Hayward H250 Pool Heater Natural Gas 250K BTU
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✓ Includes Manufacturer Warranty
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The W3H250FDN is a natural gas pool heater built for in-ground pools and spas on Hayward's Universal H-Series platform. It delivers 250,000 BTU/hr of heating output, operates in low ambient temperatures down to 40 degrees F, and connects via 2" x 2-1/2" CPVC union fittings that simplify new installs and replacement jobs. The forced-draft combustion system and low NOx design also qualify it for use in stricter air quality regions including SCAQMD Rule 1146.2 jurisdictions.
W3H250FDN Universal H-Series Natural Gas Pool Heater - Specs and Features
The W3H250FDN ships factory-wired for 240V single-phase, 60 Hz power but can be field-converted to 120V by swapping a jumper on the ignition control board. It draws only 5.5 circuit amps with a 15-amp maximum breaker - a minimal electrical footprint for a 250K BTU unit. It supports water flow between 25 and 125 GPM and uses a cupro nickel heat exchanger rated for salt water and chemically demanding pool environments. The cabinet measures 24" H x 25" W x 29.5" L and weighs 165 lb - noticeably lighter and narrower than the 400K BTU model, which helps on tighter equipment pads.
W3H250FDN Installation and Clearance Requirements
The W3H250FDN requires 6 inches of rear clearance and 12 inches on each side. The forced-draft design eliminates the need for a high-wind stack, which simplifies positioning in enclosed or semi-enclosed equipment areas. Plumbing connects via 2" x 2-1/2" CPVC union fittings. Before setting the pad, confirm your natural gas meter capacity and supply line sizing are sufficient - a 250K BTU heater draws significant gas volume, and undersized piping or a low-capacity meter will cause performance problems at startup.
Universal H-Series Combustion System and Pool Sizing
The Universal H-Series platform uses a forced-draft combustion design that pushes air through the chamber at a controlled rate regardless of wind conditions. That removes stack dependency and keeps combustion consistent across installation environments. Hayward's hydraulic design maintains uniform water velocity across all heat exchanger tubes, which produces faster heat-up times and reduced pump run time - Hayward rates that advantage at up to 18% compared with less efficient gas heater designs. At 250,000 BTU/hr, this unit is well matched for pools in the 20,000 to 50,000 gallon range in moderate climates, with longer heat-up times on the larger end.
Cupro Nickel Heat Exchanger and Salt Water Resistance
The W3H250FDN uses a standard cupro nickel heat exchanger, which handles salt water and aggressive pool chemistry better than standard copper alternatives. For pools running salt chlorine generators or elevated sanitizer levels, this is a meaningful spec - heat exchanger corrosion is one of the more common failure points on gas heaters over time. The cupro nickel material also holds up well in coastal installs where airborne salt adds to the chemical load on the unit.
W3H250FDN vs. W3H400FDN - Choosing the Right BTU for Your Pool
The W3H250FDN and W3H400FDN run on the same Universal H-Series platform with identical electrical, clearance, and plumbing requirements - the difference is output. The 250K model is the right fit for most residential in-ground pools up to around 50,000 gallons in warm climates. Step up to the 400K BTU model if you have a large pool over 50,000 gallons, a pool-spa combination that needs fast spa recovery, or a pool in a colder climate where more BTUs help offset heat loss. If your site runs propane instead of natural gas, the W3H250FDP is the LP equivalent of this model on the same platform.
| Specification | Value |
|---|---|
| Brand | Hayward |
| Model / SKU | W3H250FDN |
| Series | Universal H-Series |
| Fuel Type | Natural Gas |
| Application | New Construction, Renovation |
| Pool Type | In Ground |
| Heating Capacity | 250,000 BTU/hr |
| Kilowatts | 73 kW |
| Heat Exchanger | Standard cupro nickel |
| Low NOx | Yes |
| Cooling Capability | No |
| Low Ambient Operation | Yes |
| Minimum Operating Temperature | 40 degrees F |
| Voltage | 120/240V (ships 240V; field-convertible to 120V) |
| Phase | Single |
| Frequency | 60 Hz |
| Circuit Amps | 5.5 |
| Maximum Breaker Size | 15 Amps |
| Water Flow Rate | 25 to 125 GPM |
| Plumbing Connections | 2" x 2-1/2" CPVC union |
| Rear Clearance | 6" |
| Side Clearance | 12" |
| Product Dimensions (H x W x L) | 24" x 25" x 29.5" |
| Product Weight | 165 lb |
| Shipping Dimensions | 30.6" x 32.8" x 33.3" |
| Shipping Weight | 171 lb |
| Refrigerant | No |
| Active Defrost | No |
| Boost Mode | No |
| Silent Mode | No |
| Channel | Open Line |
| GTIN | 610377387231 |
Frequently Asked Questions
Is this unit for natural gas or propane?
Natural gas. The W3H250FDN is configured for natural gas only. If your site runs propane, you need the W3H250FDP instead. The two are not interchangeable without a conversion, which should be performed by a licensed technician.
What size pool can a 250,000 BTU heater handle?
At 250,000 BTU/hr, this unit is well matched for in-ground pools in the 20,000 to 50,000 gallon range in moderate climates. Larger pools or colder climates will see longer heat-up times on the high end of that range. If you have a large pool over 50,000 gallons or need fast spa recovery, the W3H400FDN may be a better fit.
What type of pool is this heater made for?
In-ground pools and spas. It works on both new construction and renovation jobs, and the CPVC union connections make it a practical swap for older H-Series units already plumbed with those fittings.
What electrical service does the W3H250FDN require?
It ships wired for 240V single-phase, 60 Hz with a 15-amp maximum breaker, drawing only 5.5 circuit amps. It can be field-converted to 120V by swapping a jumper on the ignition control board - see the installation manual for that procedure. Either way, the electrical draw is minimal since most of the energy comes from the gas supply, not the grid.
Why does the cupro nickel heat exchanger matter for salt pools?
Salt water is more corrosive to standard copper than to cupro nickel alloy. On a gas heater that runs at high temperatures, exchanger corrosion accelerates faster than on heat pumps, so the material choice has real long-term impact. Cupro nickel holds up better in salt systems and in pools that run higher sanitizer levels.
Does this heater need a special vent stack or chimney?
No. The forced-draft system pushes combustion air through the chamber mechanically, so performance is not dependent on wind or stack height. Indoor and semi-enclosed installations still require proper venting - see the installation manual linked below.
Does the W3H250FDN meet low NOx requirements?
Yes. It meets Low NOx clean air standards including SCAQMD Rule 1146.2, which applies in parts of Southern California and some other air quality districts. If your municipality requires low NOx compliance for pool heaters, this model qualifies.
W3H250FDN Warranty, Manuals, and Install Documentation
The W3H250FDN includes a 1-year parts warranty with no labor coverage. Review the installation manual before any work begins to confirm gas supply, venting, and clearance requirements are met at the site.