Re: T87 Thermostats

[chasbo@xxxxxxxxx]

On Tue, 27 Oct 2009 18:47:48 -0400, JoeRaisin
<joeraisin2001@xxxxxxxxx> wrote:

>CH®IS wrote:
>> <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
>
>Winland also has the MTA-1 which is really just a smaller TA-1 but in a
>much more attractive case.  Good enough that is can be out in the open
>without making the living room look like a factory floor.

Thanks for the suggestion, but.....

I recently bought this one, reluctantly, and after examing it, I found
that it was just a smaller model of a larger one I bought 15 or more
years ago.  The larger one is the one that would not trip the alarm
panel when the rod reached and touched the contact point.

Though I installed the smaller unit, I subsequently removed it because
of my lack of faith in the rod and contact point mechanism.
Additionally there is no easy way to test the unit on the job, without
taking the unit off the wall, and undoing the locknut.  The design and
reliability of the T87 is (was) much superior to the Winland.

Somebody out there must know of a better solution.