According to MARSHAM:
>
> I haven't seen this point made in other postings, so I'm adding my two
> cents, recording hygrothermographs are useful because they give you an
> instant reading of an area.  Or if an area develops a problem you'll know
Both right and wrong. Get a datalogger that has a digital LCD
readout if you are interested in instant readings in addition.
> immediately, not 2 months later when you download the datalogger.
> Downloading the datalogger doesn't take a great deal of time for one
> unit, but it does take some time.
The handiest way is to download _in situ_ into a laptop.

>Bill Lull was at OHS on an IMS-CPS
> grant for an environmental survey and he recommended to us the use of
> both.  I have 6 hygrothermographs, 7 dataloggers, and an aspirating
> psychrometer.  I use the dataloggers for monitoring of spaces,
> downloading about every 2 months;
Dataloggers are constantly discarding the oldest data as they
collect ("log") new samples. You have ones that will hold onto
data for 2 months? What is the frequency of your sampling
interval?

and the hygrothermographs for "spot"
> checks and if a problem occurs that I want instant data on.  I have to
> admit that I don't recalibrate as often as I should, but I also don't
> move the hygrothermographs around very much.  The other problem with
> hygrothermographs is going around and winding and changing charts every
> week, something that I wasn't always successful with.
I would be the last person in the world to contravene Bill
Lull. And also the last to argue against system redundancy . .
. which mean contravening the space program. Those people may
be engineers, but at least they know about "Murphy's Law."