we are alive!..Seller Disclosure nightmare scenario

[Marcello Di Gerlando]

Nightmarish scenario! 1 hr after taking possession of our new dream mountain home in Colorado we discover the furnace is emitting fumes. I call the emergency gas tech. He detects lethal levels of Carbon Monoxide (CO) 1000-2000 ppm Red tags both furnaces and locks the gas at the main shutoff. 

Some bone head mistakes and other points:

1. I did not use a real estate agent

2. I did have a home inspection - No material defects found.

3. I did not have an HVAC specific inspection 

4. I did not purchase a home warranty

5. seller disclosure - Furnaces and CO monitors working and present

6. seller removed CO detectors when he vacated

7. cash purchase

Who eats the bill? one quote came in at 14K!!! for two furnaces. We were in the house literally 1hr and are unable to go back until everything is safe and operational. How could the seller not know? the entire house engulfed in fumes within minutes of turning furnace on. My son almost passed out, my daughter and wife both fell ill and the internet installer is lucky to be alive. ( I have a recorded statement from him explaining his symptoms).

I spoke with the seller and he is basically calling it my problem in not such a pleasant way. He also told me, post sale, that he serviced the furnaces himself and he himself converted them from propane to natural gas. 

HVAC tech says the conversion was done incorrectly and incomplete. HVAC Tech believes the conversion is the cause of the trouble. Also the inducer motor had some kind of sloppy DIY repair job.

I say the seller knew and he did not disclose. This seller, literally, almost killed my entire family. I don't believe for a micro instance that he did not know. Thoughts please.