Fixing Noisy Portable Fan Heaters




We’ve dealt with the problem of noisy portable fan heaters for several decades now in our second floor bedrooms, third floor attic apartments, and drafty condos.

Portable fan-based electric heaters, whether portable or permanently installed, are terrific for temporarily supplementing the primary heating system (the furnace) in the home. However, unless you’ve spent the extra money for a quiet premium fan space heater, average quality forced air electric heaters generally tend to be noisy at the beginning due to the whirring fan blades inside as well as the expanding and contracting heating elements and their mounts and fittings. They squeak, creak, ping, pang, pop, squeal, hum, whine, bang, zing, buzz, whistle, and ring even, when energized, as the warming parts change size and rub against each other. Then, when their built-in thermostats turn them off, portable heaters make similar noises, as their metal parts and the heating element itself contract during cool-off.

Here are a couple of the tricks we’ve attempted with moderate success on Patton and Dayton electric fan heater units, to fix or reduce the din. Note that these procedures apply only to fan-based electric heaters, as these tend to exhibit lower surface temperatures than the hotter, radiant units. Do not use lubricants on or near any glowing-type heating elements found in radiant heat sources such as quartz or halogen heaters.

  • Tighten all screws that secure the fan motor, wiring, and other components inside. Preferably, the screws should be driven into the thickest, most solid parts of the heater case, to provide a more solid, less vibration transmitting backing for moving and heating components.
  • Clean all vents.  Make sure the intake and heat output vents are clean and free of obstructions that can cause loud whirring or whistling as the air moves through them.
  • Lubricate all brackets, joints, and any places where different pieces of metal meet and could rub and bind. Since many of these joints get quite hot during normal heater operation, be sure to use a thick oil or grease that can withstand these high temperatures without drying out, catching fire, or otherwise breaking down. We’ve used the WD-40 Specialist Water Resistant Silicone Lubricant, and various brands of white lithium grease with some positive results. Unfortunately however, no oil or grease that keeps electric resistance heating elements quiet without periodic re-application. Typically, we’ve “re lubed” the heaters every two years.
  • Reinforce all brackets and joints. Hoping to reduce the need for lubricants mentioned above, we’ve reinforced the metal stand-off brackets in typical small portable heaters. These brackets suspend the resistive heating element (which resembles a thin, finned bar). During warm-up and cool-down, the places where these brackets are fastened to the heater cabinet created much tapping, squealing, ringing, and clicking. So we drill a single hole in each bracket where it meets the cabinet, and then drive a sheet metal screw through. This step showed the greatest effect at quelling heating element sounds. While they still click and pop some, they do so far less than before applying the sheet metal screws. The squeaks and squeals completely disappeared.  Since most portable fan heater cases are plastic, you might use a nut and bolt combo to tightly fasten the brackets inside.
  • Secure the heating element. Electric fan heaters also tend to hum and buzz while operating; especially the higher power residential 1500 watt units, when operating at highest speed and maximum heating power. This hum problem isn’t as easy to address as the squeaks, pings, and pops. But you can minimize hum and buzz by assuring that the heating element is secure in the standoff brackets mentioned above. This can reduce the buzzing and ringing sounds that result when a loosely secured heating element vibrates within the standoff bracket. The bracket should clamp the heating resister snugly, but still allow it to expand and contract. Bending the bracket can be done to provide this tighter fit. But do not flex the bracket too many times; lest it snap apart on you.
  • Choose a thermostat wisely, to control your electric fan heaters, if you’ve decided to have an external thermostat. This becomes critical now that electronically switched (triac based) thermostats have made their ways into mainstream markets. These devices employ the same device (a triac) for switching as do light dimmers, and anyone who’s ever experimented with a light dimmer knows that the light itself, as well as the dimmer unit, can buzz loudly when the dimmer is not set at the brightest (fully on) position. It’s also the case that a poorly designed electronic thermostat may not always turn the triac fully on during each AC power sine wave cycle, and can thus, lead to louder-than-usual buzzing in your heater, not to mention generating lots of radio and TV interference (RFI). Thus, replacing your thermostat may solve some buzzing problems from the fan motor and heating element. Temporarily bypassing the thermostat you have by applying jumpers across its switched terminals will verify whether your thermostat is introducing the buzzing. If the buzz disappears when you jumper the thermostat terminals, but the heater remains on, then the thermostat is your culprit. If you do replace the thermostat though, use caution when selecting an electro-mechanically switched external model. These contain physically operated micro switches, that click when turning on and off. Thermostats like these can therefore add their own brand of distracting noises to the base board heating cacophony.
  • Replace the Heater. Sadly, the cheaper electric portable heaters are inherently louder, and so, may not be suitable for bedrooms or other areas requiring the quietest environment. For these rooms, we recommend portable and fan less hydronic heaters.  The hydronic liquids in this type of radiant heater completely surround and envelop the heating element, which mitigates vibration transmissions. Plus, they maintain cooler element temperatures during operation. In hydronic electric heaters therefore, such as the oil and water filled electric radiators, you don’t have the large temperature swings within the heating element when going from cold to hot that you do in more modestly priced fan convection heating units. So there’s less expansion and contraction of the element itself and supporting brackets, screws, the case, and other securing parts. Plus, there’s no fan generating whirring noise.  As a result, you experience less noise overall from portable hydronic units. With hydronic heat plants, you indeed get what you pay for, and the portable units cost just a few percentage points more than fan heaters.

We ultimately replaced our bargain-basement electric fan heaters with hydronic electric radiators.  No regrets.  There are lots of very quiet heating units on the market today. We’ve observed them in operation in the homes of friends and on school campuses. But until you’re ready to purchase these top-notch heaters, the steps outlined above have proven to make our existing forced air heaters quiet enough to put up with.

 

References

Revision History

  • 2017-01-25: Updated tags list.
  • 2015-10-23: Originally published.