A Pentair UltraTemp doesn't show numbered codes. It spells out the problem on its control panel, in alarms like LOW WATER FLOW, HIGH REFRIG and FIVE ALARMS. Here's what each one means, what you can check yourself and when it's a repair, from Pentair's own installation and user's guide.
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A Pentair UltraTemp alarm is a full-word message on the heat pump's control panel that names what stopped it, from low water flow to a failed sensor. There are no numbered codes to look up.
When an alarm is active, the SERVICE light comes on. Press the MENU SELECT button until you reach the Alarm Status screen. ALARM STATUS NONE means there's no alarm right now. From that screen, the DOWN arrow steps back through the last 30 alarms, newest first, which helps when the fault has cleared by the time you look.
The alarms below come from Pentair's guide (Rev. P, 2016). The list varies a little with the age of the unit: a 2012 edition doesn't list SERIAL COMM LOST, and newer editions add LOW AMBIENT TEMP.
| Alarm | What Pentair says it means | What to check |
|---|---|---|
| LOW WATER FLOW | The pressure switch sensing water flow is open | Pump on, filter clean, valves set, and any bypass around the heat pump closed |
| HIGH REFRIG | The refrigerant high pressure switch is open | Flow first, with the same checks, plus the pool's water level. After a long idle period, cycle the unit on and off up to 3 times |
| LOW REFRIG | The refrigerant low pressure switch is open | If it's cold, wait for it to warm up. Clear debris and shrubs from around the unit. Low refrigerant or a fan fault is a service call |
| LOW AMBIENT TEMP | Too cold for the heat pump, or a defrost that didn't finish within 15 minutes (newer editions) | Wait for the ice to melt and the air to warm |
| HIGH WATER TEMP | Water above 107°F | Test the water. If it isn't that hot, the sensor or control board needs testing |
| LOW WATER TEMP | Water below 40°F | Test the water. If it isn't that cold, it's the sensor, the control board or debris shorting the connections |
| WATER THERM SHORT / OPEN | The water temperature sensor circuit is shorted or open | A technician tests the sensor, then the control board |
| SUCTION TH SHORT / OPEN | The defrost sensor circuit is shorted or open | A technician tests the sensor, then the control board |
| BROWNOUT | The 24 VAC supply to the control board is low | A technician. Pentair lists a bad transformer or low supply voltage, which should be 208 to 260 volts |
| REMOTE POOL/SPA | Pool and spa remote inputs are energized at the same time | Your automation: only the pool or the spa input should be on |
| SERIAL COMM LOST | The control board hasn't had a message from the automation controller for 2 minutes | The automation controller and its connection to the heat pump |
| FIVE ALARMS | Five faults in one hour | Press ON/OFF, or it resets itself in an hour. The alarm behind it is the real problem |
Some screens look like a problem but are the heat pump working normally:
Pentair's guide gives a button reset for one alarm: FIVE ALARMS. Press the ON/OFF button to clear it, or it resets itself in an hour. Then watch the heat pump over the next few minutes and hours, because Pentair says the alarm that comes back is most likely the one that caused it.
HIGH REFRIG has its own step. If the heat pump hasn't run for an extended period, Pentair says to cycle it on and off up to 3 times. If that doesn't correct it, call for service.
For everything else, the fix is the cause, not the button. If the display is blank, start with the breaker.
Pentair's first checks are the same for both alarms: the pump has to be on, and enough water has to be moving through the unit. Its minimum is 30 gallons a minute and its maximum is 120.
If the filter gauge stays high after cleaning, see our guide to filter pressure that stays high after backwashing. On a variable-speed pump, a low speed that's fine for filtering may not move enough water, so check the speed while the heat pump is on.
Pentair also lists low flow when switched to spa mode, a clogged pump impeller, an automatic pool vacuum causing a restriction, a unit plumbed backwards, a heat exchanger clogged with debris and a damaged or clogged internal bypass valve. If it's still showing LOW WATER FLOW with good flow, the pressure switch itself may be bad. Those are jobs for a technician.
