Ridge vents are common on roofs, they are the default way of venting an attic. Ridge vents work with soffit vents through natural convection ie, the hot air rises up and gets vented through the ridge vents while fresh air comes inside through the soffit vents. But sometimes homeowners want to give an extra boost to their attic ventilation and install solar attic fans for this purpose. But will it work?
Solar attic fans can be installed with ridge vents as long as they are installed in the right location. If installed in the wrong place, a solar attic fan can mess up your entire attic ventilation.
Then, what is the right location to install a solar attic fan, and how they can mess up your ventilation? Let’s first see how they can mess up;
The problem with installing solar attic fans with ridge vents
A ridge vent or any other mainstream form of vent depends upon natural air convection to draw heat out of your house. This procedure requires no electrical energy and is entirely reliant upon airflow, which is why it does barely enough to keep your attic’s temperature close to stable. Homeowners might try to elevate their ridge vents’ performance by adding a solar attic fan into the mix. We don’t blame them though. Solar attic fans operate on solar energy and are advertised as complementary products to your ventilation system. However, most of the time, their involvement only takes things south, especially in this case.
Though their use can be beneficial in some cases, solar attic fans do not always go perfectly with ridge vents. You see, ridge vents are there to direct the hot and humid air out of your attic. Once the hot air is removed, the make-up air comes through soffit vents. What this means is that the normal flow of air in a naturally ventilated attic is from the soffit vents to ridge vents. Since soffit vents are at the bottom of the roof, and the ridge vents at the top, the air movement between them will cover the whole attic area.
If you install a solar attic fan near the ridge vents, the power of the fan will disrupt this natural airflow and instead creates a circuit between the ridge vents and the fan. Therefore, the air will move through the ridge vents into the attic and out through the solar attic fan. As a result, there will be no air movement through the rest of the attic area keeping the air there hot and humid.
This shows that adding a solar attic fan will not always improve attic ventilation.
The above scenario doesn’t happen in all cases. Since we are talking about solar-powered attic fans and not electric attic fans, there is a way they can be installed to boost attic airflow.
Compared to normal attic fans that run on your mains, solar attic fans are less powerful. Therefore, they do not pull air that strongly. So if solar attic fans are installed away from the ridge vents, for eg; on the gable, they can actually boost the attic ventilation. However, this ‘right’ location depends on your attic design, and you will have to find it by trial and error.
The use of ridge vents is becoming more and more popular because it’s an investment that pays off better than other attic ventilation solutions. There are other ways to enhance a ridge vent’s performance but a solar attic fan might not always be one of them.