Digital vs. Mercury Thermostats

28 Sep

Have you recently had your thermostat replaced from an old Mercury to a new digital?  Are you wondering why you are having to set your digital thermostat a little lower than what you had your Mercury thermostat on? Why is Digital better than Mercury? Let me start by first saying that it’s good that you finally made the change to digital.  Mercury t-stats are made up of several moving parts, including a glass vial containing Mercury.  These contain the highest amount of mercury found in any ordinary household item!  Now that I’ve scared you, the accuracy of a mercury thermostat is not really dependable.  Even when properly calibrated, mercury t-stats are still not 100% exact.  They can have at least a 2 degree differential by design.

Differential is the difference between the point the t-stat turns on and off.  Lets say you set your t-stat to 76 and it rises to 78 before the air kicks back on again, there is your 2 degree differential.  It may also overshoot what it is set for (making it cooler than what the t-stat is reading).  That is a big reason why we get a lot of phone calls after a new t-stat was put in.  The consumer feels that because they’ve had to set there new digital t-stat lower than what they’ve set there mercury one to, there must be something wrong.  What they didn’t know was that the temperature was probably the same, however the mercury t-stat was inaccurate as to what the temperature really was.

Digital types are by far the best and most accurate currently on the market.  Generally, they measure degrees in tenths.  So if you set it to 75, it may turn on at 74.7 and turn off at 75.6.  Plus you have the option on some digital t-stats to program it change to a certain temperature at the same time certain days of the week.  Besides the accuracy, the savings are far greater than mercury t-stats.  Digital stats are much more efficient by the nature of their design.  They use a thermistor to record temperature.  Thermistors react almost instantly to the temperature change which results in a much more efficient operation of your equipment.  Efficiency = saving money.  This does not mean you have to go out and by the most expensive and fanciest digital thermostat you can find.  Most people don’t even want that.  They want simple and easy to use.

Do your home or business a favor and replace any mercury thermostats you may have.  It just makes sense and happens to help you save a little money in the end.


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