Does the Voltage or the Amperage Kill You?

I hear the following phrase a lot

It's the amperage that kills you not the voltage

While there is truth to the statement it is sort of like saying “it's the size of the vehicle not the speed that kills you when it hits you”…

OK so that's a pretty bad example, but hopefully, it gets the point across. BOTH of them are needed to cause injury or death and in the case of voltage and amperage the higher the voltage the higher the amperage.

This statement about amperage being the real danger as led to many people inaccurately believing it is the size of a panel or the gauge of wire that makes something more or less dangerous… which is 100% incorrect.

Let's take a quick look at OHM's law –

Amps = Volts ÷ Ohms 

The resistance (ohms) of the human body depends on a lot of factors including things like the moisture content of the skin, what other objects the current path is traveling through, what path the current is taking through the body etc…

While the resistances vary based on these factors Ohms law still holds true that when you increase the voltage you ALSO increase the amperage.

Take a look at this chart from the CDC

Effects of Electrical Current* on the Body [3]
Current Reaction
1 milliamp Just a faint tingle.
5 milliamps Slight shock felt. Disturbing, but not painful. Most people can “let go.” However, strong involuntary movements can cause injuries.
6-25 milliamps (women)†
9-30 milliamps (men)
Painful shock. Muscular control is lost. This is the range where “freezing currents” start. It may not be possible to “let go.”
50-150 milliamps Extremely painful shock, respiratory arrest (breathing stops), severe muscle contractions. Flexor muscles may cause holding on; extensor muscles may cause intense pushing away. Death is possible.
1,000-4,300 milliamps (1-4.3 amps) Ventricular fibrillation (heart pumping action not rhythmic) occurs. Muscles contract; nerve damage occurs. Death is likely.
10,000 milliamps (10 amps) Cardiac arrest and severe burns occur. Death is probable.

*Effects are for voltages less than about 600 volts. Higher voltages also cause severe burns.
†Differences in muscle and fat content affect the severity of shock.

Let's say that a particular shock is traveling through a 20 KOhm (20,000 ohm) path in your body

At 120V this would produce a 6mA shock

At 240V it would be 12mA

At 480V it would be 24mA

It becomes clear pretty quick that higher voltage does lead to more dangerous shocks as does the resistance of the path.

High Resistance and Low Voltage = Safer

Low Resistance and High Voltage = Danger

This is why working around live electrical should only be done with insulated tools, proper PPE and in dry conditions. These all serve to keep the resistance up to reduce the likelihood of a fatal shock. The higher the voltage the more diligent you need to be.

Some people may bring up high voltage shocks from a taser or static electricity as proof that “voltage doesn't kill”.

In these cases, the power supply is either limited, intermittent or instantaneous. This means that while the voltage is high it is only high for a very short period. Unfortunately in our profession, those sorts of quick high voltage discharges aren't the big danger we face, most of the electrical work we do is on systems that will happily fry us to a crisp before the power supply cuts out.

A circuit breaker or fuse will never protect us because we draw in the milliamp range when we are being shocked as almost all fuses or breakers don't trip or blow until much higher levels are reached.

Be safe around high voltage and keep your resistance high.

— Bryan




Oxyacetylene Torches: Tips and Operation


Everyone in the HVAC/R trade uses some form of torch to braze or solder alloys together. So what is the proper way to handle an oxyacetylene torch? Turns out, there’s more than one right answer. Depending on which torch rig you use, the manufacturer’s manuals for operation may vary. 

Everyone (hopefully) knows a neutral flame on a torch tip is suitable for most applications. Sometimes a carburizing flame is useful for reducing oxidation. The only flame we all should avoid is the oxidizing flame. However, in order to achieve the correct flame, a technician must fully understand the type of torch tip they are using, and the application for which the torch is being used.

For example, a “rosebud” tip is a (often) a large high BTU tip, and may be too large for most residential applications. A lot of technicians will attempt to lower the fuel and oxygen pressures feeding the tip to reduce the temperature. However, the tip begins to starve due to a lack of adequate fuel/oxygen mixing, and the flame will back into the torch tip and coat the inside with a carbon coating, which can damage the tip and torch over time. On the other hand, a torch that is too small will never get hot enough for an application outside its design parameters.

So what tips are best? At what pressures must tips be set? There are many answers to these questions, and they all depend on the brand of equipment you use, and the application in which you work.

I had the opportunity to speak to Tim Thibodeaux from the Service Dept. at Victor Technologies, and with Matt Foster from Uniweld Products, Inc. Both confirmed that pressures are tip specific, and operating procedures are brand-dependent. For example, many technicians have been taught to shut off the FUEL first when shutting down the torch, but this contradicts manufacturer instructions.    

Uniweld states in their operation manual to shut off the OXYGEN first at the torch when following proper shutdown procedures. This is done to prevent flashback, or backfire. 

