Does A/C encourage mold growth

air-conditioninghumiditymold

I think i'm being sold bunk by a mold company, but not sure.

We live in the tropics, we recently had our bathroom ceiling flood due to a burst pipe, and went away immediately after. (the landlord had the bathroom ceiling removed a bit under a week into our holiday)

Before we left, we called a mold control company and said we were going to leave the A/C on to keep the humidity down to prevent mold growth (we have a new A/C, very efficient, was going to keep it on the lowest setting just to dry the air a bit, so the energy usage would not have been a concern). They said not to do that. They're the "experts" so we followed their advice.

When we returned, the apartment had bloomed (literally bloomed) with mold.

Our landlord now is saying that this is because we use the A/C a lot (we don't), and need to open the unit windows more, and buy a dehumidifier. If we actually did use the A/C a lot, wouldn't the cooling and drying of the air have prevented the mold growth more than opening the unit?

We live next to a rainforest, so I would've thought that opening the unit would invite spores and damp air in rather than prevent mold?

Thanks in advance for any help

Best Answer

Yeah, that advice was super wrong. Moisture encourages mold growth.

After a water leak you need to go to extremes to dry the air to get wet things to evaporate into the air, which you then continue to dry. I would run dehumidifiers, or shoot, if your house has A/C, just run the A/C since that is a dehumidifier.

The only risk is if you excessively chill the air, because cooler air has less capacity to hold moisture. This drives the British crazy, their masonry buildings often have utility spaces with "the damp" which are 40-50F (5-10C) and freon dehumidifiers just don't work well at those temperatures. They are forced to heat the space just so the dehumidifier will work effectively. I've witnessed it myself, a dehumidifer that fills in 8 hours at 75F takes a week to fill at 45F. The goal is measured in gallons, and time is a factor, so that is a total lose. And mind you, dehumidifiers do heat the space since all the energy they use winds up in the room as heat. Air conditioners remove the heat.

So you need to also heat the house, which fortunately is something solar load (i.e. The sun hitting your roof) does automatically. All you need to do is have a system whereby the air conditioner doesn't cool the house more than it's being heated by the sun... Some sort of, gosh, I don't know, thermostat :)

Oh yeah, you have one of those. Set it aggressively enough to run a lot, but not so aggressively that you create the British problem. Something like 60-ish (16C), let it go nuts.