Pump Question
Pump Question
(OP)
On like chiller or cooling towers, is it better to pump through or suction through them? I would think pumping through (chiller or CT downstream) to overcome the pressure loss through the unit. I can understand their concern with downstream units, that there is higher pressure at that point which puts more stress on the piping joints and flanges, but it should be able to handle it. I've heard people say it is better both ways. What do you think?





RE: Pump Question
Jabba
RE: Pump Question
Need to consider the NPSH of the pump. For a cooling tower, the cooling tower basin will provide positive NPSH. For a chilled water system the system pressurisation tanks/expansion tanks should be located on the pump suction and is typically easier to accomplish by locating the pump before the chiller.
RE: Pump Question
It isn't just convention to pump away from a boiler, it is good design and piping practice. A couple of the good reasons:
1) Doesn't expose you boiler to the discharge pressure of the pump, which may be higher than the capacity of the boiler. (Viessman condensing boilers, for instance, can have a pressure rating of only 35 psi).
2) Locates the air seperator at the lowest pressure, hottest temperature point in the loop; enhancing air removal.
3) Locates the expansion tank such that the entire system is positvely pressurized and at no point in the system where a manual or automatic air vent is located will the system pressure drop enough to entrain air.
RE: Pump Question
If you pump from cooling equipment, reducing pressure at heat exchanger will increase cooling.
RE: Pump Question
You afre doing the opposite of what every one out there is doing.
Food for thought.
RE: Pump Question
Conventional wisdom is just that: conventional.
Physics doesn't depend upon convention.
RE: Pump Question
RE: Pump Question
RE: Pump Question
Chillers: There is no hard and fast rule as there are so many primary/secondary and variable flow configurations for the chilled water it would make your head spin. However, 90% of all the chilled water installations I've seen and designed had the chiller pump pushing water into the chiller. From thousands of tons of campus chiller plant to a 10 ton air cooled chiller. Don't forget in a closed loop system with the expansion tank on the suction side of the pump to set your system minimum pressure, the pump could thoeretically be pushing into the chiller or sucking out of it - it really doesn't care as long as your minimum system pressure is set up properly to insure adequate pump suction pressure - everything downstream of the pump discharge is just friction head no matter where it is in the closed system.
RE: Pump Question
Thanks GMcD for being the one to clarify that half the world thinks of steam and the other half hot water when the subject of boilers is mentioned. I was wondering how you were going to pump away from a (steam) boiler.