As the world increasingly strives to reduce its environmental impact, demand for energy-efficient appliances grows, especially in heating appliances such as boilers, furnaces and water heaters. These “condensing” appliances, with a minimum 90% efficiency, extract more heat from the combustion gases, thereby conserving energy. In turn, they can help reduce energy bills while maintaining a high level of performance.

While these appliances provide great value and a path to a lower-carbon future, they can leave a concerning residue in their wake. When a high-efficiency appliance enters its condensing phase, the resulting vapor inside the appliance cools into a liquid condensate, which typically has a pH value between 2.9 and 4.0. As such, the condensate is highly acidic or well-below neutral (water in its purest form has a pH level of 7.0). 

The acidic condensate contains a combination of nitric, sulfuric, sulfurous and hydrochloric acid, which, if untreated, can severely damage infrastructure, the local sewage system and the environment. While the issue may seem modest with only one appliance, the scale of the problem is only expanding. 

A Growing Concern 

The advent of high-efficiency appliances developed due to increasing government efficiency mandates. National organizations such as the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy have incentivized using energy-efficient appliances as an extension of the Energy Star program. They offer discounts on appliances, tax credits on purchases and rebates on energy bills. 

Such actions, along with the growth of natural gas infrastructure across the country, have driven a surge in condensing appliance use.

As the adoption of condensing appliances rises, so does the resulting acidic condensate. In 2015, the Air Conditioning, Heating and Refrigeration Institute estimated that high-efficiency, gas-fired appliances expel an astounding 9 billion gallons of acidic condensate per year in this country.

However, there is a purpose-built solution to the growing acidic condensate problem: a condensate neutralizer. It can be installed with fuel-burning condensing devices to safely treat and discharge the acidic residue. A condensate neutralizer contains neutralizing media, such as magnesium hydroxide, that interacts with the acidic residue to reduce its acidity. 

In application, a condensate neutralizer is connected to the condensate trap at the back of a condensing appliance. Many can be mounted on the floor or wall, per the engineer’s design specifications, as long as it is below the appliance’s condensate trap.

The condensate neutralizer’s mechanics ensure that the condensate trickles into the filtering device upon leaving the appliance by using gravitational force. The residue then interacts with or “soaks” in the neutralizing media, raising its pH level between 5.0 and 9.5, safe enough to be released into the plumbing or wastewater systems.

Mitigating Infrastructural and Environmental Damage 

Due to outdated industry norms, many buildings still discharge untreated condensate into the sanitary drain system or the surrounding environment. Acidic condensate, if left untreated, can damage concrete floors and the foundation system, endangering the building’s structural integrity. Furthermore, untreated acidic condensate can damage the wastewater sewage system, including sewers, piping and septic tanks.

Acidity in the wastewater kills the good bacteria in a septic system, which is critical to breaking down human waste. Without these bacteria, the septic systems can become backed up and deteriorate, causing the release of untreated sewage into the environment. This can pose a severe public health risk and lead to expensive repairs and replacement costs. 

Plumbing engineers can mitigate these risks by specifying a condensate neutralizer with gas-fired, high-efficiency appliances in the design and planning stage. This way, they can also fulfill individual environmental goals as condensing appliances are important to a lower-carbon future.

Code Compliance 

In addition to safeguarding infrastructure, acidic condensate neutralizers can help plumbing engineers achieve code compliance. Many states and municipalities now require appropriate treatment of acidic condensate before discharging it from a building. Purpose-built neutralizers are designed to do exactly that. 

Commercial engineers, contractors and building maintenance personnel can ensure the inclusion of a condensate neutralizer when designing, installing or maintaining gas-fired appliances to achieve code compliance.

International Plumbing Code Section 803.1 considers a condensate neutralizer as a requirement for appliances producing acidic condensate. The code requires corrosive liquids and chemicals to be treated by passing them through an approved dilution or a neutralizing device. In addition, EPA Section 403.5 (b)(2) prohibits the discharge of corrosive pollutants with a pH lower than 5.0 that can cause corrosive structural damage to public infrastructure.

Compliance with these regulations is important. If a project or job is inspected and acidic condensate is found discharged without appropriate treatment, the consequences can be severe, including fines or shutdown. 

By installing and maintaining a condensate neutralizer, engineers can protect the building and its facilities and comply with environmental codes. Engineers can ensure customer satisfaction as building owners will appreciate the forethought and stewardship required to help keep their facilities open and safely operating.

Condensate Neutralizer Selection

Neutralizers come in various sizes and capacities to accommodate different needs specific to the application. When selecting an appropriate neutralizer for a condensing appliance, consider these key factors: 

BTU capacity and the estimated gallons per hour of condensate produced by the appliance(s);

Specific operating site conditions, such as the location and height of the heating appliance; 

Raw gas composition;

Number of heat days determining the degree and variance of heat required; 

System design specification, such as the type of heating system (process, radiant, snow melt or hydronic);

Operating hours of the heating equipment.

Installation and Maintenance 

Like high-efficiency appliances, condensate neutralizers must be routinely inspected for leaks and serviced. The neutralizing media, as specified by the neutralizer manufacturer, needs to be replaced about every six to 12 months or when the pH level is below 5.0 (or that of the local water authority code).

Failure to install or maintain neutralizers can cause long-lasting damage to a property, which is likely to be expensive to repair and replace. For instance, a private university in Texas installed new condensing boilers and neutralizers across the campus but failed to recognize the importance of periodic maintenance. As a result, the untreated acidic condensate collected into a brown-coppery substance in the boiler room and significantly deteriorated the concrete foundation. 

Consequently, the school was forced to pay for expensive foundation repairs and new flooring. Both activities are time-, capital- and labor-intensive. 

Additionally, untreated acid condensate can disrupt the daily functioning of commercial buildings and cause serious inconvenience to businesses and users. 

Picture this: a luxury commercial building in Manhattan installed condensate neutralizers with its condensing boilers but failed to properly size the neutralizers and maintain them. As a result, the acidic condensate was not sufficiently treated before discharge into the plumbing system running above the amenities floor. The piping began to leak into the building’s amenities floor, shutting down the amenities due to leakage from the ceiling. The repairs were costly, and the occupants could not use the space. 

In these cases, the damage and cost of repairs, along with the inconvenience, could have been avoided by sizing the condensate neutralizers properly and routine maintenance of the neutralizing media. 

Condensate neutralizers are a critical part of a condensing installation that work to safeguard the building’s plumbing system, downstream infrastructure and the environment. Importantly, by specifying the filtering device, plumbing engineers can ensure compliance with code regulations designed to protect public works. 

In turn, not only will engineers help protect wastewater systems from damage, but they also can enhance their professional reputation by delivering cost-effective, proactive solutions to their clients. 

Kyle T. Emmons is the president of JJM Alkaline Technologies, a designer and manufacturer of acidic condensate neutralizer products for the heating and plumbing industries.