I have one heat pump unit, and two thermostats (one upstairs, one down). I live in Texas and the Summer months seem to keep my unit running non-stop when I have both upper and lower set at 77 degrees, one month last year my electric bill was over $500.

Is there a general rule (ie. few degrees differential) of setting upstairs thermostat vs downstairs? I keep the downstairs at 77 degrees, the upstairs at 78, but seems my unit is still constantly running. If I lower the downstairs to 75 degrees, and keep the upstairs at 77, the unit seems to run less, but the downstairs is too cool.

Any advice?

First of all do you have two separate units or is this a zoned system?

Thanks for the quick response. Zoned system, one unit, two thermostats.

First off it is normal for there to be a temperature difference between the first floor and second floor. This has been a problem with houses since the dawn of time. The problem usually is improper duct work ( lack of space going up stairs to run duct)and the fact that the higher floor makes the cold A/C that much harder to get there since cold air wants to naturally fall and not rise.

If you have a zone system then you have dampers operated off the thermostats that open and close to maintain the appropriate temperature in the area selected. It is always possible to have these systems fine tuned but you better make sure the company that is going to do the work knows what they are doing before you let them touch those adjustments.

Thermostats do have a accuracy range that can vary by more that 2-3 degrees and that can also bring its own set of problems for accuracy. So if you are concerned about accuracy of more that 2 or 3 degrees you better spring for some big buck Honeywell stuff because according to the latest report the better Honeywell digital stats are to only real accurate ones you can buy and then you have to make sure it has a little swing or your unit will be turning on and off every 2 minutes. Not good for the unit.

Lets talk outside unit for a minute. When was the last time it had a good check up and very good cleaning. Dirty outside units can cause higher head pressure and in turn make the unit pull more current which equal a higher electric bill. This could help you with the high electric bill but to be honest the cost of electric is going out the roof almost every where I know of. The days of cheap power for anything is over for the USA just as it has been for many years in other countrys. We are spoiled and we will all have a problem when our large power consuming toys become of very limited use because of energy prices.

The new equiptment on the market promisses to save us energy usage but it takes many years of usage just to pay for the initial cost of purchase.