A heat pump heats with the air, so a cold Houston morning can stop it without anything being broken. Pentair lists air and water too cold to operate as a cause of LOW REFRIG, and its fix is to wait until temperatures warm up and see if the unit runs.
The UltraTemp may enter a defrost cycle when the air is around 50°F, if defrost is enabled in the service menu. The compressor stops and the fan keeps running for about 15 minutes. If the refrigerant hasn't warmed up by then, the unit shuts down.
If ice forms on the outer coil, Pentair says to shut the heat pump off and let it thaw, and you can use water at low pressure. Make sure sprinklers aren't spraying the unit and plants aren't blocking the air flow. Ice can also come from a refrigerant leak, so check the alarm status for LOW REFRIG. Our guide to a pool heat pump not heating in cold weather explains how to tell the weather from a real fault.
| What you see | What Pentair lists | What to do |
|---|---|---|
| Blank display, won't start | No power: a tripped breaker or blown fuse, a faulty transformer or a control failure | Reset the breaker. Anything else is a service call |
| Green light on, set above actual, won't start | Remote feature on with nothing controlling it, or the wrong pool or spa mode | Press POOL/SPA to check the active mode, and check the Remote Mode screen if you don't have automation |
| Fan runs, no cool air from the top | The five-minute safety delay, or a compressor, capacitor, contactor or control board fault | Give it five minutes, then call |
| Compressor starts, then cuts off | Debris, an air leak, reversed plumbing, a clogged heat exchanger or bypass, or a compressor or board fault | Clean the filter and check the valves, then call |
| Fan not turning | A fan relay, capacitor, fan motor or control board fault | Call a technician |
| Water under the unit | Usually condensation, at about three to five gallons an hour while it runs | Keep the drain holes in the base clear |
Call when an alarm keeps coming back after the flow checks, when it won't heat on a mild afternoon, and for any sensor, refrigerant, fan or BROWNOUT alarm. Pentair says any service must be done by an authorized service agency person, and warns against internal adjustments inside the heater.
Our heater repairs run from about $200 for a small component to $1,000 or more, and a replacement heat pump is roughly $6,000 to $6,500 installed, so a proper diagnosis comes first.
For a Hayward, see our Hayward heat pump error codes. For a Pentair gas heater, see our MasterTemp error code guide. For everything else, see pool heater repair.
Not numbered ones. It shows full-word alarms on the control panel, such as LOW WATER FLOW, HIGH REFRIG and LOW REFRIG, with the SERVICE light on. The Alarm Status screen shows the current alarm, and the DOWN arrow steps through the last 30.
The refrigerant high pressure switch is open. Pentair lists low water flow first: check that the pump is on, the filter and skimmers are clean and any bypass is closed. If the unit has sat unused for a long time, cycle it on and off up to 3 times. If that doesn't clear it, call for service.
The refrigerant low pressure switch is open. On a cold day, the air and water may be too cold, so wait for it to warm up. Otherwise Pentair lists low refrigerant, a faulty fan, a stuck expansion valve or poor air flow through the coil. Clear debris and shrubs, and call a technician for the rest.
For FIVE ALARMS, press the ON/OFF button, or wait an hour for it to reset itself. Then watch for the alarm that caused it to come back. If the display is blank, check the breaker first.
The pressure switch isn't seeing enough flow. Clean the filter, check the valves, close any bypass around the heat pump and repair any air leaks. Pentair lists a minimum of 30 gallons a minute. If it still shows, the switch itself may be bad, which a technician can test.
Allow for the 5-minute RESTART DELAY first. Then check that it's in the right pool or spa mode, and that the Remote feature isn't on with nothing controlling it. If it's none of those, Pentair lists faults such as the compressor, contactor or control board, which need a technician.
Tell us the alarm on the screen and when it started. If it's flow or the weather, we'll tell you so; if it's a sensor, the fan or the refrigerant, we'll come out and fix it. Licensed, insured, serving Cypress and Greater Houston.