When an emergency failure of your HVAC system occurs, your entire operation slows down or even grinds to a halt. Without developing a plan for this situation beforehand, you could be prone to rash decisions, exceeding your budget just to get the heat back on. Without a plan in place, even if that plan is just knowing whom to call, the outage could go on for days or even longer.
People come up with all kinds of makeshift solutions, but none of these can really get the job done. To minimize the time between your system failing and getting back to work, it could be a good idea to speak with your local HVAC contractor of choice ahead of time. Many regular preventative maintenance plans have emergency service built in. Generally, this only works if you have an existing relationship with a service expert.