Variable speed pump for hybrid solar panels

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Re: Variable speed pump for hybrid solor panels

mas985,
been traveling to China. Sorry for delay.
I have 12" of 1.5" pipe BEFORE the Flow meter and 24" of 1.5" pipe AFTER the flow meter. The pool installation person told me this was good enough.
However, I cannot find any model number markings like you pointed me to in you last post. I fear I might have a 2" flow meter installed in 1.5" pipe. Are there any good ways to know what Blue&White unit I have? Is there a conversion table for such cases?

Here are the still pictures (as a slideshow) that shows the plumbing above pump system.
http://youtu.be/RsM0TGdwvV8
It also shows the sand run-out dump from the Tritton II.
Here on YouTube is the video which shows all plumbing, the startup of solar, the pressure gauge, the flow meter, and the pool to which it goes.
http://youtu.be/OtR7JDa2MUk
If you use the "top of the float" to get GPM, then I am in the 80 gallons per minute class. I am hoping the flow meter does not match the plumbing diameter size and that is the cause for all the problems you saw with my pressures and flow rates. let me know what you think.
tjcooper
 
Re: Variable speed pump for hybrid solor panels

I am not a big fan of those flow meters but I can see a big problem from the picture. There is a valve right next to the meter. When they say straight pipe, they mean ONLY pipe. That will definitely affect the reading. I wouldn't trust it the way it is installed.
 
Re: Variable speed pump for hybrid solor panels

Wow,
you were right there. Amazing.
So I looked at the Blue&White and saw that 1.5" and 2" have different ranges on the arcylic values. I looked at my unit, it has the numbers for the 1.5" flow gauge....and then when I held the flashlight just right, there is a small designator on the block in tiny print that says 1 1/2" So I am sure I have the right meter.

If memory serves my physics background, a value or an elbow just in front of the guage would LOWER the reading because the Pitot tube would see the turbulence and not read as high a Bernoulli pressure as it would if there was laminar flow with water going straight.

So wouldn't this imply that the guage should read flows lower than is correct? And you think those flows are way too high for my pipes and the pressure gauge reading? I am confused.

What I think may be happening is that there is air in the 2" return pipes, and the water is falling like 8 feet from its long run. Could that make the flow gauge think there is much higher pressure than is really present?
tjcooper
 
Re: Variable speed pump for hybrid solor panels

Turbulence is well turbulent, it can make the flow read higher than actual, or lower, depending on fine details that are impossible to predict or compensate for.
 
Re: Variable speed pump for hybrid solor panels

In residential PVC pool plumbing, the water is always turbulent (non-laminar) because the flow rates are fairly high compared to the pipe diameter (i.e. high Reynolds number). Laminar flow in 1.5" pipe is at very low flow rates (< 2 GPM).

The blue white meters use a variable area flow meter which samples the flow rate at one side of the pipe only. When the pipe has transitions (i.e. fittings or valves) in the path of flow, this can make the flow asymmetrical within the pipe so the flow meter could read low or high depending on the asymmetry of the flow within the pipe.
 
Re: Variable speed pump for hybrid solor panels

mas985,
I was looking at a paddle-wheel flow meter on eBay. I went to the company Web site and it said it will measure the flow with any type of turbulence or valve connection because it samples the entire (almost) width of the pipe to get its little paddle-wheel going. Do you think this type of measurement device could give me a reasonable measure of flow in the pipe configuration I showed you in the video?

I have decided to go with the Hayward 3400 series pump because it can take the 12 volt signals from the Compool controller and adjust flows according to the solar signals that are changing during the day. That way I don't have to get additional controllers to adjust the pump flows as it changes from Startup to solar flow to no-solar-flow to pool sweep configuration. I know the specs show the Hayward is the most efficient per Watt, but I am not sure if it will have the reliability of the Pentair. When I had the NASA voltage controller in the system with old pool motor, I measured a few times that with solar active (but fewer panels) that I could pump a 12 foot spray from the pool sweep for about 60 watts of power. Hope I can do the same with the Hayward system. Just wish I could get an accurate flow rate to compare.
Tjcooper
 
Re: Variable speed pump for hybrid solor panels

Why again do you really care about flow rate? If the goal is get optimal flow to the panels, there are other ways of doing that (e.g. pressure rise and temperature differential). In general, you don't want more than about 4 PSI pressure rise when running solar and no more than a 5 degree temperature rise (in to out) to maintain efficiency. This tends to bound the flow rate. For example, in my system, I get a 4 PSI rise with a 3 degree temperature rise at the optimum flow rate (0.1 GPM/sq-ft).

Another way to measure flow rate that is probably just as accurate as any flow meter is to measure pump pressure and vacuum and then use the pump head curve to determine flow rate. This can tell you how far off your current meter really is.
 
Re: Variable speed pump for hybrid solor panels

Only reason to concentrate on flow rate was to answer your question that I had something wrong with my plumbing because of the meter's high flow rate. If you have a URL that details how to use pump pressure and where to get the pump head curve, I would gladly do that. My big question is will the variable speed pump save me significant money when running the solar. That is all I am trying to determine.

