Piano World Home Page Forums Our Most Popular Forums Piano Forum DAMPP CHASER

I install the de-humidifier Damp Chaser system in many pianos. I place the heating rods alongside the beams up near the soundboard. I then place the humidistat very near one of the rods about 1.5" below the soundboard. On a Steinway A or B I will use 2 50 watt rods. They definitely help in flattening out humidity spikes. The system works much better when the heater rods are nearer the bottom of the board rather than across the bottom of the beams. The trick is to have the humidistat close to one of the rods and the bottom of the board for proper control.

The thing to know about wood and humidity is that wood will absorb water vapor about 5 times as fast as it will give it up.

This is why I don't like the hot water bucket part of the system-it can over wet the soundboard area just above it and this can cause swelling and damage. The wet air will not disperse well across the bottom of the soundboard. It will move into the board in a localized way and this produces unnatural, localized stress in the panel.

If you need to raise the humidity-get a whole house system or at least a room humidifier.

That is the way to go! Protect your entire piano instead of just the soundboard. This is what Steinway reccomends. As an added bonus, your family, your pets, and your other furniture will benefit. Trane is very good equipment, btw.

A whole room/house system is the way that issues like this should be dealt with.

The DC system cycles through many temperature swings to create a stable RH. That is only half the equation: temperature must be stable too. If you have an doubts, throw a data logger or two underneath the piano and track the results--the charts don't look pretty! There is way too much temperature variation for long term conservation, IMHO--no museum would protect their collection with stable RH, at the expense of temperature swings! I suggest that people not do this to their own piano; stable temperature and stable RH is what is needed.

In extreme situations, the DC system can help out a lot--but it is NOT something that should be put on every piano for "protection."

I totally agree, I would love to have a class 100,000 house to get some major control on RH and temperature with RTDs in all corners of the rooms for temperature.

OK that sounds bit excessive, but if we can get total house temperature control and room humidifier at opposite from the piano in the same room, do you think that will be adequate?

tksler, the swings in RH where you live and inside your home will be completely different. You might consider monitoring the piano environment with a datalogger--so that you have enough information to understand/interpret what is going on over a longer period of time; that information helps you determine what your RH levels should be for your environment (i.e., 42-43% RH is not realistic in many situations).

So, if you need a humidifier in the room...then, sure, a room unit will work fine--I know many people that choose to do that.

It's not that expensive to investigate this a bit yourself. Get one of these: Lascar EL-USB-2
for about $100.

Spend some time logging temp/humidity/dewpoint at various points underneath and inside your piano and in various places in the room it's in.

Depending on where you live, you're going to see some wild variations in humidity.

Install the Dampp Chaser and repeat the study. The wild fluctuations (in and under the piano) will disappear, pretty much no matter what the weather's like outside. That's presumably a good thing for tuning stability and long-term health of the piano in general.

I went from skeptic to believer after reading ALL the threads here on the forum, but I still feel better being able to actually document the difference with the Dampp Chaser installed.

This subject has been discussed over and over again on this forum and has to be the #1 subject. It is very important which is why, I guess, it keeps coming up in postings.

Looking inside a piano you immediately notice that most of the hundreds of wooden parts are pretty small. Conforming to the laws of physics, things with less mass will be more rapidly affected by temp and RH fluctuations and things with larger mass not as much. Compare the size of a hammer to the size of your soundboard. That is why you need area control.

If your current CAC system is properly designed and installed it should keep your inside RH fairly constant at around 55 - 60% or so. A properly sized room dehunmifier should have no problem knocking that number down 10% which puts you at Steinway's "perfect" number. Ask your A/C tech about setting the evaporator fan on a slower speed to remove more moisture. Some newer systems have humidistats that measure humidity and increase or decrease fan speed as necessary. These models are very popular in extremely humid areas and may eliminate the need for addittional dehumidification.

Buying a device to record RH readings over many days seems a bit extreme for a residential application but if you wind up doing that I would suggest you retest, if necessary, after a room dehumidifier is added to the equation instad of immediately attaching something to your pride and joy. You always have the option of adding a DC if the CAC/DH combo doesn't do the trick. Just make sure you get a dehumidifier that has sufficient capacity for the area served.

The CAC/DH combo works very well for me and I live in a very humid area for 9 months of the year. My piano holds a tune extremely well. I keep my CAC t-stat set at 73 and the DH at 45%. The result is a constant 49% RH with only small and brief excursions during abrupt and extreme wheather changes.

Since environmental stability as the primary goal, when it comes to your home T-stat, "set it and forget it". Using a programable t-stat to raise and lower temps at various times is not for piano owners. Stability of both RH and ambient temp is what you are after and what Steinway & Sons labels the top priority.

Btw, a good "seal" for your home is equally important. If you have abundant air leaks all bets are off and nothing may do the trick as far as protecting your entire piano and other valuables. A tight "envelope" will also save a lot of money on energy bills... in the summer and especially in the winter. If you have a good CAC system and added dehumidifacaion but still have "wild" fluctuations in indoor RH then you have some big time air leaks in your home envelope.

This is an interesting debate, as I have friends I highly respect in the industry staunchly on the "pro" and "con" side of their installation and use. Please keep in mind I am not speaking as a technician, simply as a perceptive end-user who gets to play a lot of pianos.

There are mitigating circumstances that people seem not to consider:

1. Not everybody owns their own home where they can customize their windows and HVAC systems.
2. Some of us live in places where the low temperatures are so low, using a room humidifier to bring the RH up to 40% would damage window casings with condensation and icing.
3. Are you willing to keep up with the system's maintenance, or pay for your technician to do so? A lot of people don't want to bother even refilling the water tank when the system tells you to. Depending on your location and water quality, you also need to drop the tank, clean it (and/or put in a new liner), install a new plastic sleeve on the element, scrape the sensor wires of dirt, put in new pads and reinstall everything while sitting on your back, upside-down. I do it, but I hate doing it.
4. Do you want to install the undercover, and will you keep your piano closed when not in use? I think it creates a more effective micro-climate, but not everyone wants/remembers to close their piano. I noticed different un-scientific RH measurements above and below the soundboard based on the presence or absence of an undercover on one of the grand pianos I use.
5. Does the instrument get moved? I've seen these systems installed on concert hall pianos and worry about spilling water on the stage, electrical cords (and just keeping them plugged in), and the general unsightliness of some installations.

What do I do? Here in Wisconsin, I run a full grand system + undercover and a console humidifier at home. At the office, the HVAC is notoriously unreliable so I run full grand systems + undercovers and keep the Steinways fully closed when I'm not teaching/rehearsing. When I lived in central Texas, a DC system wasn't warranted, and just some room humidification for a couple months of winter took care of things.

For What It's Worth -- Morning Readings with full Dampp Chaser System:

8:00 am CDT

Exterior temp: 68 F
Dewpoint: 66 F
RH: 93%

Interior temp: 72 F
Ambient Room RH: 68%
RH inside Piano: 47% (with D-C System)

My home has a full house HVAC system with humidity control. Some days the weather strays from its usual patterns and it is nice to have that "Little Extra Protection."

For me, having D-C systems on my pianos has become a given. I don't even take the time to question their usefulness.

SO, here is the idea,

In southern California, do we even need the dehumidifier part of the DamppChaser? The humidity always seem to be higher than 20%, and we can control lack of humidity with room humidifier. I just feel uncomfortable with all that water being close proximity to the soundboard and other wood components, esp. with some techs thinking wood can over absorb the humidity from DC and causing localized overhumidification of piano.