[mpoulton]

Check the voltage at the motor terminals while operating (with a clean filter, all valves open etc. - you want the minimum restriction to flow for this test). If the voltage is low, that could cause higher than normal operating temperatures. However, 180 degrees sounds acceptable. You can also reduce the load on the pump by partially closing valves on the discharge lines. This increases the pump pressure, but decreases the flow rate which (counter-intuitively) decreases the load on the motor.

 

[mpoulton]

The motor is drawing 8.5 Amps at 247VAC. I don't have any valves on my discharge lines.

That voltage is fine, for sure. That current seems high. Unfortunately the manual for that pump doesn't specify operating current, only branch circuit breaker rating (15A). 8.5A at 247V is 2.1kva. Motors typically run about 1kva/hp, so your pump may be substantially overloaded. You could try installing a valve in the pump outlet line and closing it until the current drops to about 6A.

 

[mpoulton]

Why would restricting the outflow of the pump reduce the current draw of the motor? It would seem to me that he may have an oversized pump for the inlet/outlet piping diameter or inadequate pump for the head pressure.

As I said, the power requirements of centrifugal pumps are a bit counterintuitive. They require the most power at zero head (maximum flow rate, lowest discharge pressure) and the least power at dead head (no flow, maximum pressure). This is because most of the "work" the pump does is accelerating the water, adding kinetic energy to it, rather than raising the pressure. This actually makes sense if you consider the mathematical relationships involved. Anyway, figure 5 on the following web page shows a pump curve for a centrifugal pump and the relationship between pressure, flow, and power required.

http://www.gouldspumps.com/cpf_0009.html

This only works for centrifugal pumps, not positive displacement pumps.

Bottom line: the discharge restrictor valve is a classic method of throttling a centrifugal pump to keep the motor ratings from being exceeded.