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

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Stormin Mormon wrote:

I call a Godwin.
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On Sat, 18 Dec 2010 18:24:22 -0500, Stormin Mormon wrote:

A deduction is a reduction in income. A nonrefundable credit is a reduction of tax owed up to the amount on line 44 on Form 1040 (Child Tax Credit). These are on lines 47 to 53 on Fomr 1040. Refundable tax credits are the ones your neighbor pays you, such as the Making Work Pay, the EIC, the Advanced Child Tax Credit. These are the line 61 through line 70 credits.
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harry wrote:

============================Energy conservation guidebook By Steven R. Patrick, Dale R. Patrick, Stephen W. Fardo (C) 1993 Fairmount Press Inc. ISBN 0-88173-154-4
Page 85:
"The amount of air admitted to the burner assembly is normally controlled by a manual shutter on the front of the burner as in Fig 4-6. Adjustment of this shutter either enlarges or reduces the opening, according to it's position. The color of the resulting burner flame, as a rule, is a good indication of the resulting fuel/air mixture ratio. A yellow flame, for example, denotes insufficient primary air, whereas a sharp blue flame shows a proper mixture ratio. Burner effieciency is directly dependent upon the fuel/air mixture ratio"
http://books.google.ca/books?id 5IIzt4DCIC&pg=PA85 =========================== I will repeat the relevant sentence:
"The color of the resulting burner flame, as a rule, is a good indication of the resulting fuel/air mixture ratio."
I will say that I was wrong about the orange color - it's yellow that you don't want to see in the flame.
Note that there is no color indication telling you if the mixture is too lean, or that the burners are pulling too much primary combustion air through the shutters.
Besides turning down your gas-valve to create a SMALLER flame, pulling the correct amount of primary combustion air through the shutters is critical in getting the best efficiency out of an old furnace. The more excess air you pull though the shutter, the faster the combustion flow will be and the less time that the flame-heat has to reside inside the heat exchanger galley and hence more of the heat will go up the flue instead of being transfered into your house.
Almost all positions of the air shutter will give you a "sharp blue flame", but only the position where it almost gives you yellow in the flame will be the correct position.
And like I said before, it's my contention that in the majority of cases, these shutters will be set wide open by default when these furnaces were originally installed - because it's a no-brainer setting that had no percieved impact on the customer and was the "safe" setting in the eyes of the HVAC technician or installer at the time.
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On 12/12/2010 10:43 AM, Home Guy wrote:

Two problems with this source. First, it's the wrong sort of source to support your claim. It is a book about the topic of energy conservation. It is NOT a specialized HVAC manual. It's intended to provide a broad and fairly basic overview of energy conservation, and as such includes chapters on building design, lighting, HVAC, etc. Second, it's woefully out of date, as it was published seventeen years ago. You had to have noticed the page where electronic ignition is described as a "new development in gas heating systems".
It is imprudent, if not highly dangerous, to use as a technical guide an old, outdated book that only touches on gas furnaces in a brief, general, and decidedly non-technical manner.
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wrote:

No. I filled (soldered) in the gas nozzle and then redrilled it so that the gas consumption is about 1/2 of the previous amount. I verified this by checking the usage per 10 minutes, before and after, using my gas meter as the measuring instrument. I run the blower 100% most of the heating season to even out temperatures thruout the house as we have a 4-level split level house and the heat rises very well unless you are circulating constantly. My overall gas consumption is very noticeably lower. I have records dating back to 1966 when we bought the house so I can average over several years to see the difference. I'm a cheap SOB, frugal, obsessed with saving money, any or all of the previous appelations.
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"hr(bob) snipped-for-privacy@att.net" unnecessarily full-quoted:

If your furnace has a variable-control gas regulator valve, you could have more easily just turned that to dial-down the amount of gas reaching the burners.
Even if it doesn't have a dial control, I bet there's a valve on the gas line running to the furnace, maybe about 3 to 6 feet away from the furnace, and you could have also partially closed it to reduce the gas flow as well.
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.p.jm.@see_my_sig_for_address.com wrote:

There's no reason why it can't function as one.

