1HP Pump Questions

[Copperhead]

Pump sellers, please PM me, want to know if it is desirable to downsize to a 3/4hp from 1hp.
Thanks

 

[JasonLion]

Probably not, because of your in-floor cleaning system. However, it depends on which particular 3/4 HP pump you are talking about, as not all pumps are created equal. A 3/4 HP WhisperFlo could probably handle it, but most others run a significant risk of not producing enough pressure for the in-floor cleaning system.

 

[Copperhead]

Are there such animals as 1/2HP pumps, and would running two of them parallel equal a 1HP pump in GPM and pressure?

 

[JasonLion]

1/2 HP pumps do exist, though they are a little bit rare. Running two of them in parallel will move more water than a 1 HP pump would. Keep in mind that running pumps in parallel is a little bit finicky, and two 1/2 HP pumps cost quite a bit more than a single 1 HP pump. Because of the added cost and complexity, you usually only see pumps run in parallel in commercial setups.

One thing worth understanding is that not all pumps of a given HP are really the same size. Marketing types like to fudge the HP numbers to make their pumps look good, and over many years the meaning of the listed HP has become rather vague. A better number to use is the SFHP, which is the actual power available to move water. SFHP is the service factor (SF) times the listed HP. The SF is nearly always listed on the pump, and sometimes appears in the marketing literature as well.

My comment about the WhisperFlo last time relates to SF, as WhisperFlo pumps have particularly high SF numbers. I have a 1/2 HP WhisperFlo, which turns out to be a rather larger pump than the 3/4 HP pump I used to have. My old pump had a very low SF, while the WhisperFlo has a very high SF.

 

[mas985]

Parallel 1/2 HP pumps will use more energy than a single 1 HP pump and not deliver much more in flow rate. 1/2 HP pumps tend to have lower pumping and motor electrical efficiency than a larger pumps so there would be a net loss going with two pumps. However, a single 1/2 HP pump will have a better energy factor (gallons/watt-hr) than a single 1 HP pump. Here is an example of the three configurations on typical 2" plumbing:

[tr:2ho21uxe][td:2ho21uxe] Summary [/td:2ho21uxe][td:2ho21uxe] [center:2ho21uxe]Single WFE-2[/center:2ho21uxe] [/td:2ho21uxe][td:2ho21uxe] [center:2ho21uxe]Two WFE-2[/center:2ho21uxe] [/td:2ho21uxe][td:2ho21uxe] [center:2ho21uxe]Single WFDS-26[/center:2ho21uxe] [/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Pump Speed (rpm) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]3450[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]3450[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]3450[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Water Flow (gpm) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]68.1[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]84.0[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]82.0[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe][/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe][/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe][/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Suction Head Loss (ft) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]6.5[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]9.8[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]9.3[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Pad Head Loss (ft) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]25.9[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]39.4[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]37.5[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Solar Head Loss (ft) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]0.0[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]0.0[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]0.0[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Return Head Loss (ft) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]4.2[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]6.3[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]6.0[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Jet/Eyeball Head Loss (ft) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]1.7[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]2.6[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]2.5[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Total Head Loss (ft) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]38.4[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]58.1[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]55.3[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe][/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe][/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe][/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Input Power (Watts) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]1190[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]2239[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]1880[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][tr:2ho21uxe][td:2ho21uxe] Energy Factor (Gallons/Watt-hr) [/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]3.43[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]2.25[/center:2ho21uxe][/td:2ho21uxe][td:2ho21uxe][center:2ho21uxe]2.62[/center:2ho21uxe][/td:2ho21uxe][/tr:2ho21uxe][/table:2ho21uxe]