Salus
Electronic Programmable Room Thermostat

Also
consider the following tips for operating your system for maximum efficiency:
- Thermostats.
Turn down the thermostat at night and when you're away from home. In most
homes, you can save about 2% of your heating bill for each degree that you
lower the thermostat for at least 8 hours each day. Turning down the
thermostat from 70°F to 65°F, for example, saves about 10% ($100 saved per
$1,000 of heating cost). Of course, you can use a good programmable
thermostat to automate this process. You can expect to recover the cost of
the thermostat in the first year or so.
- Aquastats.
The thermostat that regulates the temperature of a hot water boiler is
called an aquastat. Normally, the aquastat keeps water in the boiler around
160-180ºF. In milder weather, however, you don't need boiler that hot. The
aquastat can be set manually to 140ºF (120ºF with condensing boilers),
reducing fuel consumption by 5-10%. The aquastat control is usually located
in a metal box connected to the boiler. If you can't locate it, ask your
service technician for assistance. Your technician can also provide
information on modulating aquastats (or outdoor resets) that automatically
adjust water temperature depending on the outdoor temperature.