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The best single room heat recovery unit

Single room heat recovery unit

What is a single-room heat recovery unit?

Single room heat recovery is a “mini” wall-mounted ventilation system with heat recovery. The perfect solution for homeowners who cannot or do not want to install a traditional heat recovery system in their home, but still want to improve indoor air quality and lower their energy costs.

The best solution for the occupied house?

Traditional extract ventilation systems exchange the stale air inside the building with clean air but at the expense of causing heat loss. The good news is that there are a number of systems that allow some of the waste heat to be recovered from extracted air and used to preheat the fresh air being supplied, which reduces the energy usage significantly.

As simple as it may seem to implement a ventilation system with heat recovery when designing and building a new building, it is not always feasible to do so when renovating an existing building.
single room heat recovery unitSingle room heat recovery units (in short - SRHR) are easy-to-install and easy-to-operate solutions that are used in both newly constructed and modernized residential or commercial buildings. This type of ventilation system is ideal for refurbishment applications.

How does a SRHR unit work?

The design of the decentralized heat recovery unit generally corresponds to that of a typical heat recovery unit, only in a compact, simplified construction. This means that as in traditional heat recovery ventilation there is an air handling unit with a heat exchanger, a fan, an automatic control system, a housing and a filter.

Single room heat ventilation

There are many models of decentralized heat recovery ventilation units available in the market, which differ in:

  • aesthetic appearance (please remember that wall heat recovery units are mounted indoors in visible places, i.e. they have an outer cover on the wall inside the house and air intake on the facade of the building),
  • the type of a heat exchanger (the most popular is the regenerative ceramic exchanger, but there are also heat recovery systems with cross-flow or counter-flow exchangers),
  • technical parameters such as power consumption, number of fan speeds, heat recovery rate or noise level,
  • type of control (using a controller connected to the units by cables, a remote control or a mobile application).

What is the best single room heat recovery unit?

The answer is "it depends". That's why our single room heat recovery ventilator series comes in 3 models that differ in terms of additional features, control type, and price.

Starting with what these 3 models have in common, the following table illustrates that their technical specifications, such as heat recovery or unit size, are almost identical. They also share the same construction, i.e. regenerative ceramic honeycomb heat exchanger, energy-saving fan, anti dust air filter, telescopic tube and casing.

single room heat recovery units

The HRU-WALL series heat recovery unit control

The differences among HRU-WALL series models come with control type. Let’s start from the basic HRU-WALL version. The heat recovery unit operation is carried out by a controller. For the HRU-WALL model, we can choose between two dedicated controllers or one can optionally connect a simple three-button switch, available at DIY stores.

Using the three-button switch, select first, second, or third speed (press 1st button, 2nd button, or both at once). The third button is used to select alternate or one-directional mode (supply only or exhaust only, depending on the jumper position on the automatic control system board).

The controller works by closing circuits. Therefore, we can buy and use any 3-button switch, available in any DIY store, because, for example, we want to match the color other switches, and our dedicated controllers are only available in white. The advantage of our dedicated controllers is that they have pictograms showing which button is used for which function. The most important thing is to connect the units and the controller together, whichever one we choose, because there is no other option to control these heat recovery units.

In the case of HRU-WALL-RC series, the control is done with a remote control (available in the package), and we cannot connect a regular controller to this model. However, we have provided a failsafe when the remote control fails, i.e. runs out of batteries or is lost. In such “extreme” cases, there is an emergency button on the unit to turn the heat recovery unit on or off. Several units can be operated by a single controller. One controller can be connected to max. 10 devices. However, we typically connect a few heat recovery units to one controller/switch and any change on the controller means changing the mode for all devices that are connected to it.

It is also worth mentioning how the device “knows” whether it should only supply or only exhaust the air when you switch to one-directional mode. The automatic control system of the unit has a jumper, the setting of which determines the direction of airflow in one-directional mode. Below is an excerpt from the Heat recovery unit manual (p. 19); setting the jumper in position A means exhaust only and in position B means supply only. More on the unit synchronization can be found in a separate subsection.

Unit synchronization

If we want two devices to work alternately(and we recommend such an option), then in the case of HRU-WALL models set the jumper in position A on one heat recovery unit and the jumper in position B on another heat recovery unit (see User manual). When the units are started, one will supply and the other will exhaust the air, and then the cycle will reverse. Obviously, in alternate mode, the devices change their modes, but please remember that if we switch to one-directional mode, the heat recovery unit will work in the direction according to the jumper setting.

For the HRU-WALL-RC model, devices are synchronized slightly different. To synchronize the operation of several HRU-WALL-RC units, we simply need to run a single pair cable between all the units, and connect them in series, thus synchronizing them. The automatic control system itself selects alternate modes for individual units. The supply only or exhaust only mode is selected on the remote control.