What is Boiler Condensation?

When a hydrocarbons are burned, the primary products of combustion are CO2 and H2O. Typically, all the products of combustion go out the exhaust vent as gasses. However, if the flue gasses are cooled down enough, the water vapor will begin to condense on surfaces and possibly rain out of the air. Higher efficiency appliances and cooler water temperatures increase the potential for condensation.

In normal boiler operation the boiler fires and cools in an effort to meet the required hot water delivery temperature. When a boilers operating temperature drops below 110^o degrees, a condition known as condensation occurs. During this condition, moisture accumulates on the inside of the boiler and combines with the Carbon Dioxide created by the burning of natural gas. The end result is a corrosive acid that can and does dramatically reduce the operational life of the boiler/water heater.

There can be several causes of Condensation;

Improper Plumbing: This occurs when the external cold water feed is plumbed directly into the boiler. The result is dramatic temperature swings as the hot water system in the loop is consumed.

Solution: Install a hot water mixing tank and plumb the cold water feed into the “boiler to storage” line. This will reduce the temperature shock by pre-warming the cold external water supply. Note, your storage tank must be of adequate size to be plumbed this way. If the tank is too small the cold water will enter the system and will over-dilute the mixing tank, thus delivering inadequate hot water to the tenants.

Boiler Pumps: Boilers are designed to heat and provide water through a designated loop. The water moves through the loop via one or more circulation pumps. Technology is available to turn off the boiler pump (the pump that circulates water between the storage tank and the boiler). In theory this would provide electrical savings by not continuously running the pump and some fuel savings by not circulating hot water from the storage tank to the heat exchanger when the boiler is off. This however creates a different problem of allowing the water in the loop to cool thus increasing the probability that the water in the storage tank will not be adequately mixed. The end result is an increased chance of thermal shock to the boiler and condensation. These lower temperatures could also lead to other potential problems, such as Legionella, uneven water temperatures, temperature swings spikes etc.. As a result you might save a small amount of energy using this technology, but at the expense of inserting other problems and costs into your environment.

Solution: All pumps on the system should be operational 100% of the time.

EDC Technologies monitors numerous locations on the domestic hot water system, including the boiler, storage tank, the feed lines from the boiler to storage and from storage to boiler. If your boiler operates at a temperature below 110^o you will be notified of the temperature drop for resolution, but most of all condensation is avoided.