What Is a Furnace Draft Inducer Blower? I'll tell you what it is ...

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It's another component that can fail on you on the coldest night of the year, over a holiday weekend, fouling up your vacation or christmas plans.
Tell me if your precious, modern furnaces with their ECM fan motors save electricity when they also have to have these draft motors running.
http://www.nextag.com/Fasco-A165-115-Volt-582267765/prices-html
Hmmm. Here's a PSC (!) draft motor, consuming 80 watts. I hope you're factoring in this 80 watts into your furnace's electricity use.
And also note the reference to "government-mandated efficiency standards". Like I said before, the modern furnace being sold today is not the result of pure market-driven competition from a design and construction point of view.
http://www.furnacecompare.com/replacement-parts/draft-inducer-blower.html
These blowers were not necessary on old furnaces. However, once the government mandated furnace efficiency standards beyond what natural convection could handle, the draft inducer was created. This enabled specific control of how much air moved through the heat exchange unit. That, in turn, made it possible to determine BTUs and the AFUE and, thus, the unit's efficiency.
Crock of shit.
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What Is a Furnace Draft Inducer Blower? By Arlene Miles, eHow Contributor updated: June 25, 2010
http://www.ehow.com/about_6648692_furnace-draft-inducer-blower_.html
A furnace draft inducer blower is a relatively new component of modern furnaces that became part of heating units after government-mandated efficiency standards were enacted. The draft inducer blower's purpose is to move air and gases out of the furnace and up through the chimney. This component determines how much and how fast air will move through the heat exchange unit.
Housing
Although variations occur, typical draft inducer blower is located in the gas burner compartment of a furnace and consists of a motor-driven wheel assembly or fan, an electrical box for power connections and a metal sleeve surrounding the assembly. Variables include size of vent pipe diameter, voltage, amperage, wattage, horsepower, and size of the cutout needed for the unit.
Manufacture
Draft inducer blower components are made of durable plastics and metals, or a combination of both. Polypropylene is used to manufacture industrial draft inducer blowers used in corrosive environments because this plastic resists corrosion better than other materials and will never delaminate. Fiberglass is also used when the component must withstand temperatures above 220° F. Blower size is determined by the size of the unit in which it is located.
Purpose
As the furnace enters start-up mode, the draft inducer blower begins to purge the heat exchanger of gases that may have remained in that area during the furnace's previous heating cycle. This makes the air in the area cleaner at the time of combustion and also prevents furnace burners from becoming clogged with soot. By improving the quality of air moving through the furnace, the draft inducer blower helps improve efficiency of the system.
Operation
When a furnace begins a new cycle, the draft inducer blower fan begins whirring 30-60 second before the furnace burners actually ignite. The fan motor must also run properly and usually has a safety pressure switch connected to the fan housing. Pressure switches ensure that the motor is running according to the manufacturers' specifications. If the inducer fan motor cannot turn on, the furnace will generally shut off and lock out. Several other reasons may also cause the draft inducer blower to ultimately shut down a furnace. These include a faulty pressure switch, a bad rubber tube component, or there may be a blockage in the gas vent flue, or even the blower itself may not be working properly.
Replacement
Because many draft inducer blower models are nearly impossible to rebuilt, an entirely new unit must be purchased in most cases when one wears out. The exceptions to this rule, according to Furnace Parks USA, are units manufactured by Carrier and Bryant.
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    Hate to break this to you, Homey, but the type of blower motor has nothing to do with the presence or absence of a draft inducer motor.
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On Sat, 11 Dec 2010 20:21:24 -0500, .p.jm.@see_my_sig_for_address.com wrote:

And the draft inducer motor can be single speed PSC, dual speed PSC, or dual or variable speed ECM.
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On Dec 11, 10:00 pm, snipped-for-privacy@snyder.on.ca wrote:

What is/are PSC and ECM? I have a 50 year-old furnace that is more efficient than some of the new ones after I modified the flame to use 1/2 the gas it originally used.
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On 12/11/2010 10:35 PM, hr(bob) snipped-for-privacy@att.net wrote:

Did you keep the same BTU output? ;-)
TDD
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The Daring Dufas wrote:

I bet he did, because by reducing the flame his duty-cycle is probably longer (just like a modern furnace).
Obviously if his house is reaching the desired temperature as called for by his thermostat, then his furnace must be putting out the required amount of BTU's over time.
Reducing the flame is as simple as turning the dial on the gas regulator in the furnace, or partially closing the gas shut-off valve on the line going to the furnace.
Increase the efficiency even more by reducing the combustion-air intake baffles (the round disks mounted on the front end of each burner). These are usually set wide-open. By closing them down so that they're about 1/6 to 1/8 open, you reduce the amount of combustion air that can be pulled into the burners, and you "slow" the flames down by doing that (you slow the speed of the updraft) which means less heat is wasted up the flue.
Turn them down to the point where you just see a little bit of red / orange in the flames.
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On 12/11/2010 11:57 PM, Home Guy wrote:

