switch to suction?

[salinda]

I am speaking to a pool-efficiency expert on reducing my pool costs. Most of his recommendations are sounding pretty good, including a more efficient pump and replacing all of the els with smoothly shaped pvc lengths (their design). He is also recommending that I switch from a Polaris to a suction-side cleaner (I think he said 2 x2 type). The gist is that it will increase the efficiency of the new pump by providing another input source and my booster pump alone is currently drawing 7.5 amps for 3 hours a day, which is quite a bit these days. He is pretty sold on them and is offering to let me try a demo unit he has for a week to see how it works.

Thoughts?

[duraleigh]

The drop in TDH by going to wide 90's will be minimal....IMHO, not worth the cost of replacement. Typically, a suction side cleaner will not be as effective so you may end up having to clean longer. Again, IMHO, it is certainly a step backwards to get rid of your pressure side cleaner to PERHAPS save a little electricity.

[bbb]

I am speaking to a pool-efficiency expert on reducing my pool costs. Most of his recommendations are sounding pretty good, including a more efficient pump and replacing all of the els with smoothly shaped pvc lengths (their design). He is also recommending that I switch from a Polaris to a suction-side cleaner (I think he said 2 x2 type). The gist is that it will increase the efficiency of the new pump by providing another input source and my booster pump alone is currently drawing 7.5 amps for 3 hours a day, which is quite a bit these days. He is pretty sold on them and is offering to let me try a demo unit he has for a week to see how it works.

Thoughts?

What exactly are the pool costs you are trying to reduce? Are you trying to save money, or is greater energy efficiency your goal?


Here's two examples why I'm asking:
Some of the person's recommendations sound like they are aimed at giving you slightly greater energy efficiency at a greater upfront cost to you (and more profit for the person, possibly). For example, have you considered running your Polaris every other day for 3 hours (that's how I do it)? You will cut booster pump costs in half, at zero cash outlay to you.

Here's another angle - what kind of filter do you use? Using a suction-side cleaner (as opposed to the bag of your Polaris), in theory should cause you to backwash more often - and backwashing waste water. If you are using a DE filter, you are not only using more water, you are also introducing more DE waste to the environment.

The more we understand your goal, the more we can understand why you want to move to suction (or even to consider other alternatives like robotic cleaners).

[salinda]

BBB,

Thanks so much for your time on this! I am trying to save money through greater energy efficiency. My 2hp whisperflo is running at 29 psi with solar on and 22 with it off. This is with new cartridges in my Clean & Clear Plus 520. The estimated current energy cost of my pool is $2152.79 and that is only going to go up. The estimated energy cost with the new system would drop to $439.93.

They are also recommending a new zeolite filter that I am going to pass on right now (would require backwashing), although I am getting a little tired of opening and closing the filter cartridge on our large filter properly.

The biggest changes would be to remove the existing filter pump and the booster pump and replace them with variable speed and to repipe the water path to remove any sharp turns. The new filter pump should run at a higher flow rate than my current one due to lower tdh.

(Should we move this post to equipment?)

[bbb]

I'm from the Northeast so I don't have the pleasure (or the energy cost...) of a long swimming season, and I'm far from an expert on energy usage. However, switching to the variable speed pump for the main pump seems to make a lot of sense. My filter is a DE filter from the mid-1980's that is still going strong, so I'm not an expert there (though it sounds like you have correctly identified it as a "don't fix it if it isn't broke" issue). What is the energy savings if you switch to the variable speed pump, keep the booster pump, and clean less often? Another option could be to get rid of the booster pump (if the increased flow really helps the pump performance, but I'm skeptical on that point!) and switch to a robotic - they draw (IIRC) around 7 amps, but they can clean your pool in 1/3 of the time (correct me if I'm wrong, Dolphin or Aquabot owners), resulting in a net energy savings while you still clean your pool every day. However, you have an initial cost of somewhere around $1K. Do you like how I got that shifted back to pool cleaning

[salinda]

He is coming back today for more readings and measurements. I am very impressed with the analysis process of this bid. They he has used an ammeter to test all of my draws under all of my conditions (solar on/off, cleaner on/off). He put a vacuum gauge on the pump to get true pressure readings in combination with my filter pressure.

