High Head vs. Medium Head Pumps

 

Not all pumps are designed for the same application Pool and spa pumps can be designed to provide differing levels of pressure and flow.  Some applications (like spa jets or fountain heads) require high pressure, while other applications like waterfalls require high flow at lower pressure. The key is to properly evaluate the needs of your pool, spa or fountain.

Total Dynamic Head

Every pool, spa or fountain system will have a different level of Total Dynamic Head (TDH).  This could also be understood as resistance to flow.

Every element of the system creates a certain amount of resistance to flow.  Piping - every foot of pipe and every fitting creates a certain amount of resistance and adds to the TDH.  The higher the flow through the pipe, the greater the resistance to flow. Valves - each valve increases the resistance, but not by much in most cases. Backwash Valves - these are one of the biggest contributors to TDH.  This is because the water takes a lot of right hand turns inside the backwash valve and that creates turbulence, which in turn creates resistance to flow. Filters - a filter (especially when it is dirty) can create a lot of resistance to flow.  Cartridge filters create the least amount of TDH. Heaters - the water has to go through a lot of tubes in the heat exchanger and this creates resistance to flow. Return Fittings - the size of the return orifice can have a significant impact on the resistance to flow.  Spa return fittings are typically smaller and create resistance which creates pressure.

Sample TDH Calculation Skimmer/Drain 0.2 Intake Line 3.0 Intake Manifold 1.0 Backwash Valve 15.0 Filter 10.0 Heater 10.0 Return Plumbing 3.0 Return Fittings (inlets) 3.4   45.6 Once you have calculated the  TDH, you can look at the pump curves to determine which pump is best for your application.

Different Pumps for Different Applications

Here are some sample calculations of head pressure for different types of applications.  

Above Ground Pools -  typically require a lower head pump because the equipment is located very close to the pool and there is not as much equipment on the pool.

In Ground Pools - have more equipment and longer piping runs and therefore need a medium or high head pump.  

Spas - have more equipment and also require higher pressures to run the jets.  A fairly high head pump is needed.

Waterfalls - have very little equipment and simply need LOTS of flow.  Waterfall pumps are typically low head pumps.

Checking out the Curves

If you look at the pump curves for different type of pumps, you can see that each pump is designed for a particular application.  In this chart we have listed several of Pentair's pumps.  The Challenger is a high head pump.  The Whisperflo is sold as a a medium head pump because of its flat pump curve, but it does have some high head capabilities.  The Dynamo pump is a true medium head pump and is designed specifically for above ground pools.  The Waterfall pump is a low head pump, designed specifically for creating high flow.

THE BOTTOM LINE

THE BOTTOM LINE . . . match the pump up to the application

Carefully evaluate your pools needs and then match the pump to the application.  Most manufacturers offer a variety of pumps for all applications.  We have tried to identify which pumps are above ground or in ground pumps and in most cases, if you stay within those guidelines, you should be fine.

As always, if you have questions, feel free to call us at 1-800-394-6131 for assistance.