Dampp Chaser Operation

Posted by: Hamiltonian

Dampp Chaser Operation - 03/28/05 08:20 PM

Hi:

Since I live in a humid environment, 3 weeks ago I installed just the heating portion of a Dampp Chaser on my grand piano. Just to check, I taped a RadioShack hydrometer on the bottom of the sound board and have noted over the past week that the RH on the bottom of the piano adjacent to the sound board has varied from 34 to 51% RH. What's more, right now the hydrometer reads 36% relative humidity but the Dampp Chaser heaters are still on. In fact the heater seems to run most (but not all the time). Since the unit is supposed to regulate to 43% RH, I would have expected the unit to shut off below or very near 43% RH.

Have any of you noted this before? Does this sound like normal operation? Why would the Dampp Chaser stay on well below 43% RH? Let me repeat that I am measuring the RH within an inch or so of the Dampp Chaser controller under the piano.

Comments most welcome.

Thanks
Posted by: curry

Re: Dampp Chaser Operation - 03/28/05 08:34 PM

H, do you have the dehumidifier rods controlled by the humidistat? Or just the rods. You need the humidistat for proper control.
Posted by: byebye

Re: Dampp Chaser Operation - 03/28/05 08:44 PM

My hygrometer reads 29-43% humidity under those conditions. It probably reads low, and yours may also read low.

I wouldn't be alarmed.
Posted by: Derick

Re: Dampp Chaser Operation - 03/28/05 09:12 PM

I thought Damp-Chaser's were supposed to keep the humidity as consistent as possible. If not, then what is the point of having them?

I've heard about the fluctuations in humidity and am very glad that I did not have one installed on my piano. My evaporative humidifier keeps the humidity at a perfect 42% except when the weather outside is extreme; and even then it still doesn't vary as much as a Damp-Chaser.

Derick
Posted by: Hamiltonian

Re: Dampp Chaser Operation - 03/28/05 09:18 PM

MarkS:
Are you measuring just under the sound board as well or on top, adjacent to the strings?
Posted by: Hamiltonian

Re: Dampp Chaser Operation - 03/28/05 09:21 PM

Curry:
I am using just the heater rods connected to the controller. That is all that is typically installed in this climate.
Posted by: Ori

Re: Dampp Chaser Operation - 03/28/05 09:28 PM

Assuming you have the humidistat, it is calibrated to keep the humidity at ABOUT 42%.
Actually, it tries to keep it between 38%-46%.
When it is humid outside, the humidistat will power the dehumidifier bars and they will try to dry the air until approximately 38%. Once the RH is less then 38% the humidistat will cut the power to the dehumidifier and power the humidifier (that you don't have). Although you don't have the humidifier part of the system, as long as the RH in your house is high, the humidity near the humidistat will "creep” up by itself. Once it will reach 46% the dehumidifier will kick in again.
By your description, the system is working fairly well and it is likely that your hygrometer is calibrated to read a few % more or less RH then the humidistat.

If you don't have the humidistat then the DC is trying it's best to dry the air.
It has limitations though. When the outside humidity is 75% it won't be able to get the RH to the mid 40's but only to the mid 50's (depending on few variables).
If you don't have the humidistat then get it installed. Otherwise, if the RH in your home will be lower, you may "cook" and dry your piano.
Posted by: Steve Ramirez

Re: Dampp Chaser Operation - 03/28/05 09:38 PM

I keep my hygrometer inside the piano. When RH reads 46% or above the rod is always warm. When it reads 43% or below the rod is always cold. At 44 or 45% it could be on or off. That seems like a fairly precise cutoff considering that my hygrometer is not a high-dollar lab instrument.

There could be something wrong with your controller but why don't you try leaving the hygrometer inside the piano for a few days and see how it reads. You say that the hygrometer is close to the controller so I wonder if there isn't some RF business going on between these two electronic devices.
Posted by: neciebuggs

Re: Dampp Chaser Operation - 03/28/05 09:46 PM

How much is it approximately to have a Dam Chaser installed? Steve, you live where I am going... I didnt think the humidity varried too much in San Diego. I lived there for 8 years... without a piano... so what would I know!! I mean I know there is the rainy season and june gloom season. Wondering if i should invest in the dam chaser.
Posted by: Casalborgone

Re: Dampp Chaser Operation - 03/28/05 10:46 PM

This thread is a classic example of the dangers of a little knowledge.

