Flood recovery: A guide for home heating and cooling systems

By Melissa Holsberg


To state the obvious, a heating and cooling system was not designed to operate in or under water. If a property was flooded, it is highly recommended that an HVAC technician inspect the home’s heating and cooling system.


Should a homeowner start their HVAC system after a flood?

Appearances can be deceiving. Although an HVAC system might look the same as before the flood, there may be serious issues and concerns that are not obvious to the untrained eye. Since the flood impacts on a system are unknown, it is highly recommended that you advise the homeowner to not start their HVAC system before you perform a full inspection.


After a flooding event, should an HVAC system be repaired or replaced?

HVAC systems are designed and engineered to operate under certain conditions, obviously underwater is not one of those conditions. Because so many heating and cooling components could be affected by flood water, it may be a better choice to replace the HVAC equipment. According to the Air-Conditioning, Heating, & Refrigeration Institute (AHRI), “Flood-damaged heating and cooling equipment and systems should be replaced and not repaired.”

“It is important to realize that every home’s circumstance and HVAC system requires a caseby-case professional assessment,” says Michael Ragan, residential outdoor and packaged units product manager with Goodman Manufacturing. He experienced numerous flooding events while living in New Orleans, LA. “An HVAC technician should make specific recommendations on each system’s particular circumstances.”


How might a flooding event impact outdoor HVAC equipment?

Split systems have a condenser coil, wires and piping between the indoor and outdoor parts of the system. If the unit was running when flooding occurred, electrical components might be damaged. Fuses, wiring, and circuits may malfunction when they come in contact with water. Flood water is often a mixture of dirt, grime, and debris that may adhere to the condenser coil. If the condenser coil was exposed to flood waters, the equipment’s designed efficiency level might be severely reduced. A dirty, inefficient coil may also lead to premature failure given the extra effort required to heat or cool a home.

“If flood water has moved the HVAC equipment, even a small amount, there is the potential for a breached refrigerant system,” says Ragan. In that case, the heat pump or air conditioning system will most likely require a major repair or full replacement.


How may a flood impact indoor HVAC equipment?

If there is any question whether flood water has reached the indoor HVAC equipment, the system should have a full inspection. Natural gas furnaces have valves and controls that may be vulnerable to water damage from floods.

Damage may not be easy to detect, especially if the outside of the device is clean and dry. Corrosion may begin inside the valves, electrical components, and controls, which is not immediately apparent or visible. At a minimum, this type of damage can result in immediate operational and long-term reliability problems.


What about ductwork?

If a homeowner has a forced-air HVAC system that has experienced flood damage, pay attention to their ductwork. Ductwork that has been in contact with flood water should not be salvaged and should be replaced. It is extremely difficult to decontaminate ductwork that has been exposed to flood water or other related conditions. Doing a thorough job will require disassembling the ductwork. These ductwork repairs may also give you the opportunity to upgrade materials, properly seal ductwork joints, improve insulation.


What should an HVAC technician do after a flood?

After the floodwaters have subsided, a full HVAC system inspection should be performed. Ask the homeowner questions to determine the following: the depth of the water that flooded the property and/or home; the length of time the unit was underwater; and if the unit was running when the flooding occurred.

Necessary flood inspection steps may vary based on individual circumstances. However, depending on the circumstances, your service may include:

  • Cleaning flood residue from coils
  • Inspecting the heating and cooling system electrical components
  • Checking all electrical and refrigeration connections for both indoor and outdoor units, including all control circuits
  • Cleaning, drying and disinfecting the refrigerant system if it remained intact
  • Inspecting gas valves and ductwork
  • Identifying components that need repair
  • Recommending a system replacement, as necessary

Ragan emphasizes that technicians should make specific recommendations for restoring indoor comfort on a case-by-case basis. “In some cases, a homeowner’s HVAC system may only need a good coil cleaning and minor electrical panel components replaced,” says Ragan. “In other circumstances, the home may need a full indoor comfort system replacement.”