Got a call to service the DC on a piano that had the "pad" light on. From what I've noticed, usually only DCs with a smart bar have the "pad" light. But this one had a regular bar. Both the long dehumidifier bar and the short humidifier bar were cold. So I breathed into the humidistat, heard the relay click and the dehumidifier bar started to get warm. Then I plugged the humidifier bar directly into an outlet and it stayed cold. Obviously the rod is bad and I will replace it.

My question is how did the humidistat know the bar was bad and turn the "pad" light on? It might have sensed that there was no current going through the circuit, but that would not indicate when the pads are bad. So I think there is a timer circuit that when the humidity is low for too long the "pad" light comes one. Seems like a much better way than the smart bar with those wires that can get shorted with heavy mineral deposits and not show that the pads are actually bad.

Does anybody know how it really works?

Was the light panel one of the newer ones with the attachable "Pads" section, or the previous type with all 3 lights, regardless if you had a smart bar? (not that I'm answering your question...)

I'd call Dampp-Chaser. It might be more than a faulty humidifier bar.

Eric:

It was a three light panel, without a detachable pad light. I saw another installation like this and thought it had been cobbled together. Now I wonder. I didn't see anywhere to plug in a smart bar.

The heater bar for the humidifier is shot. I had a system with the same issues and contacted Dampp-Chaser and they sent a new heater bar under warranty. They explain why the pad light would come on but I forget what the reasoning was. It has something to do the the humidstat circuit.

The previous generation smart heater bars (SHB) had the "smart" element built onto the heater bar. There wasn't anything separate to plug in. You could order a whole system with the SHB or without. I stopped installing systems with the SHB, as I found them unreliable.

As I've become more experienced with DC systems, I too am questioning the usefulness of the so-called "smart bar". I agree with Eric that they seem to be unreliable. I have had clients pianos with very crusty pads that should have been replaced, yet the "change pad" light didn't come on. They also make it harder to clean, and it is one more thing to mess with when trying to remove and install the tank. For my next system I plan on forgoing the smart bar.

I try to get everyone to use distilled water (with the Pad Treatment). I have found if they do that, and the tank runs dry, the Smart Bar will work, shutting the humidifier off. I even supply a gallon of distilled water with every new installation.

I like that idea, Eric. I was even thinking of asking about people's experience using distilled water and if it is worth the trouble. It sounds like it is. I would expect that pad life would be at least doubled or more. I'd love to hear more about this.

Sure distilled water is better, but simplicity is better yet. I think many owners would just find the whole thing too tedious if distilled water was required in addition to the pads and water treatment.

My full time job deals with industrial control and indication (among other things...) Let's say a motor drives a belt that drives a piece of machinery. You can look to see if the motor is turned on, or if the motor is spinning, or if the machinery is turning. The best is to see if the machinery is turning so that loss of power, or a bad motor, or a broken belt will be detected.

Likewise, I think some sort of timers showing that the humidity is actually cycling is better than checking to see if current is flowing through the bars or if the pads do not conduct electricity.

There may be valid extreme conditions under which the DC is trying its best to control humidity, but it can't quite reach the trip point for cycling. In that case it is better to let the thing run 100% than to declare a "non-cycling" fault and stop everything.

And if you did have a timer, what would you use to reset the fault and try again? Manual intervention or an automatic retry with a longer timer?

BTW, Jeff, send me a PM as I am interested in your full-time work.

Robert Scott
Ypsilanti, MI

Yes, the pad life is greatly extended. In rural areas, people have to use well water. At my house, the lime in the water is a huge problem with the humidifier tanks. Before I switched to using distilled water, the pads would be ineffective in about 30 days...and this was with using the Pad Treatment, too. Now, the pads go 1 1/2 to 2 years before I change them. Plus, the humidifier tank stays clean, too.

In villages and cities, where people use a public water supply, the water seems to be sufficiently filtered, so the pads don't get gunked up as much as with well water.

Mr. Scott:

Yes, I will send you a PM.

I see no reason to stop the operation, just set an alarm. For a reset (and I had thought of this) cycling the power normally resets alarms. But the simple way is to just allow the alarm to clear. And I think that was the case in the OP. After I breathed into the humidistat, the relay switched and the "pad" light went out. DC may have taken a step backwards by going for more bells and whistles. I see it all the time.

I don't recommend piano owners change their own humidifier pads. Let the technician do it. I've yet to see anyone do it properly...and in some cases they've messed up the initial installation.

My understanding is that the additive you put in the water supplies electrolytes into it so that distilled water will still conduct electricity. Buying distilled water to avoid electrolytes and then adding it in afterwards seems to be a useless endeavor.

I have seen formation of crud in the pads even with distilled water being used with the additive. The whitish stuff is mose likely salts in the electrolyte and the the blue tinted scale is probably materials/impurities in the pad itself being leached up to the heater bar.

I tell my customers to use water from RO systems or a Brita filter (if they have them) to reduce the crud and it seems to put less buildup on the system, but this is advisable mostly when their regular tap water is unusually high in minerals content.

Many techs will trim the pad length to go to the bottom of the tank walls. I have seen some installations where they don't and leave the excess rolled up on the tank bottom. Often this puts a gap between the bar and the pad as it pushes it upwards.

