Jandy | JXTQ400NNK | JXiQ 400K BTU Natural Gas Pool & Spa Heater – Cupronickel Heat Exchanger, VersaFlo Integrated Bypass

The Jandy JXTQ400NNK is a 400K BTU natural gas pool and spa heater from the JXiQ smart heater platform, built with a cupronickel heat exchanger, polymer headers, and VersaFlo Integrated Bypass factory installed. It is the model to choose when the water is salt chlorinated, chemically aggressive, or simply hard on standard copper tubes.

Key Features and Benefits

• 399,000 BTU/hr firing rate: Full 400K class output for large in-ground pools and pool/spa combinations.
• Cupronickel heat exchanger: Far more resistant to corrosion, scale, and low pH water than standard copper. The right pick for salt systems and high bather load.
• VersaFlo Integrated Bypass, factory installed: Routes water through the heat exchanger only on a call for heat, then around it the rest of the time. Lets a variable speed pump run slower and cuts hydraulic loss.
• SMART sensor package: Monitors inlet and outlet temperature rise to protect the heat exchanger from low flow damage.
• Low gas pressure switch: Blocks ignition when supply pressure is too low, a common cause of nuisance faults on long gas runs.
• Auto-sensing dual voltage: Detects 120V or 240V on power up. No jumper cards to flip and no wires to move.
• Largest display in the industry: 50% larger screen showing up to 80 characters, plus estimated heat up time to setpoint.
• Bluetooth diagnostics: Full real time service data through the Fluidra Pro app.
• Automation ready: Works with Jandy AquaLink systems for remote control through the iAquaLink app.
• Sacrificial anode included: Pulls corrosive elements in the water away from the heat exchanger and other metal parts.
• Compact and light: Fits a 2 ft x 2 ft pad and drops straight in as a MasterTemp or Max-E-Therm replacement with no plumbing changes.
• Low NOx design: Meets strict air quality requirements, including California districts.
• Versa Plumb ready: Sweep elbow included for tight, efficient equipment pad plumbing.

Specifications

Who This Heater Is For

Choose the JXTQ400NNK over the standard copper JXIQ400NK when the pool runs a salt chlorine generator, sits in a high mineral or coastal environment, sees heavy bather load, or has a history of premature heat exchanger failure. The cupronickel tubes cost more up front and pay for themselves in service life. If the job requires ASME certified bronze headers for a commercial permit, look at the JXIQ400NS instead.

Sizing Guide

At a 20°F temperature difference with no wind, a 400K BTU Jandy heater covers roughly 1,120 sq ft of pool surface. On spas, it raises a 400 gallon spa about 30°F in roughly 18 minutes and a 1,000 gallon spa in about 44 minutes with a cover on.

What Is Included

• Jandy JXiQ 400K BTU natural gas heater with cupronickel heat exchanger
• Factory installed VersaFlo Integrated Bypass
• Sacrificial anode
• Versa Plumb sweep elbow, union nuts, caps, and O-rings
• Installation and operation manual

Frequently Asked Questions

What is the difference between the Jandy JXTQ400NNK and the JXIQ400NK?

Both are 400K BTU natural gas JXiQ heaters with VersaFlo Integrated Bypass. The JXTQ400NNK uses a cupronickel heat exchanger, while the JXIQ400NK uses standard copper. Cupronickel resists corrosion from salt water, unbalanced chemistry, and low pH much better, so it lasts longer in demanding water conditions.

Is the Jandy JXTQ400NNK safe for a salt water pool?

Yes. The cupronickel heat exchanger is the configuration Jandy recommends for salt chlorinated pools. Water chemistry still needs to stay balanced, since no heat exchanger material survives sustained low pH or salinity outside the recommended range.

How big a pool will a 400,000 BTU heater handle?

A 400K BTU heater covers roughly 1,120 sq ft of pool surface at a 20°F temperature difference in calm conditions, and about 880 sq ft in 3.5 mph wind. Larger surface areas, exposed sites, and uncovered pools need more capacity or longer run times.

What size gas line does the JXTQ400NNK need?

For natural gas, a 1 in. line works up to about 20 equivalent feet, 1-1/4 in. up to about 95 feet, and 1-1/2 in. up to about 215 feet. Add three feet of equivalent length for every elbow. Undersized gas lines are the leading cause of ignition faults on 400K heaters, so confirm supply pressure before startup.

Does the JXTQ400NNK work with pool automation?

Yes. The JXiQ platform is automation ready and pairs with Jandy AquaLink systems for control from the iAquaLink app. Pool professionals can also connect over Bluetooth for real time diagnostics in the Fluidra Pro app.

Installation and Warranty Notes

This heater must be installed and serviced by a qualified pool professional or licensed gas technician. Improper installation can void the manufacturer warranty. Jandy Trade Series Exclusive products carry warranty terms tied to the purchase channel. Call us at (818) 394-9123 before you order if you need warranty confirmation for your installation.

Ships freight. Inspect the pallet before signing for delivery and note any damage on the delivery receipt.