Different question about heater bars

[Richard Brekne]

MBrat70179@AOL.COM wrote:

> Hi list
>
> Let me preface my question by informing the list that I live in Indiana.
> Our humidity (in home) usually cycles from 65% in the summer to 30% in the
> winter.  Again these are averages of "in home" readings.
>
> I have been of the understanding that the heater bars used by Dampp-chaser
> are used to decrease humidity.  This is done by heating up the air around the
> heater bar.  Warm air holds more moisture than cold air.  So, moisture is
> drawn out of the piano and into the air... right?
>

Actually, what happens is that warming the air around the piano expands the airs
capacity to hold moisture, while the actual moisture content of the air remains
the same. That is to say the absolute humidity remains the same. This combination
results in lower relative humidity. You gotta understand the difference between
the two to get this right in your head... Moisture is not exactly "drawn out" of
the piano... rather the relative humidity is reduced.

> The question is: in the absence of a humidistat should the heater bar be
> unpluged in the winter?

No... the Damp-chaser system works better as a whole unit. Let it do its job as
it was designed.

>
> The piano in question resides in a church.  Note:  The temperature regularly
> falls to 60 degrees during the week and back up to room temperature during
> services.   Also, I have not serviced this instrument and have no humidity
> readings from the site.
>
> I don't believe the heater bar should be used as a substitute for heat.  I
> contend that the heater bar will compound the lower humidity (its' intended
> purpose).

Thats what it does... but again we are talking relative humidity. Absolute
humidity remains the same.

>
> Without installing a humidistat or complete Dampp-chaser system, should the
> partial system be unplugged in drier seasons?

You of course can do all this plugging and unplugging, but then you have to
continually check to see when it needs to be plugged back in and what not....
That is exactly what the system does itself. It turns on what it needs to turn
on, and off again... as it needs to. Let it do its job...heck thats why you
bought the thing isnt it ??

>
>
> Deeply pondering in Indiana
>
> Mike Bratcher

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway