Four Causes Of A Knocking Furnace


Knocking noises from your furnace, particularly those that persist for an entire heating cycle, can be indicative of a big problem. Fortunately, repairs are usually possible.

1. Fan Balance

Issues with the fan are one of the most common causes for a knock that persists for the entire furnace cycle. Worn bearings prevent the fan from maintaining its balance, which can cause it to knock. Damage to the fan or dirt on its surface can also shift it out of balance and lead to the annoying noise. If the bearings aren't repacked and lubricated or if the obstruction isn't removed and the fan rebalanced, it will eventually put stress on the motor and more extensive repairs will be necessary. Annual maintenance that includes a fan inspection, cleaning, and lubrication can prevent these problems.

2. Blower Wheel Dirt

Dirt can also get onto the blower wheel, which is the part of the blower assembly that moves air through the system. If dirt, dust, or other debris gets onto the wheel, its movement is drastically slowed and a knocking sound may result. You will also notice less airflow from your heating ducts as well as less heat overall. Frequent filters changes reduce the amount of dirt that can access the wheel, but it won't eliminate dust. It's still vital to schedule annual maintenance visits that include cleaning the blower wheel.

3. Gas Valve Issues

The gas valve is meant to open and deliver gas when the thermostat sends the signal that it is time to begin producing heat. If there is a delay in the valve opening, you can end up with a knocking noise. This can actually be dangerous since issues with the gas valve can cause delayed ignition or even the build-up of gas — a potentially explosive issue. There are many reasons that a gas valve can malfunction, from a damaged ignition switch to dirt on the nozzle. A repair visit is necessary to diagnose and fix the issue.

4. Duct Problems

If your furnace only knocks when it first comes on, this is the normal noise caused by the metal ducts flexing due to the hot air rushing in. If the noise continues and you can trace it to the ducts leading from the furnace, then there may be a loose or damaged duct that is moving and knocking from the force of the air blowing through it. A duct inspection and possible repair are needed.

Contact a furnace repair service if you are concerned about the knocking noises coming from your system.


22 January 2021

Home Remedies for Plumbing Problems

Hi and thanks for visiting my website. My name is Bob. I am 32 years old and single. And like many of you, I am barely making ends meet on my own. That's why I decided to create this website. I've run into a few plumbing problems in my home, and in order to save money, I found some remedies that I could do myself, rather than calling a plumber. I decided to share these secrets with you, as well as tell you when a plumber is absolutely needed. I hope my website helps all of you do-it-yourselfers when it comes to fixing your plumbing.