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Home Hayward Universal H-Series Low NOx Induced Draft Pool & Spa Heater | 400,000 BTU | Natural Gas | W3H400FDN
NOTICE: The pool & spa industry continues to face industry-wide shortages on many products that most vendors expect to last late into 2022. We're allowing items to be purchased so that customers who choose to wait will have their order shipped when product is available. Most vendors are not providing any ETA on when items will be available. WE WILL EMAIL YOU RIGHT AWAY IF YOUR ITEM IS BACKORDERED. 

Hayward Universal H-Series Low NOx Induced Draft Pool & Spa Heater | 400,000 BTU | Natural Gas | W3H400FDN

Hayward Universal H-Series Low NOx Induced Draft Pool & Spa Heater | 400,000 BTU | Natural Gas | W3H400FDN
Sale $3,799.00
$3,399.00

Quantity:
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Platinum Preferred Manufacturer
  • Part of the Hayward Energy Solutions family of products
  • Digital LED Control Panel
    Electronic control/display maintains water temperature; monitors heater performance with self-diagnostic capability

  • Cupro Nickel Heat Exchanger Totally Managed Flow provides exceptional corrosion resistance and erosion protection. Ideal for today’s salt-based electronic chlorination systems
  • Online part number W3H400FDN is the direct replacement for part number H400FDN.
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OVERVIEW
The Hayward Universal H-Series gas heater is the "universal" energy efficient remedy for any new or existing pool or spa. An industry leading hydraulic design reduces circulation pump run time to provide energy savings of up to 18% when compared to less efficient competitors. The energy efficiency of the Universal H-Series gas heater combines with environmentally friendly low NOx emissions, a standard cupro nickel heat exchanger and ultimate installation flexibility on new or existing equipment pads to responsibly heat a pool or spa today and for years to come.
 
The forced draft system in the Universal H-Series constantly moves air through the combustion chamber at a precise flow rate eliminating outside weather variables that can affect heating performance. Wind conditions are eliminated and there is no need to install a high-wind stack.
 
Presenting Hayward's world-class heater with an Earth-friendly conscience¦the Universal H-Series heater! The Universal H-Series Low NOx heater has an 84 percent industry-leading thermal efficiency and complies with all current California air quality emission standards. The low NOx emission makes it a perfect choice for the environmentally concerned pool owner.
 
Enjoy a warmer pool this season without your fuel costs skyrocketing. Hayward's Universal H-Series heaters represent innovative heating technology for pools and spas. Its hydraulic performance also saves energy by reducing the circulation time of the pump. It can raise the temperature of an 800 gallon pool 30 degrees in less than an hour you'll feel the benefits the moment you step into the water. This approach to heating your pool is an efficient use of energy showing once again the commitment to developing earth-friendly products.
 
Other performance and efficiency-enhancing advances include stainless steel burners, corrosion-resistant Finn Plate heat exchangers with Cupro nickel, and insulated Fire Tile combustion chambers. This traps the heat unlike other forms of insulation delivering the highest degree of performance from every BTU. Equipped with an LED control panel it monitors heater performance for added convenience and maximum comfort with minimum effort. The ignition system delivers dependable lighting and reliable operations with just a touch of a button. The forced draft system constantly moves air through the combustion chamber to eliminate all outside weather variables affecting heating performance, such as wind conditions, eliminating the need to install a high-wind stack.
 
Additionally, the Universal H-Series heater is easy to install and combines advanced technology with universal-fit flexibility making it virtually compatible with any new or existing equipment pad. This heating mixture sustains your swimming season, adds to your comfort, is energy efficient, and reduces your fuel costs. This low NOx emissions heater is perfect for you and the environment all at the same time.
 
NOTE: Hayward Universal H-Series heaters meet the NOx emission standards set by the California South Coast Quality Air Management Commission for 2001 and the Texas Natural Resource Conservation Commission Code.
 
Superior Hydraulic Performance - New polymer header provides superior hydraulic performance to save energy and protect against the damaging effects of erosion from high flow conditions for improved reliability.
 
Designed for today's larger diameter plumbing systems with 2" x 2 1/2" CPVC unions.
 
Forced Draft System - Forced draft system constantly moves air through the combustion chamber at a precise flow rate, eliminating all outside weather variables that can effect the heating performance, such as high wind conditions without a high wind stack.
 
State-of-the-Art Finn Plate Heat Exchanger with Cupro Nickel - The patented single header "V" baffle design heat exchangers allow for long life, fast heating and virtually no condensation. All Hayward heat exchangers are now constructed with highly resilient Cupro Nickel for greater durability and longevity even in salt-based, high flow or aggressive water chemistry set ups.
 
L.E.D. Control Panel - Easy-to-read L.E.D. Control Panel provides digital temperature readout and diagnostics for quick identification of components that might need service.
 
