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 an expensive (S$84) for a mechanical sensor triggered heater rod, 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. The accuracy of the humidity measurement is probably much better too, so i would recommend the electronic one instead. The only advantage of the mechanically triggered one is its simplicity.