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How to Select a Fan or Blower

Author: CC

Nov. 28, 2023

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Tags: Home Appliances

How to Select a Fan or Blower

To select a fan, the required data includes the flow rate (CFM), static pressure (SP), and air/gas density.

You have 3 options to select the right fan or blower for your application:

1

Use our

Use our Quick Selector to narrow your choices and sort by Price or Efficiency.

2

Contact our knowledgeable

Contact our knowledgeable local sales engineer for application assistance.

3

Follow the steps below to select a fan using catalog data.

to select a fan using catalog data.

Flow Rate (CFM)
SCFM stands for Standard Cubic Feet per Minute. It is the CFM at standard density, defined as .075 lb/cubic foot.

ACFM stands for Actual Cubic Feet per Minute. It is the CFM at an identified density other than .075 lb/ft3. It is also the required mass flow rate divided by the density of the gas being handled. Since fans and blowers handle the same volume of air regardless of density, the ACFM value (and corresponding density) is the preferred value to use when selecting a fan or blower. Note that ACFM and SCFM are not interchangeable except at .075 lb/ft3 density.

Airflow is rated in cubic feet per minute (CFM) or the metric equivalent, cubic meters per hour (M3/Hr).

1 CFM = 1.6990 x M3/Hr.

If you will be conveying material, make sure you have enough CFM for the duct, pipe or hose size so the material will maintain the required velocity to carry it completely through the system and not settle in the duct, pipe or hose. See Engineering Data catalog for material conveying velocities.

Static Pressure (SP)
Static Pressure is the resistance to airflow (friction) caused by the air moving through a pipe, duct, hose, filter, hood slots, air control dampers or louvers. Static Pressure is rated in inches water gauge (inWG) or the metric equivalent, millimeters water gauge (mmWG). 1 inWG = 25.4 x mmWG.

Standard air has a density of .075 lb/ft3 and is based on a temperature of 70°F and 29.92" Hg barometric pressure (sea level). Fan performance tables are based on using standard air. Corrections for density changes resulting from temperature and/or barometric pressure variations, such as higher altitudes, must be made to the static pressure before selecting a fan or blower based on standard performance data. The metric equivalent is in kilograms per cubic meter (kg/m3). lb/ft3 = 16.018 x kg/m3.

The temperature of the air going through the fan or blower will affect the density and performance of the fan or blower. Temperature should be shown in degrees Fahrenheit (°F). The metric equivalent is degrees Centigrade (°C).

°F = 1.8 x °C + 32

If the air temperature will vary, what are the minimum and maximum temperatures?

The altitude the fan or blower will be operating at will also affect the density and performance of the fan or blower. The altitude should be given in feet above sea level. The metric equivalent is meters (m). 1 ft = .30480 x m

Air Temperature Altitude Correction


Chart found on Page 5 of Instructions For How to Properly Select a Fan or Blower

Example:

Select a blower for 1500 CFM at 7" WG at 250°F. and at 6500 feet elevation.

  • STEP 1. From the table above, the conversion factor for 250° and 6500 ft. altitude is 1.71.
  • STEP 2. The corrected static pressure is: 7" WG x 1.71 = 11.97" inWG at standard conditions. Round off to 12" WG.
  • STEP 3. Select fan, using fan performance tables, for 1500 CFM at 12" WG.
NOTE: If the suction pressure on the inlet side of a blower will exceed 15" inWG, a correction for suction pressure (called rarefication) should be made. See chart below.

NOTE: If the suction pressure on the inlet side of a blower will exceed 15" inWG, a correction for suction pressure (called rarefication) should be made. See chart below.


Chart found on Page 4 of Instructions For How to Properly Select a Fan or Blower

EXAMPLES:

  1. With 45" of suction pressure on the blower inlet and no discharge pressure on the blower discharge, the total static pressure = 50.3" inWG.
  2. With 45" of suction pressure on the inlet and 12" of discharge pressure on the discharge, the total static pressure = 50.3"+12" = 62.3" inWG.
  3. With 0" of suction pressure on the inlet and 12" of discharge pressure, the total static pressure = 12" inWG. There is no correction required for discharge pressure.

Centrifugal fans or blowers use one of seven types of wheels that are enclosed in a scroll shaped housing. The air enters the fan wheel through the housing inlet, turns 90 degrees and is accelerated radially and exits the fan housing. Centrifugal fans are typically used for lower flows and higher pressures.

Axial fans use a propeller, having two or more blades, to move air in an axial direction through a cylindrical housing or formed orifice panel. Axial fans are typically used for higher flows and lower pressures. Do not use an axial fan to convey material.

When you were partying, we studied the blades. Of fans. For pricing data. Okay, we looked at spreadsheets. Now we're here to give you guidance on how to buy a fan, from the best place to get one to what exactly makes a good fan.

So what's the best fan to buy? That depends on what you're looking for (and even then, you'll probably have plenty of wiggle room between categories). See a brief overview of your choices below.

Types of Fans to Choose From

Desk or Personal Fans

If you're just looking for a short-range directional breeze, these fans are more cost- and space-efficient than full pedestal fans. You'll find the most basic models starting around $10. And even as you move up in size, you shouldn't have to spend much more than $15, unless you're very serious about the quality of wind in your face.

Stand or Pedestal Fans

For a more roomwide effect, a pedestal fan will work best — you can choose between oscillating and non-oscillating models, depending on how much space needs cooling. You'll find prices start from $15 here, and while some of the more industrial models or fancy silenced fans can tick over $100, you're looking at spending $40 or less for everyday use.

