Demand control ventilation takes various forms depending on manufacturer but its most common arrangement is a humidity sensitive central extract system with fresh air supplied via humidity sensitive wall grilles.

Our manufacturing partner is Aereco. Aereco are the first company in the world to develop a system around measuring and adjusting for humidity via grilles.

Each supply air room (bedrooms, sitting room, living room etc) is fitted with the EHT wall grille. This grille has a non electrical  humidity sensitive mechanism that adjusts the airflow into the room through the side of the grille. Depending on the humidity in the air in the room the grille will open and close accordingly. The grille will never close completely and therefore not let the air in the room go stale.

In the extract rooms (bathrooms, kutchen, utility) there are similar humidity grilles installed in the ceiling.  However these are individually ducted back to the central extract fan. This fan is pressure sensitive, therefore, if a grille in for example opens in a bathroom because shower is running the fan will sense this drop in pressure and speed up accordingly.

Where an extract grille is installed in a room with a toilet the grille will also be fitted with a PIR (passive infra red sensor).  This will allow the grille to respond if the room is being continuously used.

The full terminology for this system is continuous whole house heat recovery ventilation. This is often abbreviated to heat recovery ventilation or HRV.

The system works by constantly extracting air anywhere there is additional heat and/or moisture produced within the house i.e. kitchen, bathrooms, utility room etc.

The warm moist stale air is extracted back to the main unit, which is often installed in the attic.  Within the unit is a very large surface area counter flow heat exchanger. On one side of the heat exchanger is the extract air and on the other side is the outside air which is ducted into unit via a wall vent or roof vent.  The heat from the extract air is recovered across to the incoming air and this pre-warmed fresh air is ducted into all bedrooms, sitting room, living room etc.

The ducting system we use is a semi rigid duct which allows us to duct each room individually via a manifold. With this installation method we don’t have an issue with cross talk or noise breakout from one room to another via the duct.

Ther efficiency of the thermal transfer is up to 92%. This means that if the temperature in the house is 20 degrees C and the outside temperature is 4 degrees C we will still be supplying at least 18 degrees C into the supply rooms.  

Heat recovery ventilation for domestic applications has a number of positive affects on new and existing buildings.

The main advantage of heat recovery is that there is no supply wall vents required in rooms which is uncontrolled.

The heat recovery ventilation is a constant volume system which means that once the individual air valves are set at correct setting based on room size, occupancy and usage it does not need to change. The system will automate the amount of air going into and coming out of the dwelling in a clontrolled manor.

The heat recovery ventilation is a constant volume system which means that once the individual air valves are set at correct setting based on room size, occupancy and usage it does not need to change. The system will automate the amount of air going into and coming out of the dwelling in a clontrolled manor.

Therefore the heat load of the house is reduced as we are “recycling” the heat, but not the air.

There is no need for bathroom extract fans with heat recover ventilation as the system is designed to remove the excess moisture in bathrooms.