Hayward is one of the three brands — alongside Raypak and Pentair — that most pool professionals reach for first, with a Universal H-Series gas lineup and a titanium HeatPro heat pump line that between them cover almost every residential pool size. Here’s how the current lineup breaks down by price and use case.
Quick answer
The Hayward Universal H-Series H400FDN natural gas heater (400,000 BTU) is our overall pick for larger in-ground pools that want fast, on-demand heat. If your priority is the lowest monthly electric bill, the HeatPro HP21405T heat pump uses a titanium microchannel heat exchanger tested to a COP around 5.7, meaning roughly $1 of electricity buys about $5.70 of heat, according to Hayward’s own AHRI 1160 spec sheet. For a smaller in-ground pool, the H150FDN (150,000 BTU) covers the same gas-heat convenience for less money, and the compact H100ID1 (100,000 BTU, plug-in 120V) is built for above-ground pools and spas rather than a full in-ground system.
Hayward pool heaters at a glance
| Model | Type | Output | Best for | Price |
|---|---|---|---|---|
| Hayward Universal H400FDN | Natural gas | 400,000 BTU | Best overall | ~$2,999-$3,999 |
| Hayward Universal H150FDN | Natural gas | 150,000 BTU | Best for smaller in-ground pools | ~$2,419-$2,799 |
| Hayward HeatPro HP21405T | Heat pump, titanium | 140,000 BTU | Lowest running cost | ~$6,500-$7,000 |
| Hayward H100ID1 | Natural gas, induced-draft | 100,000 BTU | Above-ground pools & spas | ~$1,290-$1,550 |
1. Hayward Universal H400FDN — Best Overall
Hayward Universal H-Series H400FDN Natural Gas Pool Heater
- Cupro-nickel heat exchanger with Low NOx combustion that meets SCAQMD Rule 1146.2, the strictest state emissions standard.
- Sized for larger in-ground pools (roughly 20,000+ gallons) where a smaller gas heater would take too long to bring the water up to temperature.
- 3-year parts / 1-year labor warranty from Hayward, extendable to 3-year labor through an authorized dealer.
- Heats fast on demand, unlike a heat pump, so it's the better pick if you swim on a schedule rather than heating continuously all season.
The H400FDN is Hayward’s largest residential natural-gas heater, and the extra BTU headroom over a 250,000-300,000 BTU model pays off most on bigger pools or when you want the water ready within an hour, not overnight. If you’d rather have the heater warm before you get home, try Amazon Prime free for 30 days so accessories and replacement parts arrive in two days instead of stalling a repair mid-heat-wave.
2. Hayward Universal H150FDN — Best for Smaller In-Ground Pools
Hayward Universal H-Series H150FDN Natural Gas Pool Heater
- Same cupro-nickel exchanger and Low NOx compliance as the H400FDN, in a smaller, lighter cabinet (about 135 lb vs. 195 lb).
- Right-sized for pools in the 8,000-12,000 gallon range rather than paying for BTU output you won't use.
- Also sold as the propane variant H150FDP for pools without a natural gas line.
If the H400FDN is more heater than your pool needs, the H150FDN delivers the same fast, on-demand gas heat for several hundred dollars less. Check our sizing chart before choosing between the two — undersizing a gas heater mostly costs you heat-up time, not efficiency, but it’s still worth matching the BTU tier to your actual gallon count.
3. Hayward HeatPro HP21405T — Best for Low Running Cost
Hayward HeatPro MCHX Series HP21405T Heat Pump
- Titanium microchannel heat exchanger comes standard across the whole HeatPro line, not as an upcharge option — a real advantage over gas heaters, which still ship with cupro-nickel by default.
- Tested to a COP around 5.7 under AHRI 1160 conditions, per Hayward's own HP21405T spec sheet, meaning roughly $1 of electricity buys about $5.70 of heat.
