【 Weak current College 】 HVAC-common design knowledge and issue point rolled

A) system design issues
1. water pump in the system location:
In General, frozen water pump should be set in the chiller front-end, back from the end of frozen water is chilled water pumps back to chillers, cooling water pump located in the cooling water inlet unit of water from the cooling tower out of the Park's cooling water pump back to unit; hot water circulation pump located in the backwater dry pipe, from end of hot water after hot water circulation pump back to plate heat exchanger.
2, cooling tower design: on the valve
2, 1 into the water pipe for cooling tower and solenoid valve (do not promote the use of manual valve)
2, 2 tube valves should be set in the room, (if placed on the outside, because there are some in the water, winter easy frozen)
3, electronic water treatment installation location
Placed in front of the pump back, host.
4, filters and valves
Filters and drop the pressure gauge.
5, pumps and valves
5, 1 pump inlet in turn received: butterfly's valve-pressure gauges-soft received
5, 2 water pump outlet in turn received: soft received-pressure gauges-check valves-butterfly valves
6. diversity of water
6, 1 diversity of water between electric pressure differential bypass valve and bypass pipe (pipe diameter General take DN50)
6, 2 sets of water back into the water pipe should be located a thermometer.

7, the location of the various instruments: layout of thermometers, pressure gauges and other measuring devices should be established to facilitate the observation, valve highly general ground 1.2-1.5m, above this level, you should set the work platform.
8, unit position: two compressor distance between prominent part is less than 1.0m, refrigerator and the distance between the wall and the non-primary channel of distance not less than 0.8m, medium and large refrigeration units (centrifugal, screw, absorption chillers) its spacing 1.5-2.0m. Refrigerating units for refrigerated room upper best reserved for the biggest part of the lifting hook or sets electric lifting equipment.
(2), water design problem points summary
A problem: the pipe slope to reasonable
1, horizontal branches, trunk, along the fluent direction should consistently maintain not less than 0.002 gradient;
2. the discharge water pipes should not be less than 0.01 gradient.
3. when the limit is due to conditions, can be laid without slope, flow velocity inside the tube must not be less than the 0.25m/s.
Problem point two: condensation water dry pipe design
1, condensation water emissions should be approached, in general the bathroom floor drain
2, the length of the condensate water dry pipe design to consider because of the height of the gradient, caused by pipe ends and throw distance cannot be greater than the ceiling height
Issue 3: selecting the right point of pipeline valves
1, risers and horizontal pipe connection charge regulator
3. each of the main road, the highest located exhaust device (when no slope laying, in the end of the horizontal flow)
3, standpipe lowest connection shutdown valve for easy maintenance of risers
4. pipe thermal compensation can take advantage of the elbow when insufficient natural remedies, can also be retrofitted expansion Compensator
Issue four: tube placement point
1, the legislature is not in the pipeline well, misplaces preferably placed against the wall by PTA.
2. pipe in the horizontal plane passing through the stairs, in the prohibition of shear walls, power distribution, etc.
Issue 5: water pipe insulation
1 insulation structure generally consists of insulation and protection layers
2 thermal insulation thickness according to the thermal calculation determined that experience value can refer to the Civil Code of the air conditioning system design P279
3 insulation materials can be adapted to local conditions, the nearest, should be made of non-combustible or nonflammable materials must comply with the architectural design of the fire code.
Question six: hydraulic calculation
1 chilled water system the difference of pressure loss for parallel loops, should not be greater than 15%;
2 water pipes than the friction to control in the 100-300Pa/m,
Issue point seven: water system water
1 chilled water system water should be softened water treatment, only summer cooling system can adopt electronic water treatment;
2 system water supply system-water capacity by 2%
3 water point yishe in the inhalation of circulating pumps
(3), the end of the design of sites:

1. welcome the wind up of pipe outlet design.
1) first air and wind up outlet distance to appropriate;
2) with two outlet of wind up air pipe to reducer;
3) wind up in the air and the distance to the appropriate outlet back. (≤ 5 m)
2. fan-coil design of the inlet and outlet road.
1) inlet and outlet road is "motivated by a";
2) wind up and for the relative backwater dry pipe the elevation is not less than 200mm;
3) fles on then click Add Filter, gate valves, and soft received;
4) received on the outlet pipe, valve software.
3. same model wind up of the number of Tuyere
The same model and the trend of disk outlet number visible air conditioning zones.

4. two small rooms share a wind up in the air
Two small rooms share a trend of disk, each room can be set in a outlet, two rooms of the diffusers can be received through the series back to the wind up of draught

5. close the window of the trend of disk layout:
To withstand Outdoor cooling load, fan-coil should be as close as possible to exterior walls and window layout.

6. big space for fan coil arrangement:
In the large space arrangement of fan coil should take the "intermediate return air, ventilation air distribution means" layout of the trend of disk,
7. embedding machine layout
Embedded machine layout when the distance from the wall must not be greater than 3 m;
Such as conference rooms, function rooms, and other layout embedded machine should use small cooling capacity of multiple machines, uniform layout.
8. in the selection
Large space can choose embedded aircraft, rectangular Office the best selection of card machine
9. choice of diffusers
High space notUse diffuser air (air should not be served on the workspace), it is best to use adjustable double louver supply outlet.

