The most important thing for your HVAC System is preventative maintenance. We’ve advised you not to panic when things go wrong. Instead, the time to panic is when you notice something is off. If the furnace makes a really bad sound, treat it for the cancer that it is. When something’s not running, you can calmly poke it and see what happens. It’s not going to get any worse because you knocked on the fuel tank to see if it was really full. When there’s symptoms of trouble however, every day is going to make things worse.
The First Symptoms
It’s 2012. I’m living with my parents, about to set off for college. The furnace kicks on and immediately something isn’t right. I can hear the water trickling into the baseboards. On the surface, this might not seem bad. You hear water all the time. You should never hear water in a baseboard or a radiator.
Your radiators should be filled to the brim with water. At the most, you might be able to hear a sort of hissing noise, the sound of water moving. I heard a dripping noise. If water can drip, there’s air in the line. If there’s air in the line, the heating system isn’t running under pressure, it isn’t sealed like it should be.
The furnace and water tank are pretty much filled with just water. Water flows into the heat exchanger. Water flows out of the heat exchanger. There shouldn’t be air in the equation.
The Last Symptom
Things took an interesting turn when it was time to come home. My parents called, we talked as usual. Then came that fun line, “and oh, by the way, the heater died.” I had told my parents to check into that heater before I left. The last thing that furnace ever did was die in the middle of a freezing winter.
The good news was my parents would have to fix it now. The bad news was just how catastrophic the failure was, and how avoidable the whole mess could have been. The furnace had ruptured its internal water tank. This internal tank was essentially the entire body of the furnace.
It would have started with a small crack, potentially helped along or caused by our hard water. As water leaked out, the furnace had to run more often to compensate for the loss of water. At the same time, air got into the system through this crack. Eventually the constant cycling created stress in the metal. The fracture expanded. At some point the internal tank couldn’t hold water at all. The furnace’s low water cut off prevented the burner from igniting, which probably prevented the entire thing from burning down or blowing up. If you don’t have a Low Water Cut Off (LWCO), get one. The “furnace is broken” call would have turned to a “got room in your dorm for guests” call or a “we’re moving to grandma’s” kind of call.
At this point, there was no saving that furnace. The furnace body was made of cast iron. Anyone who could have welded the crack shut would have charged more than the cost of a couple new furnaces. The ultimate solution here was to install a water softener to prevent the mineral build ups that helped the furnace fail and to put in a new furnace altogether.
For this type of repair, it’s actually a pretty straight forward process. The fuel supply is shut off, all connections to the old furnace are cut. The old furnace is removed. A new one is placed in the same spot. The old wires plugged in just as they had before. There were some new pipes to install for everything to connect. It would have been better to fix the issue sooner or save up for the failure, but as an experience in replacing failed equipment goes, this went well.
If you transition from one air system to another, one water system to another, so long as the fuel source is the same, it should be a pretty straight forward process, like changing a tire or changing a transmission. The bolts match up and you’re good to go.