Tom DeFerrari Piano Tuning and Servicing

Humidity Control Systems

.What a piano humidity control system is

A piano humidity control system is a combination of a humidifier and dehumidifier that goes inside a piano. It is controlled electronically by an internal humidistat. They are manufactured by the DampChaser corporation, and their website pianolifesaver has explanations and very good diagrams (as well as a sales pitch) about what they consist of and how they work.

.Why humidity control is needed

I explain why stable humidity is important for a piano on the Piano Placement and Humidity Control page. Although I state there that I feel that controlling the room humidity is preferable to installing a humidity control system, for some piano owners, these systems are a good solution. This may be the case where the room humidity is impossible to control, or the piano owner likes the convenience of a humidity control system inside the piano, rather than trying to keep the room humidity constant.

Humidity control system in a grand piano, seen from underneath

Humidity control system in a vertical piano

.How they work

The humidity control system, which sits inside the piano, consists of a humidifier and a dehumidifier along with the required electronics to control them, indicator lights for the piano owner, and a fill tube for the water tank.

.Maintaining the system

The humidity control system is very easy to maintain. The light panel has three indicator lights;

  1. The green light indicates that the system has power.
  2. The yellow light flashes when water is needed, and the piano owner simply fills the system with tap water through the fill tube.
  3. The red light flashes when the pads need to be replaced.


These systems are very effective in a vertical piano (a full upright, console, or spinet), in which the system is enclosed inside the piano, which is somewhat airtight. In a grand piano there are two considerations that make them less effective.

  1. The system is open to the room, and if the room itself is very dry, humidity will tend to dissipate from the piano into the room. If the room is very humid, the dehumidifier will struggle to lower it.
  2. Only the bottom of the soundboard is protected. The pinblock, which is located in the front of the piano near the keyboard, and the keyboard or action itself, don't benefit. Keeping the soundboard at constant humidity is important for tuning stability, but for longevity, the pinblock (and bridges, which are located on top of the soundboard), also need protection.

So, in extreme conditions of excess humidity or dryness, the system (in a grand piano) tends to fight a losing battle.

However, if the room humidity is kept within reasonable bounds, say, from 35% to 65%, a humidity control system can often make up the difference, and does have the benefit of convenience.


The system parts are guaranteed by DampChaser for 5 years, but they don't include the cost of installation in case replacement of parts are needed. I include a warranty for my time in case new parts are needed under warranty and there is no charge for this.

However, if the piano is moved out of the area, then I can no longer offer that warranty The parts would still be covered, and a local piano technician in the new area could arrange to obtain the parts free of charge, but there would very probably be a fee for that technician's time.

Actually, I haven't had to install a part under warranty in 30 years of installing humidity control systems. I mention the above only because it isn't clear in the warranty card whether there would be a fee for the technician's time if warranty work is necessary. Still, it can be very frustrating to find that a warranty has seeming "loopholes", so I want to be upfront about what is covered by DampChaser and what is practical for me to guarantee. I suspect that other piano technicians, if they do guarantee labor, will have the same caveat.

Copyright © 2009 Thomas DeFerrari