Home AC & Ventilation A Redefined Engineering Analysis of HVAC&R Industry Part-2

A Redefined Engineering Analysis of HVAC&R Industry Part-2

In continuation of the series ‘A Redefi ned Engineering Analysis of HVAC&R Industry’ ‘PART-1’ published in ‘Cooling India’, February issue, this article has been framed to create awareness among the working professionals in HVAC&R sector.- Y S Rao

March 15, 2015

There was a time when HVAC&R industry in India was nursing to very limited people but in a stupendous comportment. People carried out the jobs at a slower pace but in a very précised fashion all through those days. The demand for HVAC&R projects was very much limited and the scope of career for workmen was very much alluring. For service oriented firms in HVAC&R field, the scope of generating revenue was also very much limited up to repairing of equipment. There were only a few HVAC&R establishments which were considered to be the market players. As such the competition in the market was not that much tough.

With the advancement in time, scenario has changed completely and the HVAC&R market has expanded beyond imagination. The emerging engineers and professionals of present time are abundantly opting for HVAC&R sector as their career option even at a very minimal pay in comparison to the prevailing market standard pays. HVAC&R projects are getting prominence for high rise buildings and the demand for scheduled projects is high-flying. The scope of generating revenue for service oriented firms has also stretched remarkably and opened the doors for Annual maintenance contracts, Retrofits/Revamp projects, Repair jobs and Sale of spare parts. As of now, numerous indigenous as well as foreign establishments have spread their wings in Indian HVAC&R market. The indigenous establishments include mostly the raw petty contractors and a few gigantic well-pioneered companies.

In lieu of the present prevailing situation in India, undoubtedly it is very easy to visualise the tough competition in the market. Despite of being competent enough, peerless companies are also forced to cut down the profit margins for grabbing high value business. This situation has engendered a new concept of recompensing low profitability with high volume of business achievements and by targeting the completion of scheduled assignments within stipulated time. Appointment of ineffective manpower in surplus number at a very reasonable pay has also been added in the concept. The concept of recompensing low profitability with high volume of business targets has slain the remuneration for the employees and curtailed the employment of technically efficient manpower in all the contracting firms. Considering time to be the essence for every project and service calls, all contracting and sub-contracting companies participated in the race for fastest completion of jobs. In reality, the urge for fast completion of any project or service call has created a chaos. Every individual whoever is unified with the HVAC&R industry is in the fast move for sustenance and survival. In the recent years it is observed that there had been a higher rate of reiteration in the employment with a desire to rise up in the career. Most of the working folks in HVAC&R field started an individual set up and activated a business of their own. The arbitrary pathways adapted by the folk & their ideologies have slaughtered HVAC&R industry brutally. The final outcome is disastrous and the level of disaster that occurred is uncomputable. The catastrophic symptoms appeared in the form of acclimatization of unethical practices & non compliance to standard engineering procedures. The synopsis of this article comprise mainly of such haphazard culture that has been put into practice in HVAC&R industry by the working class. After carrying out thorough surveillances at various sites, all the examination reports and their reviews are compiled together to structure this article. Efforts have been taken to expose the present predominating work culture in HVAC&R industry. Hopefully after reading this article, it will be apparent to the readers how the HVAC&R industry is crippling for its existence and survival.

Un-legislative Method of Installation at a Legendary School Project

This section emits light to expose the blunders at a legendary school project and express the competency level of the present generation engineers working in HVAC&R sector.

Observation – 1

The purpose of ventilation fans is to bring-in the fresh air and take-out unwanted air. There has always been a wrong apprehension carried by most of the site engineers while taking up the installation of ventilation fan units. Untrained engineers when get exposed to sites don’t realise the technical aspects of the subject project and perform untidy installation works.

Fig. 1 shows an illicit installation of an exhaust air ventilation fan unit. This figure also uncovers the lethargic approach shown by the site execution team while carrying out installation work. The blunders of this installation are listed as under:

Rubber pads are not provided at all the corners of the ventilation fan unit.
GI Plenum box is rested on an oil container instead of placing it on metallic frame support.
GI ducts are not provided with metallic frame/bracket supports and are rested on concrete bricks.
One of the sheet metal GI duct is rested on other sheet metal GI duct.
Cowl shaped /Semi arch duct piece is not provided at the exit point of the fan unit.
Power cables are laid down randomly without proper dressing.

