T87 Thermostats

[chasbo@xxxxxxxxx]

Win one for the environment; zero for low temperature monitoring.

Have been using Honeywell T87 thermostats for many years to monitor
low-temperatures in homes, usually set at 48 degrees, but because of
new environmental regulations mercury is no longer a part of the T87.

Since mercury in the glass envelope is no longer a part of Honeywell
thermostats, most if not all new Honeywell stuff contain a printed
circuit board consisting of the usual transistors, resistors, etc.,
and must "see" ac voltage in order for the thermostat to act properly,
which, in the case of home heating systems, is present, and is what
the product is designed for. Hence the product is not designed for DC
use.

I have not tried using an ac transformer and ac relay in conjunction
with the new CT87K, using the dry contacts to trip a zone.  Even if it
worked, I would not want to rely on it  because AC power could be lost
in the middle of a New England winter, rendering the new CT87K
useless.

I have used a Midland thermostat twice and find the product crude, and
pain in the butt to perform a test.  There is one moving part in their
product, a rod, which moves towards a contact point as the temperature
rises.  When contact is made, the alarm panel is tripped; but I have
found that contact pressure is not always sufficient to produce the
desired result (a short across the EOL resistor).

Have any of you found a reliable substitute for the best
low-temperature T87 thermostat ever made?