What to do if Pentair ULTRATEMP 90 shows low water flow alarm?
- BbarkerlisaSep 12, 2025
If your Pentair Heat Pump displays a low water flow alarm, several factors could be the cause. First, ensure the water circulation pump is running. Insufficient water flow might be due to dirty or worn filters, clogged lint traps, or a clogged pump impeller; clean or replace filters, inspect the pump impeller, and adjust plumbing valves. Check for and repair any suction air leaks. Also, verify that any external water bypass around the heat pump is closed. Finally, a faulty water pressure switch could be the culprit; if water is flowing, check the switch's resistance, and replace it if it's open.






