Water Leaks in High-Efficiency Gas Furnaces: Causes and Solutions

When it comes to heating your home without breaking the bank, high-efficiency gas furnaces are a cut above the competition. These sophisticated home heating systems can keep your home warm through the coldest winter nights while also using a very small amount of natural gas or propane. 

Unfortunately, high-efficiency gas furnaces can malfunction just like any other kind of furnace, and in some cases, a faulty high-efficiency furnace may start leaking liquid water. If you ignore the problem, you may find yourself paying thousands of dollars to repair your furnace and any water damage it has caused. A leaking high-efficiency furnace should be professionally repaired as soon as possible.

Why Is Your High-Efficiency Gas Furnace Leaking Water?

When a gas furnace burns gas to create heat, a large amount of hot exhaust gas is created. In a standard gas furnace, this waste gas is vented directly into the atmosphere. High-efficiency gas furnaces recirculate this hot exhaust gas around the furnace's heat exchanger. This allows them to extract more heat from the same amount of gas, making them significantly more efficient, cost-effective, and environmentally friendly.

However, because almost all of the useable heat in the exhaust gases is transferred into the heat exchanger, the gas is very cold by the time it is vented outside. The temperature difference created by this cold gas can cause large amounts of liquid condensation to build up inside the furnace.

All high-efficiency gas furnaces are fitted with at least one condensate drain, which funnels this excess moisture away from the furnace and into your home's wastewater disposal system(s). If the condensate drain line is damaged, rusty, poorly fitted, or clogged with solid debris, liquid condensate can start to back up into the main body of the furnace, causing it to start leaking water.

However, a faulty condensate line is not the only reason a high-efficiency gas furnace may start leaking. These drain lines are fitted with small pumps that pressurize the wastewater and force it through the line. If the pump is damaged or has burnt out due to excess use, water may start leaking from its housing. Water can also leak from the furnace's gas exhaust flue if it has been damaged or disturbed by recent remodeling.

What Should You Do About Water Leaks in High-Efficiency Gas Furnaces?

Blockages in the condensate line(s) are probably the most common cause of water leaks in high-efficiency gas furnaces, and you may be able to fix this problem yourself. Your furnace should come with instructions on how to flush and drain a blocked condensate line. Follow these instructions carefully, making sure the furnace is fully deactivated before you begin.

However, if flushing the drain line fails to fix the leak, or you are unable to flush the line yourself, you should call in a professional furnace repair service that works on high-efficiency gas furnace models. These services can rapidly remove any blockages in your condensate line, and will also be able to repair damaged lines, replace faulty condensate pumps, and refit leaking exhaust flues. 

Talk to a residential heating company for more information about this.