The above list of blunders is sufficient enough to distort the image of the HVAC&R industry as well as adequate enough to degrade the icon of all the professionals who work dedicatedly in this field.

Observation – 2

For comfort cooling application, return air is usually mixed with a small amount of fresh air (say 10%) and is re-circulated through the cooling coil of an air handling unit. The amount of fresh air to be added shall be calculated sanely as per AHRAE (American Heating Refrigeration Air-Conditioning Engineers) guidelines. The amount of fresh air to be added differs from application to application. Say for example, in critical areas of a hospital like operation theatres or bio labs etc. wherein 100% treated fresh air is mostly recommended. But for comfort cooling, it would be an idiotic act if the 100% fresh air is utilised without reusing the return air.

Fig. 2 shows a true picture of a scene that was seen at a school project wherein a ceiling suspended air handling unit was installed with a purpose to cater conditioned air to a class room. The installation was carried out with a messy approach such that the air handling unit was getting 100% fresh air and due to which the air handling unit was unable to suffice the cooling load required in the class room. This chaotic situation could have been corrected at a very initial stage of installation by providing air tight partition around the air handling unit and the return air could have been guided by providing civil opening of appropriate size within the periphery of air tight partition.

Observation – 3

While installing any equipment, special attention and care must be taken by the site engineers and site supervisors for providing ample clearance between them from maintenance point of view. There should always be ample space between two equipment for service accessibility.

Fig. 3a and 3b portrays two different views of ventilation fan units with poor service accessibility and insufficient service clearance. Usually it is experienced that the projects team always put their efforts with an approach to complete the project as soon as possible by adapting unfair or foul means and the service team faces the forthcoming problems while carrying out maintenance because of the poor vision of the projects team. An ideal project team must always carry a future realistic vision.

Observation – 4

Most of the air leakages occur generally through gap between duct collars/droppers and diff users. Mismatch between these two mechanisms are commonly found everywhere at most of the sites. This mismatch is only because of the following reasons:

Poor workmanship
Uncertainty in the false ceiling level
Vagueness in the plan of reflected false ceiling.

First reason is because of the deployment of unskilled workmen at site by the contractor/sub-contractor. The second reason is because of poor coordination at site and the third reason is due the lacking ability to understand the proposed engineering drawings by the whole project team.

Fig. 4 manifests a chaotic installation of duct dropper which is raised far above false ceiling. The duct dropper is neither in contact with the false ceiling nor aligned in line with the diff user. Such landscapes are very commonly visible in almost all projects.

Observation – 5

Mostly it is found that HVAC&R projects are executed without any vision for the future by the site execution team. Most of the present age engineers lack the maturity level to understand the complexity of an installation. The ultimate end result of such intricate situation is the convoluted incomplete state of a project. Different portions of such complicated installations are shown here which will astonish professional engineers.

Fig. 5a describes an illegitimate installation of an air handling unit. This image displayed in Fig. 5a speaks lot many issues related with the installation of air handling unit. A list of all the howlers found in the installation of air handling unit is listed as follows:

Vibration isolators are not provided for the ceiling suspended air handling unit. In such condition the vibrations generated during the operation of ceiling suspended air handling unit may get transmitted into the civil structure of the building and may aff ect the structure over a period of time.
The distance between the air handling unit on the filter section side and the civil beam is very nominal. This may aggravate the situation during the course of testing and commissioning, preventive maintenance and breakdown service calls.
Connectivity is found to be missing for the actuators provided to regulate the operation of two way valve. This makes the two way valve and the actuator quite immaterial.
Chilled water pipe lines connected to the air handling unit is tapped from the top side of main header pipe lines. This may restrict the circulation of chilled water through air handling unit during the air lock phase.
Accessibility to the service door is blocked due to chilled water pipe lines. This may obstruct the smooth maintenance of ceiling suspended air handling unit.
Provision for return air path is missing. In such a case the air handling unit will draw 100% fresh air and the heat load on the unit will be drastic.

The above list of issues related with the installation of ceiling suspended air handling unit develops a thought about the lack of knowledge of the entire team working on the project collectively with the client/customer, consultant, subcontractor , engineers , supervisors and workmen.