10. back to the bellows approach:
Air processor of return air design: in the return air Department do larger back to bellows, appears in a back to back to the bellows, the outlet is adjustable airflow to reduce noise), see Figure 1-7

11. According to the function room and cooling load design suitable wind up.
The trend of disk selection to be based on the design load, the trend of disk layout taking into account the characteristics of the air conditioning room layout appearance as much as possible. (See Figure 1-8)

(4), wind system design issues that point:
1. send and outlet of the distance to the right.
Vents and air at least 3 m distance to prevent airflow short-circuit
2. Select proper air valve.
In principle, the system pressure balance of error of 10%-15% or less, you can set the control valve, but in reality only through air tube size to reduce wind is difficult, therefore, to set the air control valve for regulation.
① air duct Branch Office should be located air flow control valve. In three branch offices can be set up three-way valves or valve at the Branch Office.
② obvious negative loop can not control valve to reduce resistance loss.
③ the required fire damper, fire control valve control valve is available in alternative
④ Air Department of louver expressing with the air control valve, the request not high may be double louver, adjusting the angle adjustable air outlet.
⑤ fresh air inlet to installed tight switches for air valve, cold regions should be installed insulation air valve, automatic control, electric air valve should be used.
3. wind pipe layout.
① to minimize local resistance, i.e. reducing elbow, three links, reducing the number of
② Bend radius of curvature of not less than the Centre of the duct diameter or side length, generally available 1.25 times diameter or side length
③ for ease of adjustment of the air duct system, in the trunk branch points, should be reserved pressure taps. Pressure taps away from the previous local pipe distance should be greater than 5b (b rectangular duct of the long side or circular duct diameter), distance back local pipe distance shall be not less than 2b. Fan outlet air flow more stable segment should be set aside on the manometer.
4. where fresh air inlet
① inlet yishe comparison in outdoor air clean place, ensuring air quality
② yishe in the North wall, avoid located in the roof and the Western Wall, and yishe building shade so that the air inhaled outdoor summer temperature lower
③ the air inlet is at the bottom margin for outdoor ground is less than two metres, when the air inlet is arranged in the green belt, you should not be less than one meter
④ should be arranged in a outlet on the side of the upper hand, and lower than the outlet, and to maintain not less than 10 m spacing
5. new Tuyere requests
① use fixed louvres
② rainy areas should be waterproof in case of rain into the Venetian blind
③ to prevent birds entering, shutters in yishe metal mesh
6. exhaust pipe of new practices
Like the hotel rooms of exhaust system design can be considered as follows: the exhaust fan is indoor air to the corridors of the ceiling in the corridor is located within the exhaust tube exhaust, to effectively use waste heat, blower can be set in the bathroom.

7. air inlet and the wall of distance
Air outlet from the wall should not be less than 1 m
8. choice of diffusers.
① new air, air double louver
② air outlet grille Tuyere with back
③ vents with double shutters
④ fluoride system because the air flow in normal smaller, if winter heating needs, the use of double blind, you cannot use the diffuser.
⑤ fan coil unit with two air outlet to date selection in a double blind with control valve
9. air inlet dew
Outlet dew is small due to the wind, temperature low. You can increase the size to prevent condensation outlet

10. calculation of static pressure Chamber
① speed control of static pressure Chamber should be no greater than 1.5m/s
② the wind section A = G/V (G-air), the direction of the cross-sectional area should be the same
③ General system can be used in place of air outlet adjustable static pressure chamber with silencer
11. a number of smoke ventilation.
① the fire pump room not less than 4 times
② transformer room 5-8 times
③ transformer room 5-8 times
12. arrangement of the exhaust port.
④ Corridor over 60 m, exhaust vents
⑤ the elevator room used penumatic leafy áir, one for each layer
⑥ stairs used for vertical louver, 2-3 a
13. the room air pressure.
① building air-conditioning rooms should remain positive pressure.
② building's toilet, lavatory room, equipment room should maintain vacuum negative pressure
③ Hotel rooms should maintain positive pressure, closets should maintain negative pressure
④ restaurant lobby should remain positive pressure, kitchen should maintain negative pressure. The air pressure within the restaurant should be in the anteroom and the kitchen.
14. ceiling of wind pipe layout principles
From top to bottom: exhaust air pipe, exhaust pipes, air tube, pipe
15. delivery, the relative position of the exhaust air outlet
Air conditioning in the room parallel to exhaust tube, exhaust air outlet try not side-by-side arrangement, it is best to interlaced layout
16. air supply pipe design
As far as possible, so that the wind is blowing tube does not go down, ensure good air flow in and out of the wind effects
17. links and wind pipe joint
And three contiguous tube diameter to the three links of diameter, not adjustable, avoiding partial loss is too large.