I am going to grill him more on the cleaner issue and maybe even ask for the demo unit trial. I think the suction cleaner he is talking about is somehow closer to robotic than the kreepy style ones. He says it is programmable and runs a specific pattern and takes a lot less time. It has a leaf can to catch the big stuff. I don't see how it can do all of this without a power source though, but I will ask him....

As far as the switch, I just need to make sure that the flow will indeed be higher than my current flow. I need to read up on the variable speed pumps a little more.

[mas985]

I think you actually want lower flow and not higher. Since head loss in a given plumbing system is proportional to the square of flow, the more flow (GPM) you have, the more head loss or PSI you will have. 2 speed pumps or multi speed pumps allow you to reduce your flow and thus the friction loss in the piping. For example, on low speed of a 2 speed pump, your flow will reduce by 50% but your head loss will reduce by 75%. In addition, the pump current draw will be reduced by over 65%. So even though you have to run the pump twice as long for the same turnover, the energy savings is still over 30%. Going from a low efficency pump to a high efficeny 2 speed will give you even more savings.

Changing the pump to a 2 speed or multi-speed is an easy way to reduce your energy consumption. Changing your plumbing is much more difficult, expensive and unless you replace all of the piping in the pool, will not give your the results you are looking for.

Also, suction style cleaners requires the main pump to run on high which is expensive. Robotics are much more cost effective in the long run and actually clean much better.

[brent.roberts]

I'm pretty astonished at the $2176 energy cost. What is your power cost per kilowatt hour. Up here ours is about 5 cents. At that rate its aobut 43,500 KW / hours and that is a bunch.

If you switch from a cartridge filter you will need to run more hours to get the same filtering on a sand type filter. The cartridge type takes out more and finer debris. I have heard some claims about Zeobrite but I have not heard any reports from forum members that it lives up to the claims.

A switch to a two speed pump makes sense.
A lot less energy.
Better filtration at lower flow rates
Your cartridge will be easier to clean because the lower flow rate will result in lower velocity impact of debris on the filter and it will flush easier.
Quieter pumping and a few other benefits I cannot recall just now.

I agree about the the elbows. It is likely a waste of time, especially if you go with a 2 speed pump. True infinitely variable speed pumps are very expensive and the drives have some electrical inefficiency built in. ( frequency inverters) You don't need that if that's what they are proposing. But there are some folks who call a two speed pump a variable speed pump so you need to clarify what they are talking about. Inverter motors can whistle or whine a lot if they are not tuned properly. ( we use hundreds of them in the machinery we build )

A robotic cleaner will have a huge impact on the frequency of filter cleanings or backwashes.

[salinda]

Thanks Brent! Our electric costs are about 30 cents a kwh at over 300% of baseline. They are still mid to upper 20's below that.

I think the filter cartridge will stay. The suction-side cleaner demo unit has been in my pool for 1 1/2 days now. The pool is pretty clean, which is a good demo because we spread the gunk from my Polaris around as a test plus some twigs and stuff to show me that I shouldn't worry about clogging in the winter. I am still worried about clogging, but the energy savings are pretty astonishing.

I might go with the smooth sweeping plumbing system they are proposing because I have found some disturbing mistakes in my plumbing that need to be corrected anyway. I think they are proposing the other equipment changes not only to make money but also because it is easier to change at this point. They also offer to put back in anything that I want back if I don't like the new equipment.

I am still worried about the flow rate on the two speed pump. I have a large pool and still need a significant gpm, but I am not sure I am getting that now.

[brent.roberts]

Wow that's a big hit on the KW/HR rate. I guess it's having exactly the effect they intended. Get you to reduce the consumption.

If you're going to do work on the plumping anyway, it makes more sense to do the elbows. I would. Is all your plumbing already 2" diameter ?? If not I would upgrade to that and make sure the pump selected is 2" without step up adapters.

I see you're in CAL. Do you run 365 days a year ???

I also note that you mention solar. You want higher flow rates through a solar panel. The more the flow the more heat you will pick up. Do you get an abundance of hours of sunlight. Up here we never seem to get enough except in July and August and the rest of the shoulder season is a bit of a struggle to get enough solar gain so we need the higher flow rates throught the panels. If you cloud cover, wind loss etc is negative then it may reduce the benefits of the two speed pump, because you could have in on high for the solar. But that would give you about all the filtration hours you need in a day anyway.

Lots of things to think about.