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

Page 6 of 7  
On Sun, 12 Dec 2010 08:20:05 -0500, .p.jm.@see_my_sig_for_address.com wrote:

But it can very much AFFECT efficiency. Maximum efficiency is achieved when the burner is running constantly to provide the required heat. Every time a burner stops and starts, efficiency is lost.
An oversized furnace is less efficient than a "right-sized" furnace.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 12 Dec 2010 17:03:23 -0500, snipped-for-privacy@snyder.on.ca wrote:

    Bullshit. It GREATLY depends.
    For instance - take a 50 year old 'right sized' POS furnace with like 70 % AFUE effective. Compared to an 'over-sized' modern unit at 95 % +. Eh ?
    Even with short-cycling, that over-sized furnace may be more efficient than the 'right' one.
--
Click here every day to feed an animal that needs you today !!!
www.theanimalrescuesite.com/
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 12 Dec 2010 18:08:11 -0500, .p.jm.@see_my_sig_for_address.com wrote:

OK, it's best to compare apples with apples, but the35 year old 75% efficient basic furnace I removed, right sized, would still be as or more efficient than a 95+% furnace of twice the required capacity. My old furnace WAS pretty well optimized, although it was slightly oversized for my house.
20X30 ft 2 storey mid--seventies brick and siding house in south-central ontario - heated exclusively with natural gas - including domestic hot water, for $700 per year. - and virtually no difference when the "old" furnace was replaced with the new high-tech non-condensing furnace escept a siseable difference in the hydro bill.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 11 Dec 2010 20:35:08 -0800 (PST), "hr(bob) snipped-for-privacy@att.net"

PSC is permanent splic capacitor motor - in other words, a simple induction motor with a run cap. An ECM is an "electrically commutated motor" - basically a permanent magnet DC motor with hall effect sensors and solid state power switching devives instead of brushes - a brushless DC permanent magnet motor.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
responding to http://www.homeownershub.com/hvac/What-Is-a-Furnace-Draft-Inducer-Blower-I-ll-tell-you-what-43183-.htm avantiservices wrote: .p.jm.@see_my_sig_for_address. wrote:

----------------------------------------- Yep! I understand your frustration. I have to drag my cold bum out into the worse than freezing weather to change them out and often on a package unit where it is ALL outdoors. Here is the facts though... There are many less deaths today caused by asphyxiation due to lack of draft or cracked exchanger and fire from burner failure. I think the whole "efficiency" statement is marketing and is more likely for increased revenue and new production markets for the economy. Whatever the reasoning, if it has saved one single life it is worth it. When yours failed it might have even saved yours or that of your loved ones.
------------------------------------- J.P. Avanti Services HVAC, Steam and closed loop Hydronic heating. In the service field for 25 years.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 15 Dec 2010 16:40:13 +0000, avantiservices_at_gmail_dot snipped-for-privacy@foo.com (avantiservices) wrote:

    On the roof.     Where there is no place to safely secure a ladder.     In a blizzard / ice storm.     In the dark.     Late at night.     When everyone else in the county followed the emergency advice on the radio and went home early.     Except the store owner who called.     Who told you when you got there that she wants to lock up and leave right away, and you should stay by yourself until it's fixed.     With no other living being within a half mile if you need help, like if your ladder blows down, or you slip on the 2 ''s of new ice everywhere.     Because she's late getting dinner on the table.     And by the way, you do give 30 days billing for new customers you never heard of before who found you in the Yellow Pages that night ?
    Oh, the memories .....
--
Click here every day to feed an animal that needs you today !!!
www.theanimalrescuesite.com/
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If you don't like it, then go to work for one of the manufacturers and show them how *you* think it should be done.
BTW... draft inducer motors are *NOT* PSC motors, and the inducer motors in some furnaces are DC.
In any case, kwitchurbitchin and go away.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/11/2010 7:24 PM, Steve wrote:

What? You don't like entertainment? :-)
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Gettin tired of playing with this one.....
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/11/2010 9:21 PM, Steve wrote:

I understand entirely. :-)
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

And some ARE PSC motors

I'll agree there.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You, with all your gabbing, have still not explained WHY a draft inducer is REQUIRED on today's furnaces.
With the high efficiency of today's furnaces, too little heat goes up the chimney to reliably create a proper draft in the chimney to be sure exhaust gasses are properly vented. The "eductor" fan starts before the flame is lit and gets air moving up the chimney, and it continues to run at high speed untill the flame has created hot enough gasses to maintain draft. The eductor motor in IN the exhaust, just like the power vent on a gas water heater.( at least it is on mine - there are apparently others that use forced air into a sealed combustion chamber.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thats exactly why I still have my mechanical (no wires anywhere) wall furnace from the nineteen forties even though the state of California offered to give me one free including installation. I will still be warm even if the electricity goes out.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's true. But with the induced draft they can safely operate at high efficiency because they can better control how much air goes up the stack.
Last summer we changed out an "old style" gas furnace with an induced draft unit. Tremendous difference in gas usage.
Because we have also switched over to nearly 100% CFL for lighting, we have saved so much electricity that we just don't notice the extra 80 watts used for the draft blower.
But I agree with your main point: the old style motors in gas furnaces do waste quite a bit of power. But the main power hog is the air circulation motor. That can easily cost $.05/hour. That may not seem like much but if that blower operates 24/7, it adds up to over $30/month. A good reason to keep the fan on "auto" rather than "on."
You furnace should be sized so that it can keep you comfortable on a very cold day by operating continuously. You can pick your own numbers but your furnace shouldn't be expected to operate 24/7 more than a day or two each year. That's an extra $1 or 2 or so.
Maybe the next generation of furnaces will also take account motor efficiency. Right now the 90 (plus) % efficiency systems are much, much more expensive than the 80% (the condensation feature adds to the complexity and cost). But like so many other things, prices will come down with competition. It may end up being less expensive to buy a high efficiency HVAC system than to "super insulate!"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
..

As the Idjit who filled in the orifice and then redrilled it, I can assure everyone that I did calculations on what size orifice I needed to get a certain BTU flow. I did this 20+ years ago and don't remember the details any longer, but it was not strictly based on cross-section of the orifice opening, but also included the effects of friction of the gas with the orifice walls.
If the flame ever gets close to the orifice opening, there will be major problems as at least in my furnace, the actual flame is several inches into the furnace from where the orifice is located. The is an air-mixing tube that goes between the orifice and the burner, and that is where you adjust the airflow to match the gas flow. It may not meet some PhD type of analysis, but it cut down the gas consumption and we stay warm on -10 degree nights and days so I guess I did something right.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

As the Idjit who filled in the orifice and then redrilled it, I can assure everyone that I did calculations on what size orifice I needed to get a certain BTU flow. I did this 20+ years ago and don't remember the details any longer, but it was not strictly based on cross-section of the orifice opening, but also included the effects of friction of the gas with the orifice walls.
If the flame ever gets close to the orifice opening, there will be major problems as at least in my furnace, the actual flame is several inches into the furnace from where the orifice is located. The is an air-mixing tube that goes between the orifice and the burner, and that is where you adjust the airflow to match the gas flow. It may not meet some PhD type of analysis, but it cut down the gas consumption and we stay warm on -10 degree nights and days so I guess I did something right.
--------------------------------------------
Your still alive, thats a plus.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
a poster wrote:

<<...snipped...>>
Most likely the unit was originally greatly oversized or grossly inefficient for your tinkering to have worked so effectively.
--
There are no stupid questions, but there are lots of stupid answers.

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 15 Dec 2010 22:50:42 +0000 (UTC), snipped-for-privacy@sdf.lNoOnSePsAtMar.org (Larry W) wrote:

MOST 30 year old and older units were grossly oversized.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Dec 15, 5:20pm, snipped-for-privacy@snyder.on.ca wrote:

It's not the unit was oversized, the unit was oversized for the particular size house or heating application.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 16 Dec 2010 08:16:19 -0800 (PST), "hr(bob) snipped-for-privacy@att.net"

What else did you think I meant? Pretty obviouse it is "oversized for the application" because if the same furnace was installed in an arena it would be grossly undersized.
The tendancy was to go with "bigger is better"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.