House Colder Than Thermostat Reads

In the dead of winter, the last thing you want is to have a malfunctioning thermostat. However, while electronics or wiring could be the issue, if you feel colder than your thermostat says, it could be leaks in your house, poor insulation, or the duct system wasn’t designed well.

These issues could lead to a misleading thermostat, so you should also know how to fix them. There are suggested temperatures to set your thermostat to throughout the year and ways to check if it’s working correctly, too.

What is the Recommended Temperature For the House in Summer and Winter?

When it comes to setting your thermostat, an excellent way to save money on your electric bill and run the equipment less is to know what temperature to set it at when you’re home or gone. For example, summer months are suggested to be set at 78 degrees if you’re home.

However, if you plan to be out of the house for an extended period of time, you might want to go up to 88 to save more energy since you won’t be there to enjoy it. The winter is similar in that you’ll want it to be set at 68 when you’re home or around 58 when you’re away.

While you don’t have to use these temperatures, it’s recommended to follow them to get the most out of your system and ensure that your HVAC systems can function longer.

Why is the House Colder than the Thermostat Reads?

While it’s a possibility that the heating unit or batteries are responsible, it’s far more likely that the other 3 main reasons for a thermostat to be off are leaks, insulation, or ducts, so let’s break them down.

1. Technology

It’s not unheard of for a thermostat to be off by a few degrees, but if it feels like 50 degrees and your thermostat says 70, there’s probably an issue. When that happens, the most likely culprit is either an outdated device or the batteries are dying.

Of course, it could also be the location of your thermostat. Because it gauges temperature based on its immediate area, if it’s close to a lot of electronics, a vent, or a closed space, it might read the heat from those while the rest of the house is freezing.

The obvious fix for the batteries is to replace them, but make sure there’s no corrosion on the coils from old batteries. If that doesn’t work, you’ll need to try replacing the actual device. If nothing works, it could be the wiring, and you’ll need to call an electrician for an inspection.

2. Zone Coverage

Not to be confused with the football tactic, HVAC zones are the area of space that an AC unit or furnace can push air to. There are a couple of reasons that would make a heater the cause of parts of your home being too colder than others: You need more zones or more units.

Zone control means changing where the air focuses in your home, so if you spend most of your time during the day in the living room or kitchen, you might want a furnace that lets you heat those rooms more. 

This is especially useful if you have a basement or attic space because those tend to be colder or hotter, respectively. Still, while zones can help with a wider home or has square footage, you might also need another heating unit.

It’s proven that multiple-story homes can have temperature differences, but, again, if it’s more than a few degrees, your single unit probably isn’t enough to compete with the floorplan. So while it might not be your first choice, you may want to consider another furnace for the other floors.

3. Leaks Through Insulation

Poorly installed insulation is one of the biggest causes of areas of a home being colder than others, which would be why the thermostat in a room with more people would read hotter. This is because the insulation doesn’t keep the air outside where it belongs; it also retains temperature.

The most common places where there are leaks in your home are the attic, basement, and rooms typically closer to the sides of your house, like the bathroom or laundry room. Electrical outlets can also be a source of leaks, as well as doors or windows.

Attics and basements are the most prone to leaks because that’s generally where the most insulation is supposed to be, but insulation can fall apart over time. Also, especially if installed incorrectly, the humidity and moisture in those areas can affect the integrity.

It doesn’t help that most homes built any time before 2001 didn’t have to reach a specific amount of insulation, so it may not be that it was installed poorly so much as it’s just not there. Either way, it might be a good idea to check the insulation levels in colder rooms.

Insulation is usually foam, fiberglass, or another substance that can buffer your home. The good news is that you can try doing it yourself with sealant or a tutorial, but you might be better off hiring a contractor if the job is big enough or too complicated.

Do it Yourself

Deciding to insulate your home yourself isn’t too difficult, but it does take some work. The first thing to know is that an R-rating grades insulation, so you’ll want to use between R-38 and R-40 insulation.

The 2 main types of insulation are batting and loose-fill, with the latter being better for corners. Batting can be more or less dense, so consider that density will affect how much you’ll need to attain at least an R-38 rating.

Essentially, the idea is to layer your attic floor to keep heat in or your basement cold out. Don’t forget that you might want to set up a floor lamp or fan for lighting and ventilation as you work. 

You can usually find a caulking agent or some form of insulating foam in a spray that can seal up any leaks for attic walls. The general rule of thumb for R-38 insulation is to have around 10 inches of insulating material, but that depends on the density.

What About Doors and Windows?

If the areas near your doors and windows feel colder, the leakage is probably due to old or bad gaskets on the doors, or the glass on your windows doesn’t do anything against the weather. If the rubber seal around the door is terrible, you can easily replace that with a new seal and glue.

Just make sure that the measurements are good enough that your door closes, and the rubber seals the space underneath as well. Many homes have single-pane windows, which don’t do as much for temperature in your home.

Investing in double- or even triple-paned windows can be expensive upfront, but save you money on your electric bill by holding in hot air or keeping out the cold.

Duct Tales

A contributing factor to heat loss in other sections of your house is leaky ducts or ducts that aren’t the right size to provide enough airflow. You can also seal the leaks in the duct structure with putty if they’re small enough, but you may have to call an HVAC professional.

If your ducts are the wrong size, whether they’re too big or small, they can cause an improper flow of heat to the rest of your home. Not only will this make other parts of your house colder, but it can cause damage to the hardware.

How to Know if Your Thermostat is Working Correctly

There are several reasons your thermostat might be working incorrectly, but the most common ones are dirt, bad batteries, wiring, or your thermostat being in a bad location. The most obvious way to tell that it’s faulty is that it won’t turn on or constantly goes on and off.

If this happens, check that the batteries still work, the thermostat is level, and the device is away from too many electronics or a vent. Also, check the interior for dirt or smoke buildup, but if none of these work, you’ll need to contact an electrician or try replacing the thermostat.


At the end of that day, insulation, leaky ducts, or the HVAC unit itself can all be reasons for the thermostat to read warmer than the rest of your home. However, keep in mind that your thermostat reads the immediate temperature around it, so other parts of your home can be cold.

Whether you fix the insulation yourself or call someone to do it, it’s also a good idea to keep your thermostat checked and clean and to follow the suggested temperature settings depending on your climate and location.