Test Balance International Final

Question 1

What are the steps of the General Balancing Procedure?

Answer 1

1. Prepare reports. 2. Check building and systems are complete and functional. 3. Check equipment. 4. Balance outlets and duct runs. 5. Recheck equipment. 6. Finalize Reports

Question 2

How do Magnehelic Gauges work and what do they measure?

Answer 2

Dry-type Manometer with internal bellows for sensing pressure. Pressure drops, inlet and discharge pressures, and velocity.

Question 3

How do Hook Gauges work and what do they measure?

Answer 3

U-tube liquid level principle for reading very low pressures and velocities. Differential between indoor and outdoor pressures, low duct velocities with pitot tube, calibrate other insturments. High pressure on left side, low pressure on right side

Question 4

What is an Anemometer used for?

Answer 4

Measuring velocity in FPM at outlets. Timed readings

Question 5

What is on the Chiller Test Report?

Answer 5

Compressor data, manufacturer, model, size, type, capacity, refrigerant, pounds, serial number, design water pressures of evap and cond

Question 6

How do Differential Pressure Gauges work and what do they measure?

Answer 6

Two connections and reads in inches WC, feet of water, or mercury. Bourdon, Bellows, or Diaphragm elements

Question 7

What are the two major categories of pumps?

Answer 7

Positive Displacement and Centrifugal

Question 8

Where do you set the OA Dampers for balancing on single fan systems?

Answer 8

Minimum, recirculation to maximum

Question 9

What are Balancing Valves, how are they calibrated, and how are they used?

Answer 9

Balance flow in a system, calibrated to measure flow-pressure relationship for each incremental setting of the valve. Totating plug, globe valve types and more. Used for presetting system balance, adjustable flowmeters, and shutoffs

Question 10

What is Ak Factor?

Answer 10

Unobstructed air flow area of outlet

Question 11

What is a Stuffing Box?

Answer 11

Second protective provision against leakage inside of the pump casing and ambient atmosphere. Seals between the shaft or shaft sleave and stationary support achieved by rings of asbestos or metal packing

Question 12

What is a Rotating Vane Anemometer and what does it measure?

Answer 12

Reads velocities in fpm at grilles, louvers, exhaust hood openings, duct openings, etc. Operates as a windmill with timed counts

Question 13

What are the different types of low pressure systems?

Answer 13

Single zone, low pressure reheat, multizone, Low Pressure Exhausts (return air and toilet exhaust)

Question 14

What are the different types of high pressure systems?

Answer 14

High pressure reheat, dual duct, induction

Question 15

What is a VAV system?

Answer 15

System that auto varies air flow proportionately to current space needs at constant volume

Question 16

What are the types of Centrifugal Fan Wheels?

Answer 16

Backward inclined, air foil wheel, forward curve wheel, radial blade wheel

Question 17

How do you Bump a fan?

Answer 17

Turn fan on and off quickly to ensure proper rotation

Question 18

How do you Traverse a fan?

Answer 18

Straight run of duct in main supply duct away from fittings, dampers, coils, etc

Question 19

What could be done is there is a large difference between the fan and outlet CFM?

Answer 19

15% or more, check duct leakage, accuracy of pitot traverse or method of reading CFM, Instrument calibration, incorrect Ak Factors, for open ducts or missing end caps, math, and design errors. Could throttle main duct damper is partially closed

Question 20

How do you balance a multi-zone system?

Answer 20

Max cooling 100% OA, pitot all main ducts at unit discharge, and compart to total CFM of zones against fan CFM. Manual zone dampers for correct amount of air in each zone and proportionately balance

Question 21

How much difference is there between RA and SA?

Answer 21

RA can handle 70-80% of SA

Question 22

What are the components of a Toilet Exhaust Fan?

Answer 22

Belt driven centrifugal fan (mushroom housing), Backdraft damper, main ducts and plenum, grilles

Question 23

How are VAV systems efficient?

Answer 23

20-30% more energy efficient

Question 24

What is the procedure for balancing a Constant Volume System?

Answer 24

Pressure control balanced. System is filled with air and pressurized. Volume of air then metered out at terminal boxes and pressure controlled with constant volume regulators and controllers, which are set.

Question 25

What are the two types of Auto Volume Mixing Boxes?

Answer 25

Self actuated spring-loaded volume regulator (closes as system pressure rises), and Constant volume mixing box (uses static pressure flow controller to maintain constant volume)

Question 26

How do you balance Cold Decks and Hot Decks in a Dual Duct System?

Answer 26

Stats set to max cooling (100% air flow through cool coil), identical to General Procedure. Balance cold deck, then check hot deck, which may not need to be rebalanced

Question 27

What are Induction Systems?

Answer 27

Generally used for perimeter conditioning under windows. Small volumes of 100% OA which inducts with RA. Smaller fans and ductwork

Question 28

What is the procedure for balancing Induction Systems?

Answer 28

Usually 1/3 OA, 2/3 RA. Follow General Procedure, 1. take static at nozzles with magnehelic, compare readings to manu. CFM ratings. 2. Start with nearest unit to fan, may take two or three passes. 3. Pitot mains and risers

Question 29

What is the theory behind VAV?

Answer 29

Delivers air at constant temp (usu. 55) with varying volumes

Question 30

What are some details on the pressure of the return side of a VAV?

Answer 30

Usually low pressure low velocity ductwork. Separate return air fan needed on larger systems

Question 31

Where is the Static Sensor located on a VAV system?

Answer 31

Downstream in main duct to monitor changing supply duct pressure, then alters fan accordingly to whatever total volume the terminals are set to

Question 32

Where are cooling only VAV systems located?

Answer 32

Interiors of multi-story buildings requiring cooling year round

Question 33

How do you balance a VAV system?

Answer 33

Same as General Procedure.

Question 34

How do you measure OA% and what is the formula?

Answer 34

% of Outside Air: OA% = Tra - Tma / Tra - Toa & Outside Air Balance: Tma = (OA% x Toa) + (RA% x Tra)

Question 35

How do Centrifugal Fans work and what are they?

Answer 35

Most widely used, scroll housing with air entering round inlet on one or both sides, turning 90 degrees, and discharging through rectagular opening

Question 36

How do Vane Axial Fans operate?

Answer 36

Wheels in housed in tubes like centrifugal inline fan wheel, but wheel is a turbine type. Air flow is in a straight line. More blades than propeller and are either flat or curved

Question 37

How do Prepeller fans operate?

Answer 37

Best with very little or no static. Can’t tolerate load and much ductwork

Question 38

What is the best way to measure grilles and registers?

Answer 38

Evenly spaced readings across the surface of the outlet with Velometer

Question 39

What is a Velometer and what does it measure?

Answer 39

Instantaneous direct reading for velocity in fpm and pressures in in. WC. Great for SA at ceiling diffusers. Also reads exhaust velocities at grilles, hoods and duct openings, currents in open spaces, etc.

Question 40

What system did VAVs replace?

Answer 40

Constant volume high pressure system

Question 41

What is a Venturi Flow Meter and how does it work?

Answer 41

Narrow neck of venturi causes pressure drop, manu has calibrated curve to match readings against in inches WC versus GPM flow

Question 42

How does a Tachometer work?

Answer 42

Direct contact or photo type. Timed readings and touches shaft or reads marked point on and counts revolutions