Uniweld Shut-down Prodedure

Victor Shut-Down Procedure

Victor, too, requires the operator to shut off the OXYGEN first at the tip, then the operator may shut off the fuel valve. The reasoning remains the same: to prevent backfire/flashback. So where does this “Shut off the fuel first” myth come from? Turns out, it’s been taught that way for decades, but not without reason.

I had the opportunity to speak with HVAC/R Training Legend Bill Johnson, one of the original authors of the Refrigeration and Air Conditioning Technologies (RACT) Manual, and we spoke extensively on the topic. The RACT Manual offers an alternative method of shutting down the torch rig. The textbook teaches to shut the FUEL off at the torch first

“Shut off the fuel gas (acetylene) valve at the torch first”
Refrigeration and Air Conditioning Technologies (8th Edition)

I asked Bill Johnson why that was, and he explained it was a way of protecting the technician over the tool. Starve the flame of its fuel first, and eliminate the flame right away. Also, this was the way he had been taught many years ago, and the first edition of the RACT Manual was published in 1987. Perhaps there was once a manufacturer operation manual that specified the “fuel off first ” method, but the procedures have since changed. This method is not without merit, as its intentions are pure.

With the proper PPE and setup procedures, following the manufacturers’ approved operation instructions should be standard across the trade. Some would argue that shutting the oxygen off first can cause the little carbon “bunnies” that are created when the acetylene pressure is low enough. This is easily rectified by changing the way you setup the torch to begin with keeping acetylene pressure at the tip specified level.

Uniweld Tip 17-1

Matt Foster from Uniweld mentioned several operating tips for torch tips and setting a flame. The most common torch tip he finds most technicians use is the Type 17-1, and is good for pipes with an inside diameter of up to 1”. The manufacturer’s design operating pressures for this tip is 5 acetylene/5 oxygen. Another common tip is the Rosebud Type 28-2; its operating pressures are 5-7acetylene/5-8 oxygen, and it is good for pipes with an inside diameter of up to 1-5/8”.    (Caveat: According to Matt, these published operating pressures may be even higher, as torch tip engineering changes over time, and the current catalog has not yet been updated. Therefore, when in doubt, take a look at the spec sheet that comes with the torch tip, or call the manufacturer to clear things up).

The Uniweld welding/brazing tip rated operating pressures can be found in their catalog here. The Victor welding/brazing tip rated operating pressure can be found here. As you can see, there is no one right answer when it comes to setting regulator pressure at the tanks. In schools, it is often taught to set fuel to 5psig at the regulator, and oxy at 10psig at the regulator. Some say the pressures should be the same at the regulator. The purpose for the pressure specifications is to ensure proper mixing of the gasses for the best quality flame, and to protect the torch rig from damage and compromised safety functions. So the answer to how to set your oxyacetylene regulator pressures is: it depends!

In other words…RTFM! (Read the FANTASTIC Manual) Hopefully, this clears up any confusion about torch rig operation and setup/shutdown procedures. Remember to ALWAYS wear proper PPE when dealing with any flame (eye protection, gloves, etc, and avoid polyester clothing), and follow industry best practices regarding safety.

— Kaleb

5 Terror Inducing HVAC/R Stories & Facts

As the evening approaches on this All Hallow's Eve, Reformation day or Halloween (depending on your preference), let us take a moment to focus on some of the truly terrifying elements of our trade, because the Scariest stories are TRUE.

Real Ghost Stories 

The year was 1921 and a wealthy family purchased a new home in quiet part of town. It was a large, old building and the family was excited to live in such a majestic home.

The trouble started almost right away and the lady of the home (referred to only as Mrs. H) began to recount her experiences in the home to her doctor in letters that were later published.

This house was lit by gaslights and had servants quarters and passageways, a perfect house for a haunting. From Mrs. H’s account to her doctor:

“One morning, I heard footsteps in the room over my head. I hurried up the stairs. To my surprise, the room was empty. I passed into the next and then into all the rooms on that floor, and then to the floor above to find that I was the only person in that part of the house. Sometimes after I’ve gone to bed, the noises from the store room are tremendous, as if furniture was being piled against the door, as if china was being moved about, and occasionally a long and fearful sigh or wail.

“Sometimes as I walk along the hall, I feel as if someone was following me, going to touch me. You cannot understand it if you’ve not experienced it. But it’s real. As I was dressing for breakfast one morning, B, who is four years old, came to my room and asked me why I’d called him. I told him I’d not called him, that I’d not been in his room. With big and startled eyes he said, ‘Who was it, then, that called me? Who made that pounding noise?’

“I told him it was undoubtedly the wind rattling his window. ‘No,’ he said, ‘It was not that. It was somebody that called me. Who was it?’ And so on he talked, insisting that he’d been called and for me to explain who it had been.”

The hallucinations continued, with the family feeling the presence of the unknown. They experience hauntings, rattling beds, lethargy, and temporary paralysis. Even the plants began to wither and die.

Mrs. H continues:

“Some nights, after I’ve been in bed for a while, I’ve felt as if the bed clothes were jerked off me. And I’ve also felt as if I’d been struck on the shoulder. One night I woke up and saw, sitting on the foot of my bed, a man and a woman. The woman was young, dark and slight and wore a large picture hat. I was paralyzed and could not move.”

