What is the HVAC building code that requires to shut the gas off when a heat exchanger is cracked?
was this found during ruitine maintenance or a service call? honestly honestly a small hole in your heat exchanger probeble will not hurt you most of the exhaust is going out the flue pipe anyways pluss they make ventless heaters which exhaust 100% into the room. there is no law that says your gas has to be shut off, most service companies will to sell you a new heat exchanger or preferable a new unit might as well thrown in a heatpump to while there at it. they usually require there employees to shut off a furnace with a cracked heat exchanger as kind of a scare tactic and also incase anything would happen there not liable. but you are able to go back down and turn the gas on after they leave no law
The gas only needs to be turned off to the furnace. The rest of the house is OK. There should be a separate supply valve for it. Cracks in the heat exchanger can cause a fire and co2 to escape into your house. Make sure the gas is turned of to the furnace.
A cracked heat exchanger will allow co2 into the home, as combustion gasses may pass through the crack into what is normally a sealed circulation of air through the home. Since co2 is poisonious and may kill the occupants of the residence , the gas must be cut off to the furnace until the problem is resolved. You do not have to have the entire gas supply to the home cut off, only at the furnace. Hope this helps, God Bless.
The heat exchanger may be under warranty from the manufacture, however this would need to be verify with the local supply house with your model and serial number off the furnace. I would also, question the heat exchanger crack, as some furnace have whats called a front plate. The front plate over time will crack. This is a replaceable part. And is often misdiagnosed as a cracked heat exchanger. 700 is fair for the price. I would get a carbon monoxide detector and install that. You might tell the guy to hold off and have someone else look at it. Some companies out there offer a free second opinion. You could call them and say that the first company says (your fibbing here) that you have two choices here replace the entire furnace or repair / replaced the heat exchanger. And that you would like them (the second company) to verify this and give you a second quote. Its pretty rare for the heat exchanger to crack in a residential home. Its is possible but again back to my statement above about the front plate. Just trying to give you some other things to look at and ask.
I believe that's covered in NFPA 54 and 58. Possum, HVAC guy
