A larger pool or a pool-and-spa combination that needs fast heat-up in any weather.
★★★★★ 230+ Google Reviews · CPO C-105377 · 40+ years of combined founder experience
Sizing comes first.The right heater is set by your pool's surface area and the temperature rise you want, and by the flow your pump and plumbing deliver. Start with the heater size calculator; we confirm it on site before quoting.
Our own score for what saves you money and headaches in South Florida.
H400FDP
4.3
out of 5
From the manufacturer's documents listed under Sources. Where the documents disagree, the table says so.
| 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. |
Parts
3 years
Labor
1 year
Heat exchanger
Under the parts term
| Parts | 3 years |
|---|---|
| Labor | 1 year field labor (3 years when sold by a Hayward Rewards dealer) |
These are the manufacturer's published terms. Terms can depend on the installer, the dealer program and where the heater was bought, and they change without notice, so we confirm the exact term for your install on the written quote.
Copper alloyed with nickel gives up a little heat transfer in exchange for much better resistance to unbalanced water chemistry and salt. On a gas heater this is the upgrade worth having near the coast.
See every material side by side on the comparison page, or read the Hayward H-Series and HeatPro error codes guide for what the display is telling you.
Most to least forgiving of salt and unbalanced water.
Pentair · ETi
A high-use pool or pool-and-spa where fuel cost decides it, and a pad that can handle a condensing heater's condensate drain.
Automation relay (no heater app)
Jandy · JXiQ
A larger pool or a pool-and-spa combination that needs fast heat-up in any weather.
App control through automation
Raypak · AVIA HD with NiTek
A larger pool or a pool-and-spa combination that needs fast heat-up in any weather.
Built-in Wi-Fi
Every figure on this page comes from these manufacturer documents. We re-open each one and match the model number, capacity and efficiency before the date moves. How we verify.
| Document | Type | Last checked |
|---|---|---|
| Hayward — H400FDP product pagehayward.com | Product page | October 14, 2026 |
| Hayward — Universal H-Series brochure (spec table, thermal efficiency, exchanger)hayward.com | Spec sheet or brochure | October 14, 2026 |
| Hayward — Universal H-Series Quick Reference Guide (flow, gas pressure, power selection, diagnostic codes)hayward.com | Manual or guide | October 14, 2026 |
| Hayward — 2026 Expert Line residential warranty termscommerce.hayward-pool-assets.com | Warranty terms | October 14, 2026 |
| Hayward — warranty resource page (Expert Line vs Open Line, Hayward Rewards)hayward.com | Warranty terms | October 14, 2026 |
Manufacturers revise terms without notice. Treat this page as a starting point and confirm the current terms before you buy. If something here is out of date, tell us and we'll fix it.
Parts: 3 years. Labor: 1 year field labor (3 years when sold by a Hayward Rewards dealer). These are the manufacturer's terms as published; warranty terms change and can depend on the installer and the channel, so we confirm the exact term for your install on the written quote.
The H400FDP is rated at 399,900 BTU/hr input. Heater size comes from your pool's surface area and the temperature rise you want, not from gallons, and the pump and plumbing have to deliver the flow the heater needs. Use our heater size calculator for a starting number, and we confirm it on site before quoting.
Only through a compatible automation system. The H400FDP has no Wi-Fi of its own, so the app control comes from the automation system it's wired to.
Copper alloyed with nickel gives up a little heat transfer in exchange for much better resistance to unbalanced water chemistry and salt. On a gas heater this is the upgrade worth having near the coast.
Every figure on this page comes from the manufacturer's own documents, listed under Sources with the date we last checked them. Manufacturers revise terms without notice, so treat the page as a starting point and confirm the current terms on your quote.
We quote, install and service Hayward heaters across Palm Beach and Broward, managed by us under our Florida Certified Pool/Spa Contractor license (CPC1461731). You get a free on-site sizing visit and one written price. Gas lines, new circuits and refrigerant work are done by licensed contractors we manage.
We call back within 30 minutes during business hours.
