How to control heat recovery ventilation (HRV)? - the best solutions

How to control a heat recovery ventilation

More and more we rely on automation to significantly reduce time and our interference in processes we perform every day. This also refers to HRV. We automate system controls and integrate it with smart devices and sensors for better comfort and ease of use. Thanks to this we can customise the system to individual needs as well as prolong its life cycle but what is most important we are able to increase capacity, efficiency and reduce the energy consumption of the system. 

When the heat recovery unit (HRU) is controlled?

HRU is designed to transfer energy between two air streams despite the outdoor conditions. Good HRU, equipped with efficient heat exchanger can recover even up to 95% of heat from extracted air. But this might be possible only when specific conditions are met. The correct choice of HRU control system matters for its efficiency but it has to be managed wise. 

Controlling of HRU can also be done remotely using your smart-phone, tablet or other mobile devices and dedicated application, you are not limited than to control panel installed in the building. So you can optimize the operation of the unit from anywhere, for example, decrease the indoor temperature during holiday or cool down/heat up the living room just before you get back home. Unit capacity is regulated to your needs, weather conditions as well as to you habits and the way you live. Thus we decrease energy use of the system and increase room comfort.

Control panel functions (user interface)

Individual control of the HRU can be performed only when unit is equipped with special control panel, located on the unit or remote controllers installed in the building (wire or wireless). From the control panel it is possible to regulate and manage equipment installed in the heat recovery ventilation like heating coils or ventilators. Normally control panels are simple manipulators, easy to use with few buttons, and the state of art controllers have a touch screens. 

Control panel it the home has to be easy to access so install it in the central place. You will be able to check operation parameter and make adjustments whenever you need. Heat recovery unit could be regulated manually or automatically. It is possible to set the weekly schedule according to our daily routines with specific set points for each day. 
Controllers and sensors

The control system of the unit should allow to control and monitor one of the most important parameter which is freezing of the heat exchanger, common in cold climate on plate heat exchanger and in some rotary heat exchanger. This phenomenon occurs only with very low outdoor temperature. Control system monitors this parameter and inform about the freezing risk. Then antifreeze actions take place. There are few solutions: the most popular is to stop supply fan and start the pre heater if HRU has one.

Also we can control the airflow capacity. You will be able to select specific fan speed or set the percent of fan range capacity as the airflow. Next parameter we can control is heat recovery in air handling unit, done by bypass damper position and temperature set point. Other parameters to control are fresh air volume, pressure in the duct system and air distribution. 

Advanced control systems integrate even more functions. Additional functions could be integration with alarm system and fireplace function. 

Control from smartphone

Standard control panels for heat recovery units are usually wall mounted devices in easily accessible locations or optionally mobile devices like smartphone or tablet. The second solution seems to be more convenient and gives more flexibility to control ventilation system. You can make changes in unit settings from anywhere under your absence in the house i.e. from job, pub or other country during holiday. Lowering temperature in the rooms during winter holidays give you significant energy savings but the house cools down. Imagine that you can come back to warm house without paying for this when you are away, just set normal temperature remotely the day you planning to be back. Controls from mobile devices are able via special apps, designed for specific unit and installed on your smartphone or tablet.

To summarise, Heat Recovery Units can be controlled via:

  • manual selection of fan speed
  • weekly timer with scheduled operation modes
  • automatically depending on actual demands (Demand Control Ventilation) using external and internal sensors and probes to stepless regulate air flow and capacity.

Basic or advanced functionality depends on the control system used in the heat recovery unit. There are also customized solutions to create the control system for needs you expect. All this give you fresh air, healthy indoor climate but also convenience and comfort.

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. 
Alnor Ventilation Systems
Krakowska 10 Avenue
05-552 Wola Mrokowska

tel. +48 22 737 40 00