Testing, Recovery and Charging a Sealed System

There are many appliances with compression refrigeration circuits that do not have ports installed for testing, recovery, charging and evacuation.  These can include window units, PTACs, fountains, refrigerators and much more.

This presents a challenge any time you suspect or know there is a refrigerant circuit issue. How can you diagnose and make a repair when you can't connect?

First, when an appliance is a sealed circuit DONT OPEN IT UNLESS YOU HAVE A GOOD REASON TO DO SO.

If you do need to open the circuit, first look for factory “process tubes” often on the compressor or on the lines near the compressor.

You can then either add a piercing valve to the tube or you can often pinch off the tube with a pinching tool, Leave the tool in place, cut the process tube/stub near the end and solder / braze in a Schrader to the end.

Common pinch off tools

Once the new port is added you simply remove the pinching tool and form it slightly back into shape. It does not need to be completely re-rounded because the size of these types of systems will generally be small so recovery speed will not be a huge factor.

You can then recover the charge and once the charge is fully recovered you can add in additional soldered/brazed in ports.

Another method is to use a piercing line tap valve to access the system like the ones shown below.

These should also only be left on as a temporary measure to get the refrigerant recovered. You then must repair the “pierced” hole, usually by putting a tee schrader in the same spot where the piercing was.

Once you have good, solid access points in place (don't forget to flow nitrogen), now you can proceed to evacuation, weighing in a factory charge and then performing further diagnosis.

If done correctly the appliance will have no leaks at the ports and will be much easier to service next time.

Keep in mind when working on systems with very small charges that hoses can hold a lot of refrigerant. You may consider using Smart Probes with tees and only one short 1/4″ hose from the charging tank to the suction probe to reduce losses.

Also make sure the hose is well purged before starting the charging process. Keep the air and moisture out.

— Bryan

Common Concrete Anchor Fails

No matter what trade you work in you will need to use a concrete anchor at one time or another. Here are some mistakes I have seen (and made) that you are going to want to avoid.

Know your concrete

Is it concrete block hollow cell? Poured cell? Concrete slab? What is the PSI? Not all anchors are created equal for every type of concrete. Make sure you know exactly what you are fastening into and choose the right anchor.

Tapcons are light duty

First off “tapcon” is just a brand name for a type of screw in concrete anchor so take the name with a grain of salt.

Your typical threaded “tapcon” is for light duty tasks. While a tapcon may be fine to hold down a condenser (that already want to stay down), it would probably (definitely) be the wrong option for mounting a heavy motor assembly to the wall. For big jobs go with a tougher anchor. Hint: if it has threads and you “screw” it in, it probably isn't the toughest option.

Anchors embedded too shallow

Most concrete anchors have a minimum embedment depth. You can usually embed deeper but you need to at least hit the minimum, read the directions.

Anchors too close

All anchors have a minimum distance they can be from one another. If you get them too close the whole kitten kaboodle can pull right out on you (I've done this).

Don't over drill

Wedge anchors (Red Heads) are a common heavy duty anchor. When drilling the hole wrap electrical tape on your bit at the depth you want to go so you don't over drill the hole or worse…. blow out the other side.

Clean the hole

With a wedge anchor, the dust in the hole can act like a lubricant, making it easier for it to pull out. When done drilling use a round bottle brush or vacuum to clean the holes out. This is especially true when using an epoxy “chemical” bolt.

Warbling the bit

With concrete anchors, use the right size bit and run it straight it. No warbling the bit around… unless your desired result is having the anchor pull out and destroy a monastery, then warble away.

Torque it down

Sorry, you do really need a torque wrench, especially if you are working with large wedge anchors. Torque that sucker down to factory specs and you won't need to worry. Keep in mind, you may wanna retorque it after it's been put under load a few times, especially in safety-critical applications.

Don't overload it

Before you get started make sure you know the  Ft/lbs of force the anchor will be under and play on the safe side. Like GI Joe says… now you know, and knowing is just scratching the surface.

— Bryan

P.S.- you can watch a video on wedge anchors HERE

Technician Head Trash

It's Friday at 6PM… The schedule is clear as far as you can tell… other guys have been getting cleared right and left… so you call in standby.

