Hayward W3H400FDN Universal H-Series 400,000 BTU Natural Gas Pool and Spa Heater for In-Ground Pools and Spas
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Availability:
In Stock.
Arrives
Jun 17 – Jun 18
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Size: 400,000 BTU (W3H400FDN)
Features
- The Hayward Universal H-Series 400,000 BTU Natural Gas Heater delivers premium heating performance for years of reliable, long-lasting comfort
- A durable cupro nickel heat exchanger offers exceptional protection against corrosion and premature failure caused by unbalanced water chemistry
- Industry-leading hydraulic design reduces circulation pump run time to provide major energy savings
- Front-panel-only access and intuitive control pad provide easy operation, service and maintenance
- Low NOx emissions meet air quality standards in all low-NOx areas, ensuring low environmental impact
Description
The Universal H-Series 400,000 BTU Natural Gas Pool & Spa Heater from Hayward provides reliable, long-lasting comfort for pools and spas with a surface area up to 1,200 ft. Built with a durable cupro nickel heat exchanger, it offers exceptional protection against corrosion and premature failure caused by unbalanced water chemistry, ensuring you get season after season of premium heating performance. The Universal H-Series boasts industry-leading hydraulic performance coupled with lightning-fast speed-to-heat capability—so you spend less time waiting, and more time swimming. Its low NOx emissions meet air quality standards in all low-NOx areas, so you can rest easy knowing its environmental impact is low, too.
Product Dimensions: 39.6 x 32.8 x 30.6 inches
Item Weight: 195 pounds
Manufacturer: Hayward
Item model number: W3H400FDN
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Jun 17 – Jun 18
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Similar Products
Top Amazon Reviews
Size: 400,000 BTU (W3H400FDN)
Received on time works excellent have not had problems have had it a year now
Reviewed in the United States on May 24, 2025 by Tom c
Size: 250,000 BTU (W3H250FDN)
We recently installed this heater to go with our Core 35 which is $1,400.00 itself to convert to a pool salt system. Usually our pool is cloudy but since going to salt it’s cleared up considerably. We decided to install a heater after talking about doing so for years now as the pool is almost always cloudy during the summer and Generally we can only swim May - September due to the water getting to chili in October- April. We are hoping with this heater to extend our swimming season to 11 months out of the year. It took roughly 4 days to install it So it was a little hard to hook up we had to run gas lines literally all over the side of our house and through our attic and underground to get to our heater as you can see from the pictures. We tested it out the first night and overnight it warmed our pool from 65* to 80*F, Def can feel the warm water coming out of the jets. Looking forward to trying this out more in October and November when temperatures really drop down but so far I’m pleased with it. Spent roughly $1,200.00 in labor to get the work done and another $800 in parts, like gas line pipes, fittings plumbing and valves… thankfully lowes was able to cut and put the fittings on our gas lines for us but I would say this is a minimum $4,500.00 project undertaking perhaps a bit more if using a pool company, professional plumber or if you live in a big city. We got the 250,000 btu heater and our pool is roughly 22,500 gallons which maybe overkill but wanted to go to big rather than to small on a nice heater…Just wanted to throw that out there for anyone considering getting one installed. That price includes the cost of the unit. The unit really isn’t loud. Update we have had it a little over a week now and we love it! We are in the pool almost daily now. I generally keep the heater on 78* degrees and when I get off work and home around 530pm I’ll cracked it up to 104* and by 7:30pm it’s over 94*! Talking about nice and relaxing I could literally sit in the pool as if it were a hot tub! Updated after a month we are in October now and still like the heater. Gas bill was about $60 more than it normally is for this time of the year and we generally keep the heater on 82F in the pool. One issue we have had is the heater will show the code LO every now and then and will go into a protection mode and will not work until you backwash and let the pressure out
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Reviewed in the United States on September 16, 2022 by wkmgator wkmgator
Size: 250,000 BTU (W3H250FDN)
I am very pleased with this heater. Delivery took a little longer than originally anticipated but the communications were consistent if not necessarily the answers I wanted, I did always get an accurate answer. I would attribute it to the hang ups with LTL Trucking in general. I honestly can not fault the vendor, they seemed to be hobbled by the difficulties from the trucking industry. They always did respond. The installation is for an 15 x 30 that goes from 3 to 8 feet deep, in ground pool in the Midwest. I intentionally Oversized the heater because we don't plan on maintaining the temperature, but will fire up the heater prior to when we plan on using the pool. All of the calculations indicated that 150K BTU was sufficient but with the 250K BTU heater I am able to bring up the temperature 1.5 to 2 degrees per hour. So far this theory seems to be working out for us. If during the week the lows are in the high 60's and the highs are in the high 70's to low 80's on Friday after noon or Saturday early morning we can have the pool a pleasant 85 degrees for Friday after work or Saturday late morning. The old heater was removed a couple of years ago and just replaced. But so far it is tough to tell exactly what it has cost to operate because of the overall increase in utility bills, but to date not awful. The installation manual is complete and easily followed but the processes do require significant plumbing, both Gas and Water, and an electrical connection, which may not be present if you are replacing an older milivolt type heater. Fortunately I have done a lot of this type of work over the years and owned the tools and had the skill to complete the installation over the better part of a Saturday afternoon with a few trips to the hardware store. Our pool guy understandably didn't want to install a heater that he didn't sell. I am sure that if we had wanted to we could have hired an Electrician to hook up the electrical and a plumber for the gas and water and still been $$ ahead. The down side is that the policy of the MFG is that the warranty is only valid if installed by one of their Dealer's installers. We have had no issues so far and will cross that bridge if it comes up. ****only lasted one season and now it is rusted inside and junk. We are out 3,000.00 and company will not help us. I should have listed to the other reviews.
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Reviewed in the United States on August 22, 2022 by SEF SEF
Size: 400,000 BTU (W3H400FDN)
Fast delivery, great pool heater. I would recommend to my family and friends.
Reviewed in the United States on May 10, 2025 by Steve Bumgardner
Size: 150,000 BTU (W3H150FDN)
Unit had an AO reading as soon as it was installed, faulty blower switch . Hayward ‘s warranty techs were booked 2-3 months out. This company did not step in to help, they tried to pass bill onto Delivery company . I ended up paying my own tech 250.00 to repair brand new unit instead of 150 to uninstall to return and 350 more to put in new unit. Unethical sellers , no help from Amazon here either. Buy elsewhere!!!!!!! Update. The company ended up, reimbursing me for the labor.
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Reviewed in the United States on March 17, 2023 by Nancy Jafari
Size: 400,000 BTU (W3H400FDN)
Excellent service, ordered on Thursday and arrived the following Tuesday. Only 5 days, well packaged in excellent condition.
Reviewed in the United States on May 6, 2025 by Sergio
Size: 400,000 BTU (W3H400FDN)
AOK
Reviewed in the United States on May 17, 2025 by T Bullock
Size: 400,000 BTU (W3H400FDN)
Good product
Reviewed in the United States on April 21, 2025 by Amazon Customer