Pipe Connections; Restrictors; Fitting Losses - Marstair CC 875 Technical Manual

these sizes and lengths is recommended in order to achieve optimum system performance. Smaller sizes may be
used, but at the risk of loss of performance.
MAXIMUM EQUIVALENT LENGTH
UNIT 5/8
MCU+ 60 14
MCU+ 80 11
MCU+ 90 10
MCU+ 100 7.5
MCU+ 130
MCU+ 150
MHPUE 80 11
MHPUE 100
MHPUE 150
4. In calculating equivalent lengths of pipe runs, the effect of bends and fittings must be taken into account. The table
below covers the fittings most likely to be encountered in this type of installation. The equivalent lengths of all the
fittings in a particular pipe run must be added together and the total added to the actual length of pipe in the run, in
order to calculate the total equivalent length.
5. Use the shortest possible route, avoiding sharp bends.
6. Fully insulate both the suction and expansion lines, including the expansion device, since both lines may sweat.
Fitting
45° Bend
90° Bend R/d = 1
90° Bend R/d = 1.5
180° Bend C/d = 1.5
180° Bend C/d = 2.5
90° Elbow
R = Radius of bend
FITTING LOSSES, in equivalent straight lengths of pipe (metres).

PIPE CONNECTIONS

Pipework is terminated with flare nut connectors, adjacent to the access panel.
Units are supplied with the following male flare connections (sizes in inches):-
Model
Size
80
Suction 5/8
Expansion 1/2
NOTE: Ensure that both service valves on the outdoor unit are closed (IN, fully clockwise) before commencing
installation.
Indoor units have a low pressure holding charge of nitrogen, which may be released into the atmosphere without damage
to the environment. This should be done prior to making pipework connections.

RESTRICTORS

Outdoor units are supplied with cooling restrictors fitted; refer to page 14 for any
restrictor changes; those ticked do not require changing. Where appropriate, the
alternative restrictor is supplied with either the indoor or the outdoor unit.
For units needing a change of cooling restrictor, replace the restrictor in the outdoor unit by:
a. Completely removing the expansion assembly from the outdoor unit.
b. Split the expansion assembly in the middle.
c. Remove the existing restrictor.
d. Drop the new restrictor vertically downwards into the field connector.
e. Reassemble in the vertical plane (field connector lowest) and refit the
expansion assembly to the outdoor unit.
Tel: 01823 665660
Heronhill - for all your Marstair requirements
OF SUCTION PIPE (m)
3/4 7/8 1-1/8 1-3/8
36 80
30 80
25 55 80
22 45 80
15 30 80
12 27 80
30 80
22 45 80
12 27 80
Pipe Size (outside diameter in inches)
3/8 1/2
0.12 0.15
0.37 0.43
0.24 0.27
0.73 0.91
0.46 0.55
0.67 0.85
d = Diameter of tube
CC875
110 140 60
3/4 3/4 5/8
1/2 1/2 3/8
www.heronhill.co.uk
EXPANSION
LINES
3/8 1/2 5/8 3/4
7.5 50 80
50 80
20 80
15 80
12 60 80
8 50 80
50 80
15 50 80
8 50 80
5/8 3/4 7/8
0.18 0.21 0.24
0.49 0.55 0.61
0.30 0.37 0.43
1.10 1.28 1.46
0.64 0.76 0.85
1.04 1.25 1.46
C = Centres of bend
MCU+ / MCUP / DCUE
80 90 100 130
5/8 5/8 3/4 3/4
1/2 1/2 1/2 1/2
20
FACTORY CHARGE
OF REFRIGERANT
(g)
R407C R22
2000 1900
1880 1800
2060 1960
2520 2400
4170 3970
4170 3970
1780 1840
3380 3490
4200 4300
1-1/8
0.3
0.79
0.52
1.83
1.07
1.89
MHPUL(E)
150 80 100 150
3/4 5/8 3/4 3/4
1/2 1/2 1/2 1/2
Fax: 01823 665807