positive pressure ventilation vs Balanced transfer ventilation
There has been some talk about the different types of ventilation systems for homes.
Positive pressure systems use dryer air from the roof cavity and filters it into the home, this is the most common in NZ and has been the most successful method as the main problem that we have to deal with is high humidity in summer (saturated damp air), and damp cold air in winter.
By taking the air from the roof cavity it has had the opportunity to be dyed in a warmer space than the outside and as the air becomes dryer it will rise and is then court by the ventilation system filtered and forced into the home. This in turn is able to replace damp indoor air caused by cooking, showers, humans, and humidity, or wet cold weather.
The process continues as the cycle is on going due to mechanic and natural causes.
Positive pressure can only supplies relief in summer in the evenings when the roof cavity temp comes down to the low 20's, you can fit a summer kit to pull outside air during the day to get more air flow when the roof is in the 50's which you don't want.
Balanced transfer ventilation comes from Europe where in most cases the air is dryer or in some places even requires moisture to be added from humidifiers. If you have ever been skying in the french or Italian alps you will have found you can't make a snow ball as the snow is like powder and dry. In NZ the snow is like slush damp.
These systems bring fresh air direct from outside and in some cases mix the incoming air with heat from the home in winter to give ambient air through the home which is great.
The problem with this type of system is the NZ climate, unlike Europe it is damp in summer and winter. On a nice warm day it is great and works a treat but when theres high humidity or the air is cold and damp in winter you will be dragging all that damp air in which will not be heatable so you are wasting precious heat and will add to moisture problems.
However if you use a diverter that can draw the air from the roof and when it's hot in summer draw from outside this will give you the best of both worlds.
Remember All ventilation is good and the different systems have pros and cons so make sure you talk to more than one company and be mindful of what you want and expect from your system.
Don't be told it can cool in summer and heat in winter as this will not be the case most of the time, these systems on their own are for cleaner dryer fresher air which will make heating and cooling easer and cheaper and reduce damage and maintenance in the home and is great for allergy relief.
You MUST CHANGE FILTERS or the system will not work.
Supercell has a full range of filters for all ventilation systems at great prices.