Product Specifications:
Brand Hayward
Item Low NOx Pool Heater
Series Universal H-Series
Gas Type Natural
Headers Polymer
Control Type Digital Electric, Dual Thermostat
Tubing Material Cupro Nickel
BTUH Input 400,000
Cabinet Width 36 Inch
Cabinet Depth 29-1/2 Inch
Cabinet Height 24 Inch
Flue Diameter 8 Inch
Gas Connection 3/4 Inch
Water Connection 2 Inch x 2-1/2 Inch Unions
Voltage Rating 110/220 V
Frequency Rating 60 Hz
Phase 1-Phase


Brand: HAYWARD
SPECIFICATIONS
BTU Rating
400K
Gas Type
Natural Gas
Location
Indoor/Outdoor
Elevation
0-9000'
Ignition
Electronic
Q & A
Start typing your question and we'll check if it was already asked and answered. Learn More
Browse 18 questions Browse 18 questions and 29 answers
What are the dimensions of the base of this unit?
Daniel H on May 10, 2017
BEST ANSWER: After a grueling conversation with the Hayward support people, I was finally able to get the info that should be way easier to obtain.....

Length (Side to Side) = 36.5 inches
Width (Front to Back) = 29.5 inches
Height (Top to Bottom) = 24 inches
what is the difference between the residential model and the commercial in the 400k heater?
Bill L on Apr 23, 2016
BEST ANSWER: I Am not sure we replaced our old heater with the residential one and it is easy to use and heats up fast and hot. Very happy with it
have a 399,000 which just died (pool/spa application) can I upgrade to a 500,000 without major plumbing alterations or should I stick with a 400,000?
darin c on Nov 6, 2015
BEST ANSWER: that is something as a pool owner I can't answer..... just thinking I would question if my pump/filter/piping has the flow capacity to keep the heater from shutting down on high water temperature.....

