Universal H-Series Natural Gas 135K BTU Low NOx (Cupronickel)

Choosing the correct pool heater depends on pool size, desired heat-up time, climate, and heater type. Undersized heaters struggle to maintain temperature; oversized heaters heat faster with less runtime.

Heater Types Explained

Gas Pool Heaters (Natural Gas or Propane)

• Fastest heat-up
• Works in any climate
• Higher operating cost

Best for: Quick heating, spas, occasional use

Electric Heat Pumps

• Most energy-efficient
• Slower heat-up
• Performance depends on air temperature

Best for: Warm/moderate climates, consistent heating

Solar Pool Heaters

• Lowest operating cost
• Weather dependent
• Slowest heat-up

Best for: Supplemental heating, sunny regions

BTU Requirements for Natural Gas and Propane
Based on Dimensions and Surface Area (sq. ft.)

BTU Requirements for Heat Pumps
Based on Gallons

Hourly Temperature Increase
Based on Surface Area (sq. ft.) and BTU

Gas Supply & Electrical Requirements (Very Important)

Gas Heaters

• Must verify gas line size and meter capacity
• Undersized gas supply = poor performance or ignition issues

Heat Pumps

• Require dedicated breaker
• Higher amperage draw
• Longer electrical run considerations

⚠️ Heater sizing is meaningless if utilities are undersized.

Factors That Increase Heater Size Needs

You may need a larger heater if your pool has:

• Attached spa
• Waterfalls or spillovers
• High wind exposure
• Night swimming
• Minimal sun exposure
• Short heating windows (weekends only)

Common Heater Sizing Mistakes

❌ Choosing smallest BTU to save money
❌ Ignoring climate and wind
❌ Forgetting spa heating needs
❌ Not checking gas or electrical supply

✅ Size for how fast you want heat, not just pool volume

Replacing an Existing Heater?

Check the heater data plate for:

• BTU input
• Gas type (NG / LP)
• Voltage & phase
• Min/max flow rate

If upgrading, going one size larger almost always improves satisfaction.

If you’re unsure, contact us and we’ll help you choose the correct heater.