Ask a pool service technician to list common on-site safety hazards, and the answers likely will include diving boards, unlocked gates, and blockable main drains. But another potential source of danger — the heater — is also worthy of any serious tech’s attention.

Though many heaters operate safely and reliably for decades, it takes just one service slip-up — a failure to fully clean out the heater’s interior, or to leave the ventilation open — to turn a trusted piece of equipment into a major liability.

“I’ve been on calls where the whole garage burnt down,and all the cars inside were destroyed, because of an improper heater installation,” says Brian Diglio, president of Blue Wave Pool Service and Supplies Inc. in Hamden, Conn. “It’s unbelievable how careless some installers are.”

However, sticking to a checklist of proper procedures often is all it takes to prevent such problems. Here, veteran techs share stories of common heater-related mistakes, and offer tips for keeping this component of the equipment pad safe and trouble-free.

Installation inspection

In a perfect world, pool equipment would be installed by trained service technicians who follow manufacturer instructions to the letter. But in reality, many installations are performed by amateurs, or by the customers themselves. Thus, it’s important to be aware of some all-too-common oversights made by untrained installers.

“The biggest thing we see is a failure to adhere to venting and chimney codes; ventilation air, combustion air — all the codes that are spelled out in the National Fuel Gas Code Handbook,” says Luciano Tortorella, a Phoenix-based territory service manager for Pentair Water Pool & Spa. Tortorella notes that these codes are written with customer safety in mind, but those without proper training are simply ignorant of them.

Failures to adhere to gas heater codes typically fall into two categories: Outdoor heaters installed too close to windows, and indoor installations provided with inadequate ventilation. In both cases, the danger is carbon monoxide, a deadly but invisible gas whose odor is extremely difficult to detect.

Heater manufacturers specify safe distances from windows in their manuals — in most cases, about four feet — but it’s also important to be aware of any related regulations at the local level. Even though the manufacturer might only specify a certain distance, it’s still the service professional’s responsibility to find out what their individual county and municipal requirements are, and to maintain the heater appropriately.

As Tortorella puts it, “Always go by the more stringent code.”

When it comes to indoor ventilation, the steps to safety aren’t always as straightforward. Some unprofessional installers will place the heater in an enclosed room with no ventilation — an obvious carbon monoxide hazard — but others may assume that a door provides adequate ventilation, though this isn’t always the case. The only way to ensure safety is to vent the heater directly to the outdoors (again, making sure the vent is well clear of any windows); but at the very least, the door to any equipment room should always include a screen or vent.

It’s also crucial to check for electrical installation errors, such as ungrounded wires, or connections not protected with plastic wire nuts. Though oversights like these might not necessarily send a room bursting into flames, they can allow stray sparks to fly, often resulting in damage to electronic components.

“We see a lot of heater motherboards get fried that way,” says Chris Myers, president of Eden Swimming Pools & Landscaping in McAllen, Texas.

When any installation error is discovered, the ideal approach is to err on the side of caution — or to alert the client of the safety hazard via certified letter, to guard against any legal entanglements. “No matter how many service techs go out to that job site, the last person who visited is going to be held responsible for any damages,” Tortorella says.

In other words, a little extra paperwork now can help prevent a lawsuit over a 15-year-old heater that someone else failed to install and service properly.

For some techs, the threat of losing a customer seems more immediate than the threat of legal entanglements — a view that may lead them to keep quiet about potential hazards until it’s too late.

It always pays to err on the side of safety, and thorough documentation.

Steadfast service

Even if the installation itself is free of hazards, a lack of regular professional service can spell disaster for a heater. Because a pool heater, like a residential boiler, burns gaseous fossil fuel, any hang-ups in the flow of that fuel can create carbon monoxide leaks, which may add up to serious flammability hazards over time.

In most cases, hazards such as these can be avoided with regular checkups. But it’s essential to perform those checkups correctly. This includes inspecting not only the mechanical valves and ports inside and outside the heater itself, but also the property’s gas regulator and meter. Unusually low gas consumption could point to a blockage in the line, while unusually high consumption may indicate a leak somewhere.

Biological blockage — such as leaves, twigs and small animals — can also pose a flammability threat, or at least lead to significant mechanical problems. Particularly in cooler regions where pool equipment is shut down during winter, it’s vital to thoroughly clear all blockage out of the heater at opening time, before the equipment is switched on.

Some techs assume the heater will harmlessly incinerate minor blockages, but it’s important to remember that one tiny blockage in the wrong place can send an entire heater up in flames. “I’ve seen heaters ignite when they’re turned on, because no one thought to check that there was 15 pounds of leaves inside,” Tortorella says.

If a carbon monoxide leak becomes apparent — or if the customer calls with a flammability emergency — swift and decisive action will often prevent the situation from getting out of hand. The first step, of course, is to clear everyone out of the danger zone, and off the property, if possible. Next, shut off the gas and equipment, and ventilate the area as thoroughly as possible. While the area is venting, get on the phone with the local gas company, and explain the situation — they’ll send a technician out to the site with a carbon monoxide detector and a combustion analyzer, to ensure that any immediate danger is averted.

It’s also worthwhile to contact a repair specialist trained by the equipment’s manufacturer. These technicians are able to address unusual and dangerous malfunctions, and can often perform the necessary repairs, as well as inspect the equipment for potential future hazards. Though reporting such a disaster is likely to void the warranty, continuing to operate hazardous equipment just isn’t worth the risk.

Though these potential dangers are very real, installing any manufacturer’s heater according to all specs, and maintaining it in concert with their recommendations, is unlikely to bring trouble.“Trouble starts when someone decides to cut corners,” Tortorella says. In short, a bit of extra work up front can save equipment — and possibly even lives — in the long run.