Lowering the inlet gas pressure and adjusting baffles is not improving efficiency, generally speaking. The heat exchanger operates at differing efficiencies depending upon how much heat is applied and how much heat is removed, very much dependent upon blower speed, burner output, and the actual design of the exchanger itself. The heating and cooling rates of the exchanger and the heat anticipation in the thermostat should be matched to the building thermal time constant and homeowner preference in terms of how much swing in temperature is acceptable. Obviously very short burner cycles at high temperatures will make bigger spikes than longer, lower temperature burns with higher blower speeds / longer blower cycles.
I find it ludicrous to accept the notion that a 50 year old furnace claimed above can be made more efficient than a modern design, and moreover, even more ridiculous when the further claim is made that the efficiency gain was made by turning down the gas without making other, much more drastic modifications.
Fifty year old forced air furnaces have some nice things to recommend them, but efficiency is not one of them, and certainly not in the 95+ percent range being achieved since the mid-1980's by condensing furnaces.
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    Are you actually supporting his theory that he increased his efficiency ?

    You are truely clueless. You think burning an over-rich mixture is somehow 'efficient' ??? It's actually just the opposite.

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.p.jm.@see_my_sig_for_address.com wrote:

What "Home Guy" suggested there strikes me as potentially dangerous if not lethal. An over rich mixture creates a much higher percentage of deadly gases (carbon monoxide / dioxide) as well as other issues that can severely effect systems such as soot and acidic condensation. No?

Are you adjusting a furnace or an oxy-acetylene torch? Sheeze. Suggest shut your pie hole before somebody takes your ridiculously bad advice and kills their family.
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On Sun, 12 Dec 2010 14:42:02 +0000 (UTC), Black Dragon

    Yes. While burning the fuel LESS efficently, not MORE.

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Black Dragon wrote:

If the air balance and pressure differentials in your home, furnace and flue stack is such that there is potential for combustion gases to back-draft and enter the house-hold air, then you have a potentially dangerous situation *regardless* how the air mixture or gas regulator is set.
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    You, sir, are an asshole.
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.p.jm.@see_my_sig_for_address.com wrote:

The intelligent reader will notice the complete absence of cogent technical reasoning in your response.
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Well no, he knows that you're full of shit. He knows that there is a fuel to air ratio and what that ratio is. He knows that when a flame is burning efficiently the CO is minimal to zero. He knows that for perfect combustion you don't shoot for 17% CO2 like some other yahoo homemoaner thinks. He knows all the things that you silly homemoaners think you know but don't, so shut your yap and go away.
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ftwhd wrote:

I never did say that you should close the shutter to the point of creating a rich mixture caused by insufficient primary combustion air.
I am saying that in most cases the primary air shutter will be wide open, and that is ALSO not a correct position, and that turning the shutter down until you note a color-change (yellow) and then back off slightly is where you want the shutter to be.
And when you turn down your burners, you should also turn down the air shutter to compensate for the reduced fuel flow.
So go away you silly HVAC techs and go find some other homoaners to rip-off.
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So your basing the adjustments on a *GUESS* instead of taking actual measurements.... and you have no clue as to the actual CO, or combustion efficiency of your furnace. and you call us silly.
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wrote:

There is such a thing as an "educated guess". In my case, it was backed up by the results of the tests made by a highly qualified tech who had no idea what I had done.
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You sound like Stormys little brother.
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Finally something I can agree with "home guy" on. An overly lean atmospheric burner setting will have virtually no symptoms, but WILL reduce furnace efficiency by raising stack temp and reducing heat transfer in the heat exchanger. Like the old "quarter turn rich of lean best idle" carburetor adjustment, you don't want any more, or any less, air in the mixture than required for a clean burn. On SOME furnaces, too much primary air will cause a "roar" - so adjusting for as quiet a burn without an orange flame fringe is a method sometimes used. - and if you crank back the gas, you need to crank back the air as well for maximum efficiency.
My old gas furnace was adjusted this way (by myself) and the furnace tech who checked it last could not get over how well it was burning and how efficient it was.
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On 12/12/2010 4:16 PM, snipped-for-privacy@snyder.on.ca wrote:

Sort of like Charles Lindbergh showing the pilots in The Pacific how to get the best fuel mileage from their P-38 Lightnings. :-)
TDD
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