5 minutes pass

10 minutes pass

You check in again… and sure as &%$#!

You get sent across town to another call that YOU KNOW has been there ALL DAY. That dispatcher is trying to make you pay because of that time you threw her under the bus to the service manager because she has been taking FOREVER to get you your calls!

I'm pretty sure this exact scenario has happened to me several times and I know these sorts of thoughts go through the minds of techs all around the globe on a daily basis.

We can pick on dispatchers but it isn't just them

  • The new apprentice who ALWAYS loses your tools because he's sloppy
  • The other tech who ALWAYS gets stupid callbacks that you have to run after hours
  • The lying customer who “just changed” their filter when it looks like it's been in since Reagan was in office
  • The Wholesaler counter guy who doesn't know a drier from a TXV
  •  The Manager who hits you with a callback when it WASN'T YOUR FAULT! (and it wasn't a callback anyway)
  • The CSR who NEVER gets the address right in the call and you end up driving all over creation only to find out it was Prestwick Ln. NOT Prestwick Place
  • The idiot installer who NEVER sets the charge right and ALWAYS leaves the gas valve off!
  • And don't even get me started on SALESMEN!

People treat you wrong, they are lazy and ignorant and sloppy and sometimes they are even out to get you…

While some of this may be true it's all head trash.

What is Head Trash?

Head trash is any unproductive thought or emotion… just that simple

Head trash makes you angry, gets your blood pressure up, impacts your health, hurts your relationships, distracts you, takes you off your game and impacts your ability to make money.

Head trash leaves you feeling like a victim, like circumstances have the upper hand on you, like you have no control of your life or future.

Head trash impacts your family, your career, your goals, your friends and your co-workers.

When you live with a lot of head trash EVERYONE is a potential enemy… every circumstance could be (and probably is) a threat in your mind.

Isn't This Self-Help, Woo-Woo Bull Malarky?

It may sound like it, but all of the most healthy, fulfilled and happy people I know understand how to manage and eliminate head trash.

To me, the results speak for themselves.

Combatting head trash is simple to do but difficult to choose. Dumping head trash goes against our natural fight or flight instincts.

We have a whole portion of our brains called the Amygdala that is DEDICATED to our most basic needs and fears and it comes in HARD when we feel angry, scared or persecuted.

When I got that callback sheet that I KNEW WAS BS and I balled it up and threw it at my supervisor when I was 19…. Yeah… that was the old Amygdala at work.

I hear so many negative, angry people spouting what they call “the truth”, but then when they open their mouths all that comes out is opinions, bias and exaggeration with very little objective “truth” to be found.

Blame and complaining is popular… even comfortable, but its completely unproductive. The world has so many real problems you can work to solve without spending time thinking and talking about things you aren't doing anything about or attempting to fix.

Here are Ways to “Take Out” the Head Trash for Techs 

  • Think about the people you care most about and why you do what you do.
  • Remember that you chose and continue to choose your profession and where you work. You are COMPLETELY FREE to change at any time and find something you like better. You are in control of your career and decisions.
  • Consider your own weaknesses and mistakes. This will help you have more patience with others when they fail in different ways.
  • Remember that almost everyone values their own contributions and importance to an organization as unrealistically high, INCLUDING YOU.
  • Call someone that helped you along the way, thank them and check in on them.
  • Don't assume bad intent. Sometimes people are out to get you, more often then not, they are dealing with their own issues that you don't even know about. People are rarely thinking about or scheming against us as much as we imagine, just fault on the side of assuming the best of others.
  • Choose to be positive as an act of protest against negativity and drama.
  • Talk to someone who won't stand for your whining BS, not to someone who agrees with you about how tough you have it.
  • Stay away from the words ALWAYS and NEVER. They are ALWAYS exaggerations.
  • Give stuff up… most of what we get worked up about is meaningless.

I heard something the other day that really stuck with me.

It is impossible to be ungrateful and truly happy. It is impossible to be truly grateful and unhappy. 

If you are like me, you want to try and pick that statement apart and try to find exceptions… STOP IT!