I will hook a Watt-Killer to my system this weekend to determine exactly what I am getting now with the old put in regular mode, in solar-panel mode, and when booster pump is running along with solar-panel mode.
tjcooper
 
Re: Variable speed pump for hybrid solor panels

See my signature. Hydraulics 101 sticky and the spreadsheets
 
Re: Variable speed pump for hybrid solor panels

much thanks for info. I also found a trick that gives the flow rate. Let the solar panels get primed, then quickly removed the union coming back from the solar panels and let the water fall into a bucket. Measure how long it takes to fill 10 gallon container. I will compare that answer to your spreadsheets.
Ted Cooper
 

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By doing that you are changing the return head loss which will in turn change the real flow rate so it probably won't give you a very accurate reading. You will be able to tell by a change in filter pressure.

BTW, the most accurate way to measure flow rate, besides an highly accurate and properly installed flow meter, is to measure both the suction and pressure of the pump. This can then be used to calculate head loss and the flow rate is taken from the head curve. One of the spreadsheets helps you with this calculation "PSIVac2GPM".
 
Mas985,
thanks for all the tips and spreadsheets. I bought the Hayward 3400 Ecostar last week. A brand new unit in box with Hayward unions for $725. I think that was a good price. Reason for Hayward was to get the 24volt relay signals to do all speed switching for solar from Compool solar computer.

So I measured with magnetic pickup the AC current. Very strange. On the old Sta-rite 1HP system I was getting 5.3-5.7 amps at 240volts This was the same current regardless of whether I had solar ON or OFF. The Polaris booster pump was taking 6.7 amps at 240 volts. Had no idea the booster pump would take that much current with pool motor on.

Will install Hayward this weekend....sort of Easter for a new pool pump. Will get new current readings when that is done.

QUESTION: I was thinking of moving the blue&white flow meter from its current location in solar return to a 12" straight section of pipe that I will have on the suction side of the Hayward pump. Is that useful or would it be wasted work? Just trying to get meaningful measure of water flow.

UPDATE: I could put in a pressure gauge (actually a vacuum gauge) at the same time I put in the flow meter. Do I trust the pressure reading out of the Triton II filter as my pump output pressure? or would I need a separate pressure gauge before I go into the Triton II?
tjcooper
 
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I wouldn't waste you time with that type of flow meter. The accuracy of your meter is +- 10 GPM and the spreadsheet estimates are usually better than that.
 
Mas985,
quick question. The pressure gauge on Triton II suddenly stopped working. Bought the same model from Amazon on put it on and purged the air. No other change in system. The pressure gauge used to run at 26-28 psi. With the new gauge, the pressure is now 8-10 psi with the variable speed motor running at same speed. Even at 2800 RPM from pump, the max pressure on pressure gauge is only like 15 psi.

Is there that much difference in a pressure meter output?

Did a whole summer of measurements on heat out of solar panel. Raised the pool ambient temp during "summer" by 8-10 degrees on un-covered pool. That is at pump running at 1200 rpm after a prime to get solar system primed. That is 1/3 of what my old system used to eat in electricity to get the same heating. So I am basically a "happy camper". This summer I will use a semi-automated pool cover to get things really warm. Really happy with the Hayward pump. But really troubled by the fact that I cannot get a high quality GFI to work because the motor induces current and triggers the system each time it comes on. The GFI manufacturer is telling me I have to put in a 3KW isolation transformer to pump motor before GFI will work. That is so crazy.
tjcooper
 
tjcooper said:
Mas985,
quick question. The pressure gauge on Triton II suddenly stopped working. Bought the same model from Amazon on put it on and purged the air. No other change in system. The pressure gauge used to run at 26-28 psi. With the new gauge, the pressure is now 8-10 psi with the variable speed motor running at same speed. Even at 2800 RPM from pump, the max pressure on pressure gauge is only like 15 psi.

Is there that much difference in a pressure meter output?
Click to expand...
Assuming the second gauge is good and the old gauge was reading correctly at one time, then the lower than normal pressure is most likely a clogged impeller or a clogged suction line. We have had a lot of rain recently in the area. Did you vacuum out a bunch of debris recently?

If so, first check the impeller inlet through the pump basket access (remove basket). If that is clear then you might try back flushing from the pump toward the skimmer with a hose wrapped in a wet rag to see if you can loosen any debris.

BTW, gauges can also clog with small debris. Check the hole in the bottom of the gauge and make sure it is clear.
 
Sorry for long delay in response. Kept my pool uncovered for whole winter. Just did manual leaf skimmer and pool sweep to remove crude from filter basket and sweep basket. I always take my pump motor filter out every time I see pressure change. Mostly leaves and fern stems. Never seen any big buildups. Manually use special net to clean bottom after wind and rain storms to remove stuff that falls in.

QUESTION: is the 8-10 psi at 1800 RPM a reasonable pressure in the Triton II? I was wondering if all my sand had gotten out of filter tank.
tjcooper
 
A signature of all your equipment would be useful but which VS pump is it? Sorry, I don't want to read through all the posts to find it.
 

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