With the cold season approaching, for many of us, it’s about time to start thinking about doing your Albuquerque Home furnace service. More recent furnace models don’t require much as far as getting set up for winter. A decade and more ago, it was recommended to have our furnaces and boilers checked annually. Now, thankfully, we have electronics on our side to do most of the work. Service techs now still clean and check them, but there are only a few things they really need to do to maintain the machine.
The old days:
Back in the old days, when a service man went out on a “clean and check”, he had several more things to look over. (Over 21 years ago, the politically correct term was “service man”, but has since been changed to “service tech”.) First, all the burners needed to be removed and blown clean with co2, the heat exchanger needed to be checked for cracks using a mirror, and then vacuum up any dirt and debris he finds he had dislodged. The “thermocouple” also needed to be changed. (On standing pilots, when the pilot flame is continuously burning, the thermocouple signals to the gas valve that it is safe to open, because there is a pilot light on. This starts the heat sequence.) The thermocouple is located with the pilot light, so the pilot light assembly needed to be blown out to ensure correct positioning on the thermocouple and that the flame would burn cleanly. Positioning on the burner pilot runner was also important to double check.
Next, he would pull the blower. There are two types of blowers, belt driven and direct drive. On a belt driven blower, he would check the belt for cracks, and oil the motor bearings and the squirrel cage bearings. On the direct blower, only the motor bearings needed to be oiled.
When all of these things are taken care of and put back into place, then he could move on.
A good service man would check the “limit switch”, which happened to be the most important part of the unit. In every furnace or boiler, there is a limit switch. Its purpose is to activate the blower and shut it off at proper temperatures. It usually kicks on at about 200’ and disengages at 100-110’, which would be about when you would feel like a draft was present. The most important function of the limit switch is to communicate with the gas valve if the blower fails, to shut down the burners. It keeps them from overheating and starting a fire. Boilers, like hot water heaters, also have a safety relief valve.
If the service man was more experienced and thorough, he would start the furnace burners after pulling the blower wire off of the limit switch. Once this happens, the blower cannot start. When the furnace reached about 200 degrees, the burners should turn off and until it cooled to about 140 degrees, it should reignite. Some checked only by playing with the dial on the limit switch and settings for the blower until the burners shut off. Taking the wire off the limit switch is a more preferred m flue could be considered a common occurrence. Sometimes, they even made it into basements. New furnaces no longer have that problem. Last, they would check for gas leaks.