My great-great-great red-headed grandfather (bless his whiskey-drinking soul) who lost the family distillery when he hastily threw another gentleman out the top of a barn, haunts me daily. Perhaps the most famous of my forebearer's axioms is: If anything can go wrong, it will; much more commonly known as Murphy's Law. Still, there are many other laws from the House of Murphy, most of which are ignored - in similar fashion to the way that I am ignored in my own house today. One of those laws states: Never miss an opportunity to dispute the authority and impugn the integrity of the father.

There is a vast array of laws that pertain to our daily lives, whether we know it or not. The law of gravity keeps our feet planted firmly on the ground. The law of relativity, simply stated, is the relationship of all things understood by the particular viewpoint from which they are seen. As the viewpoint shifts the relative relationship of those things also becomes different. For example, the relative viewpoint of someone looking at the front of a horse is somewhat different than the view of another person from behind the horse.

In the world of HVACR there are even Thermodynamic Laws that govern some of your daily activities. Thermodynamics is the field of physics that studies the properties of systems that have a temperature and involve the flow of energy from one place to another. (Wow! I just thought it was about gases and flatulence.)

However, perhaps the most important information to consider as guidance throughout your HVAC career is conveniently contained in the complete list of Murphy's Laws. These have even been conveniently subtitled for ease of use with the appropriate HVAC corollary. Here are but a few to help you as you plan your day:


Murphy's Law of HVAC Systems:An engineering firm will invariably lease office space in a building with a lousy HVAC system.HVAC Corollary:Charge customers more for watching over your shoulder.

Murphy's Law of Thermodynamics: Things get worse under pressure. HVAC Corollary: Be sure to test the high limit switch.

Murphy's Law of Paperwork: The legibility of copy is inversely proportional to its importance. HVAC Corollary: Invoices should be printed in your best penmanship and with concise eloquence.

Murphy's Law of Safety: A dropped power tool will always land on the concrete instead of the soft ground (if outdoors) or the carpet (if indoors) - unless it is running, in which case it will fall on something it can damage, such as your foot. HVAC Corollary: Do not skip out on the company safety meetings.

Murphy's Law of Tools: After you bought a replacement for something you've lost and searched for everywhere, you'll find the original. HVAC Corollary: Take care of your tools and do not loan them to anyone.

Murphy's Law of Repair: When a broken appliance is demonstrated for the repairman, it will work perfectly. HVAC Corollary: Customers do not understand how to set their thermostats.

Murphy's Law of Golf: The best golf shots always occur when playing alone. HVAC Corollary: Some things are best left alone. The boss doesn't need to know you're playing golf on his time.

Murphy's Other Law of Golf: Nothing motivates a person more than to see the boss putting in an honest day's work. HVAC Corollary: If you're the boss, don't tell the employees you're golfing on Friday afternoon.

Murphy's Law of Cell Phones: Having the right of way won't make you any less dead. HVAC Corollary: Pay attention while you're driving.

Murphy's Law of Service: The mud that won't come off on the doormat immediately adheres to the carpet.HVAC Corollary: Take off your shoes before entering a customer's home.

Murphy's Law of Invoices: If mathematically you end up with the incorrect answer, try multiplying by the page number. HVAC Corollary: Use a calculator.

Murphy's Law of Parts: A difficult task will be halted near completion by one tiny, previously insignificant detail. HVAC Corollary: Check your truck inventory before leaving the shop.

Murphy's Law of Electricity: It is never wise to let a piece of equipment know that you are in a hurry. HVAC Corollary: Don't forget to throw the disconnect switch.

Murphy's Law of Callbacks: Don't fix something that ain't broke because you'll break it and you still can't fix it. HVAC Corollary: Parts changers never prosper.

For your own copy of Murphy's Laws, contact Murphy. Resources for this article include

Mike Murphy, Editor-In-Chief, 248-244-6446, 248-244-2905 (fax),

Publication date: 05/08/2006