Fig. 5b presents a view of intricate installation of a ceiling suspended air handling unit. Even though sufficient space is provided for the free movement of the service personnel in the region of the equipment, yet there is a question mark on the accessibility to the fi lter section of equipment. The chilled water pipelines and the condensate drain water pipeline both obstruct the free accessibility to air filters.

Only a few of the landscapes in the referred school project are taken into consideration for framing up this article. Yet there are many other fi ndings during the investigation on this project which are not covered in this article.

Unreasonable Installation methods at a Residential Tower : There are several cases of installation activities that were taken up in an unscientific way by Indian engineers and contractors in abroad also. Indian engineers and professionals as such are mostly preferred in middle-east countries to carryout HVAC&R works. The reason for the demand of Indian engineers and professionals can be estimated in two ways: (a) either the middle-east countries don’t possess skilled manpower of their own, (b) or else they have the trust on the capability of Indian professionals and workmanship of our workmen. Instead of upholding the level of faith and the level of confidence these foreign countries do have on us, Indian engineers and workmen have performed in a most perturbed manner. This article unveils the iniquity act performed by Indian contractors & engineers at a residential tower project in abroad. Various observations are presented in a sequential manner in this article to expose the performance of Indian engineers and contractors in abroad.

Observation – 6

As a standard engineering practice, Outdoor AC units are always advised to be installed at location where free flow of air can take place. Any restriction in the pathways of air may cause short cycling of air thereby increasing the ambient temperature of the surroundings. At high ambient temperature, the AC unit starts ailing by screening the following behaviour:

Frequent tripping of the AC unit due to high discharge pressure
Coefficient of Performance of an AC unit declines at high ambient temperature & its cooling capacity gets de-rated.
Refrigerant oil loses its viscosity at high operating temperature & its lubricating property gets diminished. This condition may lead to wearing of compressor parts.

Fig. 6 shows a series of outdoor split AC units installed in an un-engineered and congested pattern. The former part of Fig. 6 shows a series of outdoor split AC units installed closer to each other and facing each other, while the later part of Fig. 6 shows a series of outdoor split AC units installed facing & closer to terrace parapet wall. The consequences in both these cases are symptomatic as the hot air dissipated to the surroundings will get accumulated there itself. This condition will develop a hot pocket zone nearby outdoor split AC units and fi nally the end result will be system failure.

Observation – 7

Indian engineers, supervisors & workmen are unmatchable in their lethargic work culture as compared to any other professionals across the globe. This can be proved from the fact that they follow the same casual approach while working in abroad. A few instances are presented below in the pictures taken in Bahrain. Fig. 7 displays a pathetic site condition where refrigerant carrying copper pipes connecting Outdoor split AC units to Indoor split AC units are laid down on the roof top without providing any proper supports. A few of the copper pipes are randomly rested on concrete bricks and others are just scattered like crawling snakes.

Such grubby installation of refrigerant copper pipes develops leakage in the refrigerant circuits very easily as they don’t have any sturdy support to hold them. An ethical engineering practice prescribes for the installation of refrigerant pipes on a tray or a trench.

Injudicious Installations

Uncountable faults do crop up in every phase of HVAC&R projects. As such there is nothing that can be hidden because the tendency of all the contracting and sub-contracting companies in the present Indian market have established a mindset of committing errors and justify themselves by exposing the mistakes of other competitors. Even the representatives from the client/customer’s side don’t bother about the technical aspects and the commercial impact on the whole project. In today’s set-up, HVAC&R projects are nevertheless always incomplete due to uncared snags. Although, the left over snags by the project team may be minor but sometimes lays a severe impact on the project. A few of the disorders that are commonly prevalent at almost all the HVAC&R projects is listed herewith.

Observation – 8

Flexible connectors are provided at the outlet of Air handler units or Ducted Indoor Split AC units. The purpose of providing flexible connectors is to curb the jerk at the start up of these units. The installation of fl exible connector becomes worthless if it is put in a wrong manner as shown in Fig. 8.

Most of the times, duct installation, pipe installation and equipment installation doesn’t go simultaneously and hence there is always an opening for the other activity to correct and rectify the fl aw in whole installation. In Fig. 8, the duct installation and the Air handler unit installation was not synchronised in single line & hence the flexible connector was stretched towards one corner. This could have been corrected by slightly shifting the Air handler unit prior to the pipe installation & connection which has never happened because of the hasty decision taken by the site engineer/site supervisor.