You can and will beat head trash if you –

  • Take responsibility for your choices
  • Choose a positive outlook
  • Surround yourself with happy people who want to make you better
  • Stay away from dramatic complainers
  • Take time for gratefulness

Here is some tough talk

In the good old USA you decide what type of person you are going to be and what sort of life you are going to have.

Take out the head trash

— Bryan

Two Less Common TXV Issues to Watch For

The most common diagnosis on with expansion valves is failed closed or restricted resulting in underfeeding of the evaporator. The symptoms are low suction, normal subcooling and high superheat when a TXV fails “shut”, but there are some other issues to watch for that can actually result in overfeeding the coil.

Schrader in the Port

The external equalizer tube on a TXV connects into the suction line at the evaporator outlet and provides a closing force to the valve. Many valves use a 1/4″ flare fitting to make the suction line connection. The only issue is that sometimes the 1/4″ port on the suction line will have a Schrader core in it and the equalizer tube has no core depressor.

Without the closing force, the valve would tend to stay too far open and the superheat will be too low (flooded) but NOT ALWAYS.

Because there is no flow through the Schrader and the potential for a little leakage through the valve and into the equalizer it can actually store some pressure that leaks in during the off cycle and cause the valve to stay shut once the equipment starts running. Because this is a weird one that can go either way, just keep your eyes peeled for it when there are 1/4″ ports at the evaporator.

The fix is simple, just pump down or recover the charge and remove the Schrader.

Bulb Insulation

Much is made of bulb placement when installing TXVs and while it certainly can matter how you position the bulb, especially in larger systems. It is much more important that the bulb is tightly strapped to the suction line and insulated. The bulb is designed to measure the temperature of the suction line alone. When it is uninsulated the valve will generally run a lower superheat. This isn't usually a big deal if the evaporator superheat is in the proper range of 6 – 14 degrees but sometimes you will find it lower.

I am aware that some manufacturers don't insulate the TXV bulb and in most cases, it will be fine.


Just recently I was working on a new system that was running a consistent low superheat of 3 – 4 degrees. I insulated the bulb and the superheat stabilized at 6 – 7 degrees. Not a big deal, but I felt a lot more comfortable afterward.

— Bryan

Thoughtful Termination (Of Wires)

When you are checking a unit of any kind you should be keeping your eyes open for signs of arcing and melting at all of your wire connections and contact points. We find issues with melting terminals on contactors and in disconnects regularly, but rarely do we think about the relationship between circuit ampacity and wire size and the connections to our equipment.

First, consider the fact that a #10 wire doesn't always have an ampacity of 30 amps, it has an ampacity of 30 amps with a 60° Celsius rated assembly at 30° Celsius ambient.

Now, look carefully at the wire and the contactor at the start of the article.

The wire (conductor) is rated at 90° and the contactor is rated at 75° when torqued down to 22 in/lbs on screw type terminals and 40 in/lbs on lug type.

So the entire assembly is only as good as the weakest link and the weakest link is the terminals and the terminals are only as good as the contact they are making.

Conclusion: The termination (connection) points are usually the weakest point of the circuit

When sizing conductors don't forget ANY of the termination points. From the breaker to the disconnect to the unit, every termination point should be properly connected and the rating checked if you intend to use any ampacity other than 60° Celsius.

Check those connections. make sure they are snug and that they are properly suited for the ampacity of the circuit.

For more great info on this go HERE

— Bryan

Introduction to Pool Heat Pumps

Air-to-water pool heat pumps are seeing more and more popularity in the climates that can support them over the more traditional gas and electric pool heaters we usually see.  While they definitely contain some familiar operating principles to an air-to-air heat pump, there are some striking differences in the way the heat is transferred as well as how the components are controlled and protected.

Heat Exchange in a Pool Heat Pump

Most residential and light commercial heat pumps are packaged systems, containing all but a few necessary components for it to perform its duty of heating the body of water it serves.  We have some strong similarities with an air-to-air system: a large air coil mounted on its perimeter, an outdoor fan to perform heat exchange over this coil, a compressor to pump refrigerant, and a metering device to control the capacity delivered to the evaporator.  On many, you'll also find a liquid receiver and / or a suction accumulator to make up for the wide temperature loads they're designed to handle.  The system gets interesting with the introduction of a water coil.

