Pentair UltraTemp High Refrig Alarm

The HIGH REFRIG alarm on a Pentair UltraTemp indicates the refrigerant high pressure switch has opened. This typically means pressure in the refrigerant system has exceeded safe limits, triggering protective shutdown.

This alarm often points to water flow issues rather than refrigerant problems, as restricted water flow causes refrigerant pressure to rise.

Understanding High Pressure

In a heat pump, refrigerant transfers heat from the air to the pool water. If water flow is restricted, heat cannot transfer properly, causing:

• Refrigerant pressure to rise
• High pressure switch to open
• Heat pump to shut down for protection

Common Causes

Water Flow Issues (Most Common)

• Circulation pump not running
• Insufficient water flow (below 30 GPM minimum)
• External bypass valve open
• Dirty filter restricting flow
• Clogged pump impeller
• Heat pump plumbed backwards

Refrigerant System Issues

• Unit overcharged with refrigerant
• TXV (thermal expansion valve) stuck closed
• Bad high pressure switch
• Restricted refrigerant lines

Compressor Issues

• Compressor thermal protector tripped
• Compressor internal relief valve activated

Troubleshooting Steps

Step 1: Check Water Flow First

1. Verify circulation pump is running
2. Check filter pressure (service if high)
3. Ensure bypass valves are CLOSED
4. Verify all isolation valves are OPEN
5. Clean pump and skimmer baskets

Step 2: Verify Proper Installation

• Confirm water inlet goes to bottom connection
• Confirm water outlet comes from top connection
• If reversed, water won't flow properly through heat exchanger

Step 3: Reset and Test

1. Press ON/OFF to clear alarm
2. Wait for 5-minute safety delay
3. Monitor operation
4. If alarm returns, further diagnosis needed

Step 4: Check for Debris in Heat Exchanger

Scale or debris in the heat exchanger restricts water flow:

• Look for calcium buildup (especially in hard water areas)
• Check for debris that may have passed through filter
• Professional cleaning or descaling may be required

Thermal Protector Check

On units with LG compressors (manufactured after 11/1/2020, except UT70):

1. Locate thermal protector on top of compressor
2. Trips at 240F (115.6C)
3. Resets when temperature drops below 170F (76.7C)
4. If repeatedly tripping, check for underlying cause

When HVAC Tech is Needed

Call a licensed HVAC technician if:

• Water flow is verified adequate but alarm persists
• Unit needs refrigerant recovery and recharge
• TXV replacement is required
• Compressor issues are suspected
• High pressure switch needs testing/replacement

Prevention

• Maintain proper water flow (30-120 GPM)
• Keep filter clean
• Ensure bypass valves are closed during operation
• Have system checked annually by qualified technician