Observation – 9

The most important building blocks for any of the projects are Standards, Inspection, Measurement, Testing, Quality etc. But all these building blocks are hardly /rarely pursued in HVAC&R projects. In India, quality management procedure is quite inactive and infrequent to be seen in HVAC&R projects. Networking all the quality management procedures and activities result in customer satisfaction.

Fig. 9 shows the level of quality work executed by all the team members working on the project. The threaded rods have been provided arbitrarily to aid support for the ducts. Instead of using threaded rods of required size, lengthy threaded rods are used and are left uncut & bent. These threaded rods are installed in an uneven manner and in a tilted position.

Observation – 10

Flow switches/flow sensors are most essential accessories of a Chiller unit. These components must be installed on chilled water pipe lines as well as on the condenser water pipe lines. There has always been an argument on where to install fl ow switches/ fl ow sensors i.e. on the inlet water pipe lines or on the outlet water pipelines. All manufacturers have different opinions on this subject. Experience says, it hardly matters on which pipe line these accessories are installed. What matters is, at which location and in which position these flow switches/flow sensors are installed. Fig. 10 shows the installation of flow switches on condenser water outlet pipe line but the most important point to be noticed is its location i.e. near to an elbow.

Engineers commonly fail to understand that, the turbulence of the flowing water is more at or near the elbows and fittings which cause the flow switch/flow sensor to chatter and finally cause frequent tripping of chiller unit. Lay technicians bypass the flow switches to get rid of the nuisance but are unaware of the ill consequences of bypassing the fl ow switch/flow sensor. The purpose of providing a flow switch/ flow sensor is to stop the operation of chiller unit in case of restricted water fl ow or insufficient water fl ow in the hydroponic circuit. Restricted and insufficient water fl ow on the evaporator side of the chiller unit may sometimes burst the tubes and even evaporator shell also due to frost formation. On the other hand, restricted and insufficient water flow on the condenser side of the chiller unit increases discharge pressure enormously & discharge temperature which in turn may damage the compressor parts.

Observation – 11

While installing chilled water or condenser water pipe lines special care has to be taken especially while tapping distributor pipe lines from the main header pipe lines. While tapping the distributor pipe lines from the main header pipe lines it must be ensured that a shoe piece or semi arc piece has to be provided at the tapping point for proper distribution of water in the hydroponic circuit. The shoe piece or semi arc piece provided at the tapping reduces the turbulence effect and thus reduces the pressure drop eff ect. Fig. 11 shows both the ways of tapping the distributor pipe lines from the main header pipe lines. The former part shows the outlaw tapping technique and on contrary to the former, the later shows highly recommended practice of tapping.

Orientation of the shoe piece/semi arc piece is very tricky and this can be judged correctly only by an experienced and prudent engineer who executes the project with full involvement and dedication. Any wrong alignment/orientation of the shoe piece/semi arc piece may cause fatal failure of the system since it will hamper the appropriate fl ow of water in the hydroponic circuit.

Overlooking of Key Engineering Practices

One of the most important procedures involved in commissioning of refrigerating equipment is its pressure testing to check the leakages followed by vacuumizing and gas charging. Failing to follow these steps may cause disaster to the system. Prior to charging of refrigerant gas into the refrigerating equipment pressure testing has to be carried out positively for 24 hours using dry nitrogen at a pressure slightly less than the safety pressure. The pressure test using dry nitrogen confirms that the system is leak proof.

Many a times, it is very obvious to fi nd technicians in a confused state and act unwisely in a dilemma while taking up nitrogen pressure testing activity. Generally uneducated technicians charge the system with nitrogen up to a certain pressure level, check for leakages and leave the system for 24 hrs. or 12 hrs. and cross check the pressure to ascertain a leak proof system. This methodology is totally unacceptable. While carrying out nitrogen pressure testing, following activities must be ensured:

Whether the system is free from gases i.e. the existing refrigerant gas has been removed or recovered.
Usage of dry nitrogen is highly recommended for pressure testing.
The nitrogen shall be charged in the system to maintain a maximum pressure of at least 50 psig less than the test pressure as specified by the manufacturer. Or else nitrogen shall be charged in the system to maintain a maximum pressure of at least 20 psig less than the safety valve pressure as specified by the manufacturer. Or else nitrogen shall be charged in the system to maintain a maximum pressure of at least 1.5 times the operating pressure of the refrigerant gas that shall be used in the system.
The ambient temperature must be recorded followed by date and time at which the initial pressure is recorded.
The system must be kept pressurised with dry nitrogen for minimum 24 Hours.
The ambient temperature must be recorded followed by the date and the time at which the final pressure is recorded.
There may be quite little difference between the initial reading and fi nal reading but not exceeding 5%. This difference may be due to variation in the ambient temperature or else due to fine settlement of nitrogen in the system.

