by Jake Lawson, HVAC Insights Expert
Introduction
One of the most misunderstood specifications on a PTAC heat pump isn’t the cooling capacity, the efficiency rating or even the heat pump itself. That’s the electric backup heater.
Most buyers spend their time comparing BTU ratings, looking at room size recommendations, or evaluating brand reputation. All those are important factors but many property owners never think much about the electric heat package sitting behind the front cover of the unit. And then winter comes, temperatures fall, guests begin to turn down thermostats and the importance of backup heat becomes very clear.
In my years of working with hotel operators, apartment managers, facility maintenance teams and property owners, the same question always comes up. Should they spend the extra money for a PTAC heat pump with a larger 5 kW electric heater? Some people thought that bigger was always better. Some people thought the heat pump would meet all their heating needs and that backup heat was little more than an emergency feature.
The truth is somewhere in the middle. Not all buildings need a 5 kW backup heater, but there are times when it can make a huge difference in comfort, reduce complaints, and provide a much better occupant experience. To know when that extra heating capacity is valuable, one needs to look beyond the equipment specs and think about how PTAC units really work in real-world conditions.
How Does a PTAC Heat Pump Work With Backup Heat?
Before explaining why heater size is important, it helps to understand how a PTAC heat pump heats a room. Unlike a conventional electric heater, which produces heat directly through resistance elements, a heat pump moves heat from one place to another. Even in cold weather, outdoor air contains useful heat energy. The heat pump sucks that energy out and moves it inside.
This process is one of the reasons heat pumps are growing in popularity in the hospitality and multifamily housing industries. The Heat pumps transfer heat instead of generating it, so they can provide much more heating energy than the electrical energy they consume, says the Department of Energy. This efficiency advantage often means lower operating costs than electric resistance heating alone. If you’re a property owner who wants to know more about the science behind heat pumps, the Department of Energy has a great overview at https://www.energy.gov/energysaver/heat-pump-systems.
But heat pumps aren't magic. The colder the outdoor temperature, the more difficult it is to pull usable heat from the air. The heat pump needs help at some point. This is where electric backup heat comes in. The resistance heater turns on automatically when more heat is needed, helping keep the indoors comfortable when the heat pump struggles with outdoor conditions.
The amount of supplemental heat you have available is directly related to the size of that heater. A smaller heater might be okay in some cases, but a larger one can offer more support when conditions get tough.
Why Do Manufacturers Provide Different Heater Sizes
Many buyers believe that the availability of several sizes of heaters is primarily a marketing gimmick. In fact, manufacturers offer different configurations because heating requirements vary dramatically from one property to another.
Say you have two buildings with the same PTACs. One is a South Carolina beach-front hotel, where winter temperatures rarely dip below freezing for long. The other is an extended-stay property in Minnesota, where subfreezing temperatures are part of the winter experience. The need for cooling may be the same, but the need for heating is quite different.
That’s why they have electric heat packages in a variety of sizes. The goal is not merely to add more heat. The goal is to provide the right amount of supplemental heating for the climate, occupancy patterns and comfort expectations of the property.
A 2.5 kW heater works great in a moderate climate where supplemental heat is used only occasionally. A 5 kW heater could be a lifesaver in cooler climes where backup heat is frequently used to keep indoor spaces cosy.
It’s less about choosing the biggest heater you can get and more about choosing the right heater for the operational needs of the property.
The Hotel Scenario: Where Bigger Backup Heat Often Provides the Best Value
🏨 When it comes to one industry where larger backup heaters often pay for themselves, it is hospitality.
Hotels have special challenges not faced by many residential applications. Guest rooms are frequently empty for part of the day. Thermostats can be dialled back to save energy. Housekeeping schedules lead to lower occupancy periods. Then a guest arrives after driving for a few hours, and immediately turns up the thermostat setting.
At this moment it is important to recover quickly.
HVAC systems are not typically rated for guests based on engineering specs or efficiency. They judge them by comfortability. A guest notices if a room is cold and takes a while to heat up. When the room is comfortable quickly, the HVAC system is essentially invisible, which is what hotel operators want.
In such situations, the temperature recovery of the larger 5 kW heater can be greatly improved. The extra heating power means that the room will reach the desired temperature faster, especially when the outside temperature is low. The cost difference in equipment is minor to many hotel owners when weighed against the potential impact on guest satisfaction and online reviews.
Comfort is directly related to reputation in the hospitality industry. A bigger heater can help make sure that winter weather is not part of the guest experience.
Multifamily Housing and Satisfaction of Residents
The issues are different for multifamily properties, but many of the rules are similar.
Flat dwellers often adjust the thermostat to suit their work schedules and personal tastes. Expect to feel rapid comfort when they return home as some lower temperatures away during the day. Some have different settings from room to room or change the temperature setting often with the weather.
In cold climates, these patterns result in repeated recovery demands. A PTAC unit with a bigger backup heater is better able to handle requests from residents for a large increase in the temperature.
Keeping tenants is a key factor in resident satisfaction. Property managers spend a lot of money attracting and keeping residents. Tenants rarely select an apartment based on the backup heat size of a PTAC unit, but they do notice when their heating system cannot keep up in the winter.
A bigger heater can make sure residents are comfortable in cold weather and reduce complaints and enhance overall resident experience.