Window Fans

Window fans don't just circulate the air in the room — they actually draw in fresh air, or if you reverse the flow, pull stale air out. They don't cool that air, though, so if you pull in muggy air, you'll feel it. We've seen many deals on window fans that cost $15 or so, but if you're looking for a best-in-class option, you'll likely end up spending over $50.

Tower Fans

Tower fans' place in the market has been almost entirely usurped by their bladeless counterparts (to the point where Wirecutter doesn't even have a recommended model anymore). But that means if you're a smart shopper, you can get a great price on these fans. As recently as January, we saw one for just $22, and we're unlikely to list one for over $50 these days. (If you want to spend more than that, move on to the bladeless category.)

SEE ALSO: The Best Home Office Setup Ideas to Try Today

Bladeless Fans

We could very likely do everyone a favor and just call these "Dyson fans" — you know the sci-fi-looking style we're talking about. (Especially since they're not really bladeless, apparently. The blades are just cleverly hidden rather than eliminated altogether.) These come in two main categories:

Bladeless Desk or Pedestal Fans
These are probably what you're picturing, and you'll be pleased to know that they've started to see significant reductions in price. (Surprisingly, we've seen better discounts on the larger pedestal models than the smaller desk fans.) In March, we saw a Dyson pedestal fan going for just $136 — a Staff Pick, record-low price for this style of fan.

That was part of a trend, where good prices have become great prices thanks to a coupon at a store like Rakuten, or factored-in store credit like Kohl's Cash. While you won't always be able to get these prices, with a little luck or a bit of patience, you should be able to get this type of bladeless fan for less than $200.

Bladeless Fans With Purifiers
If you're facing the twin enemies of heat and pollen (or whatever other allergen you care to name), a combination fan and purifier could make things a little more bearable. You'll pay for the privilege of a decent model, though: even the best Black Friday discounts we saw last year only dropped new ones to $200, and it's not surprising to see them closer to — or even breaking — the $400 mark.

Ceiling Fans

Consider these more-permanent additions to your home wisely before purchasing, taking into account everything from price to size to features. A typical small bedroom should have a 36" to 42" ceiling fan; a standard master bedroom requires a 44" fan; and living rooms or other large spaces need a fan in the 50" to 54" range.

We've seen 42" ceiling fans priced as low as $23, and 52" ones that cost less than $30.

We've seen 42" fans for as little as $23 quite often, but this is a category where the prices vary considerably depending on size and style. Though we've seen 52" fans drop below $30, we've also seen 54" fans for $75 that were discounted heavily enough to be Staff Pick deals. (If you don't have room for a ceiling fan, a wall-mounted fan might suit you better!)

Where to Buy a Fan

Now that you hopefully have a better idea of what style you're looking for, you're probably wondering, "Where can I buy a fan?" Starting with the most expensive kinds, your best bet for the pricey Dysons is a marketplace like Rakuten or eBay. There you'll often find discounts from Dyson's own storefronts that stack with extra coupons or store credits.

For ceiling fans, we most consistently see discounts from Home Depot — almost 40% of the ceiling fan deals we've seen in the last two years have come from them. For the more standard desk and pedestal fans, you won't find many stores offering better prices than the big hitters like Amazon and Walmart provide.

When to Buy a Fan

The bulk of the very best prices come, unsurprisingly, after the summer heat, from September through Black Friday and Christmas. That doesn't mean you won't see fantastic deals year-round, though. And unless discounts are dependent on a coupon or credit offer that's expiring, many tend to stick around for a few weeks. (And obviously, throw any predictions for this year out the window for now.)

SEE ALSO: Here's How to Buy Space-Saving Furniture for Your Apartment

Features to Look for When Buying a Fan

Now to the important questions of what, and who, makes a good fan. There are several features to look out for (not all of which will be important for you, or even for each kind of fan). They include the following:

Airflow and Range
The strength with which a fan moves air around, and the range it covers, is going to be a large factor in the price you pay. A desk fan doesn't need to be strong enough to cool an entire room, and a pedestal fan that doesn't reach the people on the opposite side of the room won't be of much use.

Noise
We like to keep cool, but we also like to keep our cool, and few things are more irritating than the constant whir of a noisy fan. Your tolerance will obviously vary, but the ideal is a fan that stays reasonably quiet even at its highest speeds.

Reliability or a Warranty
We've all bought electronics that seem perfectly fine but fail right as they fall out of warranty. Read user reviews to catch any red flags, and make sure you're getting a warranty to match whatever price point you decide on. (If a $10 desk fan survives a summer of heavy use, that's probably a job well done, but your ceiling fan should last considerably longer.)

Ease of Cleaning
No one wants a fan that's covered in dust and grime and various things that fell off your body. That becomes a less likely outcome if the workings of your fan are easily accessible for a good wipe-down every so often. But!

Safety
It shouldn't be so accessible that young, vulnerable fingers can meet spinning fan blades. The hazards of a full-speed fan, or the unsteadiness of a naturally top-heavy pedestal fan, are things to keep in mind if you have children or pets running around.

Miscellany
Depending on the utility of the fan, you may want features like oscillation, fine-grained speed control, a remote control, or adjustable heights and angles. For the brands to keep in mind, Wirecutter's picks weigh heavily in favor of Vornado and Dyson, as well as Westinghouse in the ceiling fan category. Other popular names are Holmes, Seville, and Hunter.

Readers, what features do you look for when buying a fan? Is there a brand you tend to favor? Let us know in the comments!

How to Select a Fan or Blower

What to Look for When Buying a Fan

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