Air Heater vs Coolant Heater for EV Cabins: A Total Cost Comparison

Let’s start with “breakdowns,” since this is precisely where heating systems generate additional costs. If a heater breaks down in January, the vehicle will be stranded in the parking lot; at that point, it no longer matters which equipment was cheaper at the time of purchase. This risk exists with both technical architectures, and no sales brochure from either side will tell you that. We manufacture coolant heaters, so please bear in mind that we may have a vested interest—but even so, be sure to run the numbers, because the purchase price actually represents the smallest portion of the overall cost.

In terms of price, air heaters have a clear advantage—and the difference is significant.

Air-type PTC heaters consist of heating elements, a fan, and a housing—a simple design, which is actually an advantage. Coolant heaters, on the other hand, are pressurized liquid heating devices that include high-pressure connectors, seals, and control boards, and require a matching pump and piping system. Looking solely at the equipment itself, air heaters have lower procurement and shipping costs; if a supplier claims otherwise, they are most likely trying to sell you their product. In terms of price, air heaters do indeed have the edge.

The key to installation lies in whether a ready-made circulation loop is available.

Air heating systems require the installation of air ducts and high-voltage wiring directly to the passenger compartment. Coolant heating systems, on the other hand, require hoses, fittings, and venting procedures, and must be integrated into an existing liquid circulation loop. On quotations, the two are often treated as requiring equivalent amounts of work, but this is not the case in modern commercial electric vehicles: since the battery itself is liquid-cooled, the circulation loop already exists—the piping is in place, the water pump is installed, and the coolant is already included in the maintenance schedule. In this scenario, connecting the heater to this loop is merely an “incremental” operation, rather than building an entirely new system.

If we consider a different vehicle model, the conclusion changes accordingly. For older platforms or models with air-cooled batteries, since there is no existing liquid circulation loop at all, introducing a coolant heater means a complete system must be installed—including a water pump, hoses, a reservoir, and so on. In such cases, air heaters have a clear advantage in terms of installation. We make sure to inform the buyer of this fact.

The battery is the key factor.

An air heater can only heat air; it cannot provide heat to a liquid-cooled battery. This is not a limitation that can be overcome through engineering; rather, it is an inherent characteristic of the device itself. In cold climates, the battery must receive heat—which is critical for ensuring charging efficiency, maintaining power output, and extending battery life. If a fleet—such as one located in the north—chooses a cheaper heater to save on initial procurement costs, it will often need to install a separate battery heating system as well; this requires integrating a second control system and further complicates the vehicle’s configuration.

In contrast, a coolant heating system can perform both tasks simultaneously through a single circuit and a set of valves: preheating the battery pack before the vehicle departs and heating the cabin while driving. This is why, despite the higher unit cost of coolant-based heating systems, they still dominate the commercial electric vehicle sector—not because the heaters themselves are cheaper, but because this solution eliminates the need to purchase a second heating system.

From an energy consumption perspective, the two are actually on par with each other.

Regardless of the type of heating device, resistive heating generally converts electrical energy into thermal energy at a ratio of roughly 1:1. Operating at 20 kilowatts for one hour consumes 20 kilowatt-hours of electricity, regardless of the device used. If someone claims there is a huge difference in efficiency between the two, it is most likely just marketing hype.

The differences between the two mainly lie in the details. A coolant-based heating system can preheat the battery pack and cabin using power from a charging station before the vehicle departs (consuming grid power rather than battery power); during operation, it can also incorporate waste heat generated by the electric motor into the same circulation loop for reuse. While an air heater can quickly raise the cabin temperature, the heat dissipates rapidly as soon as the doors open and the fan stops running—under typical city bus operating conditions, this is reflected in energy consumption records. The difference amounts to only a few percentage points; it hardly constitutes a revolutionary breakthrough.

What challenges will the fleet face after installing the heating system?

First is the issue of maintenance. Coolant heaters are integrated into the fleet’s existing piping system, which is already part of routine maintenance; tasks such as coolant replacement, hose inspections, and water pump lifespan monitoring are all familiar maintenance procedures for the fleet. Air heater assemblies, on the other hand, are installed in dusty air ducts and are subjected to thermal shock during every cold start. Regardless of what product brochures may promise, neither of these systems can be considered “maintenance-free.”

If a heater fails in January, regardless of the technical architecture used, the vehicle will be unable to continue operating; the difference lies in how the situation is handled afterward. If the entire fleet uses a single type of heating system, only one type of spare part needs to be stocked, and all technicians need to master only one diagnostic procedure. Some fleets mix different technical architectures to save on procurement costs, but after just a few winters, the money saved will be offset by the additional costs of spare parts inventory and staff training.

Finally, there is the driver factor—something that cannot be quantified in a spreadsheet. If the cab warms up slowly on a January morning, drivers will not only complain but also come up with various “workarounds,” which may ultimately lead to them requesting that the vehicle idle for extended periods (something that should not happen). If the vehicle can be preheated (preconditioned) while plugged in, the interior will already be sufficiently warm by the time the driver gets in, naturally eliminating any complaints.

Summary Recommendations

If the vehicle lacks a liquid-cooled circuit, operates in a mild climate, requires only cab heating, or is part of a retrofit project for older vehicles where piping cannot be installed, an air heater should be selected. Localized heating for small vans or sleeper cabs is a typical example—in these scenarios, our product (the liquid-cooled heater) is not the optimal choice. If the battery uses a liquid-cooling system, the winters are extremely cold, or the vehicle needs to be preheated (preconditioned) while connected to an external power source, a coolant heater should be selected—most commercial electric vehicle projects we’ve encountered fall into this category. Before evaluating quotes, be sure to comprehensively consider the above costs in light of the vehicle’s actual operating conditions.

Frequently Asked Questions on This Topic

Is it necessary to install a coolant heater in a small electric van?

This depends on the battery type and local winter climate. If the battery pack uses a liquid-cooling system and operates in a cold climate, it is generally necessary because the battery itself requires heating. If the battery pack uses an air-cooling system and operates in a warm climate, an air heater is the more reasonable choice—and that is the recommendation we would give.

Does a coolant heater take longer to heat the cab?

During a completely cold start, it does take a bit longer because the entire piping system needs to warm up first. This difference is usually only a matter of minutes; if the vehicle is preheated (preconditioned) while plugged in, this difference disappears entirely.

Should we compare these two solutions with a heat pump system?

For any new platform, a comparison should be made. In mild to cold climates, heat pumps can effectively reduce heating energy consumption; however, their efficiency decreases in extremely cold conditions. For this reason, many vehicles combine heat pumps with PTC heaters. We’ve compared these two solutions in our article on heat pumps.

Are you evaluating the costs of heating architectures? Please provide vehicle specifications, climate conditions, battery cooling methods, and operating cycles. We’ll work with you to calculate all costs—and even if the optimal solution ultimately turns out to be an air-heating system, we’ll provide you with a clear analysis.