MVHR (Mechanical Ventilation with Heat Recovery) and PIV (Positive Input Ventilation)
MVHR - Mechanical Ventilation with Heat Recovery
Kellys Renewable Energy Solutions provide a variety of mechanical ventilation with heat recovery systems.
The Facts Regarding MVHR Systems
Will mechanical ventilation with heat recovery system save energy and money in a home compared to other methods of ventilation?
The short answer is “Possibly”. The level of effectiveness in saving energy depends on a number of highly variable and difficult to estimate factors. These are the level of air tightness in a home, the way the home is heated, the heat energy saved by the system, the energy used by the system, the type and cost of fuel used to heat the home and the cost of electricity used to run the system.
The importance of low noise levels:
MVHR systems are designed to run 24 hours a day, seven days a week, 365 days a year. Quite simply they have to be quiet in operation and acceptable to the occupants.
Correct design and installation is essential:
If optimum performance and safety is to be achieved from any ventilation system then it has to be designed and installed properly.
MVHR systems are very often the most complicated type of ventilation system to design and install in a home and some systems would be a test for tradesmen let alone the most able DIY enthusiast.
Positive Input Ventilation – PIV
How does Positive Input Ventilation work?
A positive input ventilation unit gently supplies tempered, filtered air into a home using otherwise unused heat within a roof.
The benefits of this are enormous;
- Firstly, it means that a significant proportion of external pollutants are prevented from entering the home.
- Secondly, the use of the otherwise unused heat in the roof results in the ventilation unit providing a significant net energy gain to the home.
- Thirdly, there is no better way to ventilate a home than from the inside out via a single, centrally located, supply air diffuser.
A good quality unit, fitted in your loft, will operate at an almost imperceptible noise level. You will hardly know its there. A properly designed and installed unit will ensure that old, contaminated, vapour laden air in your home is continuously diluted, displaced and replaced with good quality air. The result is improved indoor air quality and an environment in which condensation dampness cannot exist.
The old air exits through the thousands of air leakage points found in all homes. Indeed, positive input ventilation will even help to suppress unwanted infiltration (draughts).
The installation of a low energy positive input ventilation unit will ensure the air in your home is completely replaced with better quality air around 20 times a day. This is the recommended rate to maintain good air quality.
Energy benefits - Your roof is an energy source.
South east to south west facing tiles or slates absorb energy from the sun. Even the loft space itself is a substantial source of energy. During the heating season it will almost always be warmer than outside because of solar gain and conduction and convection losses from the home. Positive input ventilation units use the tiles/slates and/or the loft space itself to pre-warm the incoming air before delivering it into the home.
The input air enters your home at ceiling level, usually on your landing. This method re-circulates the warm air that rises and collects there as well as reducing the heat loss to your loft.
The slight pressurisation effect created helps reduce infiltration of unheated air through the leakage points found in all homes, having a consequential energy benefit.
In simple terms, a good quality low energy positive input ventilation unit will provide a significantly greater amount of energy into the home than the energy it consumes in the form of electricity, providing a considerable net energy gain.