VS pump vs. Dual Speed vs. keeping Status Quo

After reading a lot of posts about variable speed (VS) pumps, I am really trying to come up with a cost benefit rationale to install one or even a dual speed pump for that matter.

My set up: 13K dual spillover pool-spa; 2nd story roof solar; polaris floor sweep; 2 HP 1 spd. pump; 2" lines; loc: So.Cal.; Goldline PS-4 Salt water generator setup (thinking I;ll need a new control board ($$$) to run a VS pump :(.

My quandries:

1. Wouldn't the VS pump need to run at the higher speeds for my "solar panel season" (currently 4 -5 months)? Doesn't a roof solar setup's need for speed dig fairly deep into the cost savings of a VS pump? (curious: why couldn't I run the VS pump at high speed just long enough to get a flow circuit going in the solar lines, then program it to throttle back after running/circulating a few minutes)? Does this work to favor a VS pump?


2. Might the VS' slower speeds make for an anemic or feeble looking cascade from my dual spillover spa; I see this feeble cascade look whenever my filter needs cleaning: should that not be an indication of what I can expect running the VS pump at the low, cost effective speeds. For that matter, wouldn't even a dual speed cause that?

Help: I am someone desparate to turn off all those 75 watt light bulbs that burn for every hour my 2HP runs (I understand its like 12 or 14 of those bulbs - hourly!!!. ) To go with a VS set up looks like it is around $1600 to $2400. Dual speed: $600.

But heck, maybe neither a VS or a dual speed will work in my set up, meaning of course, work and at a cost savings.

NOTE: For those willing to post your thoughts about this, rest assured that you will be spared when we take over your planet. End of note.

The pump flow experts will need to help you. It all comes down to gpm and "feet of head" that determines how much you need to power your water demands. I have solar panels, but I'm not lifting the water higher than 3' above the pump, so it's not an issue.

VS pumps are new to me, but I've run a 2spd for 8 seasons, mostly on low, with the panels running. And, at High it's 1hp.

But again, the pump experts need to help you calculate your pumping needs. Be ready with distance and height measurements as well as more details on your pump: Brand, model, and if it's full-rated or up-rated (VERY loosely, "up-rating" is a way to rate AG pool pumps so they seem more powerful than they are. A full-rated 1hp will generally outperform a 1.5 hp up-rated).

Carl

A variable speed pump will nearly always be more cost effective over the life of the pump. Yes it costs more up front but it will save more on electrical costs even if you run it at higher speeds for part of the cycle (I do this on my two speed). In my signature below is a link to "Pump Modeling Tools" which contains a spreadsheet that I put together which will compare the lifetime costs of any pumps that are in the CEC database. But without doing the analysis, I can tell you that the VS pumps will usually come out ahead but it depends on what you pay for electricity and if you will also need a controller.

As for your questions:

#1 - Yes, you will need to run the pump at higher speed for solar if you have an elevated installation AND you have a vacuum release valve near the top of the panels. You can lower the VRV and make solar work at lower pressure and flow rates but then the efficiency of the panels will suffer. But still, a VS pump will allow you to tune the flow rate to be just enough to keep the VRV closed and the panel efficiency up.

#2 - Yes but so what? You are saving money. If you want to impress vistors, just up the RPM of the pump for the party.

I have a solar system, yet I was able to cut my pump electricity costs IN HALF from around $1400 to $700 per year (at high marginal 40 cents per kilowatt-hour rates) when I switched from a 1 HP (1.65 SF) Jandy HHP pump and a 3/4 HP booster pump (for the Letro Legend pool sweep) to an IntelliFlo VF pump. Most of the savings comes from the fact that even when I'm using solar, it isn't on for all 8 hours of pump run time. It's only on for 4-6 hours so the other 2-4 hours I'm able to run at a lower 26 GPM, 1500 RPM, 275 Watts. Even when the solar is on, I can run at 48 GPM (4 GPM per panel for 12 panels), 3000 RPM, 1500 Watts with greater efficiency than my old pump which was running at around 55 GPM (maybe 1800 Watts) or so when the solar was on (and 80 GPM or so when the solar was off, still close to 1800 Watts). The rest of the savings was using the IntelliFlo to power The Pool Cleaner at 15 GPM, 2200 RPM, 540 Watts through its dedicated line compared to the 3/4 HP booster pump at around 1400 Watts.

Richard