Jandy JXi

The JXi is the third of the three big gas heaters, and the one that gets left out of two-way comparisons. Three sizes — 200, 260 and 400, the last of which is actually 399,000 BTU/hr on its rating plate. N is natural gas, P is propane.

Jandy sells it on being small. At 22.9 by 22.1 by 26.5 inches and 117 pounds for the 200, it fits pads that the alternatives do not, and Jandy states it is designed as a straight swap for a MasterTemp or Max-E-Therm with the plumbing left where it is. On a full equipment pad that is a real advantage rather than a marketing one.

The bypass that multiplies the warranty by five

This is the thing to decide before ordering, because it cannot be fixed afterward.

A JXi carries a one year warranty. But a heat exchanger on a JXi with the factory-installed VersaFlo Integrated Bypass is warranted for five years. Same exchanger, five times the term, and the difference is an option specified at order time.

The exchanger is the most expensive part of the heater. Jandy's own spec sheets list "includes VersaFlo bypass" as a yes-or-no line per SKU, so it is worth checking which one a quote is actually for — and worth asking about explicitly, because nobody selling you a heater volunteers that the cheaper version has a fifth of the warranty on its costliest component.

Its flow window is narrower than the others

Every gas heater has a minimum. The JXi is unusual for its ceiling:

• Minimum 30 GPM — the same as a Hayward H400FD, and 10 GPM less than a Pentair MasterTemp 400, which wants 40
• Maximum 100 GPM — against Pentair's 120 and Hayward's 125

So the JXi is the easiest of the three to satisfy at the bottom and the first to run out of room at the top. On a pad with a big single-speed pump and 2½ inch plumbing, 100 GPM is a ceiling you can actually reach, and it is the number to check before assuming a heater swap is like for like.

It also wants at least 2 psi of working water pressure, which is a spec the others do not publish in the same terms.

Efficiency depends on the exchanger, and not the way Hayward does it

Three brands, three arrangements, and they do not line up:

• Jandy — 84% on the 260 and 400 with the copper exchanger, 83% on the 200 and on the cupro-nickel 400
• Pentair — 84% copper, 82% for its heavy-duty cupro-nickel
• Hayward — cupro-nickel as standard, at up to 84%

So on both Jandy and Pentair, corrosion resistance costs you efficiency. On Hayward it does not, because cupro-nickel is what ships. If your water is aggressive or the pool is salt, that comparison matters more than the headline efficiency figure — and the LSI calculator tells you whether it applies to you.

Jandy's cupro-nickel models carry a second N or P: JXi260NN and JXi400NN in natural gas, JXi260PN and JXi400PN in propane. The manual names all four in one line. The 200 is copper only. The ASME versions end in C, in the 260 and the 400.

Where it gets awkward is the efficiency figure. The sell sheet, which is the only place Jandy tabulates efficiency by model, lists the cupro-nickel 400 at 83% and does not list the cupro-nickel 260 at all — so there is no published figure for it. If that is the heater you are quoted, ask, rather than assuming it matches either the copper 260 or the cupro-nickel 400.

One caution on where you read the efficiency figure. Jandy's own product page prints 84% as the headline for the JXi200N. Its sell sheet, which breaks the range out model by model, gives that heater 83%. The table is the one to trust; the web page is quoting the best number in the family.

Vent size changes with the model

Easy to miss on a replacement, and expensive if the flue is already in the wall:

• Category I — 6 inches on the 200, 7 on the 260, 8 on the 400
• Category III — 4 inches on all three

That 6-to-8 inch spread across the line means sizing up from a 200 to a 400 is not only a bigger cabinet, it is a different flue. Worth establishing before the order rather than on the day.

Clearance from combustibles is 6 inches, with 36 inches of service clearance from the top.

Altitude, if you are above 4,500 feet

Jandy is specific where most manufacturers are vague. The JXi is CSA certified for installations up to 4,500 feet. Above that, output drops about 4% per 1,000 feet — and Jandy notes that efficiency is generally unaffected, it is the output that falls.

So at 7,500 feet a JXi400 is delivering roughly 12% less heat than its plate says, which is a sizing input rather than a fault. The heater calculator works in delivered BTU, so derate the input before you use it.

Buying one online means no warranty

Not a shorter warranty. None.

Jandy's limited warranty states that it does not apply to Jandy branded products purchased through the Internet or other e-commerce platforms, with a narrow exception for valves under three inches, parts and accessories. A heater is not on that list.

That is stricter than either alternative. Pentair's online trim still carries a year, with labor removed; Hayward's Open Line carries a shorter term than its dealer line. Jandy's position is that an internet purchase is not covered at all, and the warranty additionally requires installation by a licensed, qualified contractor where local rules demand one.

The Jandy brand page has the rest of the terms, including which product categories get longer than the one-year default.