Safety Device Connections; Piping Diagram For 2-Zone Temperature Control; Refrigerant Pipework - Mitsubishi Electric ecodan EHST20 Série Manuel D'installation

4
installation

Safety device Connections

The expansion relief valve on the secondary hot water side, and the temperature
and pressure (T&P) relief valve (*1), situated part way down the DHW tank on the
right hand side, both need appropriate discharge pipework. In accordance with
Building Regulations a tundish must be fitted into the pipework within 500 mm of
the safety device (also see Figure 4.4.1). Due to the distance between the two
safety devices it may be necessary to fit each safety device with its own tundish
before you run the pipework together to a safe discharge (see Figure 4.3.6). The
right side panel has a window (*2) so that connection can be made to the factory
fitted temperature and pressure relief valve. If you wish to make the connection in
a different position you will have to cut a hole in the side panel yourself. However
it remains necessary that the drainage parameters outlined in the appropriate
Building Regulations are complied with.
*1 Temperature and pressure relief valve fitted on EHPT20X-VM2HB ONLY.
*2 Unscrew the plate on the right-side panel, connect the T&P relief valve to the
discharge pipework, and refit the plate. Always replace the plate so that no
gaps exist between the plate and side panel and the plate and drain pipe to
avoid heat loss.
note: Alternatively the discharges from the expansion relief valve and t&P
relief valve may commonly discharge to a singular tundish, so long
as this tundish is located within 500 mm of the t&P relief valve. When
connecting discharge pipes to the safety devices, beware not to
strain the inlet connections.
diagram description
part no.
2 Pressure relief valve
6 Temperature and pressure relief
valve (Factory fitted)
Expansion relief valve
(part of inlet control group)
<Table 4.3.2>
Always refer to local regulations when installing discharge pipework.
Install discharge pipework in a frost-free environment.
It is necessary to provide appropriate drainage from the pressure relief valve
situated on top of the cylinder unit to prevent damage to the unit and the sur-
rounding area from any steam or hot water released. Relief valves MUST
NOT be used for any other purpose.
For UK use WK01UK-E kit, for other countries please see below;
• Any discharge pipework should be capable of withstanding discharge of hot
water. Discharge pipework should be installed in a continuously downward di-
rection. Discharge pipework must be left open to the environment.
<Pressure relief valve included with the cylinder unit>
* Only eHPt20X-