HVAC Repair Tips


A heat pump not warming up the house as expected can make you wonder what’s causing this issue. Is your heat pump malfunctioning or is it undersized for your house? This may be one of the thoughts going through your mind. A heat pump’s heating ability depends on many factors so you must investigate further and hire a heat pump repair technician who can conduct a load calculation for determining the heat pump size your house requires.

You can also learn and look for some signs that may hint you that your heat pump is too small for your house.

Signs Your HVAC Unit Is Undersized

You Have Made Changes To Your House

This is probably the easiest one. If you have recently remodeled your house and increased your living space, it will impact the performance of your heat pump.

To conclude this, you need to make sure about the heating capability of your heat pump before the remodeling project. If your heat pump warmed up your house perfectly before and started lacking in heating the house after the home improvement, then it’s a clear sign that the newly added indoor space is the reason your heat pump is not up to the mark.

See, your heat pump was sized according to your pre-remodeled living space. Now that you have increased it, your existing heat pump has become smaller for your house.

But keep in mind that this happens only if the home addition is significant, for instance, adding another living room. Anything too small like adding a small mudroom may not affect your heat pump as much.

The Heat Pump Runs Constantly

A heat pump that keeps running without cycling off can be due to many reasons, but it’s often associated with a wrong-sized unit.

When a heat pump is too small for the house, it won’t reach the temperature you have set because the space is much bigger than it can heat properly. So, the heat pump will keep running constantly and won’t turn off.

Usually, a heat pump or any HVAC system on heating mode heats the house and when it hits the set temperature, it turns off. After some time, when the temperature drops, the unit turns on again for another cycle. This doesn’t happen in the case of a smaller heat pump and it will run non-stop.

However, you should also note other things as well. That’s because, sometimes, this issue is due to things like clogged air filters, faulty thermostats, leaking refrigerant, or any other issue related to heat pump components.

High Energy Bills

We all hate high energy bills, but if your heat pump unit is undersized, get ready to pay higher utility bills. This happens because of the reason mentioned in the previous point.

Due to the smaller size, the heat pump doesn’t turn off and keeps running to maintain the temperature of the house. As it doesn’t turn off and it keeps using power more than an optimal-sized heat pump would, what will happen? Your energy bills will increase.

Moreover, in some cases, a smaller heat pump shot cycles. In this, the unit turns on and off repeatedly without completing its heating cycle. However, the result is quite the same. The heat pump doesn’t warm up the house up to the set temperature and yet it consumes more energy than it should for heating your house.

To notice this, you should check when you started getting higher energy bills without any difference in your overall power usage. If you replaced your heat pump with a new one, and the heating bills turned higher after that, then it may be due to the size of the unit. However, if you installed a second heat pump, then, of course, you’re consuming more energy and will get higher energy bills.

Apart from that, you must also inspect your heat pump. In many cases, the cause of high energy bills is a dirty or faulty component of the heat pump given that the size of the unit is right.

Increased Humidity Levels

A heat pump heats your house and it also keeps your indoor humidity levels balanced. Now, if an undersized heat pump can’t properly warm up the house, can it keep the humidity levels optimal? No, it can’t.

The same reason is applicable here. Due to the smaller size compared to the living space, the heat pump won’t be able to effectively remove moisture from the indoor air. In turn, not only your house won’t become warm, the humidity level will remain high.

High humidity can cause many problems for you. Mold, fungus, and bacteria thrive in humid places so they can grow in unexpected corners and areas of your house. They can cause allergic reactions and respiratory problems. If people in your house are suffering from any health problems, whether you consider replacing your heat pump or not, consider using a dehumidifier to maintain indoor humidity level.

Signs Your Heat Pump Is Not Undersized But Malfunctioning

Your Heat Pump Performed Well Before

If your heat pump was great before and recently started lacking in effectively heating the house, there is probably nothing wrong with the size of the heat pump. This is because the same heat pump has served you well in the past. So, if it’s not working as well as before, it may be due to any issues with the components or the age of the heat pump.

Leaky Air Ducts

Air ducts are connected to heat pumps and allow warm air into your house through vents. Now, what would happen if the heat pump is working fine, but when it pushes air to the ductwork, the ducts waste the air due to leakages? Your house won’t become warm and you would blame your heat pump when the culprit is leaky ductwork.

So, if your heat pump is not reaching your desired temperature or running constantly, you must check the air ducts. As air duct inspection is difficult and a person without the right skills can even damage the ducts, it’s better to hire an expert for the inspection.

Dirty Air Filters

Air filters stop contaminants from reaching the unit. They become clogged with dust over time and must be cleaned or replaced depending on the type of air filter you have. If not done, the airflow will be restricted and your home won’t heat as expected.

Faulty Thermostat

A thermostat is the component of your HVAC system that you interact with the most. However, it’s not immune to problems either. If it’s faulty, it will mess up the temperature settings and the heat pump won’t heat your house correctly.

Dirty Coils

A heat pump has condenser coils in the outside unit and evaporator coils in the air handling unit. These coils ensure the heat exchange process that results in the production of warm air when the unit is in heating mode.

As dust and debris settle on these coils, they become less effective in performing the heat exchange process, so the heating capacity of your heat pump is reduced. So, clean the coils. You can clean the outdoor unit yourself. However, it’s better to get a professional to clean your heat pump properly.


An undersized heat pump won’t heat your house and only leads to problems like higher energy bills, wear and tear of the components, and other issues. With this guide, you can now confirm whether your heat pump is undersized or is it simply malfunctioning. For inspections, repairs, or heat pump replacements, only hire the best heat pump repair services McLean.


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