Mitsubishi Electric CRHV-P600YA-HPB Service Handbook page 40

[ II Restrictions ]
6. Minimum and maximum water flow rates
A low flow rate will not only compromise the performance of the unit but also increase the water temperature difference be-
tween the periods when the unit is in operation and when the unit is stopped. A high flow rate will cause the pipes to corrode.
Adjust the circulating flow rate so that the difference between the inlet and outlet temperatures will be between 3 ºC and 10
ºC. Refer to the table below for the standard, minimum, and maximum flow rates.
Standard, Minimum, and Maximum flow rates
CRHV-P600YA-HPB
Hot water side
Heat source side
The hot water flow rate will be considered appropriate if the difference between the inlet and outlet water temperatures is be-
tween 3 ºC and 10 ºC.
If the temperature difference is less than 3 ºC
Decrease the flow rate.
If the temperature difference is more than 10 ºC
Increase the flow rate. Check the pipes for air pockets, and make sure that the pump has enough capacity to sustain appro-
priate water pressure in a given water circuit.
7. Maintaining the appropriate amount of water in the water circuit.
(1) Amount of water in the water circuit
Shortage of water in the circulating water circuit may shorten the operation time of the unit or cause large fluctuations of water
temperature. The table below shows the minimum allowable amount of water in the water circuit. If the piping length is too
short to secure this amount, install a cushion tank to ensure that the circuit has enough water in it.
Model
CRHV-P600YA-HPB
(2) Calculating the amount of water in the circuit
The amount of water in the circuit can be obtained using the following formula.
Amount of water in the water circuit = Amount of water in the water piping + Amount of water in the unit + and Amount of water
in the load-side or heat source unit
The table below shows the amount of water in the water piping per 1 m
Amount of water in the piping
Internal volume per meter (ℓ/m)
The table below shows the amount of water in the unit.
Amount of water in the unit
Model
CRHV-P600YA-HPB
8. Sizes and the material types of the pipes on the unit
The table below shows the sizes of the pipes.
Pipe sizes
Model
CRHV-P600YA-HPB
HWE1312A
Standard flow rate (50Hz)
Heating
10.3
14.7
Minimum allowable amount of hot water (ℓ)
550
3/4B (20A) 1B (25A)
0.37
Hot water side
R2 male thread pipe <SUS304>
Minimum allowable flow
rate
3.2
4.5 (counter flow)
2.0 (parallel flow)
Minimum allowable amount of heat source (ℓ)
Pipe size
1 1/4B (32A) 1 1/2B A(40A)
0.60 0.99
Hot water side (ℓ)
15
R2 male thread pipe <SUS304>
- 33 -
3
Unit: m /h
Maximum allowable flow
rate
15.0
16.0
390
2B (50A)
1.36 2.20
Heat source side (ℓ)
10
Heat source side
1 1/2B (65A)
3.62
GB