By partially closing off the gascock valve, you're not necessarily reducing the inlet pressure (the pressure beyond the valve going to the regulator).
When the burners are not going, the pressure on both sides of the gascock will be the same. When the burners light up and get going, there might be a slight reduction in the pressure between the gascock and the regulator valve in the furnace.
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crapper, HomeGuy.
With propane at 11 inches water column pressure, a .078" diameter orifice (jet) produces just over 50,000 BTU per hour. For natural gas at the same presuure you are looking at something like a 0.100" orifice.
You are going to effectively regulate that flow with a valve on a 1" iron pipe???
NOT!!!
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On Mon, 13 Dec 2010 17:49:00 -0500, snipped-for-privacy@snyder.on.ca wrote:

    You ever seen a residential system designed with NG at 11 " before ? :-)
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On 12/13/2010 5:24 PM, .p.jm.@see_my_sig_for_address.com wrote:

Yea, that was the required gas pressure input for Generac generators. :-)
TDD
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On Mon, 13 Dec 2010 18:24:18 -0500, .p.jm.@see_my_sig_for_address.com wrote:

14, with 7 apparently being roughly the "normal" for north american systems.
Still, my point is valid. It's a mighty small orifice, and the "shut-off valve" on a 1" iron pipe is going to make an awfully lousy regulator
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On Mon, 13 Dec 2010 19:59:31 -0500, snipped-for-privacy@snyder.on.ca wrote:

    I agree. And dropping pressure upstream of the unit's gas valve in an attempt to regulate BTU input / output is dumb. As others have said, changing orifices is the correct way to do it.
    And no, you don't just 'solder them shut and drill them out' with solder that melts at 400 F, like some idjit suggested.
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.p.jm.@see_my_sig_for_address.com wrote:

The orifice on the long horizontal burners is nowhere near where the flames are combusting. These orifices are mounted right to the fuel rail-pipe coming off the gas valve, where the burners are loosely inserted over them. It's cool to the touch.
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    So is your brain.
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On Mon, 13 Dec 2010 21:12:04 -0500, .p.jm.@see_my_sig_for_address.com wrote:

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On Mon, 13 Dec 2010 21:45:37 -0500, snipped-for-privacy@snyder.on.ca wrote:

    No, he's not. He's talking about 'some asshole DIY'r could get away with it', not 'the correct and safe way to do it'. Which said 'correct way' , as it happens is also very inexpensive and easy to do.
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.p.jm.@see_my_sig_for_address.com wrote:

Yes, I am.

No.
I'm saying that the orifice jets do not experience high temperatures because of where they are mounted, so your claim that their size can't be changed by filling them in with solder is wrong.
I never said that modifying them with solder is good or bad or risky or safe.
But if you want such an opinion from me, then I would say that filling them in with solder and re-drilling them to a smaller size is perfectly acceptible. Solder is dimensionally stable in this setting, and the distance between the orifice and the combustion site is such that there is no fine detail in orifice shape or construction that can have any meaningful effect on downstream combustion other than the size of the opening.
You see, this is what happens when you have no real experience with 25+ year-old furnaces, other than to tell the customer that "yup, yours needs to come out and you need to fork over $4k to me for a new-fangled one".
After all, that's what you tell people when their pilot light blows out - isin't it?
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On Mon, 13 Dec 2010 21:55:17 -0500, .p.jm.@see_my_sig_for_address.com wrote:

works and is often done to determine what the right jet size is.
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.p.jm.@see_my_sig_for_address.com wrote:

The orifice on the long horizontal burners is nowhere near where the flames are combusting. These orifices are mounted right to the fuel rail-pipe coming off the gas valve, where the burners are loosely inserted over them. It's cool to the touch.
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On Mon, 13 Dec 2010 20:18:19 -0500, .p.jm.@see_my_sig_for_address.com wrote:

since the flame does NOT occur at the jet. It would be very unlikely, in many furnace designs, for the jet to approach anything close to 300 degrees F.
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