An MVHR system is an efficient heat recovery ventilation (HVR) system. The heat is recovered through a combination of forced and natural ventilation. To maximise heat recovery, the heat exchanger must be installed outside the thermal envelope, such as on a south-facing roof. It should be located close to the house’s partition wall or an external wall with an intake and exhaust penetration. The unit should also be easy to access and install, with at least 500mm maintenance space around it.
The Passivhaus Trust estimates that an MVHR system may cost up to £45,000, whereas Sassi’s study focused on just two homes in Cardiff. Other large-scale studies have examined the performance of MVHR in UK homes and the Netherlands. The MVHR 2020 line changes SAP’s assumptions, improving the systems’ performance to match the products of the year 2020. These changes reflect the decarbonising electricity grid.
MVHR unit size
The size of a MVHR unit should be based on the standard airflow rate of 60 percent of the house’s total floor area. If there are more than two people living in a house, the unit should be sized accordingly. In addition, a house with five bedrooms would require 110 m3/h of ventilation. In addition, a good design should take into account the individual airflow rate of each room.
In order to effectively heat a house, a MVHR unit must be small enough to fit in the space. For example, if an oversized unit is used, it will achieve its required airflows, but it will be financially inefficient. Undersized units will produce excessive noise and occupants will typically switch off the unit as soon as it is at capacity. Additionally, undersized units can lead to condensation and mould problems.
MVHR system performance
The benefits of MVHR systems are well documented, but the industry still has a lot to learn. Specifically, the system’s characteristics make it difficult to achieve high performance, despite its widespread adoption in low energy-standard buildings. The study also found that MVHRs have better ventilation performance than conventional systems in mainstream buildings. The study, which spanned four years, looked at the in-use performance of MVHR systems in a variety of buildings.
The filters in a ventilation unit play a vital role in the MVHR system’s performance. Both the intake and extract filters protect the heat exchanger, and they become dirty over time. Filters in the intake and extract areas get dirty at varying rates, and some carbon particulates can clog up even very fine filters. MVHRs with a high-performance filter will reduce heat losses while improving air quality.
MVHR system installation
MVHR systems can save you money on your heating bill and significantly improve the indoor air quality of your home. The heat recovered from the air is then passed onto a new, filtered supply. This process not only improves indoor air quality, but can also cut your heating bills by up to 30%. This technology is especially important in new homes as the building envelopes are getting tighter. Choosing the right radiators can be a tricky process.
MVHR systems require commissioning. These systems should be commissioned after installation and should be checked to meet Building Regulations within thirty days. They should also be provided with adequate maintenance instructions. There are various fees for Building Control registration and they vary from authority to authority. MVHR systems are installed by specialist companies. They are highly recommended for homes with low air permeability.