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Furnace Water Leak Possible Condensate Problem

Gas Furnace with Drain Pipes to Drain the Condensation.

Furnace Water Leak Possible Condensate Problem - Richard, My furnace is leaking water. It is summer time so I am not using it for heat except for the blower fan which is hooked up for the air conditioner and the heat. I know the pipes from the outside units run into a box on top of the furnace. I think that is a part of the air conditioner. What can I do to fix the problem if you know what the problem is by my explanation here? Dan
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Furnace Water Leak Possible Condensate Problem

Dan,

The box on top of your furnace is an essential part of your air conditioner. The pipes run into the evaporator coil for the air conditioner. You are right that the blower fan from the furnace is used for both the heating and cooling. However, you need to take action right away. That is before the water causes severe damage to the electrical components of the furnace. This includes the blower fan. You have an upflow gas furnace with an evaporator coil on top of it for air conditioning.

This means the air from the return comes in at the bottom of the furnace. The air is discharged out the top of the furnace into a supply plenum. Then to the supply trunks which are probably in the ceiling. The return (where the air filter is located) is close to the floor. While the heating and cooling function well for you an up flow is better for cooling than heating. This is because the air is discharged out the supply vents in ceiling where cool air naturally falls. Alternatively, the heat is discharged from the top it will likely stay up near the ceiling. It will slowly flood the space with the heat so you can feel warm.

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Some people compensate for this by turning the thermostat to a higher temperature to feel warmer. However, a ceiling fan will suffice. However, only if the ceiling fan is set to a slow speed in the winter. If you feel a draft you will feel cooler. However, the ceiling fan will help the warm air trapped at the ceiling come down to your level. It will pull the heat down from the ceiling.

Furnace Water Leak Possible Condensate Problem

With upflow furnaces that have integrated air-conditioning the evaporator coil needs to be downstream of the furnace. This is because the evaporator will deliver saturated air that is cold and below the dew point. If the evaporator coil was before the furnace the furnace would get too cold and begin to sweat. The sweat would cause water damage such as rust and corrosion to the furnace prematurely. So it is imperative that the evaporator is installed downstream from the furnace. With upflow furnaces this means the evaporator coil will likely be installed on top of the furnace. This can present a unique problem if a water leak occurs such as you are experiencing.  A few things can happen here that will cause big problems with a water leak in your furnace.

Possible Causes
  1. The water leak can be the result of holes in the drain pan that is located under the evaporator coil. The drain pan collects the condensate that drips off the evaporator coil. Again, the evaporator coil operates below the dew point so when your air conditioner is running the evaporator coil will remove the humidity from the air. The humidity condenses into water at the evaporator coil and drips into the condensate pan. If the condensate pan has a hole in it then the water will drip onto the furnace. This will cause big problems. Some older air conditioning systems used a metal pan and over time the pan will rust and rust holes will cause water leaks.
  2. The condensation drain line is plugged and the pan is overflowing. The condensation drain line needs to be unplugged so the condensate can drain. This will eliminate your furnace water leak if this is the problem.
  3. In some cases, the evaporator coil can freeze up. Certain conditions cause the evaporator coil to operate below freezing and when the evaporator coil operates below freezing all the humidity will freeze to the coil. As the air conditioner cycles on and off the evaporator will thaw depending on the temperatures. This is directly related to the location of the furnace and evaporator coil. As the ice on the evaporator coil thaws, it will often overwhelm the drain and overflow.

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Furnace Water Leak Possible Condensate Problem

Number one and three are serious water leaks. They require the attention of a professional HVAC technician to be repaired. While number two can be taken care of by a good DIYer and a shop vacuum. Find the end of the drain and hook up the shop vac. The shop vac will suck any plugs in the drain line and you are working again although if a lot of water got into your furnace you probably still want to call an HVAC tech to check out the furnace and all the electrical components that got wet. It can save you lots of problems in the future especially when it comes time to turn on the heat. You will feel comfortable know the furnace will give you heat when the temperatures get cold.

Furnace Water Leak Possible Condensate Problem

Another good reason to have an HVAC technician check out this problem is that the technician can make recommendations about avoiding this problem completely. He can recommend adding a few safety controls. These controls will turn the system off before the water leaks on the furnace. There are many different solutions. An inline drain switch that will cut off the system if the drain gets plugged. Additionally, a moisture sensor that will cut the system off if it senses moisture. Good luck and I hope this helps.

A water leak such as this originating from your furnace or air conditioner can cause serious water damage to your home especially if the air handler or furnace is located in the attic or above any living space.

Furnace Water Leak Possible Condensate Problem

High Performance HVAC

Furnace Water Leak Possible Condensate Problem

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