What Causes Condensation On Insulated Pipes From an Air Handler Unit?

Crawl Space Moisture

• Air handlers that are located in unconditioned crawl spaces under houses are exposed to moisture that evaporates from the soil. If a house has a drainage problem that allows moisture to accumulate underneath the house, water evaporates from the crawl space floor and settles on air handler pipes, even if they’re insulated. According to Broom Heating and Air Conditioning in Blythewood, South Carolina, sweating pipes do not cause moisture under your home; the moisture under your home causes condensation on your pipes.

Insulation Issues

• If pipe insulation is of insufficient thickness or is poorly installed, condensation can accumulate. Over time, old insulation may deteriorate or fall away from pipes, which may encourage moisture to build up along exposed pipe sections. If pipes are not properly sealed where they join together, conditioned air may leak out between joints and cause moisture to condense around the pipes. Different areas of insulated piping are called “crucial condensation zones,” according to Thermaflex. If insulation is compressed along the flexible pipe in one of these condensation zones, there may be localized sweating in the compressed area.

Dirty Air Filters

• Air filters are installed inside air handler units to prevent particulate matter from moving through the system and circulating in the air. Filters must be changed or rinsed periodically, depending on type. If they become clogged, airflow is restricted. When air moves too slowly through the coil inside the air handler, it forces the system to work harder and makes the air colder than normal. This colder air lowers the outside temperature of pipes below design specifications, which causes condensation to accumulate on the pipes.

Water Drips and Leaks

• According to Broom, when an air conditioner is running and cooling air, the pipe attached to the evaporator coil naturally sweats. This pipe is encased in black insulation that is porous, which prevents condensation from dripping. However, sometimes the evaporator coil freezes and ice builds up on the pipe. When the ice melts, water can drip down onto other pipes, which causes condensation buildup on those pipes. Plumbing leaks can travel down pipes and collect as condensation on air-handler pipe insulation.