Re: T87 Thermostats

[CH®IS <sh@xxxxx>]

<chasbo@xxxxxxxxx> wrote...
> 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?



These are all from Winland Electronics...

http://www.alarmsbc.com/enviro.htm

http://www.winland.com/TempandHumidityAlerts.htm

EA-200 - Can be used for both high and low temperature without any
additional sensors and is programmable for the high and low temp limit and
NO/NC I believe.  Doesn't look bad on a wall either, even if it does stick
out 1.25" off the wall.  The programming is fairly intuitive although you'll
want to have a manual on hand for your first one, and then perhaps
afterwards since you won't remember how to unlock it again later.

TA-40 - Not sure what's inside one of these units, but being the size of a
surface contact it can pretty much be mounted anywhere.  Not programmable at
all, doesn't need power.

TA-1 - Basically a thermometer with a contact on either side of it.  Very
ugly on a wall but very easy to use and seemingly the most reliable way to
go.  There's also the TA-2HL for 2 separate zones and "custom graphics"
although I don't think I've ever seen one in use.

Perhaps there's no more mercury in thermostats because it's all needed to
make CFL bulbs that we're supposed to believe are saving the planet?  That
is... until one breaks at least.

- Chris