Product Overview

Bring fast, dependable heating and modern smart control to your pool or spa with the Hayward Universal H-Series Natural Gas Heater with OmniX 400K | HS400FDN. Delivering approximately 400,000 BTU of heating power, this high-capacity heater is designed for in-ground swimming pools and pool/spa combinations that require fast temperature recovery, durable construction, and advanced automation compatibility.

The HS400FDN combines Hayward’s proven Universal H-Series heating platform with the new OmniX embedded intelligence and Universal Display. This provides enhanced programmability, advanced diagnostics, intuitive equipment control, and connected functionality through the Hayward OmniX ecosystem.

A durable cupro-nickel heat exchanger provides excellent resistance to corrosion and premature wear, while Hayward’s totally managed water-flow system helps maximize hydraulic efficiency. Low NOx emissions meet applicable clean-air requirements, making this an excellent choice for both new installations and replacement applications.

Key Features

• 400,000 BTU class natural gas heater
• Manufacturer model HS400FDN
• Built-in OmniX smart control technology
• Hayward Universal Display
• Advanced diagnostics and programming
• Remote connectivity capability
• Durable cupro-nickel heat exchanger
• 84% thermal efficiency
• Low NOx emissions
• Forced-draft combustion
• Silicon nitride hot-surface ignition
• Totally managed water-flow system
• Front-panel-only service access
• Universal left or right electrical connection
• Designed for easy replacement installations
• Compatible with Hayward Omni automation and other supported automation platforms

Product Specifications

OmniX Smart Control

One of the biggest upgrades to the HS400FDN is OmniX embedded intelligence. The heater’s Universal Display provides an intuitive interface while OmniX technology offers enhanced scheduling, temperature management, equipment communication, and advanced system diagnostics.

When properly configured with compatible Hayward equipment and connectivity components, the heater can be incorporated into the Hayward OmniX app ecosystem for convenient pool and spa management.

Built for Durability

The standard cupro-nickel heat exchanger provides increased resistance to corrosion and premature failure caused by challenging pool environments and water chemistry.

Hayward’s forced-draft combustion system also helps maintain reliable combustion performance, while Low NOx operation reduces emissions.

Frequently Asked Questions

Is the HS400FDN a natural gas heater?

Yes. HS400FDN is specifically designed for natural gas. Customers requiring propane should select the corresponding propane model.

How many BTUs is the HS400FDN?

It has a rated input of approximately 399,900 BTU/hr, commonly marketed as a 400K BTU heater.

Does the HS400FDN have OmniX?

Yes. This model features OmniX embedded intelligence and Hayward’s Universal Display.

Can I control this heater from my phone?

The OmniX platform supports connected/app-based functionality when the system is properly configured with the required Hayward connectivity and network components.

Does it have a cupro-nickel heat exchanger?

Yes. The HS400FDN includes a cupro-nickel heat exchanger as standard equipment.

What is the required water flow?

Hayward specifies a minimum flow of approximately 30 GPM and a maximum of 125 GPM.

Can this replace an older Hayward H400FDN?

The Universal H-Series platform is specifically designed to simplify replacement installations and is compatible with Hayward plumbing adapters. Existing gas, plumbing, electrical, venting, and code requirements should still be verified before installation.

Can this heater be installed indoors?

Indoor installations require proper venting and must follow Hayward instructions as well as all applicable local building, gas, and electrical codes.

Is professional installation required?

Professional installation by a qualified pool-heater or gas technician is strongly recommended. Proper gas sizing, ventilation, water flow, electrical connections, and combustion setup are critical for safe operation and warranty coverage.