Beware of company;s who work on or replace furnaces! Please check them out carefully, If I save one person from going through the Hell of being poisoned by CARBON MONOXIDE POISONING, then I have got my point across! We had a new furnace installed and instead of hooking the new one back up to propane inwhich the were certainly aware of because they unhooked the old one and had to shut off the propane. They installed a natural gas orphas which caused the heat exchanger to crack and also make the furnace extremely hot to touch. We knew something was not right and left message after message, finally after going over the company they came out and The owner and one employee with nothing more than a screwdriver spent the entire day trying to figure out why this brand new furnace they installed had shut down and would not work.From 9 am until 5:30 pm they could not figure it out. Then at 5:30 pm his employees who installed the furnace came over and right away said" DID YOU CHANGE THE ORPHAS FROM NATURAL TO PROPANE? They forgot to tell us the furnace was completely ruined and the heatexchanger and wires were burnt and completely covered with sute. This furnace was putting co in our house for nearly 3 months, the fluke on the house was completely plugged with soot. Why did we and are we still having to battle majior health problems? From something that should of and could of been prevented. I am enclosing a link if anyone out there wants to know about some of the damage that this causes and most of the time we don't know until its to late.