Solar heating not what is use to be.

[jvmagic]

Hi,
I have a 25k gallon pool with solar heating. I recall last season during the hot spells, the water was very warm and my kids asked me to turn it down.
This season the settings have been the same (timer=6 hrs, solar heating set at highest) but the water temp is lower ( I would say 7+ degrees).
During a warm week like today, I would think the water temp would be much higher but it's not. I have deck jets and recall during a warm day, the water out of the jets being real warm unlike now.

What should I be looking for to see if it's the solar heating system or something else?

I'm in San Jose CA, 95118 weather is high 80's all week this week.

Thanks in advance.

 

[JasonLion]

There are two things to check, neither especially easy to be sure of. The first is that the diverter is sending an appropriate amount of water to the panels when solar is turned on, and the second is that all of the panels get properly filled with water. If the diverter is sending too little water to the panels the water coming back will be fairly hot, hotter than it should be, and the system efficiency will drop significantly. In some situations the panels can become air locked, where an air bubble prevents water from reaching the entire panel, which also reduces overall efficiency.

 

[ping]

Is the water coming out of the returns warmer than the pool water and if so by how much?

Can you hear the panels drain when the pump is turned off? If yes, is the time it takes to drain the same as last year?

Does your diverter move when the solar system is turned on and off?

 

[jvmagic]

@Jason: There is a drain valve to the panels, should I open this when off or on to release any air that may be locked?
@ping: Not sure of the difference between the return and water. Let me check in regards to the panels draining. I know the diverter moves when the solar system is turned on/off.

Thanks again.

 

[tgmb]

One factor you might consider-night time temperature. I'm nearby-we've been having some chilly nights. You might be starting out colder than last year. ( What were the pm temps this time last year?)

Tom

 

[JamesW]

A few things to consider:

1) Using a solar cover can help. If one was used before, and not now, then that would make a difference.
2) Check to make sure that the filters are clean. Dirty filters can restrict water flow. If the panels are especially high, then the pump might be straining to provide the proper flow.
3) You might want to consider getting a flowmeter to verify flow to the panels. They're about 60 dollars, or so. Example

 

[jvmagic]

@ tgmb: good point.
@JamesW: I did not use a cover last year either (which I will starting next yr)
I replace all 4 filters about 2 months ago.
What reading do I need from the flowmeter?

 

[JamesW]

What reading do I need from the flowmeter?

It depends on the panels. The installation and operation manual should have the specs for flow rate.

 

[Vandergraff]

I am also nearby in the Santa Cruz mountains and use 7 Sunearth Solar panels to heat my pool. Both this summer and last were a little cooler than normal but I was able to get my pool at ~85F most of this summer and last summer so it sounds like somethingb has changed in your system. If you are sure the filter is clean then you probably do need to check the flow through the panels. I use a flow meter like the one shown above. Check the installation instructions http://www.controlswhse.com/sheets/blue ... 0_spec.pdf. You need a section of straight horizontal piping before and after the flow meter - see the pdf min distances before and after the flow meter. You also need to know the ideal flow rate for your panels. My panels are glazed and work well with low flow rates - but many other types of panels need higher flow rates for best efficency.