After speaking with different people about their malady with the spirit realm, a relative suggested that they are being poisoned. He had heard similar accounts from people poisoned by combustion gases experiencing similar symptoms.

It turned out that the gas lighting and the furnace were dumping carbon monoxide in the home. As soon as the furnace was properly vented their ghosts disappeared and life returned to normal.

This preceding story is one of my favorites from the Podcast and Radio Show This American Life which was brought to their attention by Albert Donnay, toxicologist and CO expert.

It makes me wonder how many of the hauntings in these old homes is due to CO rather than the spirit realm.

The Deadly Gift 

The year was 1938 and Walt Disney was just off of his first blockbuster success with his film “Snow White”.

Walt and his brother Roy decided to buy a new home for their parents in North Hollywood, finally moving them down from Oregon to be near their now famous sons. In November of 1938 their mother complained to Walt that the furnace smelled strange so he sent some of his studio repairmen over to have a look.

Several days later the housekeeper found both of Disney's parents unconscious in the home, with their mother Flora dying shortly after. Their father recovered shortly after, but many accounts say that Walt never forgave himself and was later heard mumbling

“I told those techs to buy a BluFlame combustion analyzer from TruTech tools before they went out. Heaven knows if they used the coupon code getschooled they would have had significant savings!”

All of my facts in that story are definitely, 100%,  maybe true.

In all seriousness, testing combustion and using low level CO monitors in homes and for yourself while working around combustion appliances can save many lives as well as undiagnosed illness and even a haunting now and then. See anything wrong with the furnace above?

Roofs and Ladders 

We were called out to a new high rise condo building in our area to maintain a bunch of rooftop equipment and what we found was an acrophobic nightmare. No guard rails, no parapet wall… just equipment, with much of it a few feet from the edge with sure death awaiting below.

Our service manager promptly called the customer and let them know that we would be back once they had measures in place to make the equipment safe to service.

Guess what they responded?

Nobody else has a problem with it

Whether it's equipment that cannot be safely serviced according to OSHA 1910.1 like the ones above or extension ladders put up through scuttle holes 20′ straight up we need to start making customers responsible for providing us with safe working conditions rather than just doing it because “Nobody else complained”.

Maybe a harness tied off can work the first time until they get a proper permanent ladder or guardrail or WHATEVER WORKS, but just going back time and time again and putting ourselves in danger is the definition of insanity.

Moisture Problems 

The pager went off at 2 AM… I was on call AGAIN because the guy who WAS on call quit right in the middle of his week… he just couldn't take this thing beeping at all hours. I grabbed the on call cell phone that was as long as your forearm and dialed the after hours voicemail line… YOU HAVE ONE NEW MESSAGE… the familiar robotic voice chirped at me.

The man in the recording sounded panicked “You were all out here earlier today and replaced an evaporator coil and now my WHOLE CEILING JUST FELL IN!”

Well… It wasn't his ENTIRE ceiling, just a large portion of his master closet ceiling over his suits and ties and patent leather shoes. All of this happened because the tech out earlier that day hadn't paid attention to how he strapped drain and there was a newly formed sag resulting in a double trap. Add in the fact that he had “moved” the pan switch out of the way and forgot to reinstall it properly.

Water damage, mold and mildew, lawsuits and 2 AM service calls can be prevented by paying attention to –

  • Drain pitch
  • Float Switch Location and Testing
  • Drain Cleaning
  • Pan Positioning
  • Proper configuration of drains in horizontal applications
  • Drain Cleaning

Many of the biggest nightmares in my career have been due to drain issues and moisture due to surfaces hitting dew-point. Keep the moisture where it belongs and the pager will stay quiet… who has pagers anymore anyway?

The Tiny Plug

I was sitting on the couch the other evening watching football when my oldest son who rarely has much to say piped up and said

“Dad, what happens if you test gas pressure and forget to put the plug back in”

The hair raised on parts of me where hair shouldn't raise.

Turns out he was just curious and hadn't actually forgotten to put the test plug back in on a valve but it did get me thinking that there is nothing quite so scary in our trade as a combustible gas leak and none more odious than “forgetting” something that critical.

When working on gas appliances always make sure to leak check connections and for gas bypassing the valve during the off cycle using a combustible gas leak detector…. Trust your nose as well… if you smell gas odorants then investigate.

Most of all…


Whatever you do…

Don't forget to put the little plug back in after testing the gas pressure.

Also watch out for razor blades in your apples tonight… or better yet… don't eat fruit being handed out during Halloween. What sort of demented psychopath hands out fruit on Halloween?

— Bryan

Oxygen Safety Tip – No Oil and Grease

Some of the scariest practices that occur in the field surround brazing practices and tank and regulator handling. A few obvious tips are….

  1. Store tanks completely secure and upright with nothing nearby that can easily open or damage the tank valve
  2. NEVER store tanks in a torch kit with it off only at the torch handle. always turn off the main valves and purge out the gas and oxygen when done.
  3. Remove regulators from tanks when not in use.

