Why Are Some Rooms Colder Than Others?

Your home is your bulwark against the brutal, uncaring cold of the outside. It has served you well through these many winters, and you know it like you know your own mind. Well… except that one room.

Come to think of it, several rooms in your house are colder than others. Wait… does that mean your house is haunted? It’s ghosts, isn’t it?

Don’t call the Ghostbusters yet! There are several logical, scientific explanations for why some rooms in your house are colder than others. Most of them have to do with your HVAC system, not the possibility that your home was built on an ancient burial ground. If your problem is mundane, chances are Blue Ox has seen it before, and knows how to handle it.

Here are six of the most likely possibilities.

Air Duct Blockage

It makes sense to start with the most direct problem. If certain rooms don’t heat evenly, or if your heating bill seems high, your air duct might be blocked. HVAC systems circulate hot and cold air through ducts continuously. A block in one part of the ducts could have repercussions for the whole house.

First, check the vents themselves. Go to the room that’s not heating up and make sure none of the vents are partially or totally obstructed. Next, go a little deeper by checking the zone damper. Dampers control airflow through ducts. They can usually be adjusted manually. Make sure they’re all completely open. Take the vent off, turn up the heat, and see if you can feel warm air coming into the room. If you can’t or if the air feels weak, it’s probably because there’s a physical block somewhere in the duct.

Air Duct Leak

When an air duct is ruptured, broken, or disconnected from the rest of the system, the warm air it circulates is sucked through the gap and out of the ducts. This prevents that warm air from getting where it’s supposed to go, which means rooms that don’t get enough heat. Use a flashlight to look down your ducts for any damage, disconnection, or opening. Even small cracks can cause a lot of heat to escape.

Pay special attention to flex ductwork and your ductworks’ joints. These places are particularly vulnerable to disconnection or damage. Some small ruptures or leaks can be fixed with duct tape, but sometimes segments of duct have to be replaced.

Dirty Air Filter

Air filters fit into your HVAC system and filter particles and other contaminants out of the air flowing through your ductwork and into your home. These filters require periodic replacement because the gunk they trap collects over time. When too much of this gunk builds up in the filter, it can start blocking all air or make the filter less effective at stopping dirty air from entering your home. That means if your air filter is dirty, not only will your heating system be less effective, it will be less hygienic as well.

Different air filters have different life spans. Check your HVAC system’s manufacturer suggestions and be sure to follow them. If you lost your system’s instruction manual, a good general rule to follow is that filters should be changed out every 30 to 60 days.


Of all these perfectly reasonable, not-at-all paranormal explanations, this is probably the one that feels the most spooky. Maybe it’s not even whole rooms that don’t heat up properly. Your living room might usually feel fine, but every now and then when you sit in a particular spot or stand up to go get something, you get chills. Maybe that spot is hard to track down or seems to move. That’s got to be a ghost, right?

Wrong! Well…we guess it could be, but it’s probably a draft. We’ve written pretty extensively about why drafts happen before, but basically warm air is being pulled out of the drafty room through either gaps in the insulation and walls or out of a chimney. When the warm air gets sucked out, cold air rushes in to take its place. When you feel a sudden chill or breeze indoors, you’re feeling that cold air rush to fill the void left behind by your precious warm air. Which is pretty spooky, admittedly. But not ghost spooky.

Insufficient Insulation

If your house is older, it’s possible that a particular room feels cold because the insulation used in that room’s construction has worn away. Many homes built before 1982 have under-insulated attics. This allows more heat to rise and escape your home, which in turn means colder rooms. While contemporary insulation is designed to last the lifetime of the home, older insulation may have become damaged or worn away.

It’s also possible that mice or other pests have stripped away insulation in order to make nests or build passages into your home, compromising the insulation’s effectiveness in the process. Check unfinished basement and attic insulation for signs of damage or wear. Insulation inefficiency is more likely to be a problem in unfinished rooms or rooms with large windows or doors.

Furnace Short-Cycling

If your heater turns on and off too frequently, it might be struggling to push warm air out to every room in the house. This is called short-cycling, because the furnace is switching off before it has the chance to effectively cycle warm air throughout the ductwork.

Short-cycling happens for one of three reasons. First, you could have a dirty air filter, which is absorbing a lot of the hot air that should be moving through the ducts. Second, your furnace could be the wrong size for your house. If your furnace is too big, it will push air too hard and too quickly, which will trick it into turning off before the heat has a chance to work its way into every room. If it’s too small, it might not be able to muster the power required to get warm air throughout the house. Finally, your thermostat could be malfunctioning and sending the wrong information to the furnace. If your thermostat tells your furnace that a room is warm enough, your furnace will turn off, even if that room isn’t actually warm enough.

All of these problems are relatively simple to identify and fix for a professional, like the talented technicians employed at Blue Ox. If you suspect trouble with your ductwork or HVAC system, give us a call today. We’re cheaper than the Ghostbusters.