Small damp studio, the unit has mould at 2 years – can I keep it clean somehow?
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28 sqm studio in Militari, Apusului street, 1st floor, windowless bathroom, I dry laundry in the room. 9,000 BTU Gree, 2 years old. It already smells of mould and I see dots on the louvre. I cannot move. What can I do so I do not have to sanitise it twice a year?
What is really happening
Room relative humidity decides how fast the evaporator dries after shut-off and how much condensate it produces. At 70% RH the fins stay wet for hours; at 45% they dry in 20–30 minutes. Laundry dried indoors releases 1–2 litres of water per load, and a windowless bathroom sends all its steam into the same space. WHO and EPA recommend 30–50% (maximum 60%) precisely to keep mould in check; dust mites also explode above 50%. Your unit, used properly, can even be an ally – Dry mode pulls water out of the air – but only if it is clean and you dry it afterwards.
- A picture can document visible deposits.
- Colour and appearance do not reliably identify microorganisms.
- The appropriate assessment depends on the issue; a photo is not a laboratory test.
- EPA recommends keeping indoor humidity below 60%, ideally between 30 and 50%, to prevent mould. [US EPA, 2024]
- Mould does not grow below roughly 80% surface relative humidity, but the cold surfaces inside an air conditioner constantly exceed this threshold. [WHO / NCBI Bookshelf, 2009]
- Relative humidity above about 50% increases house dust mite levels; a clean air conditioner helps keep humidity below this threshold. [WHO / NCBI Bookshelf, 2009]
- The relative humidity range with the fewest adverse health effects is roughly 40–60%. [Environmental Health Perspectives / PubM, 1986]
What we do on site
- Full sanitising now: collection cover, cleaning solution, pressure wash in place of evaporator, roller, pan, then sanitising solution.
- Outdoor unit, washed in place.
- We measure the studio's humidity with our hygrometer and tell you where you stand – usually an eye-opener.
- We explain on the spot how to use Dry + Fan so the unit lowers humidity rather than raises it. See current rates on the Prices page.
What you can do yourself
- Laundry: a heat-pump dryer (second-hand ones are available), or dry on the balcony / in the bathroom with the fan on and the door closed.
- Bathroom fan on a timer, 20 minutes after every shower; if you have none, a 100-lei fan fitted at the door helps enormously.
- A 30-lei hygrometer on the wall; target below 55%.
- The unit: Dry in the evening 30–60 minutes, then Fan 20 minutes, then off.
What NOT to do
- Do not dry laundry on the radiator / rack in front of the unit – the vapour goes straight into the evaporator.
- Do not keep the window shut 24/7 'to keep the heat out'.
- Do not buy 'anti-mould' spray for the unit.
Prevention
With humidity below 55%, a studio unit sanitised in spring stays clean until autumn. Without the humidity measures you really do need two visits a year – which is why the fan and hygrometer are worth it.
When to call us
0764 012 943, Monday–Saturday 08:00–20:00. Militari – quick scheduling.
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The information on this page is educational and based on cited sources; it does not replace medical advice. We do not do repairs, installation or refrigerant circuit work.