Five people were evacuated on February 24 from a Hampton Inn & Suites hotel in San Antonio, Texas because of carbon monoxide exposure (CO) from the pool heater. Two people were hospitalized, but everyone was fine.
Unfortunately, carbon monoxide poisoning is not an uncommon occurrence. A pool heater malfunction in Ohio sent fourteen people to hospital in January 2022. In the United States, 13 carbon monoxide-related incidents were reported in 2018.
Carbon monoxide poisoning is a very common problem, but the majority of these incidents are avoidable. The cause of carbon monoxide poisoning is not the equipment, but rather improper installation or poor maintenance.
We have a responsibility, and even a legal obligation, to install and maintain the gas-fired pool equipment as described in the manual or local code.
READ THE MANUAL
It is important to understand the product that you are installing. The manual should be read in its entirety. Be familiar with all codes applicable to these appliances. It’s important to understand the category of venting for the equipment you are installing.
The failure of venting systems is often caused by the use of incorrect materials in the appliance.
Gas-fired pools are usually classified as Category 1, 3, or 5. Certain models may be Cat 1 or Cat 3 depending on how they are installed and vented. It’s likely that the appliance is Cat 3 if it has a fan. It’s likely Cat 1 if it doesn’t. Cat 5 is usually the category for high-efficiency appliances. Installations must verify the category of the appliance in the manual, and vent it accordingly.
Cat 1 is an atmospheric venting system with negative pressure. The unit does not have a fan or blower. Hot gases rising create a natural draft or convectional current. The venting system does not need to be sealed or gasketed because there is a negative pressure inside the vent.
A fan or blower creates an induced draft in Cat 3 appliances. It creates positive venting pressure. AL29-4C is required by most manufacturers of Cat3 appliances. This is a stainless-steel, gasketed material. Gasses from flue gases will leak through a vent that is not gasketed.
Cat 5 appliances are condensing, high-efficiency appliances. These appliances have heat exchangers that are so efficient, the flue gases remain below 140 degrees Fahrenheit if properly installed and maintained. This low temperature flue gas means that condensate will be generated within the heat exchanger or flue. The condensate produced is highly corrosive, and over time will destroy all materials except for plastic vent pipes.
PVC, CPVC, and Polyvent pipe must be used because Cat 5 appliances have lower stack temperatures. These materials are resistant to the caustic environment caused by condensate.
Although PVC is allowed by many jurisdictions, Centrotherm, a polypropylene system for venting, would be my recommendation. It is specifically designed for venting and can withstand temperatures higher than PVC or CPVC. The gaskets and clips are used to assemble the product instead of primer and cement. It can be disassembled easily and reassembled in the event that the flue becomes clogged.
Most codes dictate that a vent must terminate at least 18 inches above the proposed snowline. If the vent is blocked by snow, carbon monoxide would back up into the occupied space. Also, the gas regulator, which has a vent, is far too close to the hot surface of the vent termination, which is a potential source for ignition.
Service Work
It is important that you check your equipment regularly, particularly the venting system, if you have a service contract with a swimming pool facility.
The most effective way to test the integrity of venting materials on a Cat 1 appliance or Cat 3 appliance, as simple as it may sound, is to use the screwdriver handle and tap the metal venting against it. If punctures are found, it is obvious that the venting needs to be replaced immediately. You may hear the metal flake off the inner wall of the vent pipe. This is a sign that you need to investigate further. The vent will likely have to be disassembled, and possibly replaced.
The screwdriver test should be performed at least annually. I recommend every six months. Once a year, the heat exchanger must also be cleaned and inspected. High temperatures in the flue gases can be caused by a clogged heat-exchanger or an inadequate water flow. It will also destroy the incorrect vent material. Ensure that the combustion air supply is adequate while inspecting the system.
Cat 5 high-efficiency units have sealed combustion burners. Intake air must always come from the outside. This usually includes PVC running through a roof or wall and terminating in the burner. A Cat 5 appliance should never draw air from the inside of a building.
This is a perfect example of incorrect venting. Both the boiler and the pool heater in this image are Category 3 appliances, but are vented using standard Category 1 vent systems. The installer tried to overcome the flue gas leakage by taping the seams, which is absolutely unacceptable.
Cat 1 and Cat 3 devices can draw combustion from within the building. However, for many reasons, it is best to use outdoor air. Operating the appliance can create negative pressure in an enclosed space if there is not enough air permeation. This will lead to incomplete combustion and reduce the efficiency of your appliance. It can also cause premature fouling of heat exchangers, higher flue gas temperatures, and ultimately damage the unit.
Louvers are often found on the exterior walls of mechanical rooms containing Cat 1 or Cat 3 appliances. The louvers that are supposed to activate when the heating appliance is on should not be relied upon. We have seen far too many instances where louvers were bypassed, broken, blocked, frozen closed, or otherwise unoperable. It’s just one more reason why you should provide fresh air from the outside directly to your unit. Many manufacturers offer a kit to provide fresh air for their unit.
Many pool heaters are located near storage areas for treatment chemicals. Even in very low concentrations, these chemicals can cause premature heater failure.
Another risk is supplying combustion air to a heater from inside. The majority of pool mechanical rooms are located adjacent to a swimming pool. The heating appliance creates negative pressure in the mechanical room, which often draws makeup air from a natatorium. The chemicals in the air can damage the heating appliance as well as other equipment in the mechanical space.
A non-functioning barometric damper, as seen here, is another opportunity for carbon monoxide to escape the flue and enter the occupied space.
Training and Support
It is important to understand the installation and maintenance instructions in the heating appliance manual as well as the local codes.
Do not hesitate to ask questions directly of the representative. Ask about training options for you or your technicians. This training can be provided by a manufacturer, a representative, or a supply house.
Also, it’s important to know that local codes supersede the manufacturer’s specifications. You should establish a working relationship with the local code officials. They can provide information but, if you show them that your work is of high quality, they might also refer work to you.
The rust stains around the vent stack are a strong indicator that the interior of the venting system is deteriorating. The absence of a correctly sized starting collar between the appliance and the vent is also the site of a potential flue gas leak.
Being proactive
It is dangerous to take a passive approach when it comes to installing and maintaining venting. The pool heater and venting system is one of the most neglected systems in a hotel, a motel, or an aquatic facility. When acquiring service agreements for systems installed by your company, you should take a proactive approach.
Do not be afraid to lockout (red tag), a heating device if it isn’t installed or maintained correctly. It could literally be a matter of life or death. If you are the last person to work on the system, your liability is likely to be at stake.
We can red-tag a system and then send photos and videos to the owner. We reduce our exposure if something goes wrong. It’s a good idea to inform the local official who has jurisdiction if the customer does not take steps to resolve the problem. It could be a gas company representative, code enforcement officer or other official. You can reduce your risk by taking every step to alert others. Save all communication and make notes.
Carbon monoxide poisoning is a preventable event and the result of negligence. Carbon monoxide poisoning is not a common occurrence, but it can have serious consequences. You should make every effort to protect the public and your business from the effects of negligence.
The article was first published in AQUA Magazine, the leading resource for pool and spa retailers, builders and service professionals. All industry professionals can subscribe to the print edition of AQUA Magazine for free. Subscribe by clicking here.
