The flame pattern on the burners had a significant amount of orange flame, indicating the burners could need to be cleaned or may not be properly combusting, and 3.

Also known as a combustion reaction. 

As someone who sold my San Jose house in the 2002 dot com bust and has been locked out ever since by the rising market - prices have almost tripled since then - I would say hang on to it just so you are locked into the market.

In addition, these new furnaces are direct vented (they do not take combustion air from the conditioned space) and the natural gas ones do not require a chimney (which means that big source of heat loss can be stoppered or removed).If you are paying utilities, a new furnace will pay for itself.  

Harb Thank you - I have seen the comparison made to the .com bust many times and I completely agree with you on that.

I had done well as an owner trading up my principle residence half a dozen times as markets rose during the 80s and 90s but sold out during the dot com bust in 2002 and have been a Silicon Valley renter paying through the nose since then staying close to my tech job.

I believe it is directly tied to the dot com bust.

If you say how does it work do you want me to say turn the key and then the wheels move and it goes or do you really want to know how the key sends an electronic pulse to a computer that then sends another to other parts of the engine and then through combustion and yada yada...So ask a direct question that can be answered.

The Fed caused the housing boom by dropping interest rates to fix the recession after the dot com bust.

Just burned the gas right in the unit, and the combustion gas went into the house.