Dampp-Chasers are very well-designed and contructed devices which protect pianos from the extremes of humidity and dryness which can be very damaging to them. You don't need to know all about how they were designed and how they work but be assured that they do work very well and that they are exceedingly cost-effective.

Some information to bolster that little bit of knowledge that is causing so much worry: first, many simple, reliable control devices like the Dampp-Chaser cycle off and on over a target range of control. Examples are your home furnace thermostat and your oven thermostat.

They work very well to keep your house and oven at a sufficiently even temperature for comfort and for baking.

The Dampp-Chaser is equally effective for its purpose. Second, the wood in your piano has a lag time with regard to how it responds to changes in ambient humidity. The wood responds rather slowly.

The Dampp-Chaser's design allows for this and provides enough regulation of the ambient humidity to fully protect your piano. This assumes, of course that your Dampp-Chaser is properly installed and maintained.

If you are interested in delving deeply into the design and operation of the Dampp-Chaser, contact the manufacturer. They have literature which goes into it to a degree that you probably won't find very entertaining.
Posted by: Steve Ramirez

Re: Dampp Chaser Operation - 03/29/05 05:56 AM

 Quote:
Originally posted by neciebuggs:
How much is it approximately to have a Dam Chaser installed? Steve, you live where I am going... I didnt think the humidity varried too much in San Diego. I lived there for 8 years... without a piano... so what would I know!! I mean I know there is the rainy season and june gloom season. Wondering if i should invest in the dam chaser. [/b]
My tech decided that a humidistat with a single heating rod was best for my piano. He charged me $160 including installation.

This has been a very unusual winter with a lot of humidity. Over the past three months the RH inside our house has mostly been about 50% but has ranged from 30% to the high 60s. We have central forced air heating with the thermostat set for constant temperature around the clock. Without this system cycling through the night I think the RH swings inside the house would have been much worse.
Posted by: Casalborgone

Re: Dampp Chaser Operation - 03/29/05 06:51 AM

Steve Ramirez wrote:
"We have central forced air heating with the thermostat set for constant temperature around the clock. Without this system cycling through the night I think the RH swings inside the house would have been much worse."

Again, a little knowledge can be dangerous. Keeping your house at a constant temperature because of your piano is very likely not doing much of anything for the piano because of the slow response of the wood to ambient humidity changes. If you let your house cool at night (say by 10 or 12 degrees as would be typical with a programmable thermostat), I doubt whether your piano would suffer. You might save some money, some energy, and thereby some global warming by letting the house cool when everyone in asleep in bed.

This is what I do in Oakland which is also unusually damp this year. I also sleep better at night when it's cool.

I also think your tech charged you a very low price for the Dampp-Chaser. Sometimes even a simple installation of a heater and a humidistat takes some time to set up neatly.
Posted by: byebye

Re: Dampp Chaser Operation - 03/29/05 07:18 AM

I put the hygrometer atop a brace, very close to the soundboard.

Interior humidity readings with a hygrometer inside the closed piano are more stable.

The higher humidity readings were short "blips" which seemed to occur during humidity transitions. Also, I do not maintain constant heat in the house, which may affect these readings.

I'll bet if you could find a litmus paper hygrometer and place it near the soundboard you would find that the humidity is surprisingly constant.

Not to worry--and this is coming from a fussy piano owner.
Posted by: Steve Ramirez

Re: Dampp Chaser Operation - 03/29/05 07:27 AM

 Quote:
Originally posted by Casalborgone:
Again, a little knowledge can be dangerous. Keeping your house at a constant temperature because of your piano is very likely not doing much of anything for the piano because of the slow response of the wood to ambient humidity changes. If you let your house cool at night (say by 10 or 12 degrees as would be typical with a programmable thermostat), I doubt whether your piano would suffer. You might save some money, some energy, and thereby some global warming by letting the house cool when everyone in asleep in bed.
[/b]
Or on the other hand I could just do what I damn well please and maintain an overnight temperature that is comfortable for me and my family, with smaller RH swings as a collateral benefit, thank you very much.
Posted by: Derick

Re: Dampp Chaser Operation - 03/29/05 08:06 AM

 Quote:
Originally posted by Casalborgone:
This thread is a classic example of the dangers of a little knowledge.

