I can tell you that years ago the top fan speeds were so loud you couldn’t hear them in the kitchen. That’s why I almost always used the lowest speed.
What’s going on and how would you solve this problem? Did I accidentally cause the problem? – Monica B., Lexington, Ky.
A: I have a very similar exhaust fan for kitchen stoves as Monica. In fact, I had one in my last home that I thought was so powerful it would suck up a child. It sounded like a jet engine. The interesting thing is that after years of use, I never let a drop of greasy water drip off my hood.
I solved Monica’s problem over the phone in less than 15 minutes. I’ve offered this one-on-one problem solving service for years because some problems are so complex that you just can’t do them with back and forth email. After hanging up with Monica, I felt it was important that you know what went wrong. I don’t want the same thing to happen to you, forcing you to buy a $ 1,000 exhaust fan when it could have been avoided.
When you cook on a stove, your high school chemistry and physics teachers grin in the sky. Remember when you sat in class all those years ago muttering softly, “How am I ever going to use this useless information?” I have to admit, I said it out loud at times, and pondered the answer as I sat in detention class for 45 minutes that afternoon, copying my high school rule book onto lined notebook paper.
When cooking, heating food and boiling water generate large amounts of water vapor. When you heat or fry meat, you also melt fat and some of it is converted to steam as well, or tiny droplets of fat impede a ride with some water vapor as it floats off your stove.
It is important to get this water vapor out of your home as quickly as possible before it is converted back to water. For this reason, manufacturers of exhaust fans have very explicit requirements for the minimum diameter and maximum length of the exhaust pipe that is connected to the outside of your fan.
You should understand by now why most of these high quality exhaust fans have high speed fans. The fan tries to release the water vapor outdoors in just a few seconds instead of letting it snake through the exhaust pipe on its way into nature.
The problem of dripping greasy water is exacerbated by cool or cold weather. Monica can absolutely see this in central Kentucky. Living just 90 miles north in Cincinnati for 55 years, I know how bitterly cold the Midwest can get in the winter months. For this reason, it’s a good idea to insulate your kitchen and bathroom exhaust pipes to keep them as warm as possible.
Do you remember your physics class when your teacher talked about condensation? If you live in a humid climate, you will undoubtedly experience it in summer. Think of the cold can of beer or soda that you take out of the refrigerator and place on your patio table. It’s dry when you take it out of the refrigerator, but within a minute on a damp day there will be fog on the cold metal. Minutes later, a small puddle of water has formed at the bottom of the can!
Now imagine the enormous surface area of the exhaust pipe of your kitchen fan. It could be 50 or 100 times the surface area of a single can of soda. It should make sense to you by now why greasy water is raining from Monica’s hood.
Monica also asked me on the phone how often the filters in the hood should be cleaned. I asked her how often she cooks and she said every night. Fortunately, their filters are made of stainless steel and can be put in the dishwasher. I suggested cleaning them at least every two weeks.
I then discussed with Monica why kitchen exhaust fans often have four speeds. It is important that you adjust the fan speed according to the amount of food being cooked on the stove. If you’ve got all the burners on, boiling water pots, frying pans, etc., you’d better set the fan to high speed. If only a small saucepan is cooking, the slow speed is usually fine. Adjust the fan speed to the amount of water vapor generated.
Monica also admitted another mistake when I asked her how long she kept the fan running after the burners were turned off. “Oh, I’ll turn off the fan right now.” This is a mistake. Some high quality exhaust fans come with a built-in timer that lets the fan run for five, ten, or even 15 minutes after cooking.
This is done so any slight condensation inside the exhaust pipe can evaporate and blow out before it can drip back into the kitchen. Monica will get the same replacement hood, but this time it will probably be 25 years!
Subscribe to Tim’s free newsletter and listen to his new podcasts. Go to: AsktheBuilder.com.
Comments are closed.