Let’s Talk Thermostats

Thermostats have come a long way in the last few years. It used to be that the only available option was the non-digital mechanical thermostat, usually in a dial format. Today many (if not all) homes have at least one digital thermostat, and some of us have thermostats that are remotely connected to the heating system, or talk to us, or can react to voice commands, or can even be controlled remotely via a smart phone.

But, whatever the technology, all thermostats share two things in common: they are designed to control the temperature in our home and they do so by reading the actual temperature in our home.

A thermostat displays two temperatures on its dial/screen:
1. The reading of the actual temperature in the room
2. The setting for the desired temperature

If the thermostat (and its associated system) is working correctly the two temperature readings will be the same (or close).

A thermostat has a 2–4°F differential. This means that when the actual temperature falls to 2–4°F below the desired temperature, the thermostat triggers the heating system to come on and provide heat. The heat will run until the actual temperature rises to 2–4°F above the desired  temperature at which point the thermostat triggers the heating system to shut off.

In some instances a heating system may not keep up with the desired temperature and will, therefore, never shut off. This can be for one of two reasons:
1. The heating system isn’t big enough
2. There is insufficient baseboard, radiators, or duct work to distribute the heat

Sometimes, if the outside temperature is very cold, even an adequate heating system will not keep up, but once the outside temperature rises slightly, the house will “recover” and the heating and distribution systems will once again satisfy the thermostat.

Most of us forget to turn the heat down when we go to bed or out to work or away for a few days. With the older dial thermostats we are required to manually adjust the dial on every occasion—just one more thing to think about in our already-busy lives. But with a programmable thermostat, once we’ve set it up to do what we want, it remembers for us.

Ideally, when we are in bed or not at home we want to set back our desired temperature 4–5F° below the normal setting. By this one simple act we can save up to 5 or even 10% of our annual fuel costs.

Why only 5°F? Because if you set the temperature back more than that it can take exponentially more energy to bring the actual temperature back up to the normal desired temperature and thereby cancel out the energy savings you just made. The only time you should setback the desired temperature more than 5°F is if you are going to be away for a longer period of time. Also, if you have radiant heat we recommend setting back no more than 2°F as it takes longer for radiant heat to return a space to its desired temperature. Some radiant heat users use only one heat setting and make no adjustments through the 24-hour cycle.

When programming your thermostat add some extra minutes to allow the actual temperature to adjust to the desired—program the thermostat to drop down 30 minutes before you head up to bed, it’ll be at least 30 or more before the actual temperature gets there. Similarly, program the thermostat to come back up 30 minutes before the alarm goes off in the morning … that way it’ll be toasty warm when you get up and, if your hot water runs off the heating system your shower may be a few degrees hotter too.

Things to remember about your thermostat:

1. The location of your thermostat and what is it near

Your thermostat reads the air temperature in its immediate vicinity. If it’s in a cold and drafty hallway with no heat then the actual air temperature will likely never come up to the desired temperature and so the thermostat will never shut off the heat supply. Conversely if the thermostat is located above or below a heat source the air immediately around it will come up to temperature faster than the rest of the zone and your room will never be warm. A heat source could be as little as a reading lamp with a 100 watt bulb standing beneath the thermostat!

2. Reset the time on your thermostat in the fall and spring

Your thermostat needs you to tell it what the time is: Remember to reset the time when the clocks change fall and spring.

3. Check the batteries in your thermostat

Even if your thermostat is hard-wired into the heating system it will almost certainly be battery-powered. It’s good to get into the habit of changing the batteries a couple of times a year, for instance when we change the clocks fall and spring.

How should you program your thermostat

With a programmable thermostat you can lower and raise the temperature in your property according to your habits.

Lowering the temperature is known as applying a “set back.” As a rough rule of thumb our setback should be about 4° below the desired ambient temperature when you are home and awake. Thus, if you like the ambient temperature when you are home to be 68°F, then set it back to 64° for those hours of the day when you are not at home.

Let’s say you like to sleep with the temperature at 64°F but you like to be awake with the temperature at 68°F. You get up at 5:45 am. Set your thermostat to 64°F for the overnight but program it to change at 5:00 am to 68°F. That way it will be warm when you get up.

You leave for work at 7:00 am—program your thermostat to 64°F at 6:30 am (your house temperature will not fall all the way to 64°F until you are out the door and off to work).

You return home at 6:00 pm—program your thermostat back to 68°F at 5:30 pm so that it’s nice and cozy when you walk in the door.

You go to bed at 10:00 pm—program your thermostat to 64°F at 9:30 pm.

You stay home on the weekends. Program your thermostat to 68°F for the day and 64° for the overnights—adjust the times for later bedtimes and later morning rising. Don’t forget to set the temperature changes for 30 minutes before you go to bed and get up.

Don’t forget that you can override any programmed setting just by manually adjusting the temperature up or down. The thermostat will work to that temperature setting until the next programmed setting takes over.

Finally—if your thermostat has multiple settings: “heat,” “cool,” or “off,” make sure you’re on the right setting for your season!

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