The relative humidity in Singapore typically ranges from 50% to 100%, and this is not very good for keeping pianos in optimal shape. According to Steinway, the most favourable environment for a piano is a relative humidity of 45% to 70% and a constant temperature of 20°C. This is only possible if air conditioning is turned on all the time, which is not feasible for most people.
Well, the good news is, during sunny days, the relative humidity in Singapore is 60 – 65%, which still falls within the favourable range. When it rains, though, the relative humidity easily shoots up to 90+%. Over time, there is a definite risk of damage to a piano with such swings in relative humidity, especially to a Grand Piano. The built-in heater rod placed near the keys of a Grand Piano is insufficient to keep the rest of the strings and nuts and bolts free from the damage from humidity.
To improve the situation, i purchased a humidity control system from Taobao. On hindsight, it is quite expensive (S$84) for a mechanical sensor system, because there is an electronic one available for cheaper (almost half the price in fact), which allows you to track the humidity through an App on your smartphone (probably only in Chinese though). The accuracy of the humidity measurement could be better too, so i would recommend the electronic one instead. There is also something in-between (no smartphone app but comes with a digital display to show current humidity). The only advantage of the mechanically triggered one is its simplicity.
To validate the accuracy of this humidity control system, it makes sense to buy a hygrometer. For 125 Yuan (S$25), this one is pretty good. I placed the sensor probe inside the piano housing so i would know the exact humidity inside, which should be different from the ambient humidity if the humidity control system is working as it should.
Anyway, having monitored this system at work, i noticed it did bring down the humidity a few percentage points when triggered, and this is probably a good thing.