Hayward recalled 4,600 pool heaters that can produce high levels of carbon monoxide

Hayward Industries is recalling about 4,600 gas-fired pool heaters because they can produce high levels of carbon monoxide while running. The affected units are the 400,000 BTU Universal-HC Series, model HDFS400, made in the United States by Hayward of Charlotte, North Carolina and sold from March 2026 through July 2026 at roughly $5,600 each. No incidents have been reported, so the recall rests on a hazard identified before anyone was hurt.

Owners are told to stop using the heater immediately. The fix is a free in-home inspection and repair by a qualified technician, not a replacement unit and not a refund.

The Universal-HC recall as the CPSC filed it

In recall 26-777, published on September 17, 2026, the Consumer Product Safety Commission says about 4,600 heaters can produce high levels of carbon monoxide during operation, “posing a risk of serious injury or death from carbon monoxide poisoning.” The heaters are brown with black tops, measure about 21 inches long, 28 inches wide and 31 inches high, and have a digital display control panel and a molded base with tie-down connections.

The sales channel is unusual for a consumer recall, and so is the price: at about $5,600 a unit, 4,600 heaters represent on the order of $26 million in equipment at the notice’s per-unit figure. The notice says the heaters went through pool equipment distributors, builders and service professionals nationwide, not through a retail shelf or a single website. Many owners may therefore know the heater only as part of a new pool or a renovation, and may not have bought it themselves. Hayward’s contact line is 855-500-5288, and the company runs a recall page at hayward.com/productrecall.

Combustion, venting and where carbon monoxide comes from

Carbon monoxide is a product of incomplete combustion. A gas burner that gets enough air converts nearly all its fuel to carbon dioxide and water; one that is starved of air, fed too much gas or fouled by blocked exhaust passages produces more CO. The Hayward notice does not say which of these conditions applies to the Universal-HC, and it does not describe a cause at all.

For a general picture of how such failures happen, CPSC staff have documented the failure modes in other gas appliances. In a letter proposing CO shutoff provisions for gas furnaces, the agency listed disconnected vents, partially blocked vents, over-fired appliances and inadequate combustion air as conditions the standards at the time did not address. The same letter cited 278 estimated CO deaths from 2002 through 2011 tied to gas furnaces, boilers, wall furnaces and floor furnaces, and proposed limiting emissions to below 0.04 percent or shutting the appliance off at that level.

The pool heater standard and the furnace rulemaking

Gas-fired pool heaters have their own design standard, ANSI Z21.56/CSA 4.7, which covers heaters for natural gas, manufactured gas, mixed gas and liquefied petroleum gas, including units installed within 5 feet of the pool. The CSA Group listing shows the 2017 sixth edition as withdrawn, so the recall notice itself is the better guide to what Hayward and CPSC consider the defect in this case.

CPSC’s own CO rulemaking has focused on residential furnaces and boilers. A proposed rule published October 25, 2023 would require those appliances to monitor carbon monoxide concentration during combustion and shut down or modulate combustion to keep emissions below set thresholds. It cites about 21 CO deaths a year from 2017 to 2019 and 539 deaths from 2000 through 2019, plus an estimated 30,587 nonfatal injuries from CO leakage between 2014 and 2018. CPSC concluded that existing voluntary standards were inadequate despite more than 20 years of industry engagement. Pool heaters are not part of that proposal.

Symptoms, alarms and the repair visit

CPSC’s guidance on carbon monoxide lists the warning signs of poisoning as headache, dizziness, weakness, nausea, vomiting, sleepiness and confusion, symptoms easily mistaken for heat or fatigue on a pool deck.

The commission’s carbon monoxide information center recommends battery-operated or battery-backup CO alarms on every level of a home and outside sleeping areas, and says interconnected alarms are best because when one sounds, they all sound. The same page states that more than 200 people in the United States die every year from accidental non-fire CO poisoning associated with consumer products.

For the Universal-HC heaters, the instruction is narrower. Owners are to “stop using the pool heater immediately” and contact Hayward at 855-500-5288 or email [email protected] to schedule a free in-home inspection and repair by a qualified technician. The notice reports no injuries among the roughly 4,600 units sold in the March to July 2026 sales window.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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