By Tom Soukup
There are a lot of considerations a pool professional must consider when stepping into a customer’s facility. Is the filtration system working as intended? Is the water quality up to snuff?
The water temperature is unique in several ways. It is what bathers are most likely to complain about, and it significantly impacts water treatment. Automated chemical treatment systems are calibrated for specific water temperatures, as these dictate how treatment chemicals react within the pool’s body of water. Suffice to say, if there is a problem with the pool heater, it has the potential to be far-reaching.
Over the years, many pool companies tasked with maintaining aquatic facilities do not have the tools they need to properly work on a heater. They are pool specialists, as opposed to heating appliance professionals.
The aquatics industry requires professionals to have a diverse skill set, including the basics of pool heater diagnosis and repair. However, only certified gas fitters, as mandated by the Canadian Gas Association (CGA) B:49 Code book, are permitted to work on this equipment to ensure safety and compliance.
Tools of the trade
Aside from the pool heater manufacturer’s installation and operation (I&O) manual, the two most important tools for diagnosing heater issues are a multi-meter that allows the technician to check voltage and resistance, and a gas monometer for checking gas or liquid propane (LP) pressure. These are the essential minimum requirements for any professional pool heater service or troubleshooting call.
Other tools that would benefit the technician are a high-quality gas sniffer, thermometers, and flow meters. If the pool heater is not equipped with flow meters, one should be installed on the influent or effluent side of the heat exchanger. Some technicians also tap in thermometers on each side of the heat exchanger, and these items remain installed in the system.
Establishing the flow rate and the temperature differential across the heat exchanger provides information that can be used to diagnose an issue or determine how many British thermal units (BTUs) are entering the pool.
Keeping an inventory of frequently used components at the shop and in service vans is also good practice. This could include thermometers, pressure gages, flame sensors, ignitors, pumps, etc.
The performance exhibited by the equipment is often a determining factor when a customer decides to repair or replace the appliance.
Inspect the situation
When a technician goes out on a troubleshooting visit, the first thing they are trained to do is look at the overall heater installation. Does the installation meet manufacturer requirements? Does it meet local prevailing code requirements? If the answer is “no,” then those issues should be written down and the owner should be notified.
After that, the technicians have a conversation with the customer about what is wrong. They ask if other people have looked at it, and if so, what have they done to the piece of equipment, if anything. An initial inspection and the answers to those questions will help steer the diagnosis.
If the unit has power but is not receiving a signal to operate the case, technicians inspect the automation system to determine why it is not enabling the unit to operate. If there is voltage at the heater and it is receiving a signal to operate, technicians should proceed to the equipment manual to begin the rest of the troubleshooting procedure.
If the heater has electric power but will not fire, the problem could be caused by a fuel supply issue. It could still be an electrical issue but start by confirming a lack of fuel. If the unit is propane-fired, check if the tank has sufficient fuel. Whether the system runs on natural gas or LP, check to see whether all valves within the gas system are open.
After completing the basic checks, the technician must verify there is sufficient water flow through the heat exchanger. This involves ensuring the pump is operational; if it is not running, the technician should investigate the cause. Heaters are equipped with either a pressure switch or a flow switch to confirm that water flow is established. To protect the heat exchanger, most heaters are designed not to activate unless water flow is confirmed.
Low flow can generally be attributed to clogged filters or valves in the wrong position. Therefore, it is important to ensure all valves are open and the filters are clear. Power, fuel, and water flow are the external requirements that must be met first. If these needs are met and the issue prevails, it is time to troubleshoot the heater.
Fuel supply issues
If the heater runs through its cycle but will not ignite, it is likely there is a more complicated fuel supply issue.
A common issue in the field is the use of undersized gas piping. Most I&O manuals provide gas piping sizes based on the capacity of the unit and the distance from the heater to the fuel source, whether that be an LP tank or a natural gas meter.
Gas systems are designed on pressure and distance. It is worth noting that by distance, the author means developed pipe length. Developed pipe length is the length of the pipe including the pressure drop created by elbows and other fittings. One can determine whether the size and length of the gas piping is adequate by reading the I&O manual.
Technicians must ensure the gas valve inside the unit is operating correctly. They should check for voltage going to this gas valve; if voltage is present, it indicates that all other safety devices in the unit are functioning as intended.
At this point, a monometer must be used to verify there is incoming gas pressure to the valve. Some valves allow the technician to check the manifold pressure to verify there is sufficient pressure on the burner side of the valve. All these values are unit-specific and will be outlined clearly in the manual.
