Solutions page - What not to do

Solutions page - What not to do

By Grant Laidlaw

Over time, I have seen many pictures of faults and poor workmanship in installations. Let’s have a look at what went wrong with these installations. 

Firstly, thank you to all for your input. If you run into situations like these, please send me your pictures as they are a valuable training aid.

We will smile, yes, but the tragedy is that more often than not, the people who are responsible are really none the wiser; they carry on regardless. Perhaps I am preaching to the choir, as surely our readers know better. However, someone may learn something. I am really just looking at the common issues in this issue and keeping to basic explanations.

So, let’s go.

Placement matters

The picture of poorly installed condensing units (Figure 1) was sent to me in 2015. This type of issue is quite common. Aside from the unsupported pipework and possibly questionable electrical connection, the units seem to be placed in a flowerbed. Plants will grow and possibly block the airflow. If we have rain, dirt will splash up onto the condensers, causing issues. Then of course there is the matter of the airflow. These condensers are blowing heated air onto each other. This causes increased pressures, reduces the unit’s efficiency, and places unnecessary strain on the components, reducing lifespan. I could go into more detail, but simply put: do not do this. Each unit should be correctly secured and in such a way to have proper airflow through each condenser. On rooftops, also consider the impact of the radiant heat from direct sunlight.

Grant001Figure 1: Poorly installed condensing units.

Too close

Have a look at the picture of the condenser that was installed too close to the wall (Figure 2). It highlights the same issue, albeit on a better-quality installation. The condenser is too close to the wall at around 120mm from the wall, restricting airflow. This is a common phenomenon. Check the installation manual.

Grant002Figure 2: Condenser installed too close to wall.

Understanding pressure

Figure 3 was sent to me in 2017. After many questions, it transpired that the component had been exposed to high pressures while the unit was undergoing pressure testing.

When pressure testing, we need to determine what is in fact the test pressure applicable. For example, an R600a domestic unit can be pressure tested to a maximum of 600–800kPa, depending on manufacturers’ specifications. An R410a system can be tested to, say, 3 800kPa. Should you neglect to set the nitrogen regulator after testing an R410a system and expose a domestic fridge to 3 800kPa, the evaporator will explode.

Let us focus on quality, pride of workmanship, and safety.

So, let us consider this accumulator. Well, as it transpires, the technician made up his own fitting and did not bother with a regulator at all. People die because of this type of attitude.

Before pressure testing, understand the procedures and applicable pressures — and no shortcuts. Always use a correctly set regulator.

Grant003Figure 3: Suction accumulator.

Using the right gas

Whilst on the topic of pressure testing: we use nitrogen. In Figure 4, oxygen was mistakenly used with, need I say, rather interesting results. Teach your staff the colour codes and the differences between the cylinders. In this case, the worker confused the two cylinders.

Besides, this drives home the need for the minimum training and assessment required by the South African Qualification and Certification Committee for Gas (SAQCC Gas) — aka, the safe handling course.

Grant004Figure 4: New condenser pressure tested with oxygen.

Pipework techniques

When Figure 5 was sent to me some time ago, I remember thinking, “What a disaster.” But looking at this situation now, I think this highlights the lack of knowledge and skills in our industry. We speak of the importance of pressure testing and system integrity and then we have these types of situations.

This work was done by a refrigeration ‘contractor’. The message here is: Please leave the radiator hoses and jubilee clamps to the motor mechanics. Use the correct tubing and pipework procedures when working with refrigerants. The industry is evolving, and the use of flammable refrigerants is becoming increasingly prevalent. It therefore follows that this type of workmanship is becoming more and more of a problem, with the likelihood of an incident occurring, increasing. Before this results in a disaster, use the correct pipework techniques.

Grant005Figure 5: Radiator hose used on condenser.

Capacity control

Figure 6 shows how a condenser was purposely restricted to compensate for a mismatched system. An evaporator from a small system was connected to this condenser and the technician manually reduced the capacity to match the evaporator. Looking at this, the technician had some understanding of the system’s operation. Unfortunately, this led to the loss of the compressor.

The lesson here is that an HVAC&R system is carefully designed and the components work in unison. The capacities of the components must be matched. This is not Texas — bigger is not always better!

Grant006Figure 6: Manual capacity control.

Don’t try this at home

I have shown Figure 7 before, but it remains remarkable.

A computer company decided to repair their own air conditioner. It actually did work … somewhat!

Grant007Figure 7: Twenty-eight-fan evaporator.

Illegal welding

The picture of a fitting welded onto a disposable cylinder (Figure 8), depicts a situation that is simply unacceptable. Aside from the fact that this is illegal, you are endangering yourself and everybody around you. Regrettably, this happens quite often. I have walked into large refrigeration companies and have come across this issue. Honestly, this has to stop.

Grant008Figure 8: Fitting welded
onto disposable cylinder.

The consequences

But rather than me telling you to stop, let me show you why you should do so. Have a look at Figure 9: Here is the consequence of welding valves onto disposable cylinders.

This curious young man decided to investigate an illegally filled disposable cylinder in his father’s workshop. The cylinder exploded and he lost two fingers and the lower half of one leg. This tragedy was of course avoidable, and he paid the price for someone else’s disregard for safety. In addition, in this case, the safety plug was leaking, so the plug was brazed in place. I do not have the full story, but the cylinder was in all likelihood also overfilled.

Grant009Figure 9: This boy was injured after an illegally filled disposable cylinder in his father’s workshop exploded.

Do not weld/braze onto disposable cylinders. End of story.

That is it for this issue. At the end of the day, ignorance, negligence, and poor workmanship are all on display here. Let us focus on quality, pride of workmanship, and safety.


Thank you for all your questions. Send your problems (and sometimes your creative solutions) to acra@netactive.co.za with “Solutions Page” in the subject line. You may include pictures.



References

  • SARACCA
  • Pressure Equipment Regulations
  • ACRA.


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