In any region of the country where pools sit unused for a few months, opening day is the time to tune up equipment for the coming swim season. A gas heater that’s been kept outside all winter can be particularly vulnerable to environmental wear and tear.

Debris can obstruct its airflow, moisture can rust its interior, and animals can chew up its components or build their nests inside.

Gas pool heaters are more essential in some areas of the country than others, but service veterans across the nation run through their own tried-and-true systems of checks when starting them up. Here, we compare common heater start-up issues in several major markets where pools and heaters take the winter off.

Organic debris

Leaves and other debris can easily clog up a heater during the winter, when the absence of airflow allows them to accumulate. For this reason, techs recommend beginning a seasonal start-up by thoroughly inspecting the heater for any organic matter.

“If we can get access to the top of the heat exchanger, we’ll take off the draft hood and vacuum it out,” says Brian Diglio, president of Blue Wave Pool Service in Hamden, Conn. It’s also important to check that the burner tray and the area around it are clear, and that the openings near the bottom are unblocked.

Leaves are a common cause of such blockages, so it’s often helpful to check for nearby foliage. “A lot of people have trees with leaves hanging over top of the heater, and those can fall in,” says Scott Houseman, president of Leisure Time Pool Service & Repair in Rancho Cordova, Calif.

Customers who have their backyards landscaped over the winter may introduce another type of obstruction to the heater. “A lot of times, they’ll bury the area around the heater and the pump motors with mulch,” Diglio says. This means it’s important to clear any mulch or dirt away from the base of the heater before trying to start it.

Even if it makes a bit of a mess now, clearing away debris will prevent damage to the heater in the long run. “I tell my guys all the time, even if you have to make it look not as nice, the idea is to move the mulch out of the way,” says Chas Bogardus, service manager at Budd’s Pools and Spas in Deptford N.J. “You want to really hose that whole area down to make sure it’s clear.”


When heaters are turned off for the winter, they provide a sheltered nesting spot for all sorts of creatures. Each region’s service professionals have developed some practical solutions for handling pests.

One animal annoyance unique to the Pacific Northwest is a species of white nesting spider, which builds its home in heaters and other dark spaces over the winter months. “Little spiders are a big thing out here,” Houseman says. “They crawl up in the orifices on the bottom of the heater, and cause it not to start.”

Thus, Houseman’s heater start-up checklist includes probing for spiders with a wrench or wire.

Meantime, rodents are among the most frequently mentioned animal problems in New England.

“Mice like to build their nests inside the heater, and they love to chew up the wires too,” Diglio says. Thus, in rodent-populated areas, it’s important to inspect the wires throughout the heater — especially those that feed into the ignition and the main circuit board — before starting it up.

A number of newer heaters will indicate if there’s a sensor fail, which may mean that rodents have chewed through crucial wires. By following those failure signals to their origin points on the back or sides of the heater, techs can often track down a broken electrical connection.

Rodents also tend to seek shelter under and around the heater’s burner tray, and will often chew up the heater’s reflector blanket to build their nests. If the damage to the blanket is severe enough to produce a “hot spot” on one side of the heater, it may well be necessary to replace the blanket.

“If you don’t replace the blanket, then you’re going to have a hot spot leader, so all the heat’s not going to reflect up into the heat exchanger,” Bogardus explains.

Moisture and wind

In regions with wet winters, snow can pose a major problem due to its tendency to accumulate on and around an inactive heater. “In the past few years, we’ve seen some more corrosion [on heaters] than we usually see, just because the snow hangs around, and that moisture blankets the heater,” Bogardus says.

If small parts like the high limits and temperature sensors are rusty, it may be necessary to replace them — in fact, performing such a replacement now may save the heater’s life.

Moisture that gets into the heater due to an irrigation inaccuracy can be trickier to track — but the interaction between water and electricity can lead to even worse problems than corrosion. “Heaters are set up to address water dropping from above, not coming up from below,” says Chris Myers, president of Eden Swimming Pools & Landscaping in McAllen, Texas. “We’ve seen cases where [sprinkler water] fried the motherboard.”

Thus, it often pays to inquire if a customer has recently had a sprinkler system installed — and if the answer is “yes,” to ask for a live demonstration of it. If any sprinkler is spraying at or near the heater, it’s a smart idea to point it in another direction.

Whether you’re starting up heaters in a snowy region, a windy tropical area or a temperate forest, it’s important to remember that a few preventative checks will save a pound of trouble in the long run.