In the event of the gas valve opening and there is sufficient pressure, yet the heater still fails to ignite, sputters, or runs for a short period of time before shutting down, the control is not seeing establishment of flame (flame proving). This could either be the result of a defective flame sensor or an insufficient gas supply. Simply verifying whether there is sufficient gas pressure at the burner at one moment in time is not enough to say with certainty that gas supply is not the issue.
The ladder chart in the manual will show both static and dynamic gas pressure must be verified. Checking static gas pressure must be completed while all other appliances on the same gas supply are running at the same time, but with the pool heating unit off. Checking dynamic gas is the same as static, except the pool heating appliance will be turned on.
If the dynamic gas pressure drops below manufacturer requirements at any point, this suggests the issue is likely an undersized piping system, regulator, or meter. Just because most heaters have a 19 mm (0.75 in.) gas pipe connection does not mean 19 mm (0.75 in.) is sufficient of the developed length of pipe.
Technicians should always inquire about any changes on the property that could possibly cause this issue. Even small additions to the load on a gas meter can be the culprit, such as installing a larger gas range, adding a gas fireplace or outdoor fire pit, etc. If any appliance has been added to the gas or LP system, it could be the culprit.
Gas supply issues can only be fixed by increasing pipe size or increasing pressure, which requires a licensed gas professional to replace the necessary components.
Power supply
Electrical issues are often the result of work done on the property, such as the addition of outdoor lighting, etc. Any kind of changes or additions can create a variable. Eliminate these variables before diving into a deeper diagnosis.
If power is properly delivered to the heater and the unit is not functioning as intended, most heaters have some form of built-in diagnosis displayed on the control interface. The display may report there is a sensor error, or where the error stems from. Keep in mind, a sensor error does not mean with certainty the sensor is bad. Many times, the sensor is doing its job exactly as it is designed for the safety of the system.
This is another reason it is critical to have the I&O manual, which will show the possible causes of a specific sensor error. Technicians should work through the manual and use process of elimination to determine the source of the sensor error.
Flow
Flow is one of the simpler issues to diagnose. As previously mentioned, the heating unit will likely be equipped with a pressure switch or a flow switch to ensure flow is established. If flow is not present, the unit will not fire.
The most frequent cause of a low- or no-
flow situation is clogged filters. The second most common issue is an inoperable or underperforming pump.
Technicians should clean the filters and inspect the pump. They need to refer to the heater’s manual to identify the appropriate flow rate through the heat exchanger and compare it with the readings from a flow meter on the effluent side of the heat exchanger.
If the flow is insufficient, it may indicate that the piping system was not designed or installed properly, or the pump might be too small. To address this issue, the author’s company installs booster pumps on all their pool heating systems. This design hydraulically separates the filter loop from the heater loop, ensuring that even if the filters become dirty, the pool heater still receives the necessary flow.
Much like diagnosing any mechanical problem, fixing pool heating systems is best done via process of elimination. It takes time, it takes the right tools, and it takes the appliance manual. Experience expedites the process.
One final thing every maintenance professional should understand is the importance of service. The best heating equipment in the world will not operate as intended if it is not properly serviced and maintained. Equipment that is properly cared for will last longer, will operate more efficiently, and will be less likely to unexpectedly fail, so be sure to service equipment routinely.
Alternative technology
As a contractor in the Mid-Atlantic states, the author’s customers are often high-end homeowner associations (HOA), waterparks, and resorts. Companies are finding these customers want to provide the best amenities possible to their clientele, while maintaining the smallest carbon footprint possible.
Most of these facilities have multiple bodies of water, and they are either looking for extended bathing season or year-round bathing. As a result, many of them are moving toward centralized water heating plants. In this scenario, one mechanical system serves multiple bodies of water.
These centralized plants include large gas-fired units or large commercial heat pumps. While this heating solution generally includes a larger upfront cost, the payback comes in the form of lower maintenance expense, higher efficiencies, and greater dependability/redundancy.
These types of systems often require more specialized training and equipment to service, but they also offer better control, especially if the owner operates more than one property.
Tom Soukup is the principal of Patriot Water Works Co. with more than twenty years as a hydronic designer and installer. He specializes in high-efficiency and green technology and brings his expertise to custom hydronic work, pool heating, and agricultural projects. Reach him at twsoukup@PatriotWaterworks.com.
