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Whole House Ventilation | ||
Why do we need ventilation?
Building regulations require a minimum rate of ventilation equivalent to one air change for the whole building every two hours.
General improvements in house construction, building regulations and much higher levels of insulation in modern dwellings mean that houses are becoming almost airtight. Consequently, the air inside becomes stale with a build up of moisture and smells. The moisture can result in condensation and mould, and a generally ‘stuffy’ atmosphere.
What types of ventilation are available?
1) Single room extractors
Traditionally, ventilation has been provided by individual extract fans fitted to bathrooms and other ‘wet’ rooms. These provide short term ventilation, usually very noisily. The extracted air is replaced by fresh air entering the house through trickle vents in the window frames. These are neither attractive nor particularly sensible (having spent a lot of money on a well insulated house with high specification double glazing, a hole is made in the window frame in order to create a draught!)
2) Central Extract Ventilation
As modern houses have more wet rooms, so it becomes more economical to replace several individual extractors with one Central extract ventilation unit. With a CEV unit, only one vent to the exterior is required (via wall grill or roof vent) in order to expel the stale air & only one electrical connection with the obvious savings in installation costs over individual extract fans. | ||
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The (warm) stale air from the wet rooms & the (cold) fresh air from the exterior both pass through a heat exchanger, in opposite directions & without mixing. The heat contained in the extract air is transferred to the incoming fresh air, which is introduced back into the living areas of the building. Heat Recovery Ventilation does not produce heat, but minimises the amount of heat which would otherwise be lost through ventilation, with degrees of efficiency varying between 70 - 97%. In doing so, it reduces the amount of heat that needs to be produced to keep a house warm. | |||||
Heat Recovery Ventilation systems are designed to run continuously, virtually silently, providing clean fresh air throughout the building. Normal operation is at a very low speed, allowing the gentle movement of air from dry rooms to wet rooms and then to the exterior. Heat recovery units have two or more speed settings so that larger quantities of air can be extracted as the need arises. Depending on which system is chosen, humidistats, digital programmers, CO2 sensors and timers can also be used to control the ventilation. | |||||
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