There are two different types of common water coils in use currently.  The first one we'll go over is the coaxial coil.  This is a coil inside a coil, designed to rapidly exchange heat between the refrigerant and water we're adding heat into.

The mainstay material for coaxial coils has been a unique alloy of copper (Cu), nickel (Ni), iron (Fe), and manganese (Mn), known as cupronickel (pictured above.)  It has all of the pressure characteristics of copper, but with the added benefit of being much more resilient to corrosion from a variety of sources.  Interestingly, all of the “silver” U.S. coinage is made with this same alloy.  Titanium (Ti), while less noble than copper, has also entered the market as an alternative to cupronickel with a lighter weight and greater corrosion resilience.  However, these coils are often larger in size given titanium exchanges heat less effectively than copper and is much more difficult to work.

Coaxial coils are fairly simple in their construction.  The outside of the coil carries refrigerant, while the inside handles the water.  These coils are designed to counterflow the two mediums in order to exchange heat rapidly.  The inside of the coil is also rifled, creating a swirling effect that helps this process along further (see the diagram below.)

An alternative heat exchanger that's used is the tube in shell coil, which, just as its name implies, is a refrigerant coil inside of a water tank.  Counterflow makes an appearance here as well, passing the influent water across the effluent refrigerant.  Depicted below is a dome-style tube in shell titanium coil.  This particular coil is found in a water-to-water pool heat pump.  Note how the copper adjoins to the titanium using a ferrule just before entering the coil.

Safeties and Controls

Pool heaters are thermostatically controlled just as you would expect.  In most cases water temperature is measured with a thermistor inserted into a temperature well that contains a heat conductive paste to provide the most accurate measurement of the water flowing across it.  These are made of either a polymer composite, brass, or copper.  They also double as a safety measure on systems employing cupronickel as they will breach first should a chemistry imbalance present in the pool water, alerting service persons before a water flooded refrigeration system occurs.

Another unique safety we'll discuss is the water flow switch.  This switch is akin to the pressure fall switches found inside induced draft furnaces.  They contain a pressure sensitive diaphragm connected to a normally open switch that closes when pressure is applied, thus informing the unit control when water flow is absent.  Just like air-over designs, a refrigerant coil with no water to transfer heat into can be severely detrimental to the compressor it serves.  High discharge pressures can result, leading to premature mechanical failures.  While a high-pressure refrigerant cutout may also be employed, this water flow safety acts as a first response to protect the system from catastrophic damage.  This will prevent the system from operating whether the pool pump is off due to scheduled downtime, a power interruption occurs, a pool filter becomes impacted, or any other condition that ceases water flow.

A majority of systems contain an internal water bypass that controls how many gallons per minute are allowed to flow through the condenser coil.  Too much supply water and the temperature rise will be too low; too little, and the temperature rise will be too high.  This is one of the most important contributing factors to efficiency in an air-to-water system.  These bypasses are usually preset by the factory without any adjustment required in the field.  Be aware that there will likely be an external bypass as well which can wreak havoc on the heater operation should it be tampered with.  Remember to check these first if the water flow switch is keeping the system off!

Similarly to air-to-air systems, air-to-water heat pumps will occasionally require defrost cycles during cold weather. This is achieved primarily by demand defrost with a temperature sensor affixed to the air coil.   Care needs to be taken with the placement of these sensors, as a quickly frosting circuit can produce short cycling of the equipment.  Pools and spas tend to lose heat very quickly, and recovery can become impossible with excessive defrost cycles during cold days.

Finally, many heat pumps will feature a method to pair multiple units to cycle on and off together to provide extra capacity for large pools.  This helps keep equipment wear to the minimum as all heat pumps will be operating in concert during a demand cycle.

In Conclusion

While pool heating can be daunting at first glance, they are relatively simple machines that are usually easy to service with some prior exposure.  The basic refrigeration principles all remain the same.  The next time a customer asks you why their pool is cold, don't shy away from getting some hands-on experience.  You may find a niché at your company!

— Zach


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