How to HVAC Chiller Commissioning

What Is HVAC M.T.O? (Material take off)

                                                  Centrifugal Chiller                                   

1. Material take off is a term used in engineering and construction and refrers to a list of materials with quantities and types that are required to build a designed item.

2. This list is generated by analysis of a blue print or design document

3. A material take off  is the process of analyzing the drawings and determining all the materials required to accomplish the design

Description 

HVAC primary plant and infrastructure 1 off chilled water HVAC Equipment 

CHILLER UNITS 

Air cooled Chillers complete with screw compressors condensor coil, Micro processor controller total capacity 450 tons,Refrigerant - 134a Fluid type chilled water,Entering water temperature 58'F, Leaving water temperature 42'F, Fluid flow rate 675 USGPM, power supply 380v-3ph - 60HZ 

Out door Ambent kit suitable for operation up to 125F, water flow switch and condenser coil made of copper tubes and aluminium fins coated with anti corrosive material chillers shall be provided with fully integrated control panel suitable for single point electrical connection

CHILLED WATER PRIMARY PUMPS 

                                         

            CHILLED WATER PUMP                                                         

Base mounted flexible coupled, END suction pumps with variable speed drive,670 USGPM,100ft Head,Nema 40hp,1400RPM TEFC Accessories,Vibration isolator's Pumps shall be provided with fully integrated control panel suitable FOE single point Electrical Connection 

Underground Chilled Water pipes 

Carbon steel ASTMA53 Grade B,ERwor seam less,Schedule 40,thick polymer thane Foam insulation with hope jacketing as outer casing protective jacket complete all fitting,support,Hanger,and accessories with the following Diameters 

EXTERNAL ABOVE GROUND CHILLED WATER PIPING

Shall be schedule 40 black steel ASTM A53 all external chilled water pipes to be insulated with 3 thick ARMA flex rubber insulation 

The insulation shall be covered with aluminium jacket with joined SEAMS located at the bottom of the pipe work complete with all fittings 

Support Hangers and accessories with the following pipe size 

3/4 D/A Chilled Water Fan Coil units 

Pressure Guages 

Pressure guages shall have A range from to 16 bar (0.To 233psi) And shall be size 100 as manufactured by Dirmex or approved equal above specified

Instrument shall be used for Chillers pumps 150

THERMOMETERS 

Thermometers shall have a range from 0'c to 120'c 32'F to 248'F shall be of the liquid type and have a system suitable to match pipe Dimension and field conditions, THERMOMETERS shall be as manufactured by Dirmex or approved equal 

Flexible connectors for Chiller inlet and out let shall be SMILAR To MASON industries Saf ELEX SFDEJ OR approved equal and shall be double sphere connectors 

Connector material to have temperature to erance up to 120'c (250'c) connectors to be weather proof

Makeup water system

Makeup water system is a assembly valve packaged for air seperator (Chiller yard)

CHILLED WATER CONTROLS AND TESTING 

HVAC control complete with sensors,instruments,DDC,Actuators and all Necessary instrumentation and accessories 

HVAC DDC Control points, Testing and Balancing1 

AIR SIDE HVAC EQUIPMENT 

Air Handling Unit 

                                                   AHU                                              

1.Electrical switch gear room near Chiller yard 

Chilled Water type total cooling capacity 642 MBH sensible cooling capacity 45 8mbh 

Chilled Water temperature in out 42'F/58'F water temperature difference ^T 16'F

Water flow rate 8.0 USGPM Cooling coil entering air dry Bulb wet Bulb temperature 79

Air Flow 2650 CFM external static pressure 0.5 wG 220v/3PH 60HZ power supply 

Fan motor HP 2Hp Refrigerant R22a Complete with All standard accessories and interconnecting Refrigerant lines,Cooling coils shall be made of copper tubes with Anti corrosive coated aluminium fins 

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HVAC Air Distribution system

HVAC Air Distribution

                                          DUCTING                       

      

