Hvacwbact40

Name______________________________________________ Date_________________________ Activity 40-1: Split-System Air Conditioning Match each split-system air conditioning system component with the appropriate letter. �� 1. Low-voltage wiring �� 2. Outdoor condensing unit �� 3. Condenser coil

H

G

I

J A

�� 4. Indoor furnace unit �� 5. Service valve �� 6. High-voltage wiring �� 7. Blower �� 8. Fan �� 9. Line set �� 10. Evaporator coil F

E

D

C

B

Activity 40-2: Refrigerant Line Sets (Vertical Line Set Runs) Match each refrigerant vertical line set run component with the appropriate letter. �� 1. PVC pipe

A

H

�� 2. Sleeve �� 3. Outside wall

B

�� 4. Vapor line

G

�� 5. Wood block

C D

�� 6. Strap

E

�� 7. Liquid line F

�� 8. Wire ties 307

308 HVAC AND REFRIGERATION SYSTEMS WORKBOOK

Activity 40-3:Troubleshooting—Investigating a Complaint/No Leak Testing Use the information provided to answer the questions.

SERVICE TICKET No. 56937 Name: Address: City: Zip Code: Phone No.

Dan Adams 1643 Westminster Ave. Lawville State: IL 60444 555.555.1212 (mobile)

Date: Other Info: Time Called: Time Arrived:

Call after lunch. 2:10 pm 2:22 pm

August 12, 2014 Mechanical: New Installation: Maintenance:

Complaint: Until recently, the system seemed to be cooling fine, but now is not cooling at all.

Information: Very hot weather

Equipment: New furnace, condenser, and evaporator split system. The owner says system installed last spring and seemed to work well until yesterday.

Diagnosis: Thermostat set at 74°F, but the temperature is 82°F. An evaporator check indicates the coil is frozen over. A condensing unit check indicates compressor suction line is heavily frosted. Manifold gauge set is connected to condenser, and low-side pressure is 95 psi.

Work Performed:

�� 1. Does the information above indicate a “too hot” or “too cold” service call?

Unit 40 — Installing Residential Forced-Air Cooling Systems 309

Table Tab b e 1 – Suva Suvva® 410a 410 4 410A 10A 0A Saturation S Saturati Saturation aturation Properties Propertiess –– Temperature Properti Temperature Table Temperatur Tab Table be Temp. °F

Pressure (psia) Volume (ft3/lb) Density (lb/ft3) Liquid (Pf) Vapor (vg) Liquid (1/vf)

Enthalpy (Btu/lb) Liquid (hf) Vapor (hg)

Entropy (Btu/(lb)(°R) Liquid (sf) Vapor (sg)

12 13 14 15 16 27

80.09 81.65 83.23 84.84 86 46 105.98

0.7557 0.7415 0.7276 0.7140 0 7007 0.5719

76.24 76.11 75.97 75.83 75 70 74.17

18.0 18.4 18.7 19.1 19 5 23 23.5

119.5 119.6 119.7 119.8 119 7 9 120.7 1

0.0407 0.0414 0.0422 0.0430 0.0520 0437 0.0520

0.2559 0.2556 0.2554 0.2551 0 2548 0.25 0.2518

28 29 30

107.91 109.86 111.84

0.5616 0.5516 0.5417

74.03 73.89 73.74

23.8 24.2 24.6

120.8 120.9 120.9

0.0528 0.0535 0.0543

0.2516 0.2513 0.2510

95.00 psi + 14.70 109.7 psia

�� 2. Using the saturation chart for R-410a shown above, is the low-side temperature above or below freezing?

3. What would be the most likely reason for the evaporator to freeze up?

4. Name at least one other possible cause that could lead to an evaporator freeze-up.

5. Given the fact that the unit operated properly for months, what would be a reason for a low charge?

6. What would be a solution to this situation?

310 HVAC AND REFRIGERATION SYSTEMS WORKBOOK

Table Tab b e 1 – Suva Suvva® 410a Saturation Properties – Temperature Table Temp. °F

Pressure (psia) Volume (ft3/lb) Density (lb/ft3) Liquid (Pf) Vapor (vg) Liquid (1/vf)