And now to the point of this article that you may not be aware of –

Do not use oil or grease anywhere on oxygen regulators unless it is a product specifically designed for that use

Many techs incorrectly believe that an open flame is required for combustion and this is simply not true. If you have ever seen or heard of a fire starting in a pile or barrel of greasy rags you know that heat can build when fuel sources oxidize until the the temperature increases to the combustion point. Pressurized oxygen can cause “adiabatic” combustion when a fuel source is present and can be a very real risk.

So keep your regulator threads and adjustment screw nice and clean and don't put grease or oil on them unless you know 100% the product you are using is for that purpose.

Stay safe out there and treat all pressurized gas containers like you would a loaded gun, with great caution and attentiveness.

— Bryan

Lifting Techniques Part 4 – Using Unistrut

This is Part 4 series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one folks, I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life.


This article is written by a technician representing his real-world experiences and his advice for best practices. You MUST understand the particular application, weight of materials and load strength of every item you use. From struts to pulleys, to anchors, ladders, ropes etc.. HVAC School is NOT giving OSHA approved safety advice. Refer to your managers, safety professionals and OSHA guidelines first and foremost. Apply any and all of these practices at your own risk with the knowledge that we are trying to help keep you from hurting (or killing) yourself.

Unistrut is your friend

The idea for a site built, customizable, gantry struck me about 4 or 5 years ago. I started by throwing a piece of unistrut over a pair of plastic folding sawhorses on the roof. The whole shebang collapsed and I had to muscle the compressor plus the weight of the strut onto the roof but I was convinced that the idea was sound. From that simple setup, I've experimented with using ladders, fall protection fences, and various supports I built out of unistrut. I've had varying degrees of success and have settled on a design that works and can be modified to suit the conditions on a job site.

Let's start with a solid base. Looking at the “T” shaped part laying on the roof, make each piece 6’ long at a minimum and and bolt them together with a proper brace. From that solid base, install an upright and the angle bracket, again using proper fittings. The angle brace should be 2 to 4 feet long depending on the height of the upright and the height of the upright depends on what your job requirements are. I've used them from 30” high to one that was almost 15 feet high. Now, build a second upright, same as the first one. Remember that crossbar I said we had to just “accept” that is was there? Now it's time to put it there for real. Using a couple 90° brackets, bolt your cross piece to the two uprights and check for level..

This may seem complicated to build and maybe it is, but a part of this is laying out the basis for some other stuff later. These pictures are from a lifting job I did. 2 15 ton Copeland scrolls up through a roof hatch that came out on a mezzanine, trolley over and lowered to the main roof level.

Note in the last picture, the chainfall is connected to a device extending out of the unistrut. That's a trolley and it makes moving those loads once you get them up onto the roof very easy. Let's go back to our block and Tackle example earlier. The crossbar is a piece of unistrut and, instead of connecting your pulley and rope to the bar directly, connect it to this trolley. It is now very easy to lift that load right through the roof hatch, trolley it to one side or the other and lower it onto a cart or a dolly for transport across the roof surface.

A really nice, slick setup based on this that I use very frequently is for loading and unloading these out of your truck. My van is outfitted with commercial steel shelving. If yours isn't, you may want to just skip this part. So, cut a piece of unistrut to fit across the top of those shelves. You should really have to work to get it in and out. Once it's wedged in there, it isn't going anywhere. Now, take a longer piece and support it across the rungs of a ladder parked 4-5’ off the back bumper. Bolt that piece to the crossbar you just installed and, using a trolley and a ¼ ton hoist, you can easily move a compressor in and out of your truck.


Now for the cautionary stuff. Unistrut is awesome. It's strong and relatively light, but there are limitations to its strength. Please, before you build anything I'm suggesting here, know exactly how much your load weighs and exactly how much every single piece of your lifting equipment will support. I suggest a 2:1 safety factor if at all possible, so if you're lifting a 100-pound load, make sure that everything in your lifting system is capable of handling twice that weight. Strength information about unistrut in its various applications can be found HERE As you use this reference, pay attention to point load ratings and span figures. As span increases, point load decreases. You DO NOT want that strut failing under a load so keep your loads within the limits of your equipment. If you look closely at the crossbar I use, you'll see that it is thicker than normal 1 ⅝” unistrut. That's a 2 ⅛” piece and is much stronger. If you're going to do heavier lifts, you really need a heavier crossbar like that. Be aware, the engineering specs and the catalog are very dry, boring reading but take the time to learn and know what your lifting gear will do before you have to really stress it and potentially injure yourself or someone else. Remember, the point of this is to lift and move things safely…

— Jeremy
Shopping list
Genuine Unistrut P2950-EG 4 Wheel Trolley Assembly for use with P1000, P1001, P5000, P5001, P5500, P5501 and All 1-5/8″ or Taller Strut Channel

Genuine Unistrut P1325-EG 4 Hole 90 Degree Angle Connector Bracket for All 1-5/8″ Strut Channel

Genuine Unistrut P1031-EG 4 Hole “T” Shaped Connector Bracket for All 1-5/8″ Strut Channel

45° inside brackets for unistrut

Lifting Techniques Part 3 – Complex Block & Tackle

This is Part 3 series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one folks, I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life.


