Ventilation: Do not block air vents. If they are blocked during operation, the oven may overheat and eventually cause oven failure. For proper ventilation, keep three inches of space between the oven's top, sides, rear and the area where the unit is to be installed.
Recommended Vent Length
A 31/4" x 10" (8.3 cm x 25.4 cm) rectangular or 6" (15.2 cm) round vent should be used. The total length of the vent system including straight vent, elbow(s), transitions and wall or roof caps must not exceed the equivalent of 140 ft (42.7 m) for either type of vent.
Heat reaching the microwave can be caused by cooking on the cooktop or oven beneath the microwave or by multiple or extended use of the microwave within a short time span. The fan will run up to 2 hours to keep the components cool and will then shut off on its own.
You shouldn't leave your fan on for more than one to two hours while cooking. Most meals in the kitchen should take less than that to prepare. The longer you want to run your hood, the more power you'll need to vent out all the smoke and cooking fumes.
Countertop microwave ovens have vents on the sides, bottom, or both to keep them cool while the magnetron generates heat. Therefore, it is completely normal for your countertop microwave to emit warm air, given that it is from the vents.
Some over-the-range microwaves come with a venting system that is as powerful as traditional range hoods. These models can effectively reduce smoke and odor in the air while you're cooking while also providing additional cooking functionality.
All over-the-range microwaves have an automatic fan feature to help protect the electronic components as well as help the cooking area get rid of excess heat. The built-in thermostat automatically turns the vent fan on if the unit is too hot and will not turn off until the microwave is cool again.
Leaving the exhaust fan running for an extensive period of time can cause significant wear to the motor and may cause a fire. It's a cause for concern, especially when you're not home to hear your smoke detectors!
Although it can be tempting to keep your fan on overnight, households put themselves at risk if a fault was to occur in the night while they're sleeping. Electrical Safety First advises you to turn your fan off before you sleep and to check that you have smoke alarms that work in your property.
A bathroom extractor fan usually stays on for 20 seconds to 20 minutes. You can however decide for yourself how long you want the fan to be on for if you buy a timer model. Additionally, an extractor fan will stay on until it has cleared away enough humidity from a room if it is a humidity-based model.
This is normal. The microwave oven's cooling fan (on some models), which is separate from the vent fan, automatically comes on during microwave oven operation to cool the microwave oven. It may also automatically come on and cycle on and off to cool the microwave oven's controls while the cooktop below is being used.
It's normal for a microwave fan to make a low noise during operation, but a clogged fan often makes a buzzing sound. You may also notice a loud rattling sound if the fan is loose. You can usually tell if the cooling fan is causing the noise because it sounds louder at the rear of the microwave.
Ducted or vented microwaves feature exhaust fans that vent air outside of the house. Recirculating, non-ducted or updraft microwaves filter air then push it back into the kitchen. Convertible microwaves give you the option to select your ventilation type.
For optimum performance, make sure that the air duct is short and straight, with a maximum length of 50 linear feet. Long radius elbows are preferred to short radius elbows for better air intake. Note: Each elbow is equivalent to 10 linear feet of duct. Be sure to also install a wall or roof cap.
How far can you vent a range hood? Your range hood duct should not exceed 30' for a straight run, 25' for a run with one elbow, and 20' for a run with two elbows. The shorter the duct, the better. If your ductwork is too long, your kitchen air may not reach the outside.
Some people fear that a ceiling fan will overheat and catch fire if left running overnight; however, these fears are unreasonable. Ceiling fans are designed and manufactured to run for hours on end, and if you invest your money in a reputable brand, you shouldn't have any fears.
Less frequent starts and stops of the fan can reduce the stress from startup, and potentially help extend its lifespan. Leaving the fan on 24/7 ensures cleaner air, as the air is pulled through the filtration or UV light system. This can be better for people with allergies.
Fans in both the bathrooms and the kitchen can help keep the home energy-efficient and comfortable. But if you leave the exhaust fan running too long, then energy will be wasted. You will cause unwanted air infiltration and use extra electricity.
Older exhaust fans are not thermally protected. Thermal protection causes the motor to shut off should they seize and overheat.
Exhaust fans draw contaminants from the air by sucking out smoke, fumes, and other pollutants from industrial or commercial spaces. In contrast, ventilation fans work to bring fresh air into an enclosed space from outside sources without dispelling pollutants.
Microwaves are shipped from the factory to vent out the top (vertically) but can also be vented out the rear (horizontally). The duct must be the sizes listed above for proper draw of air. Both smaller and larger vents than recommended decrease venting performance. Microwaves cannot be ducted into a common duct work.
It is not a requirement that an OTR microwave should be vented outside. Some homeowners prefer it, but no harm can come from recirculating the air into your kitchen or elsewhere (provided you're not dealing with smoke or harmful fumes).