A larger pool or a pool-and-spa combination that needs fast heat-up in any weather.
★★★★★ 230+ Google Reviews · CPO C-105377 · 40+ years of combined founder experience
Sizing comes first.The right heater is set by your pool's surface area and the temperature rise you want, and by the flow your pump and plumbing deliver. Start with the heater size calculator; we confirm it on site before quoting.
Our own score for what saves you money and headaches in South Florida.
JXi400NK
3.6
out of 5
From the manufacturer's documents listed under Sources. Where the documents disagree, the table says so.
| Manufacturer model number | JXI400NK — Jandy's model key reads K as copper exchanger, polymer header, VersaFlo factory-installed. Note that the 2024 catalog addendum's ordering tables print factory-VersaFlo part numbers only on JXiQ models (JXIQ200NK, JXIQ260NK, JXIQ400NK and the propane equivalents), and distributors report shipping a JXiQ400NK against a JXi400NK order. |
|---|---|
| BTU input (firing rate) | 399,000 BTU/hr |
| Thermal efficiency | 84% (Jandy EnergyGuide label for the copper 400 models) |
| Heat exchanger | Copper fin tube with polymer headers |
| Integrated bypass | VersaFlo flow gate, factory-installed; retrofit kit JXIVFKIT fits 200, 260 and 400 |
| Water connections | 2" PVC/CPVC unthreaded, or Jandy threaded union |
| Water flow | 30 GPM minimum, 100 GPM maximum |
| Gas connection | 3/4" NPT |
| Inlet gas supply pressure | 4.0" W.C. minimum (natural gas), operating |
| Electrical | 120 VAC at under 5 A, or 240 VAC at under 2.5 A |
| Exhaust vent | 8" diameter Category I, 4" Category III |
| Minimum outdoor ambient | 40°F |
| Cabinet | 22.1" W x 21.6" D x 26.5" H |
| Certification | CSA design certified; ANSI Z21.56 / CSA 4.7 |
| Controls and automation | Onboard digital control with pool and spa setpoints; VersaFlo actuator wired to the heater PCB and driven by the call for heat; four-pin RS-485 connection to Jandy AquaLink; iAquaLink app control through that system. |
Parts
1 year
Labor
None published
Heat exchanger
5 years
| Parts | 1 year |
|---|---|
| Heat exchanger | 5 years (VersaFlo factory-installed) |
These are the manufacturer's published terms. Terms can depend on the installer, the dealer program and where the heater was bought, and they change without notice, so we confirm the exact term for your install on the written quote.
The traditional material and the cheapest to build. It transfers heat well and does fine on well-balanced chlorine water, but it's the least forgiving of low pH, high chlorine and salt. Water chemistry has to stay in range for a copper exchanger to reach its full life.
See every material side by side on the comparison page, or read the Jandy heater error messages guide for what the display is telling you.
Most to least forgiving of salt and unbalanced water.
Raypak · AVIA HD with NiTek
A larger pool or a pool-and-spa combination that needs fast heat-up in any weather.
Built-in Wi-Fi
Hayward · Universal H-Series
A larger pool or a pool-and-spa combination that needs fast heat-up in any weather.
App control through automation
Pentair · ETi
A high-use pool or pool-and-spa where fuel cost decides it, and a pad that can handle a condensing heater's condensate drain.
Automation relay (no heater app)
Every figure on this page comes from these manufacturer documents. We re-open each one and match the model number, capacity and efficiency before the date moves. How we verify.
| Document | Type | Last checked |
|---|---|---|
| Jandy — VersaFlo Integrated Bypass for JXi & JXiQ Pool and Spa Heaters, H0787800 (what the bypass does, head-loss chart, JXIVFKIT retrofit kit)cdn.fluidrausa.com | Product page | October 14, 2026 |
| Jandy / Fluidra — 2024 Product Catalog Addendum, Gas Heaters, 61356_SA (model-number key, firing rates, vent diameters, cabinet dimensions, current part numbers and Jandy's EnergyGuide thermal-efficiency labels)cdn.fluidrausa.com | Manual or guide | October 14, 2026 |
| Jandy — USA & Canada Jandy Limited Warranty, H0333803 (1 year on JXi heaters, 5 years on factory VersaFlo heat exchangers, 2 years on heat pumps with 5 years compressor and exchanger, no labor, e-commerce exclusion)cdn.fluidrausa.com | Warranty terms | October 14, 2026 |
| Jandy — JXi Gas-Fired Pool and Spa Heater Installation & Operation Manual, H0574300 (rating plate BTU, gas and water connections, flow window, electrical, venting, ambient limit, cupro-nickel model list)cdn.fluidrausa.com | Manual or guide | October 14, 2026 |
Manufacturers revise terms without notice. Treat this page as a starting point and confirm the current terms before you buy. If something here is out of date, tell us and we'll fix it.
Parts: 1 year. Heat exchanger: 5 years (VersaFlo factory-installed). These are the manufacturer's terms as published; warranty terms change and can depend on the installer and the channel, so we confirm the exact term for your install on the written quote.
The JXi400NK is rated at 399,000 BTU/hr input. Heater size comes from your pool's surface area and the temperature rise you want, not from gallons, and the pump and plumbing have to deliver the flow the heater needs. Use our heater size calculator for a starting number, and we confirm it on site before quoting.
Only through a compatible automation system. The JXi400NK has no Wi-Fi of its own, so the app control comes from the automation system it's wired to.
The traditional material and the cheapest to build. It transfers heat well and does fine on well-balanced chlorine water, but it's the least forgiving of low pH, high chlorine and salt. Water chemistry has to stay in range for a copper exchanger to reach its full life.
Every figure on this page comes from the manufacturer's own documents, listed under Sources with the date we last checked them. Manufacturers revise terms without notice, so treat the page as a starting point and confirm the current terms on your quote.
We quote, install and service Jandy heaters across Palm Beach and Broward, managed by us under our Florida Certified Pool/Spa Contractor license (CPC1461731). You get a free on-site sizing visit and one written price. Gas lines, new circuits and refrigerant work are done by licensed contractors we manage.
We call back within 30 minutes during business hours.
