Domestic pool turnover rates

[Anonymous [GDPR] European in the UK]

Apologies Mark & Richard I thought that was a Polaris, That model of cleaner hasn't made to the UK or Europe as far as I know. How do you rate it?

Ben, Legend!

[chem geek]

I switched to 4-wheel pressure The Pool Cleaner when I switched to a Pentair Intelliflo VF pump. Prior to that I had a single-speed pump and a separate booster pump for a Letro Legend pool cleaner. I'm very happy with The Pool Cleaner, but I have a cover on the pool most of the time so don't get a lot of debris. I clean out the cleaner bag no more than once a week and can usually go longer between emptying the bag. When the cleaner is on, it's at 15 GPM, 2180 RPM, 540 Watts for 2 hours each night (I have a Jandy valve that switches the main pump to a dedicated line for the cleaner). I don't need to run it that often, but I never know which day is going to get the debris and my wife swims nearly every day and doesn't want debris in the pool. When the solar is on at 48 GPM that's 1500 Watts and when it is off at 26 GPM it's 300 Watts.

[CarlD]

Richard,
I've read your posts with interest (as I almost always do). I'm baffled by one thing: Why do your solar panels require so much pressure? While I've long been an advocated of "More Flow = More Heat Energy", it seems awfully high and from what I've seen of solar panels, they are prone to leaking when the pressure is too high--I run mine on low speed all the time. When I bump the pump to high, I either turn off the panels, or shut their valves down to a crack, a trickle, to prevent them leaking. Of course FantaSea panels, nifty as they are, are far more fragile than the flexible roll-up types. I'm always checking for and repairing leaks.

As for the lower TA: I'm pretty sure it wasn't Ben who first put the concept forward. I thought it was one of the pool pros--or you--who suggested it (guess it wasn't you). Of course, in practice many of us have found it to be VERY effective to countering rising pH. Rising pH seems more mysterious than falling pH, which is almost always easy to trace, usually to Tri-Chlor or even Di-Chlor. Only with new or newly resurfaced hard (concrete/plaster) sided pools is rising pH expected.

But rising pH can be, as you know, an adverse effect of an SWCG. Many people complain about it. Yet I don't seem to have that problem and haven't in the 3 seasons I've had the SWCG. In fact, my pH has been pretty constant since I re-opened (and the Tri-Chlor tabs ran out) at 7.5-7.6 Yet my TA is around 170 due to the local water. Since pH IS stable, it ain't broke, so I'm not fixin' it!

[mas985]

Not to answer for CG but for solar panels on a roof with a VRV installed on the roof, you must have positive pressure at the VRV to keep it closed. Pressure drops with elevation so on a two story roof, you must have at least 11-15 PSI on the filter in order for the VRV to remain closed. A one story is better at 5-7 PSI filter pressure.

Carl, if I remember correctly, I believe your panels are in your deck so you can easily run on low speed to run the panels.

Lowering of the VRV would also allow someone to run at low speed on a two story roof but you still need to prime the panels on high speed so the controller must support that.

[CarlD]

Thanks, Mark. Yes, it's correct that my solar panels are part of my deck and priming them is only an issue in the spring because they were drained for the winter. Other panels I've used have also not been elevated so I've no experience with the control valves needed.

[chem geek]

The recommended flow rate for my solar panels is 4 GPM per panel and I have 12 panels in parallel so that's 48 GPM. I could run slower with somewhat less efficiency. Even going from 4 GPM per panel to 3 GPM per panel (which is the "minimum recommended") only drops efficiency from 80% to 70% while energy usage would drop from 1500 Watts down to less than 900 Watts. Or I could split the difference and do 3.5 GPM per panel at less than 1200 Watts. I've considered doing that, but haven't changed to it yet. My wife often swims earlier in the day so needs the heating to occur more quickly, but it's a dance for how high to get the temperature the night before so that it is warm enough at the start of the next day.

The other reason my pump energy cost is pretty high when solar is running is that I have a long 75 foot pipe run to and then from the solar system on the single-story roof. I lose 1.2 PSI because my PB used 2" pipe instead of 2.5" (or 3") plus the 12 panels are spread over 3 different roof hips over the length of the house. Also, marginal electricity rates are high at 35 cents per kilowatt-hour (or more). My filter pressure with solar at 48 GPM is roughly 24 PSI which is high (55 feet of head) where the highest point of solar on the roof is perhaps 20 feet high so the rest is largely inefficiency in the piping and outlets. I'm sure I could operate at a slower flow rate without the VRV opening since 36 GPM with solar on is roughly 16 PSI in my pool system.

[CarlD]

Thanks for the explanation, Richard.
Do you use a solar cover at night, too, to hold in heat? I find it's critical to efficiency.
If you have an attic, have you thought of running additional plumbing through THAT to pick up more heat energy?

Luckily, since my panels are only about 3 1/2' above my pump and, at most 10' away, I don't have to deal with all those issues you do.

[Anonymous [GDPR] European in the UK]

I switched to 4-wheel pressure The Pool Cleaner when I switched to a Pentair Intelliflo VF pump. Prior to that I had a single-speed pump and a separate booster pump for a Letro Legend pool cleaner. I'm very happy with The Pool Cleaner, but I have a cover on the pool most of the time so don't get a lot of debris. I clean out the cleaner bag no more than once a week and can usually go longer between emptying the bag. When the cleaner is on, it's at 15 GPM, 2180 RPM, 540 Watts for 2 hours each night (I have a Jandy valve that switches the main pump to a dedicated line for the cleaner). I don't need to run it that often, but I never know which day is going to get the debris and my wife swims nearly every day and doesn't want debris in the pool. When the solar is on at 48 GPM that's 1500 Watts and when it is off at 26 GPM it's 300 Watts.

Hi Richard, just backing up on this thread. Is the 48GPM what is required by the solar for good heat transfer?
What are the gauge pressures for your flow rates?
As we have discussed before elsewhere the additional 1200 watts to run your pump for solar heating could, if put through an air source heat pump produce almost 6000 watts of heat for your pool. not sure what kind of output you get?
By way of comparison roughly 26 GPM 55 Watts 1700 RPM

[CarlD]

I think Richard is telling us the 48gpm is required solely to get the water up to the roof. While I'm always an advocate that the more water you can push through your panels the more heat you'll get, short of forcing cavitation or leaks, you certainly don't need that just for the panels.

[Anonymous [GDPR] European in the UK]

Maybe Carl, that's what I was waiting for clarification over. It's normally a pressure required to lift the water not necessarily a flow rate but in this case that 48 GPM maybe where the pump flow supplies sufficient pressure to reach the panels.
It takes time to transfer the solar energy into the water so to fast and the water won't absorb enough heat so the excess flow is just a waste of energy, there will be a point where to slow and the panel stays to hot so not supplying enough heat to the pool. Finding the sweet spot is the desirable point.