I actually trim the pad a touch short of the bottom (1/4") and instruct the owner to use a touch less water on the fill up than the indicater line on the filler can. This triggers the water sensor a few days before the tank is actually empty in case they don't monitor the lights frequently. Even though that water does not make it up the pad, its residual presence in the tank still supplies some humidity in the piano. Also, heavy metals electrolytes ect will eventually concentrate in the very bottom of the tank and the pad does not soak it up as much. Take a look in the bottom of a tank after a few years and you will see the build up and sediment.

I would think if a person uses distilled water in a DC system they would only need to add the tiniest amount of treatment - just enough to conduct a current. Or alternately you could just add the treatment once every couple of months.

Another idea just dawned on me. What if the pad was made into a loop that was attached at the bottom. Then at every tuning you simply pull it around a little bit, exposing fresh pad to the heater bar. The crusty part of the pad would eventually end up submereged in the fluid adding those minerals back into the water. I think I will give this a try on the system in my own piano.

That loop idea sounds pretty good and gives me that "why didn't I think of that" feeling. Not sure what could stitch together the ends and hold fast. Maybe staples would work if they were stainless steel, or those plastic coated paper clips.

cotton thread and a fishing needle...

I'm thinking CA glue may be the easiest. My low water light just started flashing today, so maybe I'll change the pads and give this idea a try!

Folks:

The minerals in the water do not go into etherspace or something because of the pad treatment. They continue to build up, but more minerals can be suspended, or be in an ionized state, or whatever, for a while because of the pad treatment. If the pads are crusty it is time wash out the reservoir and replace the pads.

Really, if your water is too hard, a water softener is a good idea.

I don't understand why you would need to add the "conditioner" every time.
The active is ingredient is Benzalkonium Chloride (dimethyl benzyl ammonium chloride).
This compound is a white powdery solid in its pure state and, like any type of salt it will not "evaporate" with the water and will be left behind.
I can almost guarantee that this is a good percentage of the crud that builds up in the system, although that will of course depend on the hardness (amount of dissolved solids) in the water that is being used.
I use reverse osmosis water that I generate on my own (they put fluoride in our tap water here which I am not going to consume because I've done the research thank you very much) and I am not going to be adding a capful of the "conditioner" at every filling anymore.
I was for a while until I actually looked to see what was in the stuff and realized that it will remain behind for quite some time.
They also use this compound as a mold and moss inhibitor in outdoor locations because it does not easily get washed off in the rain.
When it is dry out it remains behind and is activated once it rains again.
http://www.tmkpackers.co.nz/index.php/site/product/moss_mould_killer

Probably a dumb question, but I didn't find it on the DC website.

Why do you want the water to conduct electricity? Humidification is just done with a heating bar.

I can see adding a mold and slime inhibitor, that water could get pretty funky sitting there at an ideal temperature for biological growth.

The low water warning light has metal sensor probes that extend to almost the bottom of the humidifier tank. If you use distilled water without the Pad Treatment, the low water warning light will continue to blink after filling the tank with water.

Sorry, but that's a dumb design. A float switch would be more reliable and just as cheap as the electronics, and let you use distilled water.

Then on the other hand, maybe it isn't dumb. If you have to add the treatment, you'll continue to have the pads clog up and need to replace them. I guess they've guaranteed themselves an ongoing market for parts.

A float switch would be much more expensive, take up more room in the tank, and because of the moving parts, probably a lot less reliable. The electronics required for the DC water sensor are few and really simple.

I'm speaking as someone with 22 years experience as a mechanical engineer. I wouldn't have designed it that way.

TimR

You should contact Roger Wheelock at Dampp-chaser with your idea. They are always looking to improve the product. His email is:roger@dampp-chaser.com

TimR:

Why have moving parts when none are needed?

The best that I have been able to figure, the old, old Damppchaser lights were the most simple. And in MY experience, on the maintenance side of things, simpler is better. The electrodes shorted around the neon light whose current was reduced to next to nothing with a resistor. This circuit was in parallel with the humidifier bar. It was only energized when humidification was called for and did not require any additional components.

Here's a two-fer update:

First, tuned and replaced the pads on a piano out in the country. I was surprised at how good the pads were considering the house would be on well water. There was some mildew, but no mineral build-up. The pads were not really wicking, but the pads light was not on. It did not have a smart bar, either... I was explaining the use of the pad treatment that I was leaving (I do not charge for pads or treatment) when I was told that distilled water was always used when filling the tank. The water light wasn't blinking, and I had tested it by lifting the electrodes. So I said I'd keep the bottle and for them to just add water. Fwiw, the piano hadn't been tuned for three years (not by me), was in tune with itself and there were no unisons that were way out. It was flat about 18 cents and was able to predict a good overshoot with a little pretensioning in the treble. It settled at A-440 in one pass. If I thought it would be tuned regularly, I would have tuned it without overshoot.

Second, went and replaced the faulty humidifier bar from the OP. The pads light was blinking and it went out as soon as I plugged in the replacement. (I did not breathe into the humidistat to cycle to dehumidification) So I unplugged the humidifier bar and the pads light immediately came back on. So, the circuit senses whether the humidifier bar is working.

So I am not so sure the a system with a pad light and without a smart bar senses whether the pads are actually working. The first piano had non-wicking pads and the light was off even though the bar was warm. But then again, that piano was in tune with itself, which I wouldn't expect from a console if the humidifier was not working at all.

Maybe I'll call DamppChaser sometime.

If it doesn't have a smart bar, it won't sense whether the pads are working.