This article is written by a technician representing his real-world experiences and his advice for best practices. You MUST understand the particular application, weight of materials and load strength of every item you use. From struts, to pulleys, to anchors, ladders, ropes etc.. HVAC School is NOT giving OSHA approved safety advice. Refer to your managers, safety professionals and OSHA guidelines first and foremost. Apply any and all of these practices at your own risk with the knowledge that we are trying to help keep you from hurting (or killing) yourself.

Complex block and Tackle systems

Now that we have a basic understanding of how to handle ropes, tie knots and rig a basic pulley system, we're ready to dive into more complicated systems. I reserve these for buildings that have a roof hatch so that I can setup a gantry over the hatch. I haven’t yet figured out a system to extend a beam over the edge of a building, but I'm working on it. I'll go into the basics of how I build and what I build in the next section. For now, let's just accept as a given that we have a solid beam installed over the hatch opening to connect ropes
and pulleys to.

For jobs like this, I keep a double pulley on the truck. Threading or ‘reeving’ these takes more time and is more complicated but the reduction in effort is worth it. Start by fixing your single pulley to the overhead beam and connecting the double one to a light “load” like a wrench or something similar. Tie one end of the rope to our overhead beam. Start threading by running the other end through one side of the double pulley then through the single, through the other side of the double. Now, you should have a nice mess of rope. Lower that weighted double pulley to the spot where the load is and secure the free end of the rope with a clove hitch just to keep it from falling and to keep a tiny amount of tension on the system.

The setup shown here was used to hoist a 15 hp blower motor onto the roof. Motor weight was something like 145# With 4 lines supporting the load, the effort to hoist that motor was less than

I like to stand on the roof while hoisting, so I make it a point when threading pulleys to wind up with the pull end of the rope going up. This also has the advantage of using every line to support the load and obtaining maximum effort reduction.

As before, connect to the load and hoist it slightly. Check for good balance, twisted ropes and crossed lines. Make any corrections and hoist away. Since we're hoisting to an overhead beam, there won't be any need to take 100% of the load at any time, so this method is much safer and, when we dig into the gantry build, we'll find a great way to manage the load once it's at the top of the lift. As the loads get heavier, you'll be using heavier and heavier duty hardware to attach to them. Eye bolts, shackles and chains are the rule here.

— Jeremy

Shopping list…
Stanley National Hardware 3214BC 1-1/2″ Zinc Plated Fixed Double Pulley

Crosby 1018393 Carbon Steel G-209 Screw Pin Anchor Shackle, Galvanized, 3/4 Ton Working
Load Limit, 5/16″ Size

Lifting Techniques Part 2 – Pulleys

This is Part 2 series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one folks, I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life.


This article is written by a technician representing his real-world experiences and his advice for best practices. You MUST understand the particular application, weight of materials and load strength of every item you use. From struts to pulleys, to anchors, ladders, ropes etc.. HVAC School is NOT giving OSHA approved safety advice. Refer to your managers, safety professionals and OSHA guidelines first and foremost. Apply any and all of these practices at your own risk with the knowledge that we are trying to help keep you from hurting (or killing) yourself.

Simple pulley systems

Let's get into the meat of lifting and moving heavier loads…

One thing that I use a LOT is a basic pulley. Simply put, when using a pulley or a system of pulleys called a Block and Tackle, the amount of force required to lift a load is the total weight divided by the number of lines supporting the load. An overhead pulley system doesn't reduce lifting force at all. It does nothing more than redirect the force applied. Since there is only one line supporting the load, there is no reduction in force required to lift the load.

A pulley connected to the load with one line tied off and pulling force exerted on the other end of the rope will cut the force required in half for lifting a load. Here, with 2 lines supporting the load, the force or effort required to lift the load is cut in half.


In practice, I limit this to loads of 50-100 pounds or so because at the end of the lift, you will be lifting 100% of the weight. For your first couple lifts, try to stay on the lower end of these weights until you build confidence in your techniques. We'll get into more complicated systems with more pulleys and lines in a later section.

Start by tying off one end of the rope to something secure. This is your anchor point. Best case scenario, there is something they're purpose-built to anchor to. Worst case scenario, I've actually tied a loop around the entire curb assembly of a rooftop unit.

Remember, use good knots. The ONLY knot that I trust in this situation is a bowline. Now that we've got our rope anchored, slide the pulley onto the rope and lower that pulley to your load. Tie the other end, the lifting end, of the rope off to something, anything really. A clove hitch is quick and easy here. All we’re doing is keeping the rope in place so it doesn’t fall. To connect the pulley to the load, I like to use a climbing carabiner with a screw lock. Cheap carabiners that you can get at most home improvement Warehouse stores are NOT suitable here. If all they do is bend under the load, count yourself lucky.

