Gas furnace replacement

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From what I know, Trane runs a bit expensive. If you can get a Trane for 3500, the Bryant guy sounds high.
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Christopher A. Young
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On Wed, 15 Mar 2006 15:08:48 GMT, "Stormin Mormon"

"From what you know?........." Wait a minute. Let me get my thimble out. That's where I store all you know. Bubba
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Well, thanks everyone for replies. Yes I though $800 quite high for a humidifier. My plumber who seems very honest recommended the havoc company as being honest, but I'm not sure as hvac man keeps saying he's honest. I definitely will get other bids and look to a higher efficiency unit. As for wanting a humidifier with a forced-air system, my house sure feels dry during heating season so that's a definite plus for me. And no, the $4500 does not include AC. No one mentioned other brand furnaces, my neighbor had a Trane installed a couple of years ago for around $3500.
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Because brand of unit is not the important part.
The _installation_ is.
I stress - The installation is the important part.
Get a couple more estimates. Google the equipment offered to you and educate youself about which features of the units are important to you. There are many things to consider besides price. Noise level is one. Efficiency is another. There are a few manufacturers that make 95% efficient furnaces and they will get you a tax credit. Trane is not one of those manufacturers. Don't be hasty and don't be afrain to ask specific questions.
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On Sat, 11 Mar 2006 12:35:55 GMT, "Paul Isaacs"

Your furnace works fine. The only critical factor to merit a furnace replacement is if the heat exchanger is cracked and lets in toxic combusted air into the house air circulation. Only then is it mandatory and more economical to replace the furnace than to replace the heat exchanger.
My Inter City gas furnace is 30 years old and looks as new as the day it was installed. I had been coughing last season whenever my furnace fired up. I asked the gas company for a FREE furnace inspection. Your gas company should have a similar service. The technician gave it a OK but said that the heat exchanger was already getting old. Call for another inspection in the future if I suspect anything. He also noted that I had put the fan in backwards. It will work but won't blow that efficiently. Its easy to take out the fan and turn it around to rotate the correct direction.
I spent $350 to get the furnace ducts cleaned, the only time in 30 years, and my coughing fits stopped.
25 years ago I swapped the 1/3 HP furnace blower for a 1/2 HP one from my table saw. (I upgraded the table saw to 1 HP.) That motor has been humming without trouble up to today. When I did the swapping I also took out the squirrel cage blower fan to clean it. Reassembled the stuff and it worked fine. After about a year's running the furnace had an annoying thunk everytime the fan started or stopped. So I tightened the fan belt, oiled the bearings and it will work fine.
This went on for 4 years until the thunks were rather disturbing and I decided to take the fan out to clean it as well as check the mechanism. The noise must be related to the fan as that was the only moving part. The motor was fine. I found the bronze sleeve bearings ovalled and the fan shaft worn and gouged quite deeply. I had overtightened the fan belt. The tension wore into the bronze bearings. Adding lube oil retained the metal filings to create an abrasive slurry that gouged into the steel fan shaft.
The bearings are available from any appliance repair supplies shop. They are meant to run without lubrication. Frankly the heat in the fan chamber would distill off the light oil faction and leave a gummy residue that is no good for lubrication. My 1/2 HP motor would have overcome any frictional resistance without trouble where a 1/3 HP motor might have overload burn out. The shaft is just be a 3/4 inch diameter steel rod. The repairs were quite simple and can be managed by anyone who is not all thumbs.
My advice for you is to get your gas company to give your furance an inspection. He does not do repairs and has the obligation to give a professional opinion on the safety aspects of your furnace. He also has the obligation to report any serious furnace safety problems. Besides gassing yourself your house can catch fire and burn down the neighborhood in the process.
Take apart the blower fan assembly anyway and do a thorough clean-up of that chamber. Obviously you do this only in the warmer months when you no longer need the furnace running. You will be amazed at the gunk and dust coats that had accumulated. Vacuum first. For stubborn oilsoaked dust use varsol to wipe them off. A wet cloth and maybe some soap should remove the rest. Then leave the chamber as clean bare metal. Any oil or other coating will just attract dust which will be baked onto the chamber walls. Much of the respiratory problems during winter likely arise from the dust and gunk buildup lurking inside trhe furnace.
The fan motor bearings are meant to run dry. My fan motor has been running for more than a decade now without trouble. I check and clean the fan chamber every three years or so. Do not add lube oil (ref. abrasive slurry above). Set the hinged motor such that the standoff screw will just hold the motor against the stop. The fan belt tension should be from the weight of the motor, not by tightening the standoff screw.
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PaPaPeng wrote:

Your old furnace may be working OK but it is of old technology with LOW efficiency! Would you drive a car of '60s? Gas guzzling, polluter?
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Two questions. What is the payback on a furnace replacement? How many years do you need to run the furnace to save in fuel the expense used to pay for the replacement.
The second question is what is the technical explanation for the newer furnaces to claim that it is more efficient than the older models?
A home furnace is simply a heat exchanger extracting heat from a flame. The BTU output for a particular flame is a finite qualtity. The increase in efficiency can only come only from the heat extraction process. If the heat exchanger is built like a car radiator in having lots of surface area then yes, there will be greater efficiency. But the heat exchanger functions in a pretty hostile environment. A delicate car radiator like device won't last too long in a furnace. So the heat exchanger is built of crude cast iron and there are only so many things you can do with this material. I can't picture any significant design advance between the old and the new heat exchanger elements. If you know of another explanation I am ingterested.
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PaPaPeng wrote:

Cast iron exchanger? Mine does not looks like rusty cast iron! It looks shiny. And there are high efficiency furnaces with efficiency of >90% which waste LOT less gas. Pay back period is important but as a good citizen aren't you interested in contributing to energy conservation and less pollution? And non-renewable energy source like NG and dino-juice price can only go up in coming years. I and my family are trying to do our part to help strained mother earth. How about you and yours? Also my government gives rebate when we do things to conserve energy. Of course they don't foot the whole bill but at least they help out. When I replaced my toilet with a low water consumption model, city gave me 75.00. For furnace upgrade it can be ~1000.00 depending what is done.
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Tony Hwang wrote:

I hope you scrapped the SUV. That'll save a lot more energy than anything you do with your furnace in many areas of the world.
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I just came from a friend's new home in Lethbridge and took a look at his new furnace (900 sq ft home). Its less than half the size of mine and has electronic ignition. The burners look simple enough but I couldn't see the heat exchanger. I'll probably visit the local gas company someday to see the latest technology. That said I can say for sure that there is nothing complicated in his furnace layout that would suggest any breakthroughs in heat extraction technology. There is only so much heat a heat exchanger can absorb (rate of absorbtion) at any given time. Like him I set my winter temp at 17 deg C. The odd thing is that I felt a lot colder in his house. My best explanation is that his small furnace has a much smaller blower motor and fan
[For an air standard engine with g = 1.4 , compression ratio rC = 15 and expansion ratio rE = 5, this gives an ideal diesel efficiency of 56%. http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/diesel.html (A gasoline engine is something like 40 percent. ) For a free burning furnace flame most of the burnt hot air goes up the stack (feel how hot the exhaust stack is) the efficiency is in the ~30 per cent range, not > 90 percent.]
But from http://www.columbiagaspamd.com/products_services/natural_gas_furnace.htm
[Efficiency: Modern natural gas furnaces achieve operating efficiencies as high as 96 or 97 percent AFUE (Annual Fuel Utilization Efficiencies) and thus give the homeowner 96 cents worth of heat into the living area for each dollar of gas purchased. The minimum efficiency standard for furnaces sold in the U.S. is 78 percent. While the typical furnaces of years past used chimneys, the high efficiency units of today extract so much heat from the gas they use that they can be vented through the sidewall of your home using plastic pipe. This venting is similar to the type of venting associated with a clothes dryer.
Pilot lights, which were used in older equipment, have been replaced with spark ignition systems to save energy. ]
I am suspicious as to how this >90% efficiency is calculated as it would mean that the stack plenum temperature at the furnace should be close to ambient temperature, a practical impossibility. It didn't occur to me to see the exhaust stack but it looked like the regular galvanized steel. I would never accept plastic pipe (above article) for this installation anyway.

You are referring to Tony. Me? I don't own a vehicle anymore. Just the trusty bicycle for getting around, by bus for longer distances or a rental when needed.
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<I am suspicious as to how this >90% efficiency is calculated as it would mean that the stack plenum temperature at the furnace should be close to ambient temperature, a practical impossibility. It didn't occur to me to see the exhaust stack but it looked like the regular galvanized steel. I would never accept plastic pipe (above article) for this installation anyway. > --------------------------------------------------------------------------------------------------------------------
the 90% is safely vented using plastic pipe at just ocver ambient temp by using a secondary heat exchanger.
plastic being non corrosive is actually safer in this application since steel or glvanized will rot out.
heat exchangers on 90+ furnaces are stainless steel to inhibit corosion.
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I measured my 93% unit pvc stack at 90f and that was with a very dirty air filter.
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