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This chapter is from the book

This chapter is from the book

HVAC

The HVAC design goals for Cisco TelePresence rooms boil down to three primary criteria:

  • Generating enough air flow to keep the temperature of the room comfortable for the participants. This is measured in terms of British Thermal Units per hour (BTU/hr) and is a function of the heat generated by the TelePresence system and other electronic devices within the room, plus the heat generated by the human bodies within the room.
  • Achieving the above BTU/hr performance without generating high levels of ambient noise. Simply cranking up the air conditioning is rarely the best solution because it can result in a higher volume of wooshing sound coming through the HVAC registers (the vents that supply air to the room). You must strive to achieve a balance of the air flow:noise ratio.
  • Positioning the HVAC registers to maximize the efficiency of the air flow between the supply registers and the return registers. This is critical as it can effectively reduce the total amount of BTU/hr capacity required by as much as 25%, thereby reducing or eliminating the costs associated with upgrading the capacity of the HVAC system.

Tables 8-6, 8-7, and 8-8 summarize the BTU requirements for the CTS-3000, CTS-3200, and CTS-1000. These values include all the equipment and lighting provided with the system and the participants within the room. Note that the CTS-500 is designed to be deployed within an existing room with no HVAC modifications, and, therefore, a power consumption table for that model is not provided here.

Table 8-6. BTU Requirements for the CTS-3000

Component

Maximum1

Typical1

Minimum1

Idle1

Plasma Displays

2,880w

2,658w

2,658w

9w

Primary Codec

120w

113w

113w

113w–120w

Secondary Codec (108w max / 101 average each)

216w

202w

202w

202w–216w

Light Façade

348w

348w

348w

0w

Laptop Power (240w max / 144w average each)

1,440w

864w

144w

0w

Projector

288w

225w

0w

0w–5w

Auxiliary LCD2 (325w max / 230w average each)

975w

230w

0w

0.6w

Auxiliary Document Camera2

200w

200w

0w

0w

Total Wattage

6,467w

4,840w

3,465w

324w–350w

Total Amperage (wattage / volts)

54A @ 120V

41A @ 120V

28A @ 120V

3A @ 120V

27A @ 240V

21A @ 240V

14A @ 240V

2A @ 240V

People (450 BTU/hr each)

2,700 BTU/hr

2,700 BTU/hr

450 BTU/hr

0 BTU/hr

Total BTU/hr (wattage * 3.413) + people3

24,772 BTU/hr

19,218 BTU/hr

12,276 BTU/hr

1,106–1,195 BTU/hr

Table 8-7. BTU Requirements for the CTS-3200

Component

Maximum1

Typical1

Minimum1

Idle1

Plasma Displays

2,880w

2,658w

2,658w

9w

Primary Codec

120w

113w

113w

113w–120w

Secondary Codec (108w max / 101 average each)

216w

202w

202w

202w–216w

Light Façade

348w

348w

348w

0w

Laptop Power (240w max / 144w average each)

4,320w

2,592w

144w

0w

Projector

288w

225w

0w

0w–5w

Auxiliary LCD (325w max / 230w average each)

975w

230w

0w

0.6w

Auxiliary Document Camera2

200w

0w

0w

0w

Total Wattage

9,347w

6,368w

3,465w

324w–350w

Total Amperage (wattage / volts)

54A @ 120V

41A @ 120V

28A @ 120V

3A @ 120V

27A @ 240V

21A @ 240V

14A @ 240V

2A @ 240V

People (450 BTU/hr each)

8,100 BTU/hr

5,400 BTU/hr

450 BTU/hr

0 BTU/hr

Total BTU/hr (wattage * 3.413) + people3

40,000 BTU/hr

27,134 BTU/hr

12,276 BTU/hr

1,106–1,195 BTU/hr

Table 8-8. BTU Requirements for the CTS-1000

Component

Maximum1

Typical1

Minimum1

Idle1

Plasma Displays

960w

886w

886w

3w

Primary Codec

120w

113w

113w

113w–120w

Light Façade

80w

80w

80w

0w

Laptop Power (240w max / 144w average each)

480w

288w

144w

0w

Auxiliary LCD2

325w

36w

0w

0w–5w

Auxiliary Document Camera2

200w

0w

0w

0w

Total Wattage

2,165w

1,403w

1,223w

116w–128w

Total Amperage (wattage / volts)

19A @ 120V

12A @ 120V

10A @ 120V

2A @ 120V

10A @ 240V

6A @ 240V

5A @ 240V

1A @ 240V

People (450 BTU/hr each)

900 BTU/hr

450 BTU/hr

450 BTU/hr

0 BTU/hr

Total BTU/hr (wattage * 3.413) + people3

8,289 BTU/hr

5,238 BTU/hr

4,624 BTU/hr

396–437 BTU/hr

Table 8-9. Power Requirements for Auxiliary Displays and Document Cameras

Vendor – Model

Maximum

Idle

NEC LCD1770NX

36w

<3w

NEC LCD2070NX

50w

<3w

NEC LCD4010

230w

<5w

NEC LCD4020

240w

<5w

NEC LCD4610

260w

<5w

NEC LCD4620

240w

<5w

Samsung 400PXN

230w

<1w

Samsung 460PXN

310w

<1w

Sharp PN-525U

325w

<1w

WolfVision VZ-9plus

55w

0w

WolfVision VZ-C122

200w

0w

WolfVision VZ-C32

200w

0w

HVAC Air Noise Diffusion Considerations

As mentioned previously in the "Acoustics" section, to meet these BTU requirements without exceeding the ambient noise threshold of 46dB, the recommendation is that you always use NC30-rated air registers, which diffuse the air flowing out of the register to reduce the air flow noise. To maximize the efficiency of the air flow through the room, you should locate the supply registers behind the participants and the return registers directly over the 65-inch plasma displays of the TelePresence system. Doing so can reduce the capacity requirements of the HVAC substantially. Figure 8-42 illustrates such an arrangement for a CTS-3000 room.

Finally, measure the temperature of the air flowing out of the register. (Use a laser thermometer pointed directly at the register from 3 feet [1 meter] away.) If the temperature of the air is warmer than 70-degrees Fahrenheit (21-degrees Celsius), it is probably too warm to be effective, and your HVAC system might need to be recharged. However, if the temperature of the air is colder than 55-degrees Fahrenheit (12° Celsius), it might cause discomfort for the participants standing or sitting directly beneath the register. An HVAC specialist can further assist you in measuring and designing the HVAC system.

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