pool pump selection help needed

[mrnamjama]

Hello folks

I am after some help with choosing more efficient and quieter pumps for the pool setup inherited from previous house owners. One of them is almost new (but can be sold, so that's fine) and the other is currently dead (precipitating this post).

The pool is a salt water one with a chlorinator, ~70,000L (~18490 gallons) with an Astral zx200 filter. There is a solar heating array (black piping) on the roof, about 1:1 in size. The pumps are about a metre above the pool and the roof is about 7 metres up.

The pool filter pump is a Reltech PR125P (1.25HP, 330L/min or 87gal/min flow rate, single speed).

The solar pump (now dead) is an Astralpool E170 (0.75HP, 170L/min or 45gal/min flow rate, single speed).

The chlorinator is an Astral/Hurlcon VX9.

I use a robotic cleaner which is working fantastically and I intend to keep using it exclusively. I've had no need to use any kind of vacuum cleaner at all and the pool chemistry and clarity are great (I follow the TFP guidance!).

I was thinking about replacing the pool pump with a variable speed one, however as far as I can tell the 'high' speed or 'full' speed setting is essentially there only for cleaning. I am not planning to do that, since the robotic cleaner does such a good job! Perhaps it makes sense to go to a permanently-low single speed pump? Is there a situation where I'd need a high-throughput pump if all I intend to do with it is filter the pool?

My primary concern is to lower noise levels. As quiet as possible is the goal. I would like to avoid spending $$$$ for two variable speed pumps, if I don't need to.

What are my options?

 

[mas985]

With single speed pumps, the lower the HP, the lower the pump efficiency. It really isn't worth going that route.

With solar and assuming you want to go with a single pump for both filtering and solar, highly recommended for best efficiency, I would go with a single VS pump. You may not need full speed all the time, but occasionally, it will be useful. Also, running on lower speeds is much quieter than the smallest single speed pump.

 

[mrnamjama]

assuming you want to go with a single pump for both filtering and solar

Well then. I didn't realise that was one of my options, but if it is I'm all ears - I'd much rather have a single high efficiency pump. That changes the whole game in fact.

Is there anywhere you can point me to to how to plumb all that together? I don't intend to do the work myself, but I also don't trust that any of the local pool shops would come up with a good solution.

The two systems are completely separate at the moment, as far as the plumbing is concerned. Filter pump does nothing but the filtering (takes water in at the skimmer and returns via one set of jets), and the solar pump takes water in via a couple of underwater inlets, pumps to the roof and returns via a separate line/jet.

 

[mas985]

From other discussions on the forum, it would seem that it is common to use dual pumps for solar in Australia while in the US it is uncommon: Using main filter pump for solar heating is stupid?

Here is one way to combine the plumbing:

Thermometers and flow meter are optional.

 

[AusPhil]

Yeah separate pumping circuits are the highly recommended method in Oz.

The E170 is cheap at $371 .... That's cheap over here. this would keep it simple as a straight swap replacement.

Another option that is very common over here and far less so in the US it seems is to install a three speed pump that you can fine tune the actual speed for each setting. Yes you need to physically push the button but it sounds like you have no automation and this is a tiny hardship once you get the speeds set
example Pentair EnviroMax 800 or 1500

With the current solar circuit being independent a close review of the pro's and cons should be done. The con that seems to be listed the most over here is the priming cycle of variable/multispeed pumps will cause excessive pressure in the solar system piping resulting in potential damage and reduced life.

 

[cfherrman]

Vsp are much more efficient than single or dual speed pumps in every way except buy in cost.

Use a low speed for filtering, a higher speed for the solar (probably would have to do some plumbing changes) and run high speed for a little time each day to clear the surface of debris and you also save the high speed for manual vacuum if you get a big mess for some reason.

Add your solar hp pump plus 1/2 hp for a quick and dirty way to figure how much hp you need. A lot t are 1.5 hp or 3 HP.

 

[mas985]

With the current solar circuit being independent a close review of the pro's and cons should be done. The con that seems to be listed the most over here is the priming cycle of variable/multispeed pumps will cause excessive pressure in the solar system piping resulting in potential damage and reduced life.

I would check the manufactures specifications for the panels because I know many of the panels sold here in the US can handle up to 30 PSI which much higher than the panels would reach even in priming mode. Also, most VS pumps have the ability to set the priming RPM to make sure that is not an issue.

 

[AusPhil]

I would check the manufactures specifications for the panels because I know many of the panels sold here in the US can handle up to 30 PSI which much higher than the panels would reach even in priming mode. Also, most VS pumps have the ability to set the priming RPM to make sure that is not an issue.

Hiya Mark,
I'm personally in the market for some form of solar heating and have been reading as many different install manuals as i can get for the various options available in Australia and the warning about priming speeds causing excess pressure is common ... not in a position to dig up specs just at the moment but max pressure was not one i recall seeing.
It's a non issue if you have automation that turns your solar on after everything is primed but for us manual people that is not an option.
Maybe it's the various manufacturers covering their collective backsides from people install large VSP pumps and then having issues with leaks on the panels
Anyway as i have an AGP i will end up with a single pump solution....

 

[mrnamjama]

Folks, thank you for your input. I believe I'll be up for some extensive (and currently unknown) plumbing changes in the next couple of years as a result of landscaping so for now I will stick to the two pump setup for simplicity's sake. A variable pump for the filter and a straight drop-in replacement for the E170.

 

[setsailsoon]

Jama,

My solar is set up identical to MAS985's drawing except for the flow meters. I currently use a 2-speed pump but will be switching to a VS drive (V-green). I have a separate goldline controller. I believe I could do with manual control programmed at the pump itself using a cycle of priming, then run at the least speed required for the lift to the solar panels. To get the benefit of low speed remainder of the run time I think you'd need some control for the bypass valve.

Hope this helps.

Chris