Hayward Universal H-Series H400FDP Propane Pool Heater
A large pool or a pool-and-spa combination on a lot with no gas main, where fast heat matters more than the cost of the propane it burns.
Gas heater
SKU H400FDP
- BTU input
- 399,900 BTU/hr
- Fuel / power
- Propane
- Thermal efficiency
- 84% thermal efficiency
- Heat exchanger
- Cupro-nickel
- Warranty
- Parts: 3 years · Labor: 1 year field labor (3 years when sold by a Hayward Rewards dealer)
- Controls & automation
- Onboard control pad with a two-digit temperature display and separate pool and spa setpoints; app control when connected to a Hayward Omni control system.
Modern Pool Heating Equipment Score
Our score for the equipment itself. It is not a Google or customer review rating.
How we rate heatersFull specifications
Every row below is taken from a manufacturer document. Anything the manufacturer does not publish is left out rather than estimated.
| Manufacturer product name | Universal H-Series Heater 400,000 BTU - Propane Gas, Low NOx |
|---|---|
| BTU input | 399,900 BTU/hr per Hayward's Universal H-Series brochure; the product page rounds it to 400,000 BTU |
| Thermal efficiency | 84% |
| Fuel | Propane (H400FDN is the natural gas version) |
| Propane consumption | About 4.5 gallons per hour of operation, per Hayward's product-page Q&A |
| Heat exchanger | Cupro-nickel, standard on all models |
| Emissions | Low NOx; meets SCAQMD Rule 1146.2 |
| Water connections | 2" x 2-1/2" CPVC unions |
| Gas connection | 3/4" NPT |
| Water flow | 30 GPM minimum, 125 GPM system maximum |
| Gas pressure (propane) | 10.0" w.c. minimum inlet, 13.0" w.c. maximum inlet, 7.0" w.c. manifold |
| Indoor vent pipe | 8" diameter (propane) |
| Clearances | 6" rear, 12" sides |
| Minimum operating temperature | 40°F |
| Electrical | Field-selectable voltage plug: 110-130 VAC, 2 A or 220-250 VAC, 1 A (240 VAC factory default). Hayward's product page lists 120/240V, 1 phase, 60 Hz, 5.5 circuit amps, 15 A maximum breaker. |
| Dimensions and weight | 24" H x 34" W x 29.5" L; 195 lb per the product page (the 2023 Universal H-Series brochure lists 160 lb for the same cabinet) |
| Certification | Certified by the Canadian Standards Association |
| Controls and automation | Onboard control pad with protective cover, two-digit display, separate pool (90°F default maximum) and spa (104°F default maximum) setpoints; controllable through a Hayward Omni control system. |
Why homeowners consider it
- It is the propane build of the H400FDN: same cabinet, same cupro-nickel exchanger, same 84% thermal efficiency, and the same fast recovery that makes gas worth having on a spa.
- This is the size that makes a spa practical. Hayward's own table puts the H400 at about 18 minutes to raise a 400-gallon spa by 30°F, which no heat pump can approach.
- Cupro-nickel comes standard rather than as a paid upgrade, which is the right exchanger for a salt pool and for the coastal lots where propane tanks are common.
- The heater takes the same 2 inch by 2-1/2 inch CPVC unions and front-panel service access as the rest of the line, so it drops into an existing pad and a future repair does not mean moving the unit.
- Hayward publishes real numbers for this one: its product-page Q&A states the H400 burns about 4.5 gallons of propane per hour of operation, which lets you budget the fuel instead of guessing.
What to know before buying
- Fuel cost is the headline. At roughly 4.5 gallons an hour at full fire, a 400,000 BTU/hr propane heater is the most expensive way to heat a pool on this site. Used the way gas is meant to be used — on demand, for a spa or a weekend — that is manageable; used as an everyday winter pool heater it is not.
- Propane needs more inlet pressure than natural gas: Hayward specifies a minimum inlet of 10.0 inches w.c. and a maximum of 13.0 inches w.c., with 7.0 inches w.c. at the manifold. Regulator and line sizing for 400,000 BTU/hr through a 3/4 inch NPT connection have to be right, or ignition faults follow.
- It needs a minimum of 30 GPM through the heat exchanger, with a 125 GPM system maximum. On a variable-speed pump the heating speed has to be set high enough to satisfy the water pressure switch.