If there is a lifting eye or provision to install one on the load, use it and be sure to lock the eye bolt in place with the included nut, otherwise, the load can unscrew itself from the bolt and fall. That is going to be the best and safest place to connect your pulley to the load. Now, back up to the roof and take a couple seconds to straighten out the ropes. Get any twists out of the system and lift the load a short distance off the ground. Check everything. Is your anchor solid? Are you comfortable with the load? If everything is good and you're comfortable with the lift, then continue pulling the load up to the roof edge.

Remember when I said to limit the weight? Now you’ll see why. You've got the load almost there…. You're going to have to squat to the load, grab it and haul it over the roof edge. Yeah, it sucks but not as bad as hauling the whole load all the way up the side of the building. This is where a carabiner is nice because that big metal loop gives you a solid handle to grab
and hang on to.

— Jeremy

P.S. – Today's Shopping list

Stanley National Hardware 3213BC 1-1/2″ Zinc Plated Fixed Single Pulley

Mad Rock Ultra Tech Screw Carabiner


Lifting Techniques Part 1 – Basics

This is ANOTHER series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one folks, I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life.


This article is written by a technician representing his real world experiences and his advice for best practices. You MUST understand the particular application, weight of materials and load strength of every item you use. From struts, to pulleys, to anchors, ladders, ropes etc.. HVAC School is NOT giving OSHA approved safety advice. Refer to your managers, safety professionals and OSHA guidelines first and foremost. Apply any and all of these practices at your own risk with the knowledge that we are trying to help keep you from hurting (or killing) yourself.

I know, I know… everyone is super strong and nobody needs any help lifting those big, heavy compressors and motors. At least that's what a guy could think if he just reads the HVAC pages

Reality check. If you're lifting anything over 50 pounds and are not using a mechanical device to do it, you're risking serious injury. I speak from experience here. In 2016, I spent 16 weeks off of work progressing from Chiropractic care to physical therapy and ultimately had to have surgery to repair a herniated disc. The injury resulted from a twisting motion when a 200lb compressor we were throwing into a scrap bin went sideways and started to fall on me. I caught it but I didn't avoid a painful injury…

Hopefully, I’ll be able to share more than a few tips, tricks and techniques to help you work more safely and more effectively and inspire you to learn more about this subject. By no means should this be taken as a comprehensive treatment of the subject of lifting and rigging, but just a primer with some cautions and warnings and the advice to go slow and always, ALWAYS double check yourself **before you wreck yourself** (**Added by Bryan in editing… because he's a child)

Let's lay down some baseline rules. Not to be “preachy crossfit guy” but keep your core strong. Sometimes, you just have to gut it out and move a heavy thing. Those core muscles are what prevent injury when your body goes outside of your normal range of motion and, if they aren't strong, they can't support your spine and skeletal system and that's when you get injured.

Also, when you just have to lift using body strength, use proper techniques. We all know the words “Lift with your legs, not your back” but how many of us actually DO? I can tell you for 100% certain that any time I’m moving to lift something, I’m using proper techniques whether it’s a refrigerant drum or a screwdriver I dropped. Now get down and give me 20 squats!

As we get into the application of ropes and pulley systems, we will be tying knots. Knot tying can be a very involved topic but you can do everything were going to be doing with the bowline and the clove hitch. If you can't tie either of those knots, here are links to simple videos that illustrate how to..



If you attempt any of these techniques with inferior knots, you run a very real chance of losing control of that load and injuring yourself or someone else and damaging that expensive part.
Another thing to take a bit of time to learn about is basic rope care. A knotted, twisted rope isn't as easy to set up and you'll waste time dealing with twists, knots and tangles. Learn to coil and stow your rope well and this stuff will be a lot easier.

A quick note on rope. Buy good rope. Avoid the 3 strand twisted rope. It's stretchy and the ends unravel and are difficult to manage. What you want is called Kernmantle rope. This is the type of rope that has a kind of braided “sheath” over inner fibers. It's stronger, doesn't stretch and it rides much easier through pulleys. Burn the ends well to prevent them from getting out of control.

One final note. Wear a decent pair of relatively snug fitting gloves while hoisting and lowering loads with a rope. If that rope starts to slide, the burns you will get on your hands take a long time to heal.

Now, basics covered, we can move on to actually lifting things.

— Jeremy

P.S. – Here is a good rope ROTHCO UTILITY ROPE 3/8” 100 FT / OLIVE DRAB

Boiler Basics Part 2 – Components

This article is the second in a series on boiler basics by senior boiler tech Justin Skinner. Thanks Justin.

There are many types of boilers that do a lot of different things, but most all of them have some of the same basic components. Some because they are required by regulatory agencies, some because they are necessary for proper operation and safety of the boilers. But no matter how large or small the boiler is, you can probably find most, if not all of these components.Unless noted otherwise, these are typical for hot water boilers.  



