With the cold of winter reaching its peak, it’s important to make sure that everything in your heating system is working as well as possible. Even then, however, problems still have a bad habit of surprising us at the wrong time. And what’s one of the most annoying problems in the winter – the thermostat not working.
There are a lot of things that can go wrong with a thermostat – the thermostat reading higher than setting, the thermostat not reaching the set temperature, the thermostat set to cool but heating, and more. And then, there’s the problem of not knowing how to tell if your home thermostat is bad or the problem is somewhere else.
So, if you find yourself wondering “Why does my thermostat change by itself?” let’s go over some of the main things that can go wrong with your thermostat and how you can fix them.
Make sure the HVAC system has power
It may sound silly, but a huge percentage of reported “thermostat problems” are not problems with the thermostat itself but with the power of the HVAC system. Check the breaker panel and make sure that there’s power getting to the thermostat in the first place.
Change the thermostat’s batteries
If everything else with the HVAC system is in order, try changing the thermostat’s batteries first. Different thermostats use different batteries and some have none at all. For example, most wireless systems will use AA Lithium batteries.
Give your thermostat a good dusting
This also sounds simple but very often all that’s needed is a good dusting with a small paintbrush. Dirt and dust are very often the main culprits to thermostats not offering adequate readings or malfunctioning in various ways.
Make sure the thermostat isn’t near heat sources or direct sunlight
Another silly-sounding mistake that an awful lot of homeowners make is keeping their thermostat near another heat source or in direct sunlight. Even something as simple as a computer or a night lamp can seriously screw with a thermostat’s function.
Check and adjust the thermostat’s balance
Take a level device and make sure that your thermostat is perfectly level wherever it is. If your thermostat is even a little off then its mercury switch won’t work properly and/or you’ll be getting inaccurate readings.
Fix the anticipator
Another very common problem, especially when your HVAC system is cycling on and off too frequently or not often enough is the anticipator. To find this thermostat component simply open up its housing and look for a small metal tab. It should be right next to a numbers scale that goes from shorter to longer. Now, there are several options here:
- If your HVAC system is cycling the heat on and off too frequently then you need to move the anticipator closer to the “longer” settings on the scale.
- If, instead, your furnace never reaches the desired temperatures you’re setting, move the anticipator toward the “shorter” setting on the scale.
After you’ve made either of these adjustments wait a couple of hours to see if the problem’s been fixed, if it’s gotten worse, or if it remains the same. If it’s gotten slightly better but not quite – adjust the anticipator again. It’s important to always move the anticipator with just one calibration mark at a time to make sure that you get to the right answer and not overdo it. More often than not, the anticipator will work best when it’s set between .2 and .8 amps on the scale.
Try “rebooting” the system
Another less conventional solution is to try and “reboot” the system, in a manner of speaking. This is a several-steps process that goes like this:
- Set your thermostat to “heating” but turn the temperature setting down to ~60 degrees Fahrenheit. This way your furnace won’t be getting any signals from your thermostat to turn on.
- If your furnace is still working after that, keep lowering the temperature until it stops.
- Get to the breaker panel again and turn off the power to both the furnace and the thermostat systems. If your breakers aren’t labeled and you don’t know which is which – test them out and label them now, it’s a good idea anyway.
- Leave the breaker switch off for 30-60 seconds and turn it back on. This will, essentially, reboot your HVAC system.
After that just set your thermostat to how it should be and see if it’s working properly or the problem is persisting.
Call a professional
If neither of these methods is working we’d advise consulting with a professional. Annual HVAC inspections are strongly recommended anyway so if you haven’t had your system looked at by a professional this year – take this opportunity to do that even if you are confident you can still solve the problem yourself. It’s much better to solve the problem while it’s still small than having it get unmanageable in the midst of winter’s coldest period.
