Thank you all very much for your responses. Your advice is appreciated.

So much has happened in the past three days, but I want to share it for the sake of others. I’d also appreciate your recommendation on my course of action.

My house was built in 1998 with the Janitrol / Goodman GMP125-4. With some checking, the furnace was actually manufactured in 1993. Furnace S/N is 9702854654.

I called an HVAC Contractor on Wed evening. He came out and assessed my furnace as follows "Found 4 big cracks on the heat exchanger, 1" to 2" in size coming off eyelets letting bi-products into air stream. Very unsafe to run." This is written on my receipt, and he basically told me the same thing. He then pitched me furnaces, with the "premium level" 95% Goodman 2-stage, variable speed coming in at $6,700 installed. I believe the 80% much like my current one, but with variable speed blower was quoted around $4,000. These are installed prices with any applicable duct/venting work.

I then user QualitySmith.com to set up 3 appointments for the following day, and set up one through Home Depot's services group. NOTE: Quality Smith set up the appointments only 1 hour apart, you really need a minimum of 2 hours to get new furnaces sized and quoted. Needless to say, my house looked like that Lone Tree commercial with all those lenders standing around to make their offer. Rude, but also a little commical. I told them to let QualitySmith know what happened.

Anyhow... The first contractor started to put together a quote, and I mentioned I would feel a lot better if I had a second opinion on the heat exchanger really being bad. They brought out a tech who used a CO sniffer to sniff the output air (small hold in duct right above furnace) and several heat registers. No CO measured (gauge starts measuring at 1 ppm). I asked them to quote me an 80% and 90% plus furnace, just in case, but informed them I understood if they were unwilling, given I could be wasting their time if no replacement was needed. They complied and quoted me:
80% -- Comfortmaker VS 80 (C8MPV125J20C) variable speed 2-stage furnace with a non-programmable 2 stage thermostat for $2,000 installed (parts, labor, and tax).
90%+ (as they show on quote) -- Comfortmaker VS 90 (CPMPV125L20D) variable speed 2-stage furnace with a non-programmable 2 stage thermostat for $2,495 installed (parts, labor, and tax).

Second HVAC Contractor (installed prices):
80% Carrier $3,982
80% Payne $3,207
95% Carrier $5,357
90% Payne $3,653
Above prices include the 10% off for signing before midnight that night, and 5% for cash. They also told me I don't need a new thermostat with a 2-stage variable speed furnace, which from what I have researched sounds wrong.

Third HVAC Contractor (installed prices)
80% American Standard 80 Comfort R Variable Stage with digital programmable 2-stage thermostat $3,200
95% American Standard 95 Comfort R Variable Stage with digital programmable 2-stage thermostat $4,800

Fourth HVAC Contractor (installed prices)
95% Trane XV-95 100,000 BTU 2-Stage w/Variable speed blower, programmable thermostat $3,860.
He pulled out documentation on the XCel Energy rebate of $120 and the 2009 tax credit of $150 and told me they will fill out the XCel rebate and send it in for me.

Finally, with all of that done, I was still concerned about whether I really had cracks in the heat exchanger, since there were no measurable CO emissions per the first contractor. I decided I had to call someone with no interest in selling me a furnace. I called Xcel Energy's Emergency line and they said CO is an emergency, so they sent out a tech at no charge. This gentleman was in his 50s with years of experience, and confirmed that he knows of cases where such a "selling process" had been done with no heat exchanger issue. He took his sniffer and measured at the output of the furnace (above it, just above the AC condenser) in the duct work (a hole he stuck it through), sniffed all through the furnace while running, around all the lines, etc. and then went to about 1/2 the registers in the house and several cold air returns with no presence of CO. He then went back and sniffed all around the water heater, still a reading of zero. I asked if his measurement tool was working. We then turned on the hot water so the water heater would light, and while he had the little pilot light door open with sniffer inserted, both the natural gas and CO levels went up for about 20 seconds, then fell back to zero. So, the sniffer was working, and no apparent problem with the furnace. He said that is how he would report it, but did say that there could be small cracks in the heat exchange which are not measurable from CO emissions.

Last night I read consumer reports on-line and went and bought 3 Kindle CO detectors with displays to show CO ppm measured, with a peak feature that shows highest level ever measured for the life of the device. I put one right outside the furnace door in the basement (the furnace in unfinished portion, the detector in the finished portion), one in my family room on the main floor, and one in the upstairs hallway where all the bedrooms are. None of them have come off zero on the display. I turned the furnace back on yesterday at 3 pm.

I got a call from the first contractor last night asking if I had made a decision. I expressed to the lady that I thought I was being scammed, and told her the whole story. They sent out a senior technician this morning to show me the cracks, and said if he could not, they would pay me $300 and terminate the technician. He removed the blower, then came to get me, and had me look up inside with a mirror and flashlight, and showed me what I would call very small cracks. He told me he would pull the heat exchanger so I could see them better. He took apart the furnace and called me back down 30 minutes later. Sure enough, we found not just 4 cracks, but 7. Some were 1/4" long, the longest maybe 1-1/2". I could not see that any of them would allow air to flow through them, but nonetheless there were cracks. They were not lying, but the technician had told me verbally that he measured CO at 35 ppm before he looked at the cracks, which nobody else could duplicate. He put the furnace back together in another 30 minutes. He made a call and said they could get the heat exchanger free because it was still on warranty, and put it in for $850 in labor now, rather than the $1,100 originally quoted. So, it appears their hourly rate is $425 an hour giving them the benefit of the doubt that putting a new one in rather than putting the old one back in might take twice as long.

So, apparently I have a cracked heat exchanger with no measurable CO emissions and my furnace is running as I type.

Based on the fact that I have $5,000 in my savings account and no credit cards, what would you do knowing what I know?

If you want to see pictures of the cracks, let me know. The picture files are 3 MB jpg files from my 8 mega pixel camera, so posting them in this forum is probably not the best option, but I would be happy to Email them to you.

Thanks again to all of you for your feedback.

You have been caught in the same trap as many other consumers. Are you sure you really saw cracks when he took apart the furnace and showed you them? Did he put a screw driver in the cracks to show you that it was really a crack? The reason I ask this is using a lead pencil to draw cracks on a heat exchanger is a very old heating company trick to sell new furnaces. If done right they look just like a crack except a screw driver will just slide over them and not go in.

I have a dead email link I will give you. Send the pictures there and I will look some time this evening. I use this email link for spam control so I know it works. I will post back after looking at the pictures or use your email to tell you what I think. You will have to type in the address. Copy and past will not work . Just type exactly as posted.

Send to.

[email protected]

I am curious, what prompted you to call in the first HVAC contractor? With modern induced-draft design, it is possible to have a leaky heat exchanger without contaminating the airstream; however, other problems will manifest if the condition goes unaddressed. If the unit is otherwise in good condition, repair is not an impractical consideration. A typical repair of this nature on a unit like yours in my local market would cost between $400-$500.

Could try a smoke test to see if exchanger is indeed letting burnt gasses into duckwork(airflow stream)

No email yet of pictures?

Hi
I too am having trouble getting a real diagnosis on my Janitrol furnace problems. I will spare you the details, but I did learn this...
Yes, Janitrol will replace the heat exchanger itself, but you pay the labor.
Howeever, I have a reputable guy checking for me right now about an exchange program the co. may still have. He said it was a reduced price on a new furnace(their brand of course) and the installer was not allowed to charge anything (or much?)to the consumer to put it in. That is in place of getting the free heat exchanger and putting it in the old furnace. Sounds like it wouldn't cost you much more to do that, and would have a warranty on the whole new unit. Be worth checking into.