What Happens When My HVAC System is Flooded? It happens from time to time. A bad storm moves in and everything is flooded as in recent times with the spate of hurricanes like Harvey and Irma. Whether you evacuated or stayed the flooding did its damage to your home and now its time to dry out. What happens with a flooded air conditioner? A flooded heat pump? A flooded boiler?
What do you need to do to fix things again so you can have heating and cooling? I can speak to you as an expert in HVAC and with my direct experience with surviving hurricanes and then rebuilding after the storms are long gone. So what do you do?
Of course the first thing to do is to make sure it is safe to return to your home. It may be a good idea to call an electrician to check the electrical infrastructure in your house. Depending on how severe the house was flooded some or several of you electrical circuits may not function properly. Breakers may be tripping and as we all know water and electricity don’t mix. Its better to be safe than sorry so have it checked out. We already have an article on flooded boilers here.
What Happens When My HVAC System is Flooded?
Flooded Air Conditioner or Flooded Heat Pump | Central Systems with Duct Work
It is very likely, if you have a crawl space under your house, and duct work is there that you will have to replace all the duct work. If the air handler was flooded then you will need to replace that also. Additionally, if the condenser was flooded for either a heat pump or air conditioner then it definitely needs to be replaced especially if the water was brackish or salt water. Hopefully you have insurance and the insurance will take care of the expense. In that case you need to refer to our HVAC Consumers Buyers Guide to begin the process. If you didn’t have flood insurance then its going to cost you but there are things you can do to limit the amount you pay for a new system if you are will to do some work yourself.
DIY for a Flooded HVAC System
First of all, make sure you do what I advised above and have an electrician check out your electrical system for your house. Make sure they check out the branch circuits dedicated to the air handler and the condensing unit. If the air handler or duct work was not flooded then you will save a lot of work and time. There will be lots of HVAC contractors very busy after the storm trying to get their customers up and running before cold or hot weather comes. Here we will take each separate portion of you HVAC system and give you some advice on what to do if that particular part of your system was flooded. Either way, you may want to plan on getting a whole new system in the near future.
Flooded Air Conditioner or Heat Pump Condenser
I’ve seen condenser blown over from high winds. When the condenser was set upright and basics checks done the unit ran fine. As long as the copper line set is not crimped too bad and the electrical whip and connections are still connected properly then its good to go. If the unit got flooded it needs to be washed out very good and all the electrical connections check inside the unit.If the unit was submerged for any length of time I would replace all the wire in the system and if there are any control boards in the unit I would replace those also. Any type of electrical device including the wiring would be replaced. Why? Make sure the power is off, the breakers are turned to the off position, and any disconnects for the condensers are turned off.
Water soaks into the wire and gets under the insulation. Over the long term, depending on the mineral content of the water, the wire will corrode under the insulation. That will definitely cause several issues including malfunctions and high amp draw. The circuit boards, unless they are marine rated or graded (most in HVAC systems are not) then the water and minerals in the water will cause the board to go bad and short circuit. Everything in the condenser needs to be opened up and dried out.
Flooded Air Conditioner or Heat Pump Coils
The next thing you need to look at is the coils and the cabinet. Both of those things need a thorough cleaning. I would use special coil cleaner specifically made for cleaning condenser coils. Make sure you wear gloves and use eye protection. This stuff is slightly caustic so take caution and use protection against the affects of the cleaner for your own health. Cleaning the coils with a water hose with a decent amount of pressure and cleaning solution will get most of the bad stuff off the coils and cabinet.
Some air conditioner or heat pump coils are all aluminum and some are copper with aluminum fins. The aluminum to copper will eventually stop giving you efficient heat exchange for the condenser because the aluminum will corrode where it is attached to the copper. The all aluminum coils will corrode and you will lose some of the aluminum. This will also reduce the heat exchange efficiency of the unit. Eventually, this leads to an overheated compressor and higher electric bills with an eventual failure of the system.
You need to make sure you wiring that is properly rated for the rewiring process. FYI, not all wiring is the same so make sure you use the properly rated and sized wire.
Flooded Air Handler or Gas Furnace
For this situation I would say it is best practice to simple replace the entire unit. Otherwise you will have to do nearly the same thing you do to the condenser. Except you will have to do more like disassemble the entire unit and then reassemble the unit after you clean everything. This is not safe especially for a gas furnace. For an air handler it is safer than a gas furnace however its likely not worth time and effort to do everything you need to do to make it work right again.
You have to disassemble the entire unit and throw away all the insulation and replace it. You will also have to do the same thing you did to the condenser and replace all the wiring and any control boards in the air handler. In addition to the wiring you also need to replace the blower motor and the capacitor for the blower motor.
Cleaning the Flooded Air Handler or Gas Furnace
Next you will want to wash all the panels and everything including the squirrel cage and blower wheel. Then replace all the insulation with new insulation making sure you use an adhesive that is safe for using in plenums. This is also a safety issue for both fire prevention and fumes or vapors that will end up in the air flow once the air handler or furnace is put back into service after you do all this work. If you are rebuilding a flooded gas furnace the gas valve and all gas ignition controls need to be replaced.
Make sure you turn the gas off before doing any work on a gas appliance. This can typically be found at the base of the meter. One big recent why I discourage people from rebuilding a flooded air handler is because of mold and mildew problems. If you don’t clean every crack and crevice in the air handler you can experience mold and mildew issues in the HVAC system for years to come. That can lead to health problems.
Flooded Ductwork for a Central Air Conditioner or Heat Pump
My advice on this is to replace it. As noted above, when moisture gets into ductwork is causes mold and mildew issues and that can affect your health and the health of other occupants. Additionally, when insulation is water logged (and ductwork should be insulated) then it loses its R-value. That means when you turn the air conditioner on (or heat pump to cool) and the cold air in the duct work drops the temperature of the duct work below the dew point then the ductwork will begin to sweat. This causes another problem where the sheet metal begins to corrode. That leads to leaks in addition to mold and mildew which is the original problem. Again, if the ductwork was flooded you need to replace it.
Conclusion | What Happens When My HVAC System is Flooded?
In addition to all that it is a good idea to make sure you unit will not be flooded in the future. It may require a complete design change and moving lots of things such as electrical branch circuits, duct work, and line sets that connect the condensing unit with the furnace or air handler. In other words, if this is a recurring problem then you need to look at reducing future occurrences by redesigning and relocating some of the equipment and the duct work. This goes a long ways in future comfort and dealing with storm and flood related issues for the future. Always be prepared and make sure you are and your loved ones are safe. I hope everything goes well for you and recover from the flood or storm or both!!! If you have any questions don’t hesitate to contact us using our contact form.
What Happens When My HVAC System is Flooded?
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