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Hi, my technician recommended a Dampp Chaser for my grand piano and installed it yesterday. I live in CA where it's 100 degrees lately and no rain. Why would the heating rod be really hot right now? My tech told me no maintenance is needed on the Dampp Chaser, that I should not worry about it, and keep it plugged in all the time.
Probably a dumb question but I don't understand why the heating rod is so hot when it's 100 degrees right now, and dry.
Thank you.

The Dampp Chaser humidistat maintains relative humidity to around 42%. Just because it's 100 degrees doesn't mean that the relative humidity is low enough for rods to turn off.

The heating rod has nothing to do with piano temperature and everything to do with the relative humidity. In fact, it is called a dehumidifier rod. If the R.H. is above 42% the dehumidifier comes on. Your piano doesn't care very much about what it's temperature is, but a lot about moisture content.

Hope this helps.

It's just a thought, but here in the UK where full damp chaser kit installations are rare, we often just fit a damp chaser heating rod (either 15 or 25 watt).These heating rods do not have thermostats and are on constantly allowing a slight convection of warm(ish) air to circulate, keeping any dampness at bay. Mostly fitted to uprights, and generally having the top slightly wedged open to allow good air flow.

The fact is that it cut the high Ih and allow a 18- 20% variation .

The lack of efficiency of the deshumidifaction may be the cause of the permanent cycling of the system.

Such equipment should be "OFF" when moisture level is acepteable, which happens !.

I install heating rods sometime but never without humidistat, only because during dry season it is dangerous to warm the inside of the piano air more.

The conditions may be that the moisture never lower under 50 , but the principle is to have an humidistat.

Measures I did in a vertical that was in very humid conditions (but closed)did not show much better after 1 month and one rod.

I do not agree the temperature does not change, it does, a little if not the air would not dry, but indeed it is limited and not really a problem, the warm spots create an air flow.

I wonder why you dod not use hygrometers to measure the real hygrometry in the pianos where the systems are mounted.

A customer did and have 2 years data roomand underside of the soundboard, and the system is efficient, keeping a <20% variation plague around 42% under somewhat bad conditions for the piano in the room (about 28%> 75% if memory serves)

I had that graph and data somewhere but cannot find it now.

power use was also computed.

High summer temperature may go along with high humidity level (or low, depending of the wind orientation or other things)

Now if you have an hygrometer and it reads less than 42 % (45%) the rod certainly should not be warm.
take in account error % for both your hygrometer and the hygrostat.

If the hygrostat is near the floor of the room the moisture level of that slightly less warm air is higher (in an enclosed environment) than the air at the level of your head.

Warm air may contain a lot of moisture, the warmer it is the more it accepts moisture. if that air is cooled (near the floor) the HR is raised.

You need an undercover for the system to be efficient. then the air can cycle under the soundboard and some equilibrium installs.

Hi Barb860:

Usually a tech will want to have some history with a particular piano and the in-home RH highs and lows before making a specific recommendation.

Do you recall the reason given for the recommendation?

Barb,

Your question raises questions. Even though it is 100 F outside, what are the conditions inside your home? As Bob mentioned, the reason for the installation is the missing information.

Also, do you have the complete system, with the humidifier, or is it only the dehumidifier bar?

As a SoCal technician, I can answer this.

It's because the humidity is sky-high around here. I have climate control systems on several of my customer's pianos, and all of the heater bars are running flat-out right now.

Yes you can notice heater bars warming a yet warm air.

In that case the dehumidifier is not very efficient, hence the rods hot all day long.

Jim,

Barb is in NoCal. Isn't it a bit different up there?

Marty, generally, northern CA is even more humid than the southern part of the state. Even in the Central Valley, east of the low coastal range, the dewpoint this time of year will be in the 50s. Depending on the time of day, this would result in RH ranging from 75 percent at night to 18 percent in mid afternoon. I can see why a dampp chaser heating bar could be working under those conditions.

It rarely rains in summer in northern CA, even on the coast, because that part of the country has just about the stablest air anywhere--no dramatic frontal boundaries, storm systems, or significant lift from mountains. That doesn't mean the air isn't humid.

What Anne'sson said.

If the bars are warm it means they're doing their job, pushing the moisture out of your piano. You can give yourself some peace-of-mind by getting a humidity gauge and putting it in the room where your piano is. If the RH is above 45%, the bars will be warm.

Hi everyone and I appreciate your responses! I love my technician, he is great and has been working with me and my pianos for 25 years. I am a newbie to the Dampp Chaser system. Tech knows my home very well and my pianos. He has been recommending a Dampp Chaser system (yes, it has the humidistat and all) for years and I finally agreed to one in my Petrof 5'8. I am just anxious about having something hot plugged in to the wall and installed in my piano. Just need to understand the thing more, that's why I posted here.
I do live in Nor Cal where we typically have very dry summers, however this summer we had rain just last week. So, perhaps we have humidity even with these 100 degree days recently. How hot is the heater bar supposed to get? It's hot to the touch. Thanks again, everyone, you are great here and so helpful.

I read somewhere on this forum, something about a humidifier, with water? I don't have this in my system....? There's nothing I am supposed to fill with water...

I think a lot of people misunderstand what 'dry' means. Just because it's not raining and the weather is hot, does not mean it is dry. In San Diego, it is hot in the summer and doesn't rain. Some of my clients get confused when I tell them it is not dry at all, it's actually quite humid.

You don't need to add water to your system if the relative humidity levels in your home stay above 45%. You probably don't have that part of the system installed, and even if you did it wouldn't make the 'heater bars' (the dehumidifiers) any less warm/hot to the touch.

My thermostat in the house says the humidity inside is 26% and outside 20%. I don't understand. I unplugged the system until I can talk to my technician, really paranoid here.

That's a big mistake that people make, unplugging the systems. You will destabilize the piano by doing that. How is the tuning holding up? If the piano is as dry as you say it is, then the tuning should be awful by now. If the tuning is fine, I would leave it plugged in and call your technician to come over and have a look.

I do not think humidity control is necessary in most parts of Northern California. The humidity stays pretty constant most of the year, except for localized conditions like fog, or if there is a stream running underneath the house.

The dehumidifiers (what you are calling the "heater bar") come in different powers, depending on how much de-humidification is needed. 50 watts, 38 watts, 35 watts, 25 watts, 15 watts, 12 watts, and 8 watts. The higher-watt dehumidifiers WILL be hot to the touch, just as a 30-watt or higher regular light bulb will be.

If the humidistat is working properly, and you have the proper dehumidifiers, they won't be on all the time. They will cycle on and off, depending on the relative humidity at the humidistat.

If the tuning has remained stable, do not unplug anything. That defeats the purpose.