Basic rules of thumb for open systems with wet rotor circs.
Keep the operating temp as low as possible.
Locate the inlet of the circ as far below the surface of your water column as possible. This keeps all available NPSH where it can be used.
Oversize the piping on the inlet side of your circ if possible to ensure that you have no loss of head on the suction side.
Avoid the use of high head type circs such as Taco 0011, Taco 009, Grunfos 26-99 for example. Generally the higher the head, the more inlet pressure you need to maintain.
Over size the piping on the outlet side of the circ to ensure you can use a lower head circ such as a 15-58 or 26-64 Grunfos or 007/0010 Taco.
Basically in open systems using wet rotors, it's all about the pipng.
As a last resort choose a split style circ that doesn't rely on system fluid to cool the motor section. I've been using Taco 1400 series in some applications with excellent results IE: no failures. B&G;'s PL series circs are much the same design. (There's no distribution for Wilo within 100 miles of me so I haven't tried them. Looked into getting set up with them but the minimum opening order is like $35K. So much for Wilo.)
In a lot of cases these varieties will be on the large side for most residential systems but many times they can work and will probably take more abuse than a wet rotor. In a lot of cases an old B&G100;series will do the job nicely albeit a bit more expensively. There are hundreds of thousands of those things out there quietly churning away in their 3rd or 4th decade of service. Keep 'em oiled and they'll live forever.
Keep the operating temp as low as possible.
Locate the inlet of the circ as far below the surface of your water column as possible. This keeps all available NPSH where it can be used.
Oversize the piping on the inlet side of your circ if possible to ensure that you have no loss of head on the suction side.
Avoid the use of high head type circs such as Taco 0011, Taco 009, Grunfos 26-99 for example. Generally the higher the head, the more inlet pressure you need to maintain.
Over size the piping on the outlet side of the circ to ensure you can use a lower head circ such as a 15-58 or 26-64 Grunfos or 007/0010 Taco.
Basically in open systems using wet rotors, it's all about the pipng.
As a last resort choose a split style circ that doesn't rely on system fluid to cool the motor section. I've been using Taco 1400 series in some applications with excellent results IE: no failures. B&G;'s PL series circs are much the same design. (There's no distribution for Wilo within 100 miles of me so I haven't tried them. Looked into getting set up with them but the minimum opening order is like $35K. So much for Wilo.)
In a lot of cases these varieties will be on the large side for most residential systems but many times they can work and will probably take more abuse than a wet rotor. In a lot of cases an old B&G100;series will do the job nicely albeit a bit more expensively. There are hundreds of thousands of those things out there quietly churning away in their 3rd or 4th decade of service. Keep 'em oiled and they'll live forever.
