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Mechanical Heat Recovery Ventilation (MHRV) is a very worthwhile consideration for new air tight buildings or if you desire a healthy living environment with moderate investment with minimal operational cost. Notwithstanding MHRV minimises overall heating investment and operational cost.

We don't need as much heating as we once did, however the "correct" ventilation is critical. New Zealanders have been "sold" Positive Input Pressure Ventilation Systems (PIV) such as HRV and DVS etc but this type of ventilation is limited in function and performance and requires open windows, doors etc to remove outgoing moisture and polluted air and therefore at the same time removing your paid for heating.


What is all the fuss about?

Gases, toxins and pollutants can cause concern in poorly ventilated buildings. Examples of toxic substances include:

  • Carbon monoxide, sulphur dioxide and nitrogen oxide from heating and cooling
  • Airborne toxins from household cleaners
  • Pollen, dust and dust mites
  • Volatile Organic Compounds (VOCS) and formaldehyde emissions from furniture, carpet, finishes and building materials

Heat Recovery Ventilation allows the building to regulate its fresh air supply and discharge stale air and toxic gases whilst maintaining a high indoor comfort level. For example: If using a window to ventilate your home, you are losing 100% of the energy contained in that air that escapes through your window. If you use HRV system instead, up to 90% of the energy (heat) can be captured and transferred to the fresh air supply in your home. Capturing this thermal greatly reduces your heating needs that would be otherwise required to warm your fresh air.

Importance of Air Quality Control

Both comfortable and healthy indoor climate conditions can only be achieved by constant fresh air supply while extracting stale moist air and minimising heat loss. This is called Mechanical Heat Recovery Ventilation.

What about Moisture Control?

As homes become better insulated and more airtight the risk of mould, mildew and decay increases. Unlike in old buildings, condensation existing as water vapour exits through building elements rather than as an air leak. This means moisture can be pushed into your walls, roof and floor leading to moisture problems. Moisture problems in buildings are a serious concern. Household activities often introduce more water to the indoor environment, for example clothes drying, washing, cooking and showering. This moisture must be controlled. Heat Recovery Ventilation helps regulate indoor relative humidity and allows the discharge of stale air, reducing impact of mould, mildew and condensation.

Is Decentralised right for you?

A decentralised system such as the LUNOS e2 and ego are ductless systems making them easy to install. This means they are perfect for retrofit and buildings that do not have space to install a centralised ducting system. For a new build or existing home with ample access to a roof or floor cavity, centralised systems can make sense - find out more here.

Benefits of a decentralised system include:

  • No need for complicated ducting - this is particularly useful for retrofits
  • No ducting means lower pressure drop and smaller fans - hence a more efficient system
  • Quieter - smaller and lower power fans make less noise than larger more powerful centralised systems
  • Versatile - can be installed in areas where ducting may not be able to travel

Mechanical Heat Recovery Ventilation (MHRV):

MHRV removes the home's polluted moisture laden air to the outside while at the same time replacing it with fresh air from outside by passing it through the Heat Exchanger and returning up to 93% of the energy (heat) back into your home. Modern homes are air tight and well insulated so home owners must ventilate the home to remove polluted air and toxins to ensure a healthy living home. You can open up your doors and windows and lose your paid for heating or you can invest in MHRV.

The Heating Company have two MHRV Systems: