Plumbing Question: Solar Booster Pump

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A

az1324

0
Apr 16, 2009
26
Doing some maintenance on my system and trying to figure out if I want to change the plumbing configuration.

Current Configuration:
Code: 
IN->Filter Pump->Filter->Solar Booster Pump->3-Port Valve---Tee--->Heater->SWG->RETURN
                                                  |          ^
                                                  v          |
                                                Solar ->Check Valve

That is the way it was installed, but this means when not operating the solar, the water is still being forced through the solar booster pump. Seems like it shouldn't be like that, but I guess it does prevent the pump from being dry or stagnant.

Alternate Configuration:

Code: 
IN->Filter Pump->Filter->3-Port Valve---------------->Tee--->Heater->SWG->RETURN
                              |                        ^
                              v                        |
                     Solar Booster Pump->Solar ->Check Valve

This is what I'm thinking of changing it to. Then the Solar loop can be completely bypassed and drained in the winter including the pump and just have to remember to prime it before running in the spring, although barring a failure of the JVA it shouldn't run dry for more than a few seconds. Any downside?

Alternate Configuration 2:

Code: 
IN->Filter Pump->Filter->Check Valve->Tee-->Check Valve------------------------->Tee--->Heater->SWG->RETURN
                                       |                                          ^
                                       v                                          |
                                  Shutoff Valve->Solar Booster Pump->Solar ->Check Valve

Saw this one online but not sure why it would be preferred.

Any opinions let me know. Thanks.
 
Your first alternative is the right way to do it. You want to be able to turn the 3-port valve after the filter to only go up to the solar when its appropriate. That way when the solar is turned off, the water will not go through the solar booster and only to the loop on to the heater and then back out to the pool. Let me know if you have any questions.
 
Are you sure you even need a booster pump? In most situations, you can get by without it. What main pump do you currently have model/size and how high are the solar panels above the pump?
 
I am running a 1/2 HP pump for 25 ft panels so I don't think you really need the booster. Just to make sure, do you know the manufacture and model # of the pump and/or do you still have the manual which shows the head curve?
 
Yeah I have it its WFE-8. I have a 520sqft cartridge filter with a recommended flow rate of 150gpm and an in-floor cleaning system. Assuming the system normally operates at 50ft/125gpm, if I increase the head by 20ft (any additional resistance through solar panels?) then the flow rate decreases by about 30gpm. The 1hp booster pump would produce 20ft of head at 120gpm and seemingly correctly compensate. I guess the question is: is it necessary/worthwhile to maintain that flow rate at the expense of running the booster pump?
 
az1324 said:
Yeah I have it its WFE-8. I have a 520sqft cartridge filter with a recommended flow rate of 150gpm
Click to expand...
That is not the recommended flow rate. That is the maximum flow rate. You don't need anywhere near that sort of flow rate through a cartridge filter. I have an oversized 340 square foot filter for my 16,000 gallon pool and I normally run at 26 GPM with no problem, though am at 48 GPM when the solar is on.
 
That may be true but the table printed in the manual is titled "Recommended Flow Rate". And the table on this website recommends 125gpm (http://www.poolplaza.com/pool-pump-sizing-2.shtml). Anyway I have no idea if it is running at that gpm because I don't know the real head pressure I was just assuming it would be somewhere near 50. So is there any reason to use a booster pump (taking into account filter size, in-floor cleaner, optimum heat transfer in solar panels, and possible plumbing configurations) or will a loss of 30gpm never be significant in this system configuration?
 
With a WFE-8, you really don't need a booster pump. In fact, the pump is probably oversized for your pool. The WFE-8 is a FULL rated 2 HP pump and unless you have a spa, it really is way too much pump for the pool.

One thing to realize is that the extra static head created by the elevated panels adds to total head only during the panel priming process. Once the panels are primed, the NET static head drops to 0 and you are only left with the extra dynamic head in the panels and the rest of the plumbing.

Also, the tables that you posted for "Best Flow Rate" are actually best MAXIMUM flow rate. Filters work better at lower flow rates and those are really only "not to exceed" values. If you look carefully at the full page, there are other criteria that they use to adjust the flow rate below what is specified as "Best Flow Rate", see "Step 3". The lower limit is based on turnover rates which for most pools are very low. They recommend setting a target between the two values but for energy conservation, you really want to be closer to the lower turnover rate value than the max filter value.

So for sure you don't need the booster and second, at some point you might even want to consider downsizing your pump or going with a variable/two speed.
 

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So I figured out that I need 100GPM for the in-floor cleaning @ 25GPM per nozzle. Or are those ratings maximums too?

Trying to decide if I should move to a 2HP E-Plus 2-speed or variable speed. Seems like variable speed will save me around an extra $120 a year in electricity but will take at least 4 years to makeup the cost difference.
 
The infloor cleaner is a key piece of missing information and may negate all previous recommendations. It may also be the reason that the PB put in such a large pump and perhaps even why he plumbed the booster the way he did. Also, the cleaner complicates things some if you are going to use it with solar.

Before doing anything, you might want to check on the requirements for the cleaner and even contact the manufacture and describe what you are planning to do and see if they have any recommendations. In-floors can be very problematic when it comes to the proper flow rates. The last thing you want to do is make changes that will create problems for the cleaner.

Also, how many zones do you have? Nozzles per zone (4)? Do you plan on running the cleaner with solar at the same time? Do you know the manufacture and model of the in-floor system? Also see if there is both a maximum and minimum flow rate requirement for the cleaner.
 
Well I did mention in-floor cleaner in one of the posts above. It's a Caretaker system with 5 zones and 19 total heads. I would like to be able to run both at the same time since it is a good way to distribute heat. Ideally I would never have to switch the in-floor returns off even if I am running a low speed. I don't really need the in-floor to be cleaning effectively while the solar is enabled just be able to circulate the water.
 
Sorry I missed the information about the in-floor cleaner. Anyway, the flow rate requirements for the cleaner may dictate that you need a 2 HP pump. You could still go with a variable or two speed pump and circulate through the heads on low speed although they won't work very well.

But now I am curious about your setup. Did the cleaner ever work very well with the solar pump off? I would be surprised if it did with the way it is currently plumbed. When the booster is off, it would present a lot of head loss to the system and the flow rate of the main pump should be reduced quite a bit. Are you certain that the booster is plumbed the way it is shown in your first post? Perhaps a picture of your pad equipment might help.
 
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