Fundamentals

1. Duct is simply a path to distribute and manage the air flow to the required dessined zone/Areas

2. Duct shape may be circular,square,Rectangular or spiral 

3. Galvanised  iron, Aluminium,stainless steel,Black iron etc....are some of the commonly used duct materials 

4. The thickness of the duct sheet is mentioned by its gauge 

5. Aspect ratio is the ratio of duct width to hight 

6. Aspect Ratio 1 to 4 is generally advised for duct sizing

7. The size and shape of the duct will depend upon the CFM, Available space for Ducting application etc......

8. The Duct is connected to the equipment through flexible Connector 

9. All the brancehs are fitted with VCD

10. Fire Damper is provided the Equipment out let and other Duct penitrating fire wall areas 

11. Thermal insulation is done for supply air duct

12. Accaustic insulation is done for supply duct

Some Fundamentals 

1. Air out lets are selected based on the manufactures Design data 

2. Type and Location of the air terminals will depend up on the room design and AESTHAICS 

3. Louvers are fitted at the fresh air duct entry 

4. Fittings and transitions are designed according to SMACNA And ASHRAE 

5. Flexible Canvas connection should be used to connect the equipment and ducting system

6. Access should be provided for Dampers 

7. AHU should be provided with drain pan and U trap 

8. Gaskets to be used between duct joints to prevent leakage 

9. Never run the AHU unless the AHU room is Cleanned and fitters are mounted 

Type of Ducts 

1. Supply air duct 

2. Return air duct 

3. Fresh air duct 

4 Exhaust air duct 

Duct Designing Methods

1. Velocity reduction method

2. Equal friction method 

3. Static regain method 

                                                 

            Duct Design

Velocity reduction method   

Velocity (FPM) - Velocity (CFM) - / area (SQFT)

Main duct velocity - 1200 to 1500 fpm

Branch Duct velocity - 750 to 900 fpm 

COLLAR/DROPPER Velocity - 300 to 500 fpm 

PLENUM Boxes - 500 Fpm

Return air duct velocity shall be less than supply air duct velocity 

EQUAL FRICTION METHOD 

Considers the total ducting will bear the same frictional loss 

0.08 water/100 ft to 1 water/100 feet 

The range will differ depending up on the application and use of space 

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Air Conditioning gas pressure

R 22

                                                          

          R 22                 

Standing pressure - 150 psig

Suction    pressure - 60 to 70 psig 

Discharge pressure - 250 to 300

R 32 

                                                         

          R 32

Standing pressure - 240 psig 

Suction pressure   -  110 psig

R 410 A

                                                           

R 410 A                                                          

Standing pressure - 225 psig 

Suction   pressure -  110 to 120 psig

Discharge pressure - 450 to 500

R 290

Standing pressure - 125 psig

Suction   pressure  - 65 psig 

Discharge pressure - 275 to 300

R 134 a

Standing pressure - 85 psig 

Suction pressure   - 35 to 40 

R 600 a

Standing pressure - 40 psig 

Suction pressure  - -1 to -2 hg

R 407 C

Standing pressure - 180 psig 

Suction pressure  -  75 psig 

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How to 8 pin relay working

How to 8 pin relay working ?

     

                          

          8 pin relay                                      

       

8 pin realy's are very popular for many applications

An 8 pin relay contains two single pole double throw contacts

Pins 1 and 4 and 8 and 5 are normally closed. On the other hand pins 1 and 3 and 8 and 6 are normally open

The coil of the 8 pin relay is connected across pins 2 and 7

In the following example will be connected pin 1 and 8 to a power source, four light balbs will be connected to another power source with a switch

When closing and open the  the SW, contacts change the position

When closing and open the  the SW....

Contacts changes the position 

Specifications of AHU

SPECIFICATION AIR HANDLING UNIT (AHU)

                                AHU

Body :Double skin sand which of metal with insulation between the metal sheets to provide a smooth,Cleanable interior surface 

INTERNAL CONSTRUCTION

Units should contain good accessdoors,view ports,Electrical Convenience out lets, and interior lighting for maintenance 

The casings should be tightly sealed and designed for pressures, All sealants and lubricants exposed to the air stream should be food grade to minimize the chance of air 

contamination

While selecting the fan,it should be ensured that at the lower speed the fan does not operate in the un balanced region.

In case of a heating coil,at lest a 0.5 meter space should be kept between coils,

All section's Consisting of prefilters, cooling coil, Heating coil,etc...should be mounted in between the SA and RA fans 

Location of AHU and it's importance 

1. Location of AHU play an important role in efficiency of HVAC System 
2. To avoid across contamination independent air handling system should be provided for various operations like manufacturing, coating, tabletting, inspection and packing.
3. Air Handling should be located on a separate equipment flour or zone in order to facilitate service and maintenance with out disturbance to the sterile room..
4. AHU should be located as close as possible to the main rooms they are servicing to minimize large and longer duct runs.

