Compare a pool heat pump and a gas pool heater using the intended swimming season and warm-up schedule. Heat-pump output capacity and thermal efficiency vary with ambient conditions. Proper heater size is based on the time required to heat the pool or spa.
Use the model ratings below to compare cold-weather output, then assemble the inputs for your own pool. For the wider equipment plan, start with the pool equipment hub.
How do the heat-pump ratings change?
The UltraTemp rating conditions are ordered as air temperature (°F), relative humidity (%), and water temperature (°F). Measured COP depends on the rating conditions used for testing.
Compare the heat-only models below by condition. Read the capacity and COP columns separately.
Scroll horizontally to read all columns.
| Listed BTU capacity | COP |
|---|---|
| UltraTemp 110 listed BTU capacity is 110,000 at 80/80/80. | UltraTemp 110 COP is 6.1 at 80/80/80. |
| UltraTemp 110 listed BTU capacity is 101,000 at 80/63/80. | UltraTemp 110 COP is 5.8 at 80/63/80. |
| UltraTemp 110 listed BTU capacity is 70,000 at 50/63/80. | UltraTemp 110 COP is 4.0 at 50/63/80. |
| UltraTemp 120Q listed BTU capacity is 127,000 at 80/80/80. | UltraTemp 120Q COP is 5.7 at 80/80/80. |
| UltraTemp 120Q listed BTU capacity is 120,000 at 80/63/80. | UltraTemp 120Q COP is 5.5 at 80/63/80. |
| UltraTemp 120Q listed BTU capacity is 80,000 at 50/63/80. | UltraTemp 120Q COP is 4.0 at 50/63/80. |
| UltraTemp 140 listed BTU capacity is 145,000 at 80/80/80. | UltraTemp 140 COP is 5.8 at 80/80/80. |
| UltraTemp 140 listed BTU capacity is 135,000 at 80/63/80. | UltraTemp 140 COP is 5.6 at 80/63/80. |
| UltraTemp 140 listed BTU capacity is 90,000 at 50/63/80. | UltraTemp 140 COP is 4.0 at 50/63/80. |
For your shortlist, mark the rating condition closest to the intended use conditions and retain the complete model name.
What happens during cold-weather operation?
The UltraTemp heat pump may enter a defrost cycle around 50°F (10°C) air temperature. For UltraTemp, defrost must be enabled in the Service Menus to enter a defrost cycle.
For the UltraTemp passive defrost cycle:
Passive defrost starts when the refrigerant sensor detects a temperature below the defrost set point.
The compressor stops during the passive defrost cycle.
During passive defrost, the evaporator fan draws air over the fins for about 15 minutes.
The unit shuts down with a “Low Ambient Temp” alarm if the defrost stop temperature is not reached within 15 minutes.
Which gas rating should you compare?
Heater input equals output divided by fuel source efficiency. Keep input, thermal efficiency, and output in separate fields when comparing the Raypak AVIA gas heater entries.
Scroll horizontally to read all columns.
| Listed input | Thermal efficiency | Listed output |
|---|---|---|
| AVIA Gas Heater 264 listed input is 264,000 BTU/HR. | AVIA Gas Heater 264 listed thermal efficiency is 84%. | AVIA Gas Heater 264 listed output is 221760 BTU/HR. |
| AVIA Gas Heater 404 listed input is 399,000 BTU/HR. | AVIA Gas Heater 404 listed thermal efficiency is 84%. | AVIA Gas Heater 404 listed output is 335160 BTU/HR. |
Use the output column when preparing the heating comparison. Carry the selected model’s operating instructions into the same review.
What winter limits apply to Pentair MasterTemp?
For the Pentair MasterTemp covered by its installation guide: For MasterTemp, water trapped in the heat exchanger can cause freeze damage. For MasterTemp, continuous operation below 68° F. (20° C) water temperature will cause harmful condensation. The MasterTemp guide instructs shutdown and winterization when air temperatures are expected below freezing (32° F/0° C).
Record the water-temperature condition and the air-temperature condition separately in the winter operating plan.
How should you size for your swimming schedule?
Pentair’s UltraTemp guidance describes heat pumps as best used to maintain a set water temperature. In the UltraTemp guidance, heat-pump output decreases when temperature drops at night. Gradual heating followed by temperature maintenance may allow a smaller heater. Sizing an outdoor pool heater includes determining the desired heat pickup time. Sizing an outdoor pool heater includes the average temperature of the coldest month of use.
Before comparing a heat pump with a gas heater, write down:
- The coldest intended-use month and its average air temperature.
- Pool surface area, volume, and current and target water temperatures.
- The desired warm-up interval and target temperature-rise rate.
- The swimming schedule and intended heating hours.
- Cover use and the pool’s exposure to wind.
- The exact heater model and its applicable rating conditions.
For gas equipment, use the Pentair installation checklist as a prompt for the installation review: For the heaters covered by Pentair’s checklist, check that heater and gas supply match. Pentair’s installation checks include gas supply pipe type and diameter. Pentair’s installation checks include inlet gas-valve pressure.
Take those inputs to the pool equipment list and continue with equipment pad planning. Choose the candidate to evaluate against your cold-season conditions and desired heating schedule.
Sources
- Pentair UltraTemp brochure
- Pentair Pool catalog, heaters and heat pumps
- Pentair UltraTemp Heat Pump Installation and User’s Guide
- Raypak Residential Pool Catalog
- ASHRAE Handbook, Service Water Heating
- Pentair MasterTemp Installation and User’s Guide
- Pentair Heater New Installation Checklist
- U.S. Department of Energy, Consumer Pool Heaters Final Rule Technical Support Document