12 13 14 15 38 16 39 40 41 42

80.09 81.65 83.23 84.84 128.67 28. 86 46 130.91 133.17 135.46 137 78

0.7557 0.7415 0.7276 0.7140 0.4699 0.4 0 7007 0.4617 0.4537 0.4458 0 4381

76.24 76.11 75.97 75.83 72.58 8 75 70 72.43 72.29 72.14 71 99

Enthalpy (Btu/lb) Liquid (hf) Vapor (hg) 18.0 18.4 18.7 19.1 27.5 2 19 5 27.9 28.3 28.7 29 1

119.5 119.6 119.7 119.8 121.5 119 9 121.5 121.6 121.6 121 7

Entropy (Btu/(lb)(°R) Liquid (sf) Vapor (sg) 0.0407 0.0414 0.0422 0.0430 0.0602 0 06 0437 0.0610 0.0617 0.0625 0 0632

0.2559 0.2556 0.2554 0.2551 0.2 0.2489 0 2548 0.2487 0.2484 0.2482 0 2479

7. Using the saturation chart for R-410a shown above, what would be the approximate expected pressure if the evaporator has a 40°F saturation temperature?

p

Work Performed: Indoor coil iced over, and suction line frosted. After manifold gauges were installed, low-side pressure was below freezing. A quick check of filters showed they were clean. At this point, slow leak suspected. Checked and found very small leak. Repaired leak, fully charged the system, and rechecked for leaks. Downtime of unit allowed ice and frost to melt. Unit has restarted, and the system pressures are now normal. The split system is operating properly. During spring installation, it appears that a small leak was missed. Customer satisfied with system operation.

Field Notes: Read the information above. In addition to the slow leak in the application, there are a number of other possible causes that could have created the same problem, such as the following: • A wrong blower speed or lack of airflow would have caused this problem. However, the problem would have developed immediately, not after months of proper operation. • Dirty filters would have caused this problem if the filters were never changed after the initial spring installation.

Procedure Notes: 1. Discuss various leak checking procedures and specific R-410a characteristics.

Unit 40 — Installing Residential Forced-Air Cooling Systems 311

Review and discuss the HVAC Service Order/Invoice with your instructor.

HVAC SERVICE ORDER/INVOICE 100001

Name

METHOD OF PAYMENT

Address

COD City

Credit Card Type

State

CHARGE Visa

MasterCard

CASH American Express

Discover

Name on Card

Zip

Credit Card Number

Phone

Email

UNIT

ENVIRONMENTAL CHECKLIST

Make

WORK PERFORMED

Model

Location

Serial Number

QTY.

Expiration Date

MATERIAL & SERVICES

UNIT PRICE AMOUNT

QTY.

WORK PERFORMED CONDENSING UNIT

FURNACE/ELECT. HEAT

Recovered

Replace Unit

Repair Unit

Recycled

Change Compressor

Replace Gas Valve

Reclaimed

Replace Motor

Replace Thermocouple

Returned

Replace Refrigerant

Clean Burners

Disposal

Add Refrigerant

Clean Blower

Dismantled TOTAL CHANGED OR REPLACED:

Clean Coils

Change Pilot

DESCRIPTION OF WORK PERFORMED

Refrigerant

Find and Fix Leak

Change Transformer

Oil Motor

Test Limits

Install Disconnect

CO Test

REFRIGERATION Filters

EVAPORATOR COIL

Test Limits

Replace Unit

Check Wiring

Check Drain

Hand Start Kit

Check Pump

Replace Compressor

Clean Pan

Change Thermostat

Replace Exp. Device

Replace Defrost Timer

Check Pan Seal

Find and Fix Leak

Check PVC Piping

Clean Coils

Clean Coil

WINDOW UNIT

LABOR

RATE

TOTAL LABOR

Adjusted

Add Refrigerant

Installed

Clean Selector Switch

Check Filter Rack

Replace Compressor

Check Grill

Replace Fan Motor

Adjust Actuators

Repair Leak

THERMOSTAT

TOTAL MATERIALS: HRS.

DUCT

Replace Unit

AMOUNT

RECOMMENDATIONS

FILTERS

Adjusted

Cleaned

Replaced

Limited Warranty:

TOTAL SUMMARY

Special Terms:

Total Materials Total Labor Special Charges Regular Service Contract

Warranty

Subtotal Tax TOTAL

312 HVAC AND REFRIGERATION SYSTEMS WORKBOOK

Activity 40-6: Troubleshooting—Compressor Failure Use the information provided to answer the questions.