- Replaces the older non-MCHX HP21404T generation — if you're comparing prices online, some retailers and parts sites still list the discontinued HP21404T, so double-check you're pricing the current HP21405T.
- Needs a dedicated 240V circuit and, like any heat pump, heats slowly and loses efficiency below about 50°F air temperature.
The HP21405T costs more upfront than any of Hayward’s gas heaters, but a 5.7 COP means it uses a fraction of the energy per BTU of heat delivered over a full swim season. For anyone heating an in-ground pool continuously in a mild-to-warm climate, the electric-bill savings can close that price gap within a few seasons versus running gas full-time — see our pool heating cost breakdown for the month-by-month math. It’s the wrong choice for occasional or cold-weather heating; a gas heater or a solar cover pairs better with that use case.
4. Hayward H100ID1 — Best for Above-Ground Pools & Spas
Hayward H100ID1 Induced-Draft Natural Gas Heater
- Plugs into a standard 120V outlet — no dedicated electrical circuit, unlike Hayward's in-ground gas or heat-pump models.
- One-piece copper header and heat exchanger rated at 81% thermal efficiency.
- Sized for above-ground pools and spas, not a full in-ground pool — pair it with our [best above-ground pool heater](/best/best-above-ground-pool-heater/) guide for the full field of options at this size.
The H100ID1 is Hayward’s entry point into gas heating, and the plug-in 120V design skips the electrician visit an in-ground heater or heat pump usually requires. It’s also sold as the propane H100IDP1 for pools without natural gas service, though the propane version typically costs a few hundred dollars more due to the LP conversion hardware.
A naming change worth knowing: OmniX “HS” models
Hayward is currently transitioning the Universal H-Series to new “HS” SKUs (for example, W3HS150FDN replacing the H150FDN above) that add built-in OmniX smart control — app-based start/stop and scheduling without needing a full OmniLogic automation panel. As of this writing, both the plain FDN heaters and the OmniX HS versions are sold in parallel by major retailers, so you may see two Hayward listings at a similar BTU tier and price. They’re not different quality tiers — the HS version simply adds smart control on top of the same heat exchanger and burner. If app control matters to you, confirm you’re looking at the HS SKU before buying.
Hayward vs. Raypak vs. Pentair
All three brands make comparably reliable gas heaters and heat pumps, with similar parts and service availability nationwide. On heat pumps, Raypak’s newer Crosswind V 8550 now edges out Hayward’s HeatPro slightly on COP (6.0 vs. 5.7) while also costing meaningfully less — see our Raypak vs. Hayward comparison for the full price breakdown. Against Pentair, Hayward and Pentair’s gas and heat-pump lines trade wins depending on whether upfront price or peak efficiency matters more to you. If you already own Hayward pumps or automation, staying in-brand simplifies the install; otherwise, price and local parts availability are the deciding factors.
How to size a Hayward heater for your pool
Use roughly 15-20 BTUs per gallon for a gas heater and 5-7 BTUs per gallon for a heat pump — see our sizing chart for the full formula. A typical 20,000-gallon in-ground pool needs a 300,000+ BTU gas heater (the H400FDN’s 400,000 BTU covers this with room to spare) or a 120,000-140,000 BTU heat pump like the HP21405T. For exact monthly running-cost numbers by heater type, see our pool heating cost breakdown.
The bottom line
For most in-ground pools, the Hayward Universal H400FDN is the best all-around buy — fast heat at a fair price for larger pools. Step down to the H150FDN if your pool is smaller and you don’t need the extra BTU headroom, choose the HeatPro HP21405T if minimizing your monthly electric bill matters most, and pick the H100ID1 for an above-ground pool or spa where a full in-ground unit would be overkill. Weighing Hayward against the other two major brands? See our Raypak pool heater guide or Pentair MasterTemp guide for the full head-to-head. Moving a Hayward unit to a pad with a different gas service? Our pool heater conversion kit guide covers the Universal H-Series kit for switching between natural gas and propane.