Pump Help! - Solar Heater

[falken]

I had a solar heater installed, and my pool pump is not strong enough to push to the water fast enough. It is going up 2 stories and through 3 seperate banks of solar panels (total of 12). Lots of air bubbles in the line, the installer took off the vacum relief valve and there was a trickle of water comming out. The manufacture says it should have been comming out full bore.

I have a jacuzzi cygnet 1HP pump right now. The pipes going to/from the pool are 1.5", the pipes going to the solar panels are all 2" (manufacture wanted 2" even though the rest of the pipes were 1.5"). 1 skimmer, 1 main drain, 5 returns (2 main, 1 pool cleaner, 2 step).

I was looking at the Hayward Northstar series because of the energy rating and high head specs.
My question... should I go with the 1HP full rated pump or the 1.5HP full rated pump (can't go any higher as I only have 120V service)?

Any good way for me to figure out what I need?

Thanks!

 

[mas985]

Looks like that pump has a max head of only 10'. That will be insufficient to prime the panels.

As for pump size, any medium or high head pump in almost any size is sufficient to prime panels. I use a 1/2 HP pump for priming panels on a two story house. The only requirement for the pump is to have at least 20 GPM at the height of the house (head in feet) to prime the panels.

 

[PoolGuyNJ]

What is the total distance from the top of the panels to the equipment pad?

Was the vacuum relief installed on the 1st of last panel?

Are the panels mounted to feed from the bottom to top or sideways??

Are they in series or in parallel?

How long and wide are the panels?

You are right in that you need a high head pump but a Northstar would not be my choice.

I think an Uprated 1-1/2 HP WhisperFlo (WF-26) will give you the umph to get the water up there and the flow I suspect you need. The answers will help us to accurately help you.

Scott

 

[falken]

Okay... it goes from the equipment pad about 15 feet horizontality, then up about 15 feet to a roof above the garage, it runs through 2 4x12 panels mounted vetically and T's off to also go another 10 feet in the air to the main roof where it feeds in to 2 banks 5 panels (total of 10) that are 4x10 also mounted vertically. It then heads all the way to the ground and travels about 8 feet back to the equipment pad then another 15 feet to the pool from there.

The vacum relief is on the last panel.

My current pump gets the water up and back, just not fast enough. I can't find any good specs on it as the manufacture is out of business.

The 1HP northstar says it does 59GPM @ 70 ft of head and 30GPM @ 80 ft of head. The 1.5HP northstar says 82 @ 70 and 52 @ 80. Am I reading that wrong? It seemed better than the whisperflow, but i'll admit, I know nothing about pumps.

 

[falken]

Okay... I guess the whisperflow does look better. I currently only have a 20AMP 120V circuit ran, so something that is only 1HP full rated pump would be best!

Any input on if that pump would work, or another suggestion, or anything... Highly appreciated!

 

[mas985]

Anything bigger than a 3/4 HP pump is a waste of money and energy. To raise the water 15', almost any in-ground pump can do that. I believe the pump you have now has really low head so it cannot prime the panels. As I said before, I use 1/2 HP pump to raise the water 25'! If you really want to save on energy costs, go with a smaller pump. Also, 400 sq-ft of panels only needs 40 GPM for maximum efficiency so a small pump will do. The WFE-2 would provide more flow rate than your current pump, enough head to prime the panels and still be energy efficient.

[EDIT] - After researching the Jacuzzi Cygnet pump - 1CYG, I think this may be a medium head pump. At least that is how it is advertised. The first reference I found indicated a low head pump but most seem to say it is a medium head pump. If so, it should have enough head to prime the panels. Have you check the pump impeller to see if there is anything stuck in it? Also, when you switch to solar, what does the filter pressure read?

 

[PoolGuyNJ]

I am trying understand how the 3 sets are fed. I am assuming each set is acting as a single panel but don't understand how each set is connected to the intake and discharge.

How much pitch on the roofs?

The water is going up over 25 feet. Add a couple feet for each roof's pitch and its near a 30' push. That is a large volume and a lot of water weight with 2" pipes. Add the head loss from the panels and I don't think a 3/4 HP will do it.

The multiple levels certainly adds some complexity.

I suspect the 1st level panels may not have enough throughput capacity to prime the other 10 panels that are 10 feet further up.

We really need to know exactly how it's all plumbed.

I admit I am not a solar guru but the above really makes me go Hmmm.

Scott

 

[mas985]

Scott,

A 3/4 HP will easily prime the panels with 30' of water lift. The crtical element is the head curve of the pump. A typical 3/4 HP high head pump has a maximum head of 80' so it will lift water 80' above the pump but at zero flow rate. In order to prime the panels, you need to have decent flow so you need to account for some additional head loss for the feeder pipe and panels while priming. There is no head loss in the rest of the return because no water is flowing yet. A typically 3/4 HP pump will have about 40 GPM at 70' of head so there is plenty of margin for priming the panels.

Again, I go back to my setup. I have a 25' two story roof and a 1/2 HP pump primes the panels in about a minute. When the panels are priming, pressure increases to a maximum of 17 PSI which is about 40' of head loss including the 25' of vertical lift (~15' dynamic loss). So the flow rate of the pump is about 60 GPM which is plenty of flow for priming. I could go another 10' in elevation and still be able to use a 1/2 HP pump. It just has to be the high head variety which most are these days.

 

[falken]

My pressure with the solar off is 10, with the solar on it is 25 (clean filter).
That is about 58 feet of head, correct?

According to the posted chart I should still be pushing 45GPM, which is above the maximum for 1.5" pipe anyway.
Could the pump being 8 years old affect the performance? The flow is definatly not maxed out because I can feel a significant increase on the returns with I set the filter to recirculate instead of filter.

I ordered the Whisperflo 1HP full rated pump. I was afraid to try the 3/4 as I had to buy it mail order and would be stuck if it didn't work. I can still cancel before Monday morning so if anyone has a good reason why I shouldn't get and try that pump please speak up! Otherwise, thanks for all the advise!

 

[mas985]

The only reason not get the Whisperflo right now is that your current pump may be fine and there could be a problem with your solar plumbing. A new pump may not fix that so you might want to try some troubleshooting first.

Your current pump seems to be providing enough pressure to easily fill the panels and should have enough flow rate to prime them. However, a 15 PSI rise is a little troubling and it is not normally that high for a well designed solar system.

Just to confirm your solar installation:

Are all panels connected in parallel?

Is the maximum height from the pump to the top of the top most panel is around 30' or less?

Is the flow rate out of the pool returns fairly strong when the solar is turned off?

If the answer to all questions is yes, then I would say that there something wrong with your solar install which is restriction the flow rate. Double check the installation direction of all check valves and make sure that if you have any isolation valves that they are turned on as well.