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Web Exclusive - March 2019
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Ensure Long Heater Life

By Mike Fowler

Troubleshooting Heater Problems

The symptoms associated with heater failure can generally be narrowed down to issues with a burner or with the heat exchanger. The following are a few troubleshooting tips to consider for common problems experienced with pool heaters.

Loud, high-pitched whine
This symptom is generally associated with a burner issue; specifically with the flame being too "rich." To remedy this, check the pressure tap between the gas valve in the blower inlet and verify the gas regulator setting is -0.2 in. water column (wc). In some cases, it might be necessary to replace the gas orifice.

Flame is "fluttery"
Again, this is symptomatic with a burner issue and can be accompanied by an acrid smell from the exhaust. However, in this case, the cause is most likely the result of the flame being too "lean," and the burner may even fail to remain lit. As noted earlier, check the pressure tap between the gas valve in the blower inlet and verify the gas regulator setting is -0.2 in. wc.

Flame does not stay lit
Sometimes the combustion on the heater appears to be normal, but the flame does not stay lit. The cause is most likely a result of the flame not being detected. To remedy this situation, check the igniter to see if it is wet or possibly damaged. This may require the igniter to be replaced.

Further, verify the burner flame holder is properly grounded. This might also require the ignition control module to be replaced. Finally, be sure to inspect the manifold pressure. In doing so, check the gas supply line pressure when the heater is operating.

Boiling and "bumping" sounds
The heat exchanger within the heater can also be the cause of several problems. One of the most common issues is the boiling of water accompanied by "bumping" sounds. This is commonly caused by low water flow to the heater. This problem can also be caused by a plugged heat exchanger or a bypass valve that is stuck open.

The best way to fix this problem is to ensure the pump and filter are working properly so the water flow is sufficient to the heater. If the heater is not getting good flow, first check to make sure your filter is clean and not time for backwash or element cleaning. A dirty filter can reduce proper flow through the heater as well.

The heat exchanger could also be plugged because of improper water chemistry, resulting in scale formation. More often than not, this is because the water is out of chemical balance. If this is the case, the water should be tested to ensure the proper corrective measures are taken to get the water back in balance.

Reduced water flow
It is all about water flow. If it is too fast, it results in condensation. If it is too slow, the heater is not warming the water efficiently. In some cases, when a pump is not working properly it can contribute to heater inefficiencies due to irregular water flow. If this is the problem, it might be a good time to consider a variable-frequency drive (VFD) to ensure the water flow through the heater remains consistent.

Propane and natural gas, when burned, produce water as a byproduct. If the heat exchanger is too "cool" the humid flue gases will condense on the fins of the heater. Condensation on the heat exchanger causes carbon to adhere to it. The condensate collects, then drops on to the burners. The combustion is then compromised as "raining" condensate that interferes with the flame pattern.

This poor combustion turns into "soot," which collects on the fins and causes the flue gasses to be impeded. The condensation not only causes inefficiencies in heater functionality, but also causes oxidation on copper from low return water temperatures.

Brief periods of condensation on startup is normal for most pool heaters. In fact, all category I and III pool water heaters will condense if allowed to send very low return water into the heat exchanger. However, adding airborne chemicals to condensate on heat exchanger coils will cause the unit to fail more quickly. As mentioned earlier, "sooting" is often the first sign of a problem, but is often ignored. In fact, some service technicians who have not been trained properly may place jumpers on safety devices instead of paying attention to the "sooting" that occurs.

Soot formation on heat exchanger tubes
There are several items to look for to identify soot formation on heat exchanger tubes. The first contributor to the problem is low gas pressure. The heater needs an 11 in. wc for propane gas and a 4-in. wc for natural gas. The pressure of the gas should be inspected while the burners are lit.

Soot can also form when there is too much water flow through the heater. To remedy this, a high flow modulator or a manual bypass valve should be installed. Obstruction of the burners by some foreign matter can also be a problem; therefore, it is important to remove, inspect and clean all burners.

Maintenance Program

All aquatic facilities should establish a comprehensive maintenance program for the equipment room, which must include a specific action plan for heaters, as well as the pumps and filtration systems used on pools and other water features.

It is also a good idea to keep additional parts on hand just in case an aquatic facility needs to get a heater up and running immediately. Having access to items such as pilot assemblies, orifice parts for burners, and even a gas valve can come in handy during a time of need. Most facility operators would also agree that it is wise to post the phone number of a nearby service company directly on the heater in for emergencies. Avoiding heater problems this winter is important to all aquatic facility managers and, often times, the simplest best practices are the ones that keep pools running smoothly at all times.

Mike Fowler is the commercial sales manager for Pentair in Sanford, N.C. He has been with the company since 1992, starting his career in the technical services department at Purex Pool Products. Fowler has held many managerial roles within the company, including marketing, accounting, and products.