A repairman recently found that the actuator and the high limit switches were not working when our 15+ Carrier gas furnace was only blowing cold air. There are separate thermostats for the downstairs and the upstairs.
I understand that he bypassed both of these controls until parts were ordered.This was on a Friday and left operating at full capacity like that until the new parts were installed the following Monday. Meantime, when he returned that Monday the coil on top of the unit had overheated and melted, as did a section of the ducting. My friend who lives downstairs said after the repair, when he got home from work, the CO alarm was going off.
Can these controls be bypassed and the unit allowed to operate for 3 days? I thought that this method of bypassing these controls should be for testing the unit on a temporary basis for testing, not left to have it operating at full capacity for this length of time. Could this have caused the further damage that was not present that Friday? Also, could any of these factors cause the CO alarm to be activated after the final repair? I was out of the state when all of this happened.
Please advise. Thanks.
Best Answer
Yes, you can bypass the high limit switch for testing. It's as trivial to do as it sounds.
It's the acme of foolishness to run it like that for any length of time, though, and I think you already know that it could cause more damage. The high limit switch is there to protect against the type of heat damage you describe, along with fire. I'm amazed that metal melted without burning down your house. And yes, CO can build up due to a clogged heat exchanger, which is probably what tripped the limit switch to begin with.
I'd get a different repairman and suggest to this one that he's lucky you aren't suing him for criminal negligence or unintentional homicide. Chances are what he did was actually illegal.