Carrier Aquasnap 30RAP010 Product Data page 52

Application data (cont)
by an external 4 to 20 mA signal. These features require a
signal from an intelligent central control. Do not cycle
demand limiter for less than 10 minutes on and 5 minutes
off. Duty cycling cycles electrical loads at regular intervals
regardless of need. This reduces the electrical operating
costs of building by "fooling" demand indicating devices.
Duty cycling of compressors or fans is not recommended
since motor winding and bearing life will suffer from con-
stant cycling.
Remote on-off control
Remote on-off control may be applied by hard-wired con-
nection (see Controls and Troubleshooting literature) or by
connection to a Carrier Comfort Network
Optional hydronic system selection
Select pump gpm from resulting chiller selection and total
pressure loss in the system plus the chiller internal pressure
loss.
NOTE: Maximum gpm (L/s), pressure and pump hp must
not exceed maximum on pump curve.
Pump flow can be reduced by using the factory-supplied
triple-duty valve up to 10%. Beyond that, impeller
trimming is recommended to reduce energy consumption.
Follow local codes or ASHRAE 90.1 recommendations.
Contact your Carrier representative for specific amount of
trim required.
Expansion tank supplied will allow loop expansion due
to ambient fluctuations for loop volumes of up to the values
in the table below. If loop volume exceeds the maximum
loop volume, a larger expansion tank must be field
supplied.
The supplied expansion tanks have the following
specifications: 30RAP010-030 — 4.4 total gal. (17.0 L)
and 3.2 gal. (12.4 L) acceptance volume, 30RAP035-060
— 10.3 total gal. (39.0 L) and 10.3 gal. (39.0 L) accep-
tance volume.
MAXIMUM LOOP VOLUME
30RAP010-030
CONCENTRATION
GAL.
PURE WATER 412
10% EG 239
20% EG 233
30% EG 206
40% EG 200
10% PG 233
20% PG 200
30% PG 170
40% PG 157
LEGEND
EG — Ethlyene Glycol
PG — Propylene Glycol
Maximum loop volume is based on typical system pres-
sure of 12 psig (83 kPa) and 30 psig (207 kPa) of mini-
mum and maximum pressures, and 100 F (37.8 C) mean
temperature.
52
® (CCN) system.
30RAP035-060
L GAL. L
1560 1356 5131
906 795 3009
880 767 2902
781 692 2620
755 655 2478
880 767 2902
755 655 2478
645 561 2124
595 514 1947
Parallel chillers with hydronic packages require that
pump inlets be equalized to prevent pump cavitation.
Pump expansion tanks must be removed and located
together in the common pump suction header. All materi-
als needed for expansion tank relocation are field supplied.
Appropriate measures must be taken for freeze protection.
Air separation
For proper system operation, it is essential that water
loops be installed with proper means to manage air in the
system. This is typically done by the installing contractor.
Free air in the system can cause noise, reduce terminal out-
put, stop flow, or even cause pump failure due to pump
cavitation. For closed systems, equipment should be pro-
vided 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 pres-
sures. Therefore, separation can best be done at the point
of highest water temperature and lowest pressure. Typical-
ly, this point would be on the suction side of the pump as
the water is returning from the system or terminals. Gener-
ally speaking, this is the best place to install an air separa-
tor, if possible.
1. Install automatic air vents at all high points in the sys-
tem. (If the 30RAP unit is located at the high point of
the system, a vent can be installed on the piping
entering the heat exchanger on the ¼-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
pressures — usually in the chilled water return piping.
On a primary-secondary system, the highest tempera-
ture water is normally in the secondary loop, close to
the decoupler. Preference should be given to that
point on the system. In-line or centrifugal air separa-
tors are readily available in the field.
It may not be possible to install air separators at the place
of lowest pressure and highest temperature. In such cases,
preference should be given to the points of highest
temperature. It is important that pipe be sized correctly so
that free air can be moved to the point of separation. Gen-
erally, a water velocity of at least 2 ft 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
system operation. Provision should also be made for man-
ual venting during the water loop fill. It is important that
the automatic vents be located in accessible locations for
maintenance purposes, and that they be located where
they can be prevented from freezing.