Carrier AQUASNAP 30RB060-390 Spécifications télécharger pdf (Page 40)

NOTE: Locate the 3-way valve as close as possible to the

chiller to minimize head pressure control response time.

FOR ALL UNITS

Dual Chiller Control Option

— If the dual chiller algorithm is

used, and the machines are installed in parallel, an additional

chilled water sensor must be installed for each module. For

30RB315-390, a factory-supplied thermistor and well are

shipped in the control box of each module. Install the wells in

the common leaving water header. See Fig. 34.

Parallel chiller control with dedicated pumps is recom-

mended. Chiller must start and stop its own water pump locat-

ed in its own piping. If pumps are not dedicated for each chill-

er, then isolation valves are required. Each chiller must open

and close its own isolation valve through the unit control (the

valve must be connected to the pump outputs).

See Dual Chiller Control Option section on page 57 for

more dual chiller leaving water sensor information.

Minimum Loop Volume

— The preferred minimum loop vol-

ume is dependent on the type of application. In order to obtain

leaving water temperature stability for comfort cooling appli-

cations, a minimum of 3 gallons per ton (3.25 liters per kW) is

required on all unit sizes. For process cooling applications, ap-

plications where high stability is critical, or operation at

ambient temperatures below 32 F (0° C) is expected, the loop

volume should be increased to 6 to 10 gallons per ton (6.46 to

10.76 liters per kW) of cooling.

In order to achieve this volume, it may be necessary to add a

water storage tank to the water loop. If a storage tank is added

to the system, it should be properly vented so that the tank can

be completely filled and all air eliminated. Failure to do so

could cause lack of pump stability and poor system operation.

Any storage tank that is placed in the water loop should

have internal baffles to allow thorough mixing of the fluid. See

Fig. 35. For units with heat reclaim option, a minimum con-

denser loop volume of 6 gallons per ton of heating (0.5 to 0.83

gallons [1.9 to 3.1 L] per 100 Btu/h of heating) capacity is nec-

essary. In come cases, this will require the installation of a hot-

water buffer tank.

System Piping

— Proper system design and installation proce-

dures should be followed closely. The system must be

constructed with pressure tight components and thoroughly

tested for installation leaks.

Installation of water systems should follow sound engineer-

ing practice as well as applicable local and industry standards.

Improperly designed or installed systems may cause

unsatisfactory operation and/or system failure. Consult a water

treatment specialist or appropriate literature for information

regarding filtration, water treatment, and control devices.

Figure 29 shows a typical installation with components that

might be installed with the hydronic package of the 30RB unit.

NOTE: It is recommended for units with the hydronic package

that an inlet isolation (shutoff) valve be placed exterior to the

unit to allow removal and service of the entire pump assembly,

if necessary. The hydronic package is supplied from the factory

with a combination valve for isolation of leaving water. Also,

if the unit is isolated with valves, a properly sized pressure

relief valve is recommended and should be installed in the pip-

ing between the unit and the valves, following all applicable

local codes.

Air Separation

— For proper system operation, it is essential

that water loops be installed with proper means to manage air

in the system. Free air in the system can cause noise, reduce

terminal output, stop flow, or even cause pump failure due to

pump cavitation. For closed systems, equipment should be

provided to eliminate all air from the system.

The amount of air that water can hold in solution depends

on the pressure and temperature of the water/air mixture. Air is

less soluble at higher temperatures and at lower pressures.

Therefore, separation can best be done at the point of highest

water temperature and lowest pressure. Typically, this point

would be on the suction side of the pump as the water is return-

ing from the system or terminals. This is generally the optimal

place to install an air separator, if possible.

1. Install automatic air vents at all high points in the system.

(If the 30RB unit is located at the high point of the system,

a vent can be installed on the piping leaving the heat ex-

changer on the

in. NPT female port.)

2. Install an air separator in the water loop, at the place

where the water is at higher temperatures and lower pres-

sures — usually in the chilled water return piping. On a

primary-secondary system, the highest temperature water

is normally in the secondary loop, close to the decoupler.

Preference should be given to that point on the system

(see Fig. 36). In-line or centrifugal air separators are read-

ily available in the field.

It may not be possible to install air separators at the place of

the highest temperature and lowest pressure. In such cases,

preference should be given to the points of highest temperature.

It is important that the pipe be sized correctly so that free air

can be moved to the point of separation. Generally, a water

velocity of at least 2 feet per second (0.6 m per second) will

keep free air entrained and prevent it from forming air pockets.

Automatic vents should be installed at all physically elevat-

ed points in the system so that air can be eliminated during sys-

tem operation. Provisions should also be made for manual

venting during the water loop fill.

SUPPLY

RETURN

CONSTA NT SPEED

CIRCULATING PUMPS

HEAT RECLAIM

CONDENSER

MODULATING 3-WAY

CONTROL VALVE

40 FT MAX

Fig. 33A — Three-Way Head Pressure Control

Valve Location (Preferred)

a30-4825

MODULATING 3-WAY CONTROL

VALVE (AS CLOSE TO CONDENSER

AS POSSIBLE)

HEAT RECLAIM

CONDENSER

CONSTA NT SPEED

CIRCULATING PUMPS

RETURN

SUPPLY

Fig. 33B — Three-Way Head Pressure Control

Valve Location (Alternate)

a30-4824

IMPORTANT: Automatic vents should be located in

accessible locations for maintenance purposes and

protected from freezing.

1 2 ... 35 36 37 38 39 40 41 42 43 44 45 ... 71 72

Commentaires sur ces manuels

Pas de commentaire

Carrier AQUASNAP 30RB060-390 Spécifications Page 40

Commentaires sur ces manuels

Produits connexes et manuels pour Pompes à chaleur Carrier AQUASNAP 30RB060-390