Low-profile Heat Recovery Unit - for Ceiling and Wall Mounted Installation

Suspended heat recovery unit

SlimAIR Heat Recovery Unit is a low-profile HRV unit with 89,9% heat recovery, dedicated to 140-150 m2 residential buildings with high requirements for air quality and energy-efficient solutions. By removing stale air simultaneously with filtering fresh air, the unit assures balanced ventilation at home.

Perfect For Restricted Space

With only 24.2 cm height and compact design, SlimAIR is a great space-saving solution for limited, restricted spaces. SlimAIR unit is a flat heat recovery unit designed as a one-fits-all solution, i.e. it can be installed both under the ceiling or on the wall.

The unit is extremely versatile when it comes to the installation possibilities since You can install SlimAIR in 3 positions without any additional mounting brackets (everything You would need, is included in the set):

horizontal mounting - mvhr unit

Wall-mounted horizontally

mvhr unit vertical mounting

Wall-mounted vertically

suspended heat recovery ventilator

Ceiling-mounted, vertically

For maintenance purposes, air filters can be easily removed without dismantling the front cover, which could be quite bothersome when the unit is suspended under the ceiling.

What’s more, there’s easy access to filters both from the front and from the side of the unit.  This makes sure the process of changing filters is quick and simple.

How to replace air filters


SlimAIR unit is compact and easy to handle, it weighs only 25.5kg so that one installer is enough to install it, single-handedly. For ceiling mounting, there’s an additional mounting rack available for one-person installations.

How to suspend the heat recovery unit

For maintenance and service purposes, all the most important parts of the unit, like the heat exchanger and fans can be accessed through the front cover. Without dismantling the HRV unit. An installer can easily commission the HRV and check parameter settings of the unit, by simply connecting to the USB port located on the SlimAIR unit.

Silent and energy-efficient

The heat recovery ventilation system is designed to operate continuously with low power consumption. SlimAIR unit consumes only 14.8 W at its lowest speed! Compliant with EU standards and constructed with high-quality materials, ensuring energy class A/A+, very low leakage (class A1), high thermal insulation, and minimal noise.

MVHR systems need to work non-stop, hence SlimAIR's low noise level of 50dB(A) is perfect for avoiding disturbing residents. In an effort to reduce noise, we used the following measures:
Silent heat recovery unit
1. Supply fan located upstream of the heat exchanger; 2. Profiled airflow channels; 3. Special grids for fans; 4. EPP casing with acoustic insulation

Constant Flow Function

The heat recovery unit can be equipped with the Constant Flow (CF) module that guarantees that the airflow rates preset by the installer are achieved independent of any resistance in the duct system. 
constant airflow module
After HRV installation, the ventilation system naturally gets more and more unbalanced. Dirty air filters, condensate on the heat exchanger can influence the efficiency of the unit. Adding a CF module to the MVHR system will ensure 100% capacity year-round. Only a balanced ventilation system takes full advantage of the heat recovery unit’s effectiveness.

Frost protection

The advanced algorithm that controls fans’ operation together with build-in 1kW pre-heater protects the heat exchanger, a heart of the unit, from freezing and risk of damage.
preliminary heater for hrv ventilation
The energy efficiency of this two-step frost protection system lies in the fact that merely when temperatures drop below a certain threshold, the preheater can be activated (bringing in additional power consumption).

  1. At first, the algorithm gradually modifies fans’ speed, preventing the heat exchanger from freezing.
  2. The preheater activates when the temperature drops significantly. The preheater works in conjunction with the algorithm to act as a frost protection system while the temperature remains extremely low. 


89,9% heat recovery efficiency is achieved thanks to a high-quality counter-flow heat exchanger made of PET. For cold and dry areas, we’ve added the option to change the standard heat exchanger to an enthalpy heat exchanger.
Counterflow heat exchanger

In addition to transferring heat, the enthalpy heat exchanger also transfers moisture between streams. In cold weather (when the outside air is dry), an enthalpy exchanger can help maintain a comfortable interior humidity rate (40-60%).

As a result, during the summer it will lower the relative humidity in the supplied air. Lower risk of heat exchanger freezing is another benefit of energy recovery units. 


Unit housing is made of EPP - expanded polypropylene, high-quality material with excellent acoustic and thermal insulation properties. The device has 4steel mounting brackets and 4 clamps to open the front cover.

Standard equipment includes two pleated filters with increased filtration area, which results in low pressure drops. The air filters are classified according to ISO 16890 as ISO coarse 70%.
air filter for heat recovery unit
Thanks to the unit’s unique condensate drain system, it can be mounted in three different positions without using additional mounting brackets: vertically on the wall, horizontally on the wall, and ceiling-mounted, vertically.
condensate drain for mvhr unit
Technical data - Overview

  • Applications: mechanical ventilation up to 150 square meters;
  • Capacity: from 250 m3/h at 100 Pa;
  • Energy class: A / A + (depending on the control system);
  • Heat recovery efficiency: up to 89,9%;
  • Power consumption: 14.8-91.5W;
  • Type of heat exchanger: counterflow heat exchanger or counterflow, enthalpy exchanger;
  • Installation method: in 3 positions: vertical, horizontal, and horizontal suspended.

Technical data for SlimAIR heat recovery unit

If You're looking for more tips and instructions about the MVHR (mechanical ventilation with heat recovery), check also the following articles:

  1. How can You install heat recovery unit in the ready-built house?  - the article about decentralized heat recovery systems.
  2. What is an Electrostatic Precipitator and how does it work? - the article about highest filtration efficiency solutions.
  3. 14 Things You Need to Know about PremAIR - pretty self-explanatory title about the best HRU for clients looking for "premium" solutions. 
  4. Air distribution system for the MVHR - overview of FLX-REKU system: radial, semi-rigid ducting, plenum and distribution boxes, etc.
Alnor Ventilation Systems
Krakowska 10 Avenue
05-552 Wola Mrokowska

tel. +48 22 737 40 00