Dampp-Chasers are very well-designed and contructed devices which protect pianos from the extremes of humidity and dryness which can be very damaging to them. You don't need to know all about how they were designed and how they work but be assured that they do work very well and that they are exceedingly cost-effective.

Some information to bolster that little bit of knowledge that is causing so much worry: first, many simple, reliable control devices like the Dampp-Chaser cycle off and on over a target range of control. Examples are your home furnace thermostat and your oven thermostat.

They work very well to keep your house and oven at a sufficiently even temperature for comfort and for baking.

[/b]
My home thermostat doesn't heat my house 12 degrees higher than I set it at and then turn on the air-conditioning to cool it off only to repeat the cycle over and over.

It seems to me, based on how the original poster described the operation of his Dampp-Chaser, that the system is very inefficient. Moreover, if that's how they all work, it is very poorly designed.

Derick
Posted by: RonTuner

Re: Dampp Chaser Operation - 03/29/05 08:09 AM

Hamiltonian:

Perhaps..... the system is underpowered, based on either the fluctuations in your space, or due to air currents. It's possible that the number/ wattage of the rods under your piano just can't keep up. I know of one tech that will plug in an analog clock in with the rods during high humidity and then check after some time to make sure that the rods are cycling off. Another option is the undercover, which makes preserving the "micro-climate" inside the piano easier. I don't do institutional installs without an undercover any more for just this reason. The HVAC system just whisk away anything the Dampp-Chaser is trying to do. Is it possible that there is a vent nearby?
Posted by: Sam Casey

Re: Dampp Chaser Operation - 03/29/05 12:54 PM

Focus less on dampchasers and more on the consistancy of your home. The dampchaser by its own admission is a fix for extreme enviornments and is not necessary for every piano. Your piano is built to withstand some variables. The closer kept to any consistent number in keeping with your maker's recommendations will do.

Make a commitment to maintain your whole house with consistent RH and relax. You won't need any other device.
Posted by: Hamiltonian

Re: Dampp Chaser Operation - 03/30/05 08:08 PM

Thanks for your comments.

Sam with respect to "focus less on dampchasers and more on the consistency of your home." I live on the gulf coast in a 4600 Sq Ft house. Trying to keep my house more consistent for benefit of my piano would be a bit like the tail wagging the dog.

RonTuner clever idea around using an analog clock to track the duty cycle of the unit over a 24 hour period. Could indeed be that I am a bit under powered. Also possible that my Radio Shack hygrometer is off calibration, so I am in the process of checking that.

MarkS it makes me feel a bit better that you see the same sort of "swings" on your set up. Do you have the humidification section as well?

I think Derick raises a reasonable challenge around the principles of effective control loops. Having said that, I have little doubt that the Dampp Chaser, provided it is working properly, will improve my tuning stability.

With my previous tuning, the room was at 65% RH. I noticed that the piano went out of tune within a couple of weeks. This also corresponded to a period of about 45% RH in the room. What clinched the deal was when the RH return to about 60% a couple of months later and my piano was back to perfect.

Ori and Casalborgone, thanks for sharing your professional perspectives.

Neciebuggs, I paid just shy of $250 including tax for installation of the controller and two dehumidification rods. My tech, who is very experienced, virtually never installs the humidification section here on the golf coast.

Thanks again all!
Posted by: CHAS

Re: Dampp Chaser Operation - 03/30/05 08:38 PM

Rontuner,
Tell us more about the undercover. Is it fabric?
What sort? Can it be made to muffle the piano a bit?
Posted by: Casalborgone

Re: Dampp Chaser Operation - 03/30/05 09:40 PM

This undercover is designed for humidity control for a grand piano. If you want to "muffle" your piano's sound, you must seek the appropriate means. Do a search in the PW archives, there has been much discussion regarding improving room acoustics and reducing sound levels and changing sound quality.
Posted by: RonTuner

Re: Dampp Chaser Operation - 03/31/05 06:11 AM

The undercover is something akin to "speaker cloth". Researched by Dampp-Chaser to provide a more stable climate without increasing chances of mold, while keeping sonic transparency. So no, it doesn't reduce the sound - other companies, I think, offer baffles to be cut and placed between the posts. I know some people that also close the lid and put the music rack on top of the piano. (make sure you put felt down first to protect the finish - one teacher found out the hard way!)