speed for solar

[spartan_n]

Hi ,
I recently go Jandy e VSP and I am tinkering with the speeds to optimize power consumption. I have a solar heater on the hill slope very close to the pump and wanted to get ideas on what shld the speed for solar. It is current set to 2750 which is ~1kw . My pool pump without solar runs at 1750~ 300w... What is the method to get the optimum speed to get lowest power consumption with good temp increase..

 

[PoolGate]

I had always heard that running water through a heater as fast as possible results in the most efficient heat exchange/extraction. Not sure if this also applies to solar so following to see other replies.

 

[JamesW]

Running too much water through a gas heater is a bad idea. There's an internal bypass that bypasses over a certain amount anyway. So, it's a waste of energy.

Excessive flow velocity can erode the soft copper in the heat exchanger.

Efficiency is only slightly better at higher flow. As long as the flow is above the minimum specified flow rate, increasing the flow rate does not provide any significant benefits.

For solar, you need to know the required flow rate specified by the manufacturer.

Adjust the flow to meet the requirements.

Additional flow will not provide any significant improvement in heat gain.

Excessive flow will overpressurize the panels and can damage them or shorten their lives.

 

[mas985]

Hi ,
I recently go Jandy e VSP and I am tinkering with the speeds to optimize power consumption. I have a solar heater on the hill slope very close to the pump and wanted to get ideas on what shld the speed for solar. It is current set to 2750 which is ~1kw . My pool pump without solar runs at 1750~ 300w... What is the method to get the optimum speed to get lowest power consumption with good temp increase..

Ideally, you want a flow rate of about 0.1 GPM/sq-ft. Anything above that you won't get much more in efficiency and less than that, efficiency drops off faster.

 

[spartan_n]

thanks all. @ma985, i now the sqft of the solar. how do i calcualte the GPM?

 

[mas985]

There are several ways to calculate GPM. In my signature, there are a few spreadsheet tools to help. PSI2GPM tab just requires the filter pressure and entering some plumbing information about the suction and pump to filter plumbing.The key components are:

1) Skimmer to pump distance, pipe size and number of home runs (if you don't know the fitting count, just use 5x90's as default)
2) Number of 3-way valves, fittings suction side only
3) Pipe length, diameter, fittings valve to pump
4) Pipe length, diameter, fittings pump to filter
5) Type of backwash valve (if any)

When taking filter pressure run the pump on full speed for the calibration column and then you can see flow rates at different speed in the estimate column.

If you don't have Excel, answer the above questions (PSI & RPM too) and I can run it for you.


Forgot mention earlier that the pump speed may be limited by the height of your VRV (vacuum release valve). Do you know how high the VRV is installed?

 

[jimmythegreek]

Average system with 1.5" piping should run well around 2000 to 2250 rpms. You just need to be sure the vacuum breaker seals after pump primes the system. I'm 4 panels 1 story up and I run 1800rpm about 8-9 gpm of flow. Most panels range 5min to 10max