Every boiler needs some source of heat, obviously to heat the water. The type and sizes of burners vary so much that a few complete articles would be required to really get into detail as to how they operate and the specific operations of each burner. All burners serve the same function, which to safely and efficiently burn fuel and create heat. Typically, the flame safeguards are integrated in the burner control sequence, in that certain conditions need to be met in order for the flame to light, similar to gas furnace pre-ignition sequence of operations. A blower with air dampers for adjustment is often part of the burner, and air/fuel ratios are adjusted at the burner during combustion analysis. Ignition transformers/control boards, ignitors, draft pressure switches, flame sensing devices (flame scanner/ flame rod), and a primary controller to sequence all of it together are all apart of most burners. Honeywell, Fireye, Siemens, and a few others are common  burner controls that are all different, but essentially do the same thing. Some of the most common burner manufacturers ( at least in my world) are Powerflame, Webster, and Beckett, but there are a lot of burners out there. It is  common to see a dual fuel set up on larger burners, meaning they are capable of burning 2 types of fuel, typically gas and oil. Steam and hot water boilers both use burners.

Oil Fired Boiler

Gas Fired Boiler


Water feeder

Most water boiler systems are sealed, meaning that they are filled with water, the air is bled, and the same water is circulated throughout the system. In a perfect world, no additional water would be required, but most systems lose water and pressure through a variety of ways. A automatic water feeding valve is used to keep the system at a set pressure. There are many types with many different pressure ranges. The proper term would be pressure reducing valve, but i’ve always heard them called water feeders, so that is what I call them here. Back flow preventers are often used with water feeders. Once the water enters the boiler system, it should not be allowed to go back and re-enter the domestic cold water system. Boiler water can be pretty gross, and often contains chemicals for water treatment so be mindful and safe when opening the water side of any boiler system.

Typical Water Feeders (PRV’S)


Pressure/Temperature Relief Valves 

Relief valves are used to protect the boiler pressure from rising above the safe maximum that the boiler is rated for. The pressure rating on the relief should never be above the pressure that the boiler is rated for. Also, relief valves come with a BTU rating and are sized to match the fire ratings of the burner. This is crucial to keep in mind when replacing a relief valve. A valve that is too small may open prematurely, and a valve that is too large may not open at the pressure it is supposed to. There are calculations and recommendations that are used to size relief valves that I’m not gonna give here, but if you are replacing one or having issues with one and you are unsure, ask a senior tech or contact the manufacturer for recommendations. But keep in mind that the relief valve may be the last line of defense in preventing a boiler explosion, so treat it as such. NEVER plug a leaking relief valve, it is kind of illegal. Found on both steam and water boilers.

If you do this, you are fired!


Operating/Modulation/High Limit Controls 

These are controls to maintain a set range for water temperature, the burner modulating from high to low fire (for modulating burners), and as a safety to prevent temperature rise above set point. These are used in both water and steam boilers, and i will go over them in more detail in the next article.


Circulator Pumps 

Are used to move water through the boiler and the system. Some pumps are controlled on and off by the boiler, some are controlled by building automation, some are just on   and run constantly. Flow sensors are often used to insure proper water flow is present in the boiler, and will disable burner operations if the flow is decreased below what is recommended.

Pumps come in all shapes, sizes, and voltages.


Low Water Protection 

When a boiler gets low on water, it can be a very dangerous situation. Low water safeties are used to disable the burner when low water conditions are present. Steam and water boilers both require protection, but low water controls for steam are generally much more crucial than a typical water boiler, as the risk with steam and boiler low on water can be severe.


This is by no means a comprehensive list, just a general overview, and I’m sure i missed something that you all will let me know about. With the huge variety of boilers out there, it would be tough to list every single thing that you might run into. These are all very common and the things that i seem to replace or have issues with the most.   I will expand on steam specific controls and components in the next article.

— Justin


Lifting Techniques Part 5 – Really HEAVY Stuff

This is Part 5 series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one folks, I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life.


This article is written by a technician representing his real world experiences and his advice for best practices. You MUST understand the particular application, weight of materials and load strength of every item you use. From struts, to pulleys, to anchors, ladders, ropes etc.. HVAC School is NOT giving OSHA approved safety advice. Refer to your managers, safety professionals and OSHA guidelines first and foremost. Apply any and all of these practices at your own risk with the knowledge that we are trying to help keep you from hurting (or killing) yourself.

Heavy stuff and getting creative, safely

Alright, we've got the basics down. Knots are no problem, rigging up a 100# compressor is a piece of cake and the boss has started to send you on those heavy lifting jobs because you can confidently do them easier, faster and more safely than your coworkers. Then he drops the bomb on you…. Next week, he needs you to change out another compressor. The catch?? It's a 25 HP Copeland 4D model. A big girl. A compressor like that weighs about 450 pounds. This isn't the time for ropes and pulleys, we need to get some
serious hardware out.

Enter chain hoists and chainfalls.

