Furnace
The gas furnaces have a series of valves and controls that play key role in its operation. These are highly vulnerable to damages. They can rust, if moisture trickles in from anywhere. Sometimes you may see they are running smoothly even after being under water. It may take some time for the damage to come to the surface. At a minimum, this damage can result in reliability problems. More severe consequences could be fire or explosion. It is always recommended to call a HVAC technician to get the unit inspected for possible damage. In case you want to salvage the unit, in most cases you will need to replace gas valves, pilot and burner orifices, controls, and the filter. This work should only be done by an expert professional.
There are differing opinions regarding replacement versus repair of flood-damaged heating systems; however most expert recommends replacement of the unit post flooding.
Air conditioner
Most air conditioners have outdoor units which sit on the lawn outside the house or are mounted on terraces or external walls of the house. They are hardy enough to withstand all kinds of rain and humidity. But for a machine to be immersed in water for hours is quite a different thing. It takes toll on its heath. Here’s what to look for after flood damage:
• Inspect all the wires, connectors, and electrical components for corrosion.
• Check if the seal on the condenser fan motor is broken
• Check if the motor is water damaged
• Check the coils in the unit to see if they need to be cleaned
The indoor unit is more susceptible to flood damage then the outdoor unit. Six inches of water around the unit is enough to do an irreparable damage. Therefor always get it checked by a technician, if it as flooded.