Gas Pool Heater Kalos Meeting w/ Bert
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Bert teaches the Kalos technicians about gas pool heaters, which are less common in our market but still show up from time to time.
Gas pool heaters use a gas-fueled flame to heat the pool, not a refrigerant that rejects and absorbs heat. However, like heat pump pool heaters, poor water flow will likely be the main cause of many problems you’ll encounter.
Gas pool heaters can burn either natural gas from a communal gas line or propane (if there is no communal gas line). You can look at the data tag to determine if you are dealing with a propane or natural gas pool heater. Some common fuel-related problems include empty propane tanks and air in the gas lines (from long periods of inactivity).
When dealing with gas, you must pay attention to the minimum and maximum gas pressures on the data tag. If you’re getting rollout issues or the heater isn’t burning clean, check the inlet and outlet gas pressures; the safeties could be preventing the heater from working under unsafe circumstances.
When you have successfully turned on your gas heater, the heater will try to prove that it has good airflow through its inducer motor. If your heater doesn’t sense adequate airflow, it will trip the airflow safety switch (normally open).
Sometimes, you will get an error code indicating that the heater isn’t igniting. When that happens, you’ll want to inspect the igniter and make sure you have gas going to the heater. You may come across hot surface or intermittent spark ignition in gas pool heaters.
The next safety element is the flame sensor, which merely proves that the flame is active. You must make sure it is clean enough to sense the flame and close enough to the flame to touch it. Heaters typically try to prove flame within three seconds of opening the gas valve; if the sensor fails to detect a flame, everything should shut off.
In Florida, gas pool heaters commonly rust out due to the climate and corrosion. We don’t want to fix those units if they are so rusty that they are unsafe. In that case, we must communicate the safety hazard to the customer and quote them for a replacement.
After the heater has lit and proven flame, there are a few more safeties that can halt operation. Anything related to the airflow may be clogged with animal or insect debris. If the airflow is poor, the heater will get hot, and a safety component should shut it off. Stack flue sensors work like water temperature boards and can let you know if the sensor is failed or if you have an actual problem. Limit switches go in the water and open when the temperature exceeds their rating; however, these can rust out easily or may fail due to recurring water issues.
Poor water flow doesn’t mix well with flame; the water may even boil inside the heat exchanger if the flow is poor enough, and the heater can start shaking due to the high pressure. However, we have safeties and backup safeties to open bypass valves or take other measures to prevent explosions.
When it comes to electrical problems, the main issue will be animal activity; rats, insects, and lizards may get inside the panels and damage wires. Sometimes, you may encounter issues with controls that you’re not familiar with, or you may be stumped by a gas heater problem. In those cases, manuals and tech support can be excellent resources. Before you finish, make sure you check the functionality of the heater in the EXACT same way the customer will use the heater.
Here are some of the gas pressure measurement videos Bert references:
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