Climate is a big factor in whether 5 kW is worth it
🌎 Climate is arguably the most important consideration in this debate.
A property in Florida will have a heating season that is very different than a property in Wisconsin. The same PTAC configuration can perform very differently depending on where it is installed.
To better understand the climate of the region, property owners can find detailed climate information from the National Weather Service. If you go to https://www.weather.gov and look at the historical temperatures you can get a good idea of how often you might need supplemental heat.
In areas with long winters, frequent subfreezing temperatures, and large overnight temperature swings, backup heat often plays a much larger role in maintaining comfort. Under these conditions the extra capacity of a 5 kW heater may be used on a regular basis throughout the heating season.
In more moderate climates, however, properties may be seldom in need of much additional heating. In those cases, the larger heater spends most of its life waiting for conditions that rarely occur.
Climate should certainly figure into the discussion, but in no way should it dictate equipment selection.
The Secret Weapon: Faster Temperature Bounce Back
Recovery performance is one of the most overlooked benefits of larger backup heaters.
Most of what I see in HVAC is about keeping things cool. But in practice, occupants often face recovery conditions. Overnight the rooms cool. Guests arrive and crank the thermostat up. Workers leave work to go home. Buildings bounce back from times of low occupancy.
The ability to effectively raise room temperature can have a strong impact on occupant perception.
Imagine you have two identical rooms that are initially at 60°F. The two occupants crank the thermostat up to seventy-two degrees. The room with the bigger heater generally has more heating capacity to speed up recovery. Larger heaters often reduce the time that people have to wait to get comfortable, but actual results depend on insulation, room size and outdoor conditions.
This might sound like a small thing, but comfort is often these moments. Occupants remember how quickly a room becomes a comfortable place more easily than they remember equipment specifications.
❄ Additional Heating Demands – Defrost Cycles
Another thing that many buyers overlook is the heat pump defrost operation.
In cold weather, frost may build up on the outdoor coil. Heat pumps periodically go into a defrost cycle to keep them running efficiently. The system then goes into a frost removal mode temporarily to remove accumulated frost.
For more information about this process, see the Department of Energy’s guidance on air-source heat pumps at https://www.energy.gov/energysaver/air-source-heat-pumps .
The heating output may temporarily decrease while defrosting. Backup heat helps offset this reduction and maintain occupant comfort. These periods are served by larger electric heaters for supplemental heating to reduce temperature swings that would be more obvious to occupants.
Defrost cycles are a normal part of heat pump operation, but they demonstrate why supplemental heat is still an important part of winter performance.
⚡Energy Costs and Comfort Costs
The obvious concern when talking about larger electric heaters is operating cost. Yes, a 5 kW heater can use more electricity than a smaller heater when it is operating. But the decision based on wattage alone can be an over simplification.
The larger heater is not on all the time. It only turns on when supplemental heat is required. In many cases the added heating capacity will allow the system to reach desired temperatures more quickly, possibly reducing the runtime in some recovery scenarios.
But more than that, property owners have to look at the big picture of costs. Guest complaints, resident dissatisfaction, bad reviews and comfort related service calls all cost something. The cheapest option isn’t always the one that uses the least electricity. It is the choice that gives the best overall combination of comfort, performance and operating efficiency.
The best choice depends on the priorities, climate and occupancy patterns of the property.
Building Efficiency Remains Important
No discussion of heating performance would be complete without the building itself. A poor building envelope cannot be compensated by even the best performing PTAC system. Heat loss through windows, doors, walls and air leakage is a large factor in the heating demand.
The International Energy Conservation Code still stresses the importance of building efficiency because less heat loss means less work for HVAC equipment. For more information about building energy performance, property owners can visit https://www.energycodes.gov.
In many cases, comfort improvements with lower heating costs can be achieved through increased insulation, reduced air infiltration, or window upgrades. “The selection of equipment and the performance of the building should be seen as complementary strategies rather than conflicting approaches.”
When You Might Not Need a 5 kW Heater
There are applications where larger heaters have obvious advantages, but there are also applications where larger heaters provide limited benefit.
In places with warm climates and short heating seasons, this extra capacity might seldom be needed. Buildings with excellent insulation and very little heat loss may require only modest supplemental heating systems. Certain applications simply do not have the occupancy patterns or recovery requirements that make larger heaters especially valuable.
Hence, there is no general answer to the question of whether a 5 kW heater is worth it.
It depends on the building, the climate, the people in the space.
🔧 Jake Lawson’s Final Take
When looking at PTAC heat pumps with 5 kW backup heat, I urge property owners to look beyond the equipment spec sheet. It’s a matter of comfort, the choice. It’s about how the building performs, how the users use the space and how winter conditions impact the day-to-day.
For hotels, extended stay properties, multi-family communities in colder regions, healthcare facilities and institutional buildings, a larger backup heater often provides meaningful benefits. The investment over the lifetime of the equipment is justified by faster recovery time, better performance in cold weather and more support under demanding conditions.
In moderate climates with less heating demand, a smaller heater might provide all the performance required for properties. The smartest HVAC decisions rarely involve selecting the biggest option available. They are about choosing the right choice for the application. When the application demands superior winter performance and faster comfort recovery, a PTAC heat pump with a 5 kW electric heater can be one of the most practical investments a property owner makes.
Jake Lawson
HVAC Insights Specialist
The Furnace Outlet
