Believe it or not, there's a bit more to an electronic thermostat than a digital display. These stats have different internals that make them operate more accurately and responsively than non-digital thermostats. To understand why that is, let's take a minute to talk about how those basic mechanical (a.k.a. bi-metal) thermostats work.
How thermostats work
The temperature sensor in a mechanical thermostat is made up of two pieces of metal that are laminated together. Each type of metal has a different rate of expansion when heated and cooled, which is what controls the thermostat temperature. The thing to remember with mechanical thermostats is that you aren't setting an actual temperature, its more of a temperature range. The thermostat manufacturer calibrates the thermostats so that --in the test lab -- the numbers on the thermostat closely match the actual temperature of the room. That means the temperature in your room will stay around your set point, but can be about 5 degrees above or below it at any given time. In contrast, electronic thermostats have digital sensors to read the room temperature. They're much more accurate and responsive, which means your room should stay within 1 degree of the temperature you set on the thermostat. In addition to increasing comfort, the smaller temperature swings of electronic thermostats can translate to energy savings. While mechanical thermostats aren't as responsive as electronic thermostats, there still are a few scenarios where they might be a good choice. Craig Peterson, our Vice President of Engineering, says that some people want to use a thermostat like an on and off switch. In that case, he said that mechanical ones are an excellent choice. They're also more affordable than their electronic counterparts.
Mechanical stats with "dirty" power
The other scenario where they may be a good choice is when dealing with generator or solar power or in places that are prone to power surges. We've traditionally dealt with folks who use our products with utility power, which in general is very reliable and consistent. Because electronic thermostats have electronic components, power surges or "noise" on a power line could potentially fry them. That isn't an issue with mechanical thermostats because there are no electronic components. That isn't to say that electronic stats aren't designed to withstand a certain amount of power inconsistency, but that will never be an issue for mechanical thermostats, Craig said. If you're still on the fence about which thermostat is right for you, check out a story on a customer from Idaho who upgraded from mechanical to electronic thermostats. He said the payback from energy savings made the change a "no brainer."