unit 50

1. Typically, on mini-split systems the line set going to the outdoor unit carries ________ pressure, ________ temperature saturated liquid and vapor mix.

low, high, low

2. Which of the following mini-split system indoor units requires a condensate pump because gravity condensate draining is never feasible for this type of installation?

Ceiling suspended

3. Variable refrigerant flow systems use:

Inverter driven systems and electronic expansion valves.

4. Manufacturers recommend pressurizing VRF piping to ________ with nitrogen and performing a 24 hour standing leak test.

500 - 600 psig

5. Standard wyes and tees are not used in VRF refrigeration networks as they introduce turbulence and do not ensure even flow to both branches.

True

6. A type system that allows simultaneous heating and cooling to different parts of a building is the:

Heat recovery system.

7. Designing a heating and cooling system to accommodate load shifts:

All of these.

8. Some codes limit refrigerant 410A to 25 pounds per 1000 cubic feet of space. This works out to 40 cubic feet per pound of refrigerant. The limit is lower, ________ cubic feet per pound of refrigerant for 24 hour care facilities such as hospitals and nursing homes.

20

9. Most multisplit units require connection to:

At least two indoor units, but not all of the circuits have to be used.

10. Mechanical codes limit the amount of refrigerant a system can contain if it is located in an occupied space. Because VRF systems are connected to one large refrigerant network that would release the entire charge in case of a leak, some codes limit refrigerant 410A charge to ________ pounds per 1,000 cubic feet of space.

25

11. Which of the following is NOT a type of indoor unit used on mini-split systems?

Crawl space

12. The typical number of wires connecting the outdoor unit to the indoor unit of a mini-split system is:

Four.

13. Flare connections are used on mini-split systems to avoid oxidation in the lines and also to avoid heating and destroying the sensitive electronic expansion valves used in the outdoor units.

True

14. What type of refrigerant line connections are used on multisplit systems?

Both Multiple connections on the outdoor unit and Single set of connections on the outdoor unit could be used.

15. The wiring connection between the outdoor and indoor unit typically has four wires. One wire carries power, a second wire carries low voltage communication while a third wire carries both line voltage power and low voltage communication. A fourth wire is utilized for ground.

True

16. Designing a heating and cooling system to accommodate load shifts can allow buildings to operate with ________ capacity to meet the demand.

less installed

17. It is possible for one multi-split indoor unit to heat while another cools.

False

18. Multisplit manufacturer's installation instructions will specify the maximum total installed piping length which can be supported by the charge shipped in the unit. If additional piping is installed the only correct way to charge the system is to:

Add the specified amount of refrigerant for each additional foot of refrigerant line.

19. The smallest capacity VRF outdoor units available generally equal or exceed the largest multisplit units available.

True

20. VRF systems are commercial systems. The outdoor units are normally designed to operate on ________ phase power and the indoor units on ________ phase power.

three, single

21. When more than one indoor unit is connected an individual branch selection box on a heat recovery system:

Each indoor unit must operate in the same mode.

22. Mini-split condensate pumps come in three basic varieties: two-piece pumps, monoblock pumps, and:

Reservoir pumps.

23. When factory supplied branch joints are not available for VRF refrigerant piping it is permissible to use standard tees or wyes.

False

24. Like many multisplit units, variable refrigerant flow (VRF) systems use ________ compressors and electronic expansion valves to change the volume of refrigerant being circulated in the system.

inverter driven

25. It is important when wiring multisplit systems that the indoor units connect to their corresponding A, B, C, or D terminal block on the outdoor unit.

True

26. Which system allows simultaneous heating or cooling?

Heat recovery system.

27. While multisplit units are limited to a single outdoor unit, large VRF systems can combine as many as ________ outdoor units manifolded together to increase overall system capacity.

three

28. Power for the mini-split system is supplied:

To the outdoor unit which powers the indoor unit.

29. On heat recovery systems:

One indoor unit can be in heating mode while others are in cooling mode at the same time.

30. Some multisplit systems operate all indoor units from one control while others allow individual indoor units to operate from their own controls and set points.

True

31. The refrigerant lines for single zone mini-split air conditioners are usually connected by:

Flare fittings.

32. To avoid the creation of oxides in the refrigeration lines of mini-split systems, the lines are assembled:

Using heavy-walled flare fittings.

33. VRF systems use a refrigeration network of:

Headers and branch joints.

34. On mini-split systems both refrigerant lines must be insulated because they are both:

Low pressure and low temperature in the cooling mode.

35. Most systems can operate with up to ________ feet of lines and a maximum of ________ feet vertical distance between the indoor and outdoor units.

50, 10

36. Branch selectors are boxes in heat recovery VRF systems that allow:

One refrigerant line to feed multiple indoor units.

37. Wiring for a four-port multisplit system runs:

Four wires to