"kim gross" wrote in message
...
snip

You will find that in a normal aquarium temp control setup you have
much less than a 8 degree swing. Most systems that I have worked with
have less than a 2 degree swing.

Yes home thermostates do have a much
wider range, just because it is more economical to change a few degrees
when you turn on your furnance or AC rather than just turn on for few
seconds to change your room temp a 1/2 degree.

Not so! They swing +/- a few degrees because they are sloppy, inefficient,
and ancient technology. Ignore lame rationalization coming from home
builders skimming nickels wherever they can.

While it's true that you don't want to have the system toggling frequently
for a few minutes of heat, you *do* want to keep the swing tight to no more
than 1 or 2 degrees. Expecting no more than +/- 1 degree max swing is now
quite reasonable.

Typical mercury switch home thermostats are awful in this regard and waste a
lot of energy as a result. Now that inexpensive electronic controls are
available, one shouldn't waste time replacing them. The programmability may
be a plus BUT they are substantially more energy efficient by the simple
virtue of keeping the temperature swing to a minimum.

And

My better half no longer feels compelled to set the temp to 73 when 70 is
just fine. With a good electronic (non-mechanical) control, 70 means she
doesn't have to suffer 69 and 68 degree chills before the heat kicks in.

70 degrees means 70!
Thomas Bartkus