if I was you I would call Hayward and ask them.... they have been very helpful to me in the past.....
Have error code b d what does it mean?
Barb H on May 10, 2016
BEST ANSWER: In the owners manual that came with my heater, there were 4 reasons listed for a b d error code. 1.-- Internal fault/power-up error. desc(on initial trial for ignition. Automatic reset is immediate once the gas valve relay check results are acceptable). 2. Gas valve sensed as "ON" error. (If valve is open when it should be closed the heater will shut down and go into lockout.) 3. Gas valve senses as "OFF" error. desc(If valve is closed but flame is sensed the blower will run for 5 sec than start a new ignition sequence. 4. Data retrieval error. Desc(If input data is corrupted the heater will shut down and go into lockout.
Can I leave this outside exposed to the elements or should I build a shed for it? or cover it with a tarp during the winter?
Paul on Jun 11, 2020
BEST ANSWER: They say you can but I don’t recommend it . My filter and heater are under an awning I made protected from direct rain and snow . Some lattice on one side where it’s visible from pool area open enough to not need chimney. Tarp will trap moisture and cause problems at some point
what size gas supply pipe is needed?
A shopper on Jun 22, 2017
BEST ANSWER: You really need a licensed plumber to review your home gas distribution system to make that calculation for you.
do we really need to use ( Hayward Positive Pressure Horizontal or vertical Indoor Vent Adapter Kit for H400 ) with Hayward Universal H-Series YES or NO ? .. IF ( YES ) May i know the Reason .. thanks
AhmedAbdulBaqi on Jan 29, 2016
Hayward Universal H-Series Low NOx Induced Draft Pool & Spa Heater | 400000 BTU | Natural Gas | W3H400FDN
Hayward Universal H-Series Low NOx Induced Draft Pool & Spa Heater | 400000 BTU | Natural Gas | W3H400FDN
Hayward Positive Pressure Horizontal Indoor Vent Adapter Kit for H400 Universal Heaters | 8" Diameter | UHXPOSHZ14001 UHXPOSHZ14008
Hayward Positive Pressure Horizontal Indoor Vent Adapter Kit for H400 Universal Heaters | 8" Diameter | UHXPOSHZ14001 UHXPOSHZ14008
BEST ANSWER: I think this adapter is for heaters that are indoors. Just like a chimney the smoke/exhaust needs to go outside.... As a double check I would call Hayward and ask them your question.... I have had 4 houses with pools/hot tubs and have called them many times and they have always been great to deal with....
can the gas and water plumbing be attached from left side?
john c on Mar 23, 2020
BEST ANSWER: No, the gas is on the left, while the water is on the right.
I need a pool heater and a salt system. 21,000 gal inground pool. Vinyl Liner pool. Ozonator. Recommend please?
A shopper on Jun 22, 2017
BEST ANSWER: I cannot make a recommendation on your specific application. However I can recommend that you get suggestions from the team at pool supply unlimited. I have been dealing with them for years. I have completely rebuilt my 30 year old pool system with equipment they suggested. They are trustworthy and back what they sell.
Do you have the latest Hayward heater models. Hayward upgraded their control panel with a cover? Your website is not displaying the latest model. Your competitor, Inyopools, is displaying the current model. Can you confirm if you have the heaters with the control panel cover?
Jose C on Apr 11, 2017
BEST ANSWER: Jose: I had the very same question. Although by phone order they could not assure inventory of latest units, I received the version with control cover and shipped in pristine condition. VERY PLEASED with this trusted vendor
Who pays for the freight?
Charles B on Sep 9, 2016
BEST ANSWER: You would be charged the freight fee
how to turn on? its not turning on
A shopper on Jul 28, 2018
BEST ANSWER: the front display has temperature up temperature down and a mode selecting button for spool spa and off
what is the width between the intake and return valves/pipes?
jim K on Mar 18, 2017
BEST ANSWER: Exactly 10” c-to-c
What size heater do I need for 25,000 gallon pool?
A shopper on Aug 23, 2021
Well the Hayward H400FD work fine with 208 volts?
Dustin V on Aug 16, 2021
Can the 2” water connection be reduced to 1 1/2” to fit my current piping?
A shopper on Mar 24, 2021
is this product in stock?
A shopper on Mar 19, 2021
what is the differences between the residential and commercial 400 btu heaters?
A shopper on Jul 27, 2017
REVIEWS
4.7 / 5.0
9 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
7
1
1
0
0
Rated 5 out of 5
installed easily and works very well
We just installed the 400 BTU Hayward heater to replace an electric heat pump. It installed easily as others have stated and heated the pool quickly. It seems to heat a little more than 2 degrees each hour in an in-ground 18 x 36 pool with deep-end. it heated our pool in MA from 55 to 85 degrees running during the daytime in two days. Most of the summer it should run only an hour or less to recover overnight heat loss. I'd describe it as quiet, I think the standard pool pump is actually louder. Very pleased overall.
May 22, 2018
Purchased
over 4 years ago
Rated 3 out of 5
Not sure yet, having problems getting it to start up.
Not sure here what's going on yet, it worked once for about 30 minutes and has not worked sense. Doing what trouble shooting recommends before going back to the seller to see what can be done, I hope it's not something major, so it's hard at this point to rate this one way or another, I need to see how with the seller or Hayward will handle this problem then I can make an accurate purchase review.
June 18, 2017
Purchased
over 4 years ago
Rated 5 out of 5
Replacement Pool Heater
Our original Hayward H400FDN developed a leak in the heat exchanger which caused water to pool in the combustion chamber. After replacing burner tubes, circuit boards and the rain shield, came to realization that it was pool water, not rain water, that was accumulating in the heater and making operation problematic. The new W3H400FDN is a perfect fit, direct replacement for the original and is working as advertised. The original lasted eight years; hope the replacement goes even longer since it now has a cupro-nickel heat exchanger.
October 30, 2020
Purchased
1 year ago
Rated 5 out of 5
So far so good
The Hayward pool heater is performing excellently and was easy to install. Time will tell how it holds up to the wear
August 23, 2016
Purchased
over 6 years ago
Rated 5 out of 5
A fantastic upgrade
Bought a new house with a pool and original heater that I wouldn't trust to put on. This was the first upgrade to the pool we did and I am so glad we did it! It heats my 29,000 gallon pool about 2 degrees or so an hour (faster on warm, sunny days with humidity). No need for any shed. Mine has been outside in the elements for three years with no issues.
June 11, 2020
Purchased
over 5 years ago
Rated 5 out of 5
H400FDN
Just received my replacement pool heater from Pool Supply Unlimited- this is the latest model and was received earlier than expected in excellent condition. Appreciation to Pool Supply Unlimited for a fair price of top quality Hayward products.
November 5, 2018
Purchased
over 3 years ago
Rated 4 out of 5
Great value
Just installed the heater and everything went well. Hayward has a well known name and the price was very competitive. The fact that Hayward heaters come with the upgraded heat exchanger that you have to pay extra for with other heaters, was definitely a factor in my purchase.
March 9, 2014
Rated 5 out of 5
100% happy with ny heater. New when i purchased it.
October 13, 2016
Purchased
over 6 years ago
Rated 5 out of 5
Great!
Great site, great service, unbeatable price and the delivery was quoted to be 7 to 10 days - I had it in 3!! The best experience buying online I've had. The heater works great too -
August 9, 2014
RESOURCES
WARRANTY
Warranty applies only to products that were purchased from Hayward authorized sellers. Pool Supply Unlimited is a Hayward Authorized Online Reseller.
 
See Warranty Information PDF for warranty details.
 
For Hayward warranty registration information, and to submit online, please visit www.hayward-pool.com
 
This information was updated on 4/22/2022. For the most current information and full warranty policy please visit www.hayward-pool.com


 Adobe Acrobat PDF Warranty Information
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ABOUT THE STORE
Pool Supply Unlimited is an e-commerce company that loves water. We love to pump it, filter it, heat it, chlorinate it, light it up and stare at it while we're barbequing a fat, juicy steak. There are real pool professionals working here. Our guys have seen thousands of pools in their careers, no exaggeration. We are based in Southern California and can land most products to your door (within the 48 contiguous states) in less than a week.
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