Evaporative air conditioners (How they work and the health risks they pose to your family & employees)
evaporative air conditioners pose a health risk

In the blistering heat of the Middle East, ancient Egyptians had the right idea. They used to hang wet reeds and cloth on the door frames so the breeze would pass through the damp cloth cooling the air inside the home. This idea of passing hot air over damp surfaces, effectively removing a significant amount of the heat from the air, is the basic principle behind modern day evaporative air-conditioning systems.

While efficient (as long as the hot air you are trying to coil is also low in humidity) there are two significant hazards associated with the method – 1. as the heat is drawn from the air, moisture from the cooling surface evaporates in to the air increasing its humidity and 2. the cooling filters, designed to be wet during operation, are designed to dry out completely when the unit is not in operation.

Fire hazard

There have been a number of reports where evaporative air conditioners have proven to be a hazard.

evaporative air conditioners pose a health risk

Fire investigators have confirmed that half the houses destroyed by fire in the 2014 Perth Hills burnt down because of their air conditioning units.

Investigators from the Fire and Emergency Services Authority have spent the morning in Roleystone and Kelmscott trying to track the behaviour of the fire that razed 72 homes.

It is believed the blaze was sparked by an angle grinder on Sunday and spread quickly, fanned by a strong easterly.

FESA’s Craig Hynes says many of the homes destroyed were not in the line of the fire and it is now evident they burnt down because of evaporative air conditioning units.

“The dry filters are really a wick for properties; embers get into them and they burn quickly through the roofs,” he said.  Reference ABC News Australia 

Embers from bushfires and even small backyard fires can get into your evaporative air conditioning and set fire to your home.

Hidden health hazard

evaporative air conditioners pose a health risk

But it’s the health aspect that is the hidden hazard.

Because evaporative air conditioning works by blowing air through water laden filters, the humidity in the building is significantly increased and this represents a potential health problem.

As you can see in the photo mould can grow unseen and the spores and mycotoxins are spread right through your home or office triggering many respiratory health symptoms.

Moisture + heat = health risk

evaporative air conditioners pose a health risk

Mould and damp can also result inside the building with the use of an evaporative air-conditioner as the indoor humidity can rise to > 80%, a similar scenario to mould growth in your bathroom or shower when you haven’t turned on the exhaust fan. 

Furthermore, according to the Victorian Government, evaporative coolers can cause swelling to doors, doorframes and furniture.  Reference

Mould in your home caused by water leaks and high humidity is a health hazard.  Anything that increases humidity in the house or roof space must be avoided.

If you do operate an evaporative air-conditioner in your home or office there are a few simple things you can do to safe guard against some of these hazards.

Ensure the cooling unit of any air-conditioner is regularly inspected; filter and the cooling coils are cleaned to remove any dirt, debris or biological growth.

When using an evaporative air-conditioner open windows and / or doors to allow the moist air to ventilate and prevent condensation on walls and ceilings, opening a widow does not decrease the effectiveness of the cooling.

When bush fires occur turn off any roof mounted air-conditioning system and, if safe to do so, fit the winter covers or otherwise protect the filters to prevent them catching fire if sparks or ash affect your property.


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