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How to maintain pool & spa heaters

There are many good reasons to recommend that customers upgrade to a new pool and spa heater, and one good reason not to: availability.

Pool industry professionals are well aware of the increase in pool use in the last year and more. That, and various calamities and shortages that have affected nearly every aspect of the economy, have resulted in longer than usual lead times on pool and spa equipment. New heaters can be hard to locate.

But with many families still home and still maximizing the use of their backyard investments, pool owners want to be able to swim in the fall and winter. And that means that pool service techs need to ensure that their existing heaters are operating as efficiently as possible. That means that heater maintenance is singularly important this season.

To that end, it is essential to maintain proper water chemistry and to develop a regular heater maintenance program.

Gas Heater Maintenance

Why soot develops on fins and heat exchanger coils and how to clean

Soot can develop on the fins and heat exchanger coils due to condensation, which is a natural by-product of burning gas. But when the heat exchanger is too cool, condensation on the fins and heat exchanger will cause carbon to adhere to them. And when the condensed water falls onto the burners, it interferes with the heater’s combustion and affects the heater’s efficiency.

Check for low gas pressure. Proper fuel supply is critical for heater function. Mainline gas pressure for natural gas operation is the inlet gas line pressure upstream from the gas valve of the heater. It is measured as inches of water column pressure (in. wc).

Ensure that the heater is sized to the existing gas line. Also, make sure that no add-ons like barbeques or fire features have been added to the heater’s gas line, reducing the amount of gas getting to the pool heater. With propane heaters, make sure there is plenty of gas in the tank.

According to the APSP Technical Manual, to operate correctly, the heater needs an 11 in. wc for propane gas and a 5-10 in. wc for natural gas. Check the gas pressure while the burners are lit. It may be necessary to have a plumber correct a clogged gas line.

Too much water flow through the heater can also result in soot. To solve this problem, install a high-flow modulator or a manual bypass valve.

If the burner is plugged with some foreign material, soot may also result. Make sure to inspect and clean the burners.

Lack of ventilation can also lead to soot.

Be sure to take the time to clean out leaves, debris, and spider webs that gather in heater vents and within the heater itself that restrict air flow. Use a wet-dry vac to remove dirt and debris. If you notice any nesting material, take action to prevent access to birds and rodents.

The color of the heater’s flame is an indication of whether the unit is getting enough air. Look for a clear, blue flame. Yellow or orange flames indicate inadequate air flow, resulting in the release of carbon soot that will clog heat exchangers. This is another indication that burners need cleaning.

To clean the burners, turn them off and allow them to cool. Brush the burners with a wire brush. This is usually only necessary once a year.

To clean the heat exchanger, remove it and place on a clean surface. Clean heat exchanger and fins per manufacturer specification.

This may involve the application of a degreaser. Give it some time to loosen any soot. Wash it off with a garden hose.

Next, spray non-pressurized water on the evaporator to remove dirt from the aluminum fins. Pressurized water can damage the fins and void the warranty.

Heat Pump Maintenance

Keeping a heat pump properly maintained will ensure top performance and extend the unit’s lifespan. Part of that maintenance is cleaning the coil in the heat pump at least once a year. This helps maintain the unit’s efficiency in transferring heat from the air to the pool water. A dirty air coil reduces the airflow and the transfer of heat in either direction.

If the heater is in a dusty location, it may require more frequent cleanings. Also, keep weeds and landscaping vents clear of the unit.

To clean the coil, nothing more than a simple garden hose is required. In general, detergents should not be necessary. Use fresh water only and not reclaimed or recycled water, which tends to be acidic. Also, don’t use pool water.

Avoid using too much water pressure, as excess pressure can bend the fins.

Shut off the power to the heat pump at the breaker, and use the hose to spray the external coil from top to bottom. If greasy dirt is observed, use a mild cleanser. Many service techs recommend Simple Green. With the power shut off, clean out the leaves and muck at the bottom of the unit. A wet-dry vac is useful here. Make sure to clean the side openings for rain to run out and not build up inside.

Clean the fan blades with a cleanser and rag, taking care to get the tips of the blades, which can develop a dirty edge.

Check that the wiring is in good shape and not chewed by animals. Make sure that all wires have good, tight connection points.

Inspect the refrigerant line insulation, which can deteriorate over time. Replace insulation as needed to keep the heat pump operating efficiently.

Restore power when finished.

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