Uneven Heating? Check for These Common Causes

No single cause clearly explains uneven or weak heating in the home. If you notice that some rooms are warmer than others, you must troubleshoot the problem to determine which of several causes are at the root of the issue. The good news is that your home will be much more comfortable once you have solved the problem leading to the uneven and weak heating.

Here are a few of the possible causes you might encounter in your home.

Duct Issues

Uneven heating is often symptom of an issue somewhere along the duct system. Warmed air simply does not make it to some rooms at the same rate as it does to other rooms, which results in different temperatures throughout the home.

Blocked Ducts

Ducts become block in two main ways — a register vent or return vent is closed in a room or debris has collected in the ductwork and is blocking air flow. First, check every vent in the house and make sure it is open and that no furniture or curtains block the air flow. If the ducts are open but you still suspect a blockage in the system, schedule a duct inspection to look for the problem.

Leaky Ducts

Air leaks in the ducts effectively waste heat and money by warming up wall cavities while leaving the livable parts of your home cold. Leaks can typically be found in walls or where the ducts run through the basement. A duct inspection can catch leaks so that you can have them properly sealed and insulated against heat loss.

Thermostat Failure

Sometimes your furnace is in good working order, but the thermostat is faulty. Some thermostat issues can be fixed, while other will require replacement.


Thermostats may need periodic calibration to ensure the device is properly reading the room temperature. You can check your thermostat for calibration by taping a glass thermometer next to the thermostat. If the reading on the thermometer matches that on the thermostat after 15 minutes, then the calibration is accurate. Otherwise, you need to have your thermostat re-calibrated.


Thermostat malfunctions can lead to reduced heat simply because the thermostat is not controlling the furnace operation as it should. If your thermostat gives inaccurate readings that calibration doesn’t fix, or if the furnace is not heating to the inputted temperature, then it may be time to replace your thermostat.

Consider installing a zoned thermostat that allows you to control the heat level in rooms individually.

Furnace Problems

Problems with the unit itself are more severe than minor thermostat or duct repairs. Furnace-level issues may mean that you need to replace your unit, as sometimes repair isn’t possible.

Wrong-Size Unit

Furnace output is measured in BTUs. Generally, you can determine what size of furnace you need by multiplying your home’s square footage by 30. The resulting number is how many BTUs your furnace should provide. If your furnace has a lower BTU output, then this is likely the cause of your uneven heating options. Upgrading to a properly sized unit will heat your home better and more efficiently.

Unit Failure

A myriad of reasons can cause the unit to fail. Some problems, like a poorly functioning ignition or a malfunctioning blower, may only require repair or replacement of the specific problem part.

Other issues, such as a cracked heat exhanger or malfunctioning control board, are so expensive and time consuming to repair that often a new furnace is a more cost-effective choice. A full inspection can determine if your issue is best repaired or if replacement is the better choice.

Contact Lakeside Heating & Air Conditioning to schedule a consultation so you can solve your heating issues.