8 Things To Know About MVHR
1. Essential Element
Ventilation is an essential element of construction. Since it is invisible it is easy to take air quality for granted. We spend more time indoors than previous generations. It is often estimated that we spend 90% of our lives indoors. We understand the importance of fresh water, healthy food, and having an active lifestyle. The air we breathe is as much a part of a healthy lifestyle.
Without ventilation buildings become uninhabitable. Common under ventilation leads to internal material fabric becoming saturated with moisture, accelerating breakdown. High indoor humidity levels provide favourable conditions for insect pests and increase the conditions for bacteria and viruses to thrive. Increased CO2 levels affect our mental and physical performance. Volatile organic compounds accumulate, bombarding us with chemicals with potentially harmful effects.
We are now reminded often of how important ventilation is at helping reduce the spread of corona virus/ COVID-19. How increased air changes decrease the airborne transmission. Yes, air quality is invisible but it is important.
2. House design
House design has a direct impact on the cost of your ventilation system. Larger properties have larger volumes of air to change and so invariably larger homes require larger capacity ventilation equipment. More complex designs often lead to slower installation time and increased associated labour costs. Engaging early in the project or at design stage with your MVHR installer can help reduce or overcome some complexity issues.
It is worth remembering that airflow capacities can vary from manufacturer to manufacturer. It is then down to your supplier/installer to size appropriately for your home. A system working closer to its maximum output will be less efficient.
There is no MVHR system on the market that will not require aftercare. The very minimum level of aftercare is filter service. Adequate backup and support should be considered when selecting your MVHR installer and is essential in the long run. It is always tempting to cut costs but opting for a specialised MVHR installer should give you the best aftersales backup and lifecycle service.
4. Professional installation or self-installation.
Best advice is to let the professionals do the work for you. This ultimately should provide better standard of install, performance from your system, lower electrical consumption and better back-up. The common problems with self-installation are: difficult aftercare, un-balanced airflow, poorly sealed system, forgotten components, generic designing, lack of proper commissioning. The new NZEB building regulations in ROI places greater emphasis on competent designers and installers. With commissioning to be validated by an independent third party. Therefore those self-builders chancing self-installation appear to run an increased risk of non-compliance.
Noise is a common complaint regarding MVHR systems. Noise is an inherent part of a mechanical system. The amount of background noise from a MVHR system will be a combination of the MVHR unit, the ducting design and the installation work. Typically low cost MVHR systems will sacrifice performance for price and can be noticeably noisier. In terms of ducting, generally speaking the more restrictive the MVHR ducting system the harder the MVHR unit has to work to provide the necessary air change. This is where many systems fail.
The ideal MVHR system will have almost unnoticeable background noise and reducing it to near such low levels can require a great deal of experience.
Independent third party certification can be a useful indication of performance. Bodies such as Eurovent test a MVHR unit off the open market to see that it can perform to the levels claimed by its manufacturer. Such independent testing has been a ‘must have’ quality symbol for commercial specifiers for quite some time and can play a role for domestic clients seeking a quality MVHR system. Passive House is another third party certification that can help clients distinguish between the many MVHR units available on the market.
7. Filtration & Controls
Filtration is a key component of an effective MVHR system. It dramatically increases the potential benefits from installing a MVHR system. Selecting an MVHR system with top quality filtration will minimise particles that trigger allergies or other respiratory ailments entering the home from the outside environment. Sadly, filtration can often can be forgot about in the selection process, instead customers will often be drawn to exaggerated or unrealistic ‘best case’ efficiency figures which can lead to a disappointing end user experience. Modern easy to use controls can help the end user feel more comfortable with the ventilation system, instead of seeing it as something intimidating or hard to understand.
8. Naming Confusion
MVHR, HRV, MHRV, Heat Recovery. Just a selection of the acronyms and short hand used in place of the more accurate title, Mechanical Ventilation with Heat recovery.
We have found through the years that the industry’s over emphasis on ‘heat recovery’ has often been a source of confusion for the customer. In many cases end users are expecting a blast of heat from their vent or a system that can heat their entire home with one central multifuel stove, with some sad results. Fortunately a MVHR system, when properly designed and installed, is a great benefit to homes especially as we continue to insulate more.