Every now and then we get a service call from a customer stating that the furnace is gurgling. Strange but true, furnaces do make gurgling noises. When the condensation drain becomes partially or even completely blocked, a gurgling noise can sometimes be heard. Where is the water coming from that drains through this line? All furnaces rated above 90% AFUE produce condensation during the heat cycle. It is a natural by product of cooling combustion fumes. The other sources of water are the whole house humidifier as well as the air conditioner. Large amounts of condensation may be produced by the air conditioner, especially on very hot days.

Damage Caused by Condensation Leaks

Combustion condensation, air conditioner condensation and humidifier run off all drain into a condensate pump or a floor drain. These lines can become slow or blocked if the drain line is not cleaned periodically. The gurgling noise is a nuisance but a condensation leak because of a slow or blocked drain can be expensive. Water damage from a small condensation drain leak has ruined more than one hardwood floor in the past. Problems like this generally go unnoticed until it’s too late. After a floor starts to buckle or carpet starts to smell hundreds of dollars of damage has all ready been done. Let’s not forget if this condensation leaks or backs up into your furnace it can cause a catastrophic failure of the control board, motor, gas valve or any of the other electrical components it comes in contact with. » Read more: What is that Gurgling Noise?