Once the pressure test is fi nished, and the results are found to be favourable then vacuumization of the refrigerating equipment has to be followed without fail. Vacuumization is a process by which the moisture & foreign particles present in the refrigerant circuit gets removed. Vacuumization has to be done very precisely. The consequences of improper vacuumization may leave traces of moisture in the refrigerant circuit & may cause following ill effects.

The left over moisture present in the refrigerant circuit gets trapped in the expansion valves and restricts the fl ow of refrigerant in the circuit due to ice formation. This situation hampers refrigeration effect.
A very small amount of moisture if remained in the refrigerant circuit when mixes up with the refrigerant gas & refrigerant oil, starts circulating in the system. These small traces of moisture cause oxidization on metallic surface of copper and mild steel. The oxidation of metal surfaces cause corrosion and forms sludge at high temperature in the refrigerant circuit. The sludge causes several ill eff ects on the functioning of refrigeration system. The sludge may even jam up the moving parts of the compressor and may even lead to burn out of compressor motors.

Considering all the above ill effects of moisture, it is highly recommended to carry out a thorough vacuumization. The scale for measuring the level of vacuum created/achieved is recorded either in microns or in pascals or in m-bars. Ideally 500 microns is minimum level of vacuum required to be achieved to affirm for the perfect functioning of a refrigeration system. Once the required level of vacuum is achieved the refrigerant circuit is charged with sufficient amount of refrigerant gas. There are a few scales to ensure the correct amount of refrigerant charge in the system. Superheat and sub-cooling temperatures are the best scales to ensure for optimum amount of refrigerant gas charge and establish the ideal performance of a perfect refrigeration system. Unfortunately in India, neither the technicians nor the engineers are conversant with precise vacuumization technique, proper nitrogen testing, exact calculation of superheat & sub-cooling temperature.

Any malicious act of the project team during execution stage calls for frequent maintenance. The present trend pursued in HVAC&R projects is that the residues of project activities are taken care by service/maintenance team by default. The client/customer is also assured for the maintenance and service calls which will be taken care of, during the defects liability period by the contractor and hence accepts the handing over of the project. The ultimate sufferer is always service delivery team who has to attend all the breakdown calls and preventive maintenance services as well.

In India, a non government organization is established so called ISHRAE (Indian Society of Heating, Refrigerating and Air Conditioning Engineers), was founded in 1981 at New Delhi by a group of eminent HVAC&R professionals. ISHRAE is an International Associate of ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers). The primary objective of ISHRAE is the advancement of the art and sciences of Heating, Ventilation, Air Conditioning, Refrigeration Engineering & other related Building Services. ISHRAE conducts conferences, seminars, workshops, and catalogue shows throughout the country with both national and international participation on the latest in terms of technologies, systems and services. The most agonizing part is that, most of the principle contractors, sub-contractors, consultants and even the clients in HVAC&R fraternity are the members of ISHRAE who contributed their share in exploiting this industry religiously and as such ISHRAE don’t hold any authority to put a restriction on such shameful act of its members.

Illiterate and untaught technicians always have a tendency to prove their smartness in making the system operational by passing all the safety procedures. It is the moral duty of engineers to guide and impart training to technicians and workmen about engineering aspects. The aim of a HVAC&R professional should never be limited up to making the equipment operational. The aim should be stretched further to make the whole HVAC&R system perfectly functional without any technical compromise. Engineers shouldn’t restrict themselves up to commercial part and must emphasis basically on technical part. No sooner a day will come when this HVAC&R industry will be only limited up to road side repairers and will be taken care by petty vendors if it is not esteemed. Now it’s the peak time for every HVAC&R professionals to act judiciously and protect this industry from getting endangered. If not today, then never.