Location of out door air inlet lowers must be Carefully considered

1. It should be on height from ground 
2. Should not be in parking area 
3. Should be away from chimneys or dust and fumes generating Equipments or Area 

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VRF vs AIR COOLED CHILLER

MERITS, DEMERTIS 

Depending on the buil Requirement unit to analyse the requirement of what exactly going to be Installation 

MERITS -VRF (VARIABLE REFRIGERANT FLOW)

Different IDU options can be used like hiwall unit,Cassette unit,concealed unit,ducted type units and so on this can help in blending the air Conditioning system with the appropriate interior design of the space.

Operation is very simple,probably is simple as operating a split air conditioning system and heance no separate man power is required for operating the system.

Good option for providing air conditioning to apartments,villas,small installations where in the complexity to the system (major demerits of this system) Can be kept to a minimum.

DEMERITS OF VRF

1. Complex system architecture, large amount of refrigerant piping running around in conditioned space.
2. If decided to use for larger capacities more space required to install many number of ODUs.Access to ODUs is necessity as all the maintenance work required will be mostly on the ODUs 
3. Will not be of much benefit where the cooling load has limited diversity.such as in offices,malls,multiplexes etc........where in the diversity is limited to some conference rooms and or Cafeterias 
4. Highly skilled labor required for installation and commissioning and maintenance, Especially to identify and correct leakages.
5. Not recommended for High rise building the Compressor will be very big to over come additional piping and pressure loss.
6. Identifying pipes and their leakages complication for High rise building the system not suitable.

MERITS OF AIR COOLED CHILLER 

1. The most matured technology with the history of over 6 decades.
2. Highly energy efficient enables comfortably complying to ASHRAE,AHRI and LEED,platinum  requirement 
3. With proper system design and installing multiple chillers, Even in case of high diversity chillers become a good option due to their good efficiency even at part load conditions 
4. Project size is not the constraint at all

DEMERITS OF AIR COOLED CHILLER

1. Availability of water is a must 
2. Requires additional space for plant room for Chiller,AHU  Rooms and space for mounting the cooling towers 
3. Trained man power is required for operating the central chiller plant 
4. Highly skilled labor required for installation and commissioning and maintenance,Especially to identify and correct leakages

CONCLUSION OF VRF

For smaller system's,up to 100-200tr with limited ODUs and IDUs VRF System can be a good solution,as for smaller central plant system,space availability for Chillers,AHUs may not be available.also for such small systems the VRF System can remain simple with limited refrigerant piping and with out much complexities 

CONCLUSION OF CHILLER

How ever when the installation size starts increasing VRF Systems,As seen above start becoming complex and in such cases,planning the installation for aicooled chiller is always beneficial.The life cycle cost such a system is not only lower then the VRF System, But it also avoids safety related issues such as leakages of refrigerant in conditioned space, Better air circulation,better indoor air quality, etc........

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HVAC BASIC KNOWLEDGE CHAPTER 2

UNIT Of Refrigeration

                                       

TR:1TR is amount of heat to be extracted from the atmosphere for melting one metric for of in 24hrs

1TR:12000 BTU/HR 

1TR: 3000 kcal/hr 

        =500 kcal/mn 

STEP OF SELECTING THE SYSTEM

• Calculation of cooling load requirement 
• Selection of techno-ecomical system 
• Equipment selection 
• Designing air distribution system
• Designing water distribution system
• Designing refrigerant distribution system 
• Evaluation of system to be used.

Factors to considering during cooling load requirement

• Building detailed layout 
• Use of space 
• Physical dimension of space 
• Inside room design condition
• Filtration level required 
• Ambient condition 
• Glass area exposed to sun 
• Occupancy 
• Lighting load 
• Equipment load 
• Fresh air requirement 
• Infiltration of out side air 

Factors affecting system selection 

• Budget of client 
• Need/requirement of client 
• Use of space 
• Out side condition
• Floor layout 
• Location and dimension of beam/column 
• Power availability 
• Space availability and many more.....

Types of air conditioning system 

Dx-system - Direct Expansion

• A direct expansion air conditioning (DX)SYSTEM uses a refrigerant vapour expansion compression (RVEC)Cycle to directly cool the supply air to an occupied space
• DX system (both packaged and split)