Damp Chaser in old upright

[Tony Caught]

Hi Terry,

>
> > By the time that the RH has come down to 65% the humidistat will switch
of
> > because it has dryed the air out to show 38% RH
>
> Is there a typo here? I do not understand what this statement is. Please
> clarify.

Try it this way: By the time that the RH  has come down to 65% (actual
humidity prior to the air being heated by the rod which by my simplified
rule of thumb reduces thr RH to approx 40%) the humidistat will switch of
because it has dryed the air out to show 38% RH
>
> I guess I have to say the same thing. Assuming proper appliance function,
> the 55% humidistat will not lower the RH more than a couple % below its
> rated %. So, the 55% humidistat will turn a rod off at 52% (or so), and
the
> 42% humidistat will turn a rod off at 39% (or so). Neither will be part of
> an operating system that lowers RH to 30%.

Right.

How could the 55% humidistat
> lower RH to 40%? How could the 42% humidistat lower RH to 30%. How are you
> getting your measurements? If these reflect actual measurement, I would
> suggest that one dry snap was simply more dry than the other dry snap, but
> neither has anything to do with the Dampp-Chaser system installed on the
> piano.

Timber does not react immediately to the drop in RH, it take a little time.
What I mean is that if one system has dried the Piano to say 55%RH and the
other system to say 42%RH, then when both pianos (with different sysyems
installed) are subjected to the same drop in RH to 30%, then the first will
drop down to approx 40% in the same time span as the second drops down to
30%.

> > If your average RH is in the higher levels you should be using a "WET"
> > 55%RH humidistat in your area If you are using the "DRY" 35% one, my
> opinion
> > is that you are over stressing the piano. Check with Dampp-Chaser.
>
> Only on a full DC system installation. Not, IMHO in a partial
installation.

I remember in one of your earlier posts that you mentioned that the majority
of homes with pianos were air conditioned.  In Darwin it is the reverse.
Sure, lots of air cons, but only turned on in extreems.
If the rooms where the pianos are installed are subjected to air
conditioning, then the RH%'s we have been talking about do not apply as the
piano is not in the RH enviroment directly.

> Again, the objective is maintaining a consistent RH in the piano all year
> long. If you use a "WET" calibration humidistat (55% - assuming it is
> accurate) on a partial system installation, you will get humidity swings
> from 58% during the wet season, to let's say a low of 35% RH during the
dry
> season (35% seems consistent with the low RH numbers for both our areas).
> So, with the wet calibration humidistat, you have a 23% RH swing AND the
> piano does get dried out to the 35% RH level. If you use the "DRY"
> calibration humidistat (I think they advertise that it is 38%) in a
partial
> DC installation (dehumidifier only) you will minimize your RH swing over
the
> year from about 41% RH max (again, assuming product funtion as
advertised),
> to 35% RH min. In this case you would have only a 6% RH change over the
> year. How does that stress the piano more than the other way? (It does
> indeed stress the capacity of the DC system (that is why they have to be
> sized properly), but I want it to work for me - I am seeking consistent RH
> values for my piano environment.) I would suggest that the dry calibration
> humidistat is a better choice for a partial DC system installation, where
> the RH dips to 40% or less during the dry season. Such a system will help
> minimize shrinking and swelling of wood and be much less stressful to the
> piano than using a wet calibration humidistat.
>
> Terry Farrell

Terry what works works, maybe you are right but I am not game enough to try
and find out. It terrified me when I started installing 50W rods in general.
In my mind I agreed with my self to use these rods only with the "WET"
humidistats.

My reasoning is this. Darwin, average temprature during the wet season is da
ily MIN 25 Celcius Maximum 33 Celcius.  A 50W rod is HOT, if it stays on all
the time (which it would if it was with the "DRY" humidistat), how hot would
it make the piano ?. And what damage would it do ?.  Would this mean that
the piano is capable of being at a temp of say, 50 C for half the year then
28 C for the other half ?

Regards

Tony Caught

>