- The cabinet is 34 inches wide and 195 pounds on Hayward's product page (its 2023 brochure lists 160 pounds for the same cabinet), with 6 inches of rear and 12 inches of side clearance required, and a 40°F minimum operating temperature. Indoor propane installations need an 8 inch vent pipe.
- Standard Expert Line coverage is 3 years parts and 1 year field labor; 3 years of field labor applies only when the heater is sold by a Hayward Rewards dealer, and the W3-prefixed online version is an Open Line SKU with 1 year parts and no labor.
- If you want the heater itself to be the smart device — app control, remote diagnostics, no separate automation panel — the OmniX equivalent is the HS400FDP.
Warranty, term by term
The warranty only matters on the parts that actually fail. Here is how this one splits up.
- Parts
- 3 years
- Labor
- 1 year field labor (3 years when sold by a Hayward Rewards dealer)
Hayward's 2026 Expert Line residential terms cover in-ground products at 3 years parts and 1 year field labor as standard, extended to 3 years field labor when the heater is sold by a Hayward Rewards dealer (the program formerly branded Totally Hayward). There is no separate longer heat-exchanger term — the cupro-nickel exchanger is covered under the parts warranty as original equipment, while a heat exchanger bought later as a replacement part carries 1 year parts only with no labor. Heating elements and o-rings are treated as normal wear items. Hayward states its limited warranties apply only to product bought from Hayward or a Hayward authorized seller, and the W3-prefixed version of this heater is an Open Line SKU carrying 1 year parts only with no labor coverage. Professional installation and authorized-channel requirements may apply. The commercial ASME variant has its own warranty document, which we have not verified.
Why the heat exchanger matters
The heat exchanger is the part of a pool heater that actually moves heat into the water, and what it is made of decides how long the heater survives Florida water chemistry. Here is what the four materials mean in practice.
- Copper
- The traditional material and the cheapest to build. It transfers heat well and is fine on a well-balanced chlorine pool, but it is the least forgiving of low pH, high chlorine and salt. On the Gulf Coast it is usually the first component to fail.
- Cupro-nickelThis heater
- Copper alloyed with nickel. It gives up a little heat transfer in exchange for much better resistance to unbalanced water chemistry and salt. On gas heaters this is the upgrade worth having in Florida, and some manufacturers now ship it as standard.
- NiTek (nickel alloy)
- A nickel-alloy exchanger used on some gas heaters as a corrosion-resistant alternative to copper. Positioned between cupro-nickel and titanium in both durability and price.
- Titanium
- Effectively immune to pool water chemistry, including salt. It is the standard on quality pool heat pumps and the reason a heat pump can sit on a salt pool for years without exchanger trouble. It is expensive, which is why you rarely see it on gas heaters.
Whatever the material, plumbing order matters just as much: a chlorinator or salt cell belongs downstream of the heater, never upstream.
How we scored it
- Warranty matches the rest of the line: 3 years parts, 1 year field labor standard and up to 3 years field labor through a Hayward Rewards dealer. Held back from a 5 by the channel condition.
- Cupro-nickel standard is what carries the durability score; it is the same exchanger as the natural gas version and the right one for salt pools.
- 84% thermal efficiency is the top of Hayward's published table and is unchanged on propane — what changes is the price of the fuel, not how much of it reaches the water.
- Serviceability scores a 5: front-panel-only access, universal unions, a published diagnostic code list and parts stocked across Florida.
- Controls lose a point because app control requires a Hayward Omni system rather than being embedded, as it is on the HS400FDP.
- Value rates the equipment against its installed price, which is strong. The running cost of propane at roughly 4.5 gallons an hour is a separate decision and is covered in 'What to know before buying'.
Real Modern Pool Heating installations
Installed locally, researched for everyone
Affordable Solar & Pool Heating, LLC installs and services pool heating in Sarasota, Manatee, Charlotte & Pinellas County, Florida. If you are outside that area this page is still yours to use — take the questions on it to your local contractor. Pool heater installation in Sarasota.
Other heaters worth putting beside it
Same job, different tradeoffs. Every one of these has its own verified spec page.
Hayward · Universal H-Series
Hayward Universal H-Series H400FDN Gas Pool Heater
Model H400FDN
- BTU input
- 399,900 BTU/hr
- Thermal efficiency
- 84%
- Heat exchanger
- Cupro-nickel
- Warranty
- 3-Year Parts / 1-Year Labor
- Wi-Fi / automation
- App Control via AutomationAutomation Compatible (Relay)
A large Florida pool, or a pool and spa combination, that needs to reach temperature on demand rather than hold it all season.
Pentair · MasterTemp HD
Pentair MasterTemp 400HD Heavy Duty Gas Pool Heater
Model MasterTemp 400HD
- BTU input
- 400,000 BTU/hr
- Thermal efficiency
- 82%
- Heat exchanger
- Cupro-nickel
- Warranty
- 2-Year Parts & Labor
- Wi-Fi / automation
- Automation Compatible
A large salt-water or coastal pool, or a pool and spa that gets used hard, where the exchanger material matters more than the last two points of efficiency.
Jandy · JXi
Jandy JXi400N Gas Pool & Spa Heater
Model JXI400N
- BTU input
- 399,000 BTU/hr
- Thermal efficiency
- 84%
- Heat exchanger
- Copper
- Warranty
- 1-Year Parts
- Wi-Fi / automation
- App Control via AutomationAutomation Compatible
A large Gulf Coast pool, or a pool and spa combination, where the spa needs to be ready in under an hour and the equipment pad has no room to spare.
H400FDP questions
How much propane will a 400,000 BTU pool heater use?
Hayward's own product-page Q&A states the H400 burns about 4.5 gallons per hour of operation. How many hours it runs is the variable: a pool that is 10°F below setpoint on a cold morning will run for hours, while holding a warm pool at temperature cycles the burner far less. Budget the fuel before you buy, because this is the most expensive heat on this site per degree.
Should I get propane gas or an electric heat pump?
If you have an attached spa or you only heat occasionally, propane gas usually wins because it heats fast and only costs money when it is running. If you swim most weeks of the year and want a steady temperature, an electric heat pump will cost a fraction of the propane to run. A lot of Gulf Coast homes end up with a heat pump for the pool and gas for the spa.
Is the propane version otherwise identical to the H400FDN?
Yes, apart from the gas valve, orifices, gas pressure requirements and the indoor vent pipe diameter. Input, thermal efficiency, cupro-nickel exchanger, plumbing connections, flow requirements, clearances and warranty are the same.
Will it heat a spa quickly?
That is what it is for. Hayward's published table puts the H400 at about 18 minutes to raise a 400-gallon covered, insulated spa by 30°F. Real spas lose heat to their walls and surroundings, so treat that as a floor rather than a promise.
What does the warranty actually cover?
Hayward's 2026 Expert Line residential terms give 3 years parts and 1 year field labor, with 3 years field labor when the heater is sold by a Hayward Rewards dealer. There is no separate heat-exchanger term, heating elements and o-rings are wear items, and the W3 version sold online carries 1 year parts only with no labor.
Do you install propane pool heaters in Sarasota?
Yes. We install and service propane and natural gas pool heaters throughout Sarasota, Manatee, Charlotte & Pinellas County, Florida, and we coordinate with the propane supplier on tank sizing and placement. This comparison content is written for pool owners anywhere; the installation offer is local.
Is the H400FDP right for your pool?
We install and service pool heating in Sarasota, Manatee, Charlotte & Pinellas County, Florida. If you are outside that area, the comparison above is still yours to use — ask your local contractor the same questions.
Licensed & insured · Florida Certified Pool/Spa Contractor #CPC1460367 · Mon-Sat, 8am-6pm
Last verified September 17, 2026
Specifications and warranty terms are taken from the manufacturer documents below. Manufacturers revise these without notice, so confirm the current terms before you buy. If you spot something out of date, email us and we will fix it.
Sources
- Hayward — H400FDP product page
- Hayward — Universal H-Series brochure (spec table, thermal efficiency, exchanger)
- Hayward — Universal H-Series Quick Reference Guide (flow, gas pressure, power selection, diagnostic codes)
- Hayward — 2026 Expert Line residential warranty terms
- Hayward — warranty resource page (Expert Line vs Open Line, Hayward Rewards)
Ratings on this site are the editorial opinion of Affordable Solar & Pool Heating, LLC, trading as Modern Pool Heating. How we rate heaters. Corrections: modernpoolheating@icloud.com.
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Mon-Sat, 8am-6pm · Licensed & insured · Florida Certified Pool/Spa Contractor CPC1460367