Now, if it needs to go onto a roof, DO NOT use these methods unless there is absolutely no alternative. I've used them on second floor indoor lifts, but if you can use a crane, USE A CRANE. I worked to develop these techniques to fill the gap between compressors like the big 4D where a crane isn't a question and something like a 9000btuh mini split compressor that doesn't weigh but 20 pounds or so and to help in the final positioning of that machine.

Now, we can lift some stuff…

Not so fast… We still have to connect to it. Up until now, the forces involved haven’t been enough to bend or break lifting hardware but, with loads weighing hundreds of pounds and the real possibility of putting angular stress on components, we need to talk about lifting eyes, shackles, chains, straps and some other fun stuff.

Lifting eyes are exactly that. They are designed to have force applied to them in a certain way and, if force is applied in the wrong direction, the bolt can bend or break.. Force is ideally exerted straight up and down. If that force needs to be applied at an angle, you need to back up a step and slow down. Can you figure a better way to do the job? Is there a better way to hook up the load to avoid stressing the bolt in that direction? If not, there are 2 basic rules for using that eyebolt with angular force applied.

#1. Keep the force applied in the plane of the eye. Pulling sideways on the eye will bend it.
#2. Don’t let the force angle go past 45°

Before we move on from eyebolts, a couple more things. There is a difference between a plain eye bolt and a shouldered eye bolt. Use the shouldered eye bolt. It’s stronger and is designed to be used for lifting, especially if you need to put any angular force on it. Also, when installing an eye bolt, it needs to be tightened properly and of proper length. If the eye bolt is sticking way out of the threads for it, that allow the applied force to be able to bend that bolt much more easily.

Chains vs. Straps

Frequently, I find myself setting up complicated lifts that require multiple anchor points. For making anchors, particularly around structural steel or unit framework, I prefer to use short lengths of chain and a shackles. The length of chain tends to be almost self centering once a little force is applied to it and the shackle is a good anchor for whatever machine I'm using to lift or pull with. Straps are handy to have around but, as my skills in this area have developed, I've come to find that most lifting straps have a degree of stretch to them which can make precise positioning difficult and, when I've got a 600# motor in the air and I'm trying to lift it a fraction of an inch, just to clear a mounting bolt or to slide a shim in place, I don't want any variables that I can't control. Chain doesn't stretch. It's just one less thing to worry about while that load is in the air.
Now, we can start getting to work. I carry 2 or 3 ¼ ton lever chain hoists on the truck and have a ¾ ton lever hoist and a 1 ton chain fall easily accessible for larger lifts. Some guys use a
cable puller or a come along to lift with, and I did so for a lot of years, but those types of devices aren't ideal for that purpose. This is where things kind of leave the realm of what can be taught or explained. I can't necessarily design or explain how to build a gantry or lifting system to move a compressor in a place that I've never seen. Look around. Use structural steel, unit framing, unistrut, and threaded rod to create a custom lifting gantry. Here are some examples of site built rigs I've used to change out compressors.




Note that the unistrut is bolted to the top of the ladder to prevent falling. Creativity and stability is key, here. Go slowly and be very careful lifting loads. Very often, you don’t have to lift it many feet in the air, but only a fraction of an inch to get it to clear whatever is holding it then, with the trolley, it will slide easily out of place and back in again…

Getting Creative

A challenge that was posed to me was to setup a rigging system to take a 30HP compressor from ground level to the second floor up a flight of stairs without touching a step. Someone in the past had made something like a pair of skis out of unistrut and dragged the compressor up the steps using that setup. This broke the edges off of several steps and created trip hazards. Take a couple minutes and consider this challenge. Come up with your plan.

Now, here is how I did it.

At the top of the staircase, I had a piece of unistrut wedged into the structural steel. A solid anchor point. I went to the ceiling above the bottom of the stairs and installed another anchor
point. At the bottom of the stairs, I installed a small anchor point away from the bottom of the steps.

At the top of the stairs, I setup a 1 ton chainfall. Above the bottom of the stairs, I setup a come along (I know I said they aren't ideal. They aren't. It's just what I had to work with) and I setup a small chain hoist between the bottom of the steps and the anchor. In practice, each hoist connected to the load. Start by pulling the load back, away from the steps. Now, start taking up the weight with the hoist above the base of the steps until it is high enough to clear the steps. Let out the small hoist and disconnect it. Now, start swinging the load up the staircase using the chainfall, adjusting the height as necessary with the other hoist. This basic technique is one that I use frequently. I've called it “the trapeze” or “pick and swing” and, to be honest, I don't know if it has a formal name, but it's a very useful lifting technique to have in your toolbox. A variant on this idea is using one hoist to primarily lift the load and two hoists to kind of steer the load into place.

Thanks for sticking with me through this. I hope that you’ll take these techniques, adapt and apply them to your own needs and hopefully you’ve found something in this to help to prevent
injury and to make those bigger jobs a little easier.

— Jeremy

Shopping list

Roughneck Manual Lever Chain Hoist – 1/4-Ton Capacity, 12in. Head Room

Lever Block Chain Hoist 3/4 Ton 1650 lbs Capacity, 5′ Lift – Tec-union

1 ton chainfall


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