Why is my furnace leaking fuel?

Furnaces can leak water or fuel. If your furnace is leaking fuel, this is a potentially immediate and high danger - especially if the fuel is propane or natural gas. Evacuate the house immediately if this is the case and call the fire department and gas company or fuel provider.


Leaking oil presents both a safety and environmental concern. Use an oil absorbent to solidify the oil to allow it to be cleaned up. Kitty litter works well for this in a pinch.


Fuel leaks should be repaired by a professional and not a home handyman.


Why is my furnace leaking water?

Water leaks also cause major problems and should be dealt with quickly. Apart from damaging flooring, furniture and walls, water leaks and moisture attract mould that is a health risk and further damaging to the home. Water leaks inside and around a furnace can also quickly damage the furnace itself.


There are several possible answers to the question "Why is my furnace leaking water?" The common ones include:


  1. High-efficiency furnaces have a cool exhaust.
    You can tell if your furnace is high efficiency by whether the exhaust is a plastic (PVC) pipe. If it is, you have a high efficiency one.When warmer air or warm, moist air comes in contact with cold, it condenses and forms drops of water. This condensation is what happens in a high-efficiency furnace. The water is drained through a hose. If the hose is blocked or damaged, the furnace will leak water. The same is true if the drain is clogged or backed up.
  2. Many heating systems also have a humidifier.
    The humidifier adds moisture to the air during cold winter months to make it more comfortable. In these cases, water is piped into the furnace to an evaporation pan. The pipe or pan can leak, which can be the cause of the problem. Because the water piped to the furnace is cold water, these pipes can have a condensation issue. Water can form on the water pipes and drip.
  3. Standard and medium efficiency furnaces have a metal exhaust pipe.
    When the furnace is running, the pipe gets warm. There will be no condensation if the flue pipe is the right size. If it isn't, the hot exhaust may cool too much and condense and drain back into the furnace, causing a leak. This type of water leak can be particularly damaging to the furnace.
  4. If the air conditioner is running, the leak may be from the air conditioner.
    Air conditioners condense water. This water is piped by a tube to a drain. So the leak could be caused by a hole or break in the hose or a clogged or backed up drain.


The next time your furnace appears to be leaking, run through the list above to assess the issue. In the end, it is best to have a trained professional diagnose and solve the problem. The cost of ignoring the leak, or not properly fixing the problem, can be very high.

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