Re: Hayward Tri-Star Variable Speed
In a technical sense, you are probably right. But it hardly matters. Far less circulation is perfectly fine in nearly all cases. There are a number of criteria to balance out. Circulation is just one issue among many, and not usually one of the more important ones.
What people seem to care about the most these days is saving money on electricity. You can save a huge amount on electricity by running the pump for far less time, and circulation will still be just fine with only 4 to 8 hours of pump run time (assuming a residential pool).
Also, many pools will not get skimmed effectively at the lowest possible speed. Skimmers need a certain minimum flow rate to skim effectively. Especially with the trend towards having more skimmers these days the lowest possible speed often won't be sufficient to clear surface debris, though this will vary from pool to pool.
Finally, "lowest possible speed" isn't always such a great idea. Most of the variable speed pumps currently available are less energy efficient at their lowest possible speed, hitting optimal energy efficiency at speeds just a bit higher than that.
Hi Everyone, first and foremost is getting familiar with the Pump Affinity law.
Affinity Law (remember 3450 rpms at high speed)
• At ½ Speed (1725 rpms)
• Approximately ½ the flow
• ¼ the Head in feet (slower moving water creates lower TDH)
• 1/8the Electrical Consumption (approximately)
The key is everytime you cut the speed in half the energy used is reduced drastically. Here was a case study
WE HAVE A 23,000 GAL POOL (2”)
We determine that at 80% the VS Pump is pumping the same amount of water at the old Single Speed pump
At 80% 56gpm X 60min X 8hrs (26,880gals) 1013 watts an hour X 8 hrs = 8104 watts 8.1 KW
At 40%28gpm X 60min X 16hrs (26,880gals) 161 watts an hour x 16 hrs = 2576 watts or 2.6KW
At 30%22gpm X 60min X 22 hrs (29,040 gals) 86 watts an hour X 22 hrs = 1892 watts or 1.9 KW
At 25%18gpm X 60min X 24 hrs (25,920gals) 60 watts an hour X 24 hrs = 1400 watts or 1.4 KW
There are other variables to determining the lowest possible speed for a specific pool. I always like to say a pool is like a fingerprint, everyone is different.
1. Making sure the pool filter fills completely with water so the filter is able to do it's job.
2. Optimum skimming is obtained around 30-50gpm. Water tension is lost over 50gpm with most skimmers
3. Making sure all the equipment that is speed dependent is met (salt system, heater is pool is heater all the time, etc)
This is a great discussion and look forward to more comments. By the way, I am located in California where the electrical rates are high.
John the Hayward tech.