SERVICE TICKET No. 56999 Name: Address: City: Zip Code: Phone No.

Walker Behavior Clinic (James Flatley) 9 Essez Road Other Info: Loveland State: IL 60999 Time Called: Time Arrived: 555.555.2121

Date: Check in for badge. 1:15 pm 1:35 pm

July 28, 2014 Mechanical: New Installation: Maintenance:

Complaint: System operating well until 2 pm yesterday. Section of building became very hot quickly. Owner states condensing unit for section of building was replaced earlier in year.

Information: Very hot weather. Small medical building. *Park in back of building. *Obtain badge at security desk.

Equipment: Multiple residential-type split air conditioning systems. Unit #3 is an old R-22 system that now has an R-410a condenser unit with an old evaporator.

Diagnosis: The thermostat is set at 72°F, but the actual temperature in the space is 80°F.

Work Performed:

�� 1. Does the information above indicate a “too hot” or “too cold” service call? �� 2. Should the cooling be on and the compressor running? Write “yes” or “no.”

3. If the compressor is not running but power is present, what would be a good course of action?

4. Given the equipment information provided in the service ticket, what procedure should have been performed when the old R-22 condensing unit was replaced?

Unit 40 — Installing Residential Forced-Air Cooling Systems 313

�� 5. If the system was not flushed properly or at all, could not flushing the system when the R-22 condensing unit is replaced cause a new compressor failure? Write “yes” or “no.”

6. At this point, what is the only course of action to get the system running again?

p

Work Performed: Located section of medical building that was hot. Quick check of outdoor condensing unit indicated compressor not running. Checked incoming power, wak ok, but the compressor would not run. Performed motor insulation test and found shorted windings (bad motor). Replaced compressor and flushed system. Charged system with R-410a. System now operating properly. Called previous HVAC contractor about flushing system (did not understand proper flushing procedures). Not flushing the system properly probably caused compressor burnout. Owner is now satisfied with system.

Field Notes: A technician cannot assume that previous work was done correctly. Tact and discretion must be used when discussing any pre-existing situation with a building owner or previous contractor.

314 HVAC AND REFRIGERATION SYSTEMS WORKBOOK

Fill in and discuss the HVAC Service Order/Invoice for proper billing.

HVAC SERVICE ORDER/INVOICE 100001

Name

METHOD OF PAYMENT

Address

COD City

Credit Card Type

State

CHARGE Visa

MasterCard

CASH American Express

Discover

Name on Card

Zip

Credit Card Number

Phone

Email

Expiration Date

UNIT

WORK PERFORMED

Model

Location

Serial Number

QTY.

ENVIRONMENTAL CHECKLIST

Make

MATERIAL & SERVICES

UNIT PRICE AMOUNT

QTY.

WORK PERFORMED CONDENSING UNIT

FURNACE/ELECT. HEAT

Recovered

Replace Unit

Repair Unit

Recycled

Change Compressor

Replace Gas Valve

Reclaimed

Replace Motor

Replace Thermocouple

Returned

Replace Refrigerant

Clean Burners

Disposal

Add Refrigerant

Clean Blower

Dismantled TOTAL CHANGED OR REPLACED:

Clean Coils

Change Pilot

DESCRIPTION OF WORK PERFORMED

Refrigerant

Find and Fix Leak

Change Transformer

Oil Motor

Test Limits

Install Disconnect

CO Test

REFRIGERATION Filters

EVAPORATOR COIL

Test Limits

Replace Unit

Check Wiring

Check Drain

Hand Start Kit

Check Pump

Replace Compressor

Clean Pan

Change Thermostat

Replace Exp. Device

Replace Defrost Timer

Check Pan Seal

Find and Fix Leak

Check PVC Piping

Clean Coils

Clean Coil

WINDOW UNIT

LABOR

RATE

TOTAL LABOR

Adjusted

Add Refrigerant

Installed

Clean Selector Switch

Check Filter Rack

Replace Compressor

Check Grill

Replace Fan Motor

Adjust Actuators

Repair Leak

THERMOSTAT

TOTAL MATERIALS: HRS.

AMOUNT

RECOMMENDATIONS

Cleaned

Replaced

Limited Warranty:

TOTAL SUMMARY Total Materials Total Labor Special Charges

Regular Service Contract

FILTERS

Adjusted

Special Terms:

Warranty

Subtotal Tax TOTAL

DUCT

Replace Unit

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