What is the purpose of a primary (pre-heater) air heater?

A primary electrical pre-heater is installed in the outdoor air intake duct just before the heat recovery unit and is designed to protect the unit's heat exchanger from freezing. When the outside temperature drops below zero, the drawn-in icy air can freeze the condensation inside a plate heat exchanger. The pre-heater slightly warms the incoming air (usually to a safe limit of -2°C or -3°C), ensuring the system operates without interruptions and your home never lacks fresh air.

What is the difference between primary and secondary duct heaters?

A primary heater is installed before the heat recovery unit to protect it from freezing, while a secondary heater is installed after the unit to warm the air supplied to the rooms. If the unit recovers most of the heat but the air still feels too cool (especially during very harsh winters), the secondary heater raises the supply air temperature to your set comfort level, for example, 21°C. This prevents any feeling of cold drafts under the ventilation diffusers.

Can a water heater be connected to a heat pump?

Yes, water duct heaters are perfectly suited for connection to the home's heating system, including air-to-water heat pumps or geothermal heating. This is a highly economical solution because the air is heated using the cheaper energy generated by the heat pump rather than direct electricity. Water heaters require an additional circulation pump and a mixing valve to precisely regulate the temperature of the water supplied to the coil.

Accessories and Heaters

Ensure uninterrupted operation of your ventilation system even during the deepest Lithuanian freezes. Electrical and water duct heaters protect your unit from freezing and guarantee that pleasantly warm air always flows into your rooms.

Discover original accessories that expand your ventilation system's capabilities and tailor it to your home's individual needs.

How Ventilation Accessories Ensure Peace of Mind in Winter

Stopped Ventilation and the Feeling of Cold Indoors

When severe frosts arrive, many homeowners face an unexpected problem. If the outside temperature drops below -10°C, standard plate heat recovery units without additional protection begin to freeze. To protect itself, the unit's automation stops the fresh air supply and attempts to defrost the heat exchanger using extracted indoor heat.

This process causes serious discomfort for the whole family. The home suddenly lacks fresh air, moisture starts to build up, and when the system turns back on, an unpleasant cool draft may be felt from the ceiling diffusers. Cold drafts not only reduce the quality of life but also force you to heat the rooms more, wasting additional energy.

A Steady Flow of Warmth and Freshness Without Interruptions

By integrating the right air heaters, your ventilation system becomes immune to any weather whims. A primary electrical heater prevents the frost from reaching the heat recovery core, so the system operates without the slightest interruption. You will not even notice that a blizzard is raging outside – the air in your home will be continuously refreshed.

Secondary heaters elevate comfort to the highest level. They ensure that the air flowing from the ducts is exactly the same temperature as the room environment. You can confidently place a bed or a desk directly under a ventilation vent without fear of catching a cold, and the smart HRV automation will only engage the heaters when truly necessary.

Uninterrupted operation at -25°C – a properly selected pre-heater guarantees that the ventilation system will not stop supplying oxygen even on the harshest winter nights.

How to Choose the Right Heaters and Accessories?

When selecting ventilation system accessories, it is important to ensure their compatibility with your main unit. Different heat recovery models require specific power outputs and connection standards:

Duct Diameter (mm) – the heater is mounted directly into the duct system, so its connection diameter (e.g., 125, 160, or 200 mm) must perfectly match the size of your main duct to avoid airflow resistance and noise.
Electrical Power (kW) – for pre-heaters, 1-2 kW of power is usually enough to perform the protective function. The power of secondary heaters depends on the home's area and the target temperature. A heater that is too powerful will unnecessarily burden the electrical grid, while one that is too weak will not do its job.
Electrical vs. Water Heater – electrical heaters are cheaper, easy to install, and perfect for smaller homes. Water heaters cost more and require more complex plumbing (mixing valves), but they are far more economical to run, especially in large homes with heat pumps.
Control Automation – ensure the heater can be directly connected to the heat recovery unit's main circuit board. This allows the unit to automatically modulate the heater's output based on external temperature sensors.

Do Rotary Heat Recovery Units Need Heaters?

Rotary heat exchangers are much more resistant to freezing. Because of the spinning aluminum drum, condensation does not form, making the risk of freezing minimal. Usually, rotary models do not require a primary pre-heater. However, a secondary heater (for warming the supply air) remains relevant for those who want maximum thermal comfort in their rooms.

Accessories Installation and Integration

Safe Installation in the Utility Room

Installing duct heaters requires knowledge of ventilation, electricity, and, in the case of water models, plumbing. Therefore, it is best to entrust this work to qualified professionals to ensure complete fire and operational safety.

Duct Mounting – the heater casing is tightly connected to the rigid metal ducts in the utility room. It is crucial to maintain the manufacturer's specified distances from the heater to any bends or the HRV itself so the airflow evenly covers the heating elements.
Electrical Power – electrical heaters often require a separate power cable from the electrical panel, as their power draw can exceed the needs of the heat recovery unit itself.
Communication with the Controller – the heater is connected via a low-voltage wire to the HRV's automation. Duct temperature sensors are also installed to measure the airflow temperature in real time.
Connecting Water Systems – for water heaters, an additional circulation pump and a three-way valve are installed to regulate the flow of the heating medium from the boiler room.

Long-Term Protection and Peace of Mind

Once professionally installed, heaters require absolutely no additional maintenance from you. The entire system operates autonomously, governed by smart algorithms. Electrical heating elements are protected against overheating by dual thermostats, so you can be completely at ease regarding home safety. It is a one-time investment that permanently eliminates the risks of ventilation freezing and guarantees a warm, cozy winter.