Why is my house cold if the heater is on?

Author: Dr. Kelly Bernhard Sr.  |  Last update: Monday, May 19, 2025

If your furnace is constantly on yet your house is still cold, it may be that you are blowing both cold and hot air into the house. If the fan switch on your thermostat is set to on instead of auto, this can cause your furnace to keep blowing even when it's not on the heating cycle.

Why is my house so cold with heating on?

This problem often points to inadequate circulation of warm air. It could be due to blocked vents, a failing HVAC fan, or issues with the furnace itself. Ensure that furniture or drapes are not blocking your vents. Also, check if your furnace's filter is clean, as a dirty filter can restrict airflow.

Why do I feel cold even with the heater on?

The causes of cold intolerance are clustered around problems involving the circulatory system, nervous system, and endocrine (hormonal) system. Often, multiple causes are involved. Even certain medications or the lack of sleep can trigger intolerance to cold.

Why is cold air coming out when the heater is on?

The heat exchanger uses coils to transfer heat from the ignited gas to the air. When cold air blows from a furnace the heat exchanger, furnace burner, or exhaust are likely the cause. This may be due to dirty components, broken parts, or the many safety mechanisms within the gas system.

Why is my furnace running but the house is cold?

If your furnace is working and blowing warm air, but you just aren't feeling it, you may have closed or obstructed HVAC vents/registers. Check your home for any blocked or obstructed vents and registers. You may also have excessively leaky or damaged ductwork.

Why is My House Cold with Heat On

Why is my furnace running but not getting warm?

Blocked Air Vents or Ductwork

Blocked or closed air vents can restrict the airflow in your home, preventing warm air from reaching the rooms. Check all vents and registers to ensure they are open and unobstructed. Additionally, inspect your ductwork for any obstructions or leaks that could hinder heat distribution.

Why is my house colder than my thermostat setting?

Dirty or worn flame sensors, blower motor problems, clogs in the condensate lines, and electrical issues are some of the many problems that can leave your HVAC system failing to deliver the temperatures you've programmed in your thermostat.

How do I stop my furnace from blowing out cold air?

Check Furnace Air Filter

A dirty air filter hinders air movement through the furnace. This raises temperatures inside the furnace, and the limit switch shuts heating cycles down if the unit becomes too hot. If you have a dirty filter, replacing the filter typically stops cold air from blowing.

Why is my heater hot but room is cold?

Very simple. The radiator is not supplying enough heat to keep up with the heat loss of the room. Get a heat loss calculation done and install the right radiator.

Why does my house still feel cold at 73?

If you're cold even though your thermostat indicates you shouldn't be, your furnace likely isn't the problem. In most cases, it's working just fine. It's your home that needs attention. Lack of insulation, severe air leakage, and/or unbalanced ductwork are frequently to blame.

How to make a cold house warm?

How to keep your house warm in winter
  1. Draught-proof your home. ...
  2. Insulate your pipes. ...
  3. Bleed your radiators and install reflector panels. ...
  4. Upgrade your heating controls. ...
  5. Top up your hot water cylinder insulation. ...
  6. Top up your loft insulation. ...
  7. Upgrade your boiler. ...
  8. Insulate your walls.

Why does my heat feel like cold air?

Two thermostat issues that could cause your furnace to blow cold air include (1) your thermostat is still set to COOL, not HEAT and (2) your thermostat fan is set to ON, not AUTO.

Why do I still feel cold when the heater is on?

If you feel chilly indoors, you might want to check for drafty areas in the home. Potential gaps or cracks around windows and doorframes can let in the cold air. According to the U.S. Department of Energy, windows are responsible for up to 30% of heat loss.

Why is my house not warming up with heating on?

If your home isn't warming up as expected, a dirty air filter, blocked vents, or thermostat issues might be to blame. Check and address these issues before considering professional assistance.

How can I find out why my house is so cold?

Heating On, But House Still Cold? 5 Possible Causes
  • Inadequate insulation. The insulation in your home acts like a cosy blanket, keeping the warm air in and the cold air out. ...
  • Draughty doors and windows. ...
  • Outdated or inefficient heating system. ...
  • Blocked or closed vents and radiators. ...
  • Thermostat issues.

Why is my house cold even with the heater on?

If your furnace is blowing hot but your home is still cold, it may be a problem with your ductwork. You may have leaky or damaged ducts that are letting hot air escape and cold air in. Sometimes a damper in the system can get miss-adjusted or come loose, thereby inadvertently blocking or reducing airflow.

Why is cold air coming out when heat is on?

You Have Cold Air Blowing Out The Vents When The Heat Is On Because of a Dirty Air Filter. Hiding in the filter of your heating system is dirt and debris. If you aren't cleaning it regularly, this will accumulate over time, leading to problems with your heating system's efficiency.

Why is my heat running but still cold?

Dirty air filters are perhaps the most common reason that furnaces fail to provide enough heat to a home. (They're behind plenty of other problems as well.) Over time, this air filter will become clogged with dust, dirt, and other debris.

Why is my heater blowing cold air in my house?

If your furnace is blowing cold air in your home, this is a sign of an issue with the flame detector, gas supply, air filter, pilot light, or condensate lines.

Should I turn my heat off if it's blowing cold air?

Yes, you should turn your heater off if it's blowing cold air to prevent potential damage to the system. Running a malfunctioning heater can strain the components, leading to more significant issues and increased energy usage.

Why is the furnace blowing out cold air?

If your system never supplies enough warm air, it could be that your ductwork is not sized properly. Unfortunately, this is too common. If the return air ducts are too small, the furnace will not be able to take in the required amount of air. Due to the lack of airflow, your heater will blow cold air.

Why is my heat not reaching my desired temperature?

Some of the most common thermostat issues include:

The thermostat is broken, not properly level, or dusty. The thermostat needs to be recalibrated. There is loose wiring causing a thermostat issue.

Why is my heat pump not keeping my house warm?

A problem in the heat pump itself that might be responsible is dirt and grime along either the indoor or outdoor coils, which will restrict heat exchange. Also check the outdoor cabinet to make sure there isn't snow banked up against it, which will make it hard for the heat pump to draw sufficient outdoor air.

Why does 68 degrees feel cold inside?

There may be drafts and pockets of colder air near the floor; The walls are colder and don't emit the usual amount of infrared radiation, so you lose heat due to your body emitting more IR than it receives; You may spend more time indoors and hence have less physical activity, so your body generates less heat.

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