Roof Turbine Vents
Question: There are two spinning turbine vents in my home. A number of people have suggested the idea of stuffing insulation into these vents during winter to make sure that warm air does not get drawn out of the attic place. Do you think this advice worthy? Are the turbine vents actually efficient? The roofs of my neighbor do not have them. Should I get rid of these turbine vents?
Answer: Those vents are actually superb devices for ventilation. Leave them alone. A long time ago I installed the very same vents in my second home. These have turned out to be hardy ones that Mother Nature operates. These vents are there on my home even now drawing air every time when the slightest of breeze blows, from the attic space.
The turbine vent as also the traditional metal pot vents and the commonly liked ridge and soffit ventilation systems are passive ventilation systems. Unlike these, the active ventilation could be electric powered such as the powered roof ventilator or the whole house fan. The advantages with the passive vents are that invariably these are silent when it operates and do not need electricity. They work for free.
Stuffing insulation into the vents is something you should do as a last measure. It is more important to often vent the attic space in winter than in summer months. Water vapor may float up and move into the attic space from inside of your home. This water vapor should be exhausted as soon as possible to the outdoors. If this is not done in time, they may condense beneath the cold roof sheathing and roof framing. When the condensation is too much, this may lead to dripping from beneath the roof. With temperature further sliding down, frost could form inside the attic. Such moisture conditions may result in mold growth and wood rot.
The volume of humid air that the turbines expel depends on the outdoor wind speed and the vent diameter. 347 cfm (cubic feet of air per minute) can be removed from the attic space with 5 mph (miles per hour) wind speed using a turbine vent with only a 12 inch diameter. 1,342 CFM of air are expelled with a turbine vent by means of a single 14 inch diameter at wind speed of 15 mph. The air drifts upwards and moves out of the attic space when the wind is still but in small volumes.
It is not true at all that warm air is removed from attic spaces by the turbine vents during winter months. If it is cold outside and the attic space is quite warm, there is something wrong. The insulation might be inadequate. Or it is a sunny day with the hot sun blazing through into the attic space.
Checking the attic temperature once the sun has set at is best. The outdoor temperature and the temperature in the interior of your attic ought to be in the same range or almost the same if the insulation in your attic is proper.
The conditioned air may be drawn in by the turbine vents from indoors. Sofftit ventilation vents are mandated in both model building codes and current building principles for intake of air. When the ridge vent, turbine vent or any other electrically powered fan draws in air from the attic space, an equivalent air should stream into the attic space where the roof goes by above the outside walls of your home. A partial vacuum will be created by the vent if sufficient quantity of soffit air is not entering. The vacuum, in order to release the build up of pressure, will then begin drawing air from the interior of yoru house. This of course is not good.
You should be buying aluminum turbine vents for your roof if you decide on adding extra turbine vents. This is to avoid rusting of the vents. The roof pitch will have to be the maximum that would work well with the turbines. The spinning part of the turbines can be adjusted as they are adjustable so that they are level even if the roof is sloping. All the roof pitches are not suitable for all the turbines. The box label indicates the maximum roof pitch that suits that turbine. You need to always make sure that the ball bearings are kept sealed and lubricated. Otherwise you will have to face a roof turbine that squeals all through on a windy night.
Related Posts:
August 11, 2008 | Ventilation
Comments
Leave a Reply
