.18/kwh electrical rate for a 3 hour cleaning cycle it costs me about 1.35/day for the pool cleaning my Polaris 380 does.

Howdy, neighbor.

So 4.5kW for the filter pump + booster pump? It's possible, I guess, although it does seem like an awful lot of power. I've read that it wasn't uncommon for filter pumps to be set to run at maximum speed whenever the booster pump was running -- is yours set that way?

Thanks for the suggestions.

I am actually running the Intelliflo at 2000 rpm when the booster pump is running which according to the Suntouch controller is 560W (just 130W more than when its solar is running without booster pump). So I don't think its that.

I have set the hot tub to run later in the morning to see what change that make - but as above the hot tub also runs in the PM without a similar power spike. It takes a day or so to see the hourly energy usage on the utility web site - but I will report back when I have it.

 

[Vandergraff]

The PB4SQ has leak issues. It may just be a bad batch so it is a roll of the dice if you get a good one or a lemon.

Yes if you the look at the Amazon reviews they are consistently bad and reports of drained pools as a result of leaks.

I know Amazon reviews are not always the most reliable - but if they are all bad....

A drained pool would be a disaster for me. Trying to refill from well water would be impractical and anyway I don't want to pull 20,000+ gallon of water from my well with the rainfall totals we have seen here in last few years. Trucking water in would be prohibitively expense.

 

[SDor]

I guess I got lucky. Thank goodness because I really like this pump because it's quiet and cheaper to run

 

[Vandergraff]

I have set the hot tub to run later in the morning to see what change that make - but as above the hot tub also runs in the PM without a similar power spike. It takes a day or so to see the hourly energy usage on the utility web site - but I will report back when I have it.

Well it looks like it was the hot tub causing much of the spike.

With the hot tub running 1 hour earlier my overall energy use for the hour when Polaris pump and filter pump were running was 2.4 kW one day and 4kW the next. As I said above I have other pumps than run randomly at different times of the day so it could been the well pump or something else running the second day. I also looked at the meter when the Polaris was running and it was reading 2.4kW - so it seems the Polaris and filter pump are probably drawing what they should. Polaris pump at 1500W and filter pump at 560W when the Polaris running.

Now I know the culprit is the hot tub. I am still surprised it is drawing so much more in the morning. The nights can be cooler here if the marine layer comes in - but at 1700ft they can also stay fairly warm if the marine layer is below that. Yesterday the hour the hot tub was running was 4.2kW in the morning and 2.3kW in the afternoon. The day before it was 4.9kW in the morning but unknown if the afternoon. Not usually power was out for a couple of hours and we were running on back-up generator when the hot tub ran in the afternoon. The pool filter pump is not running when the hot tub runs in the morning but is running in the afternoon when the hot tub runs so the difference between the hot tub usage in the morning to afternoon is even bigger than it looks at first. Anyway this hot tub is costing me more than I thought.....

The Polaris on the other hand is 1.6kW per day (1500W for the Polaris pump and additional 130W for the filter pump when Polaris is running) or $0.60 per day with recent (off-peak) rate increase to $0.37 per kWh. Yes I know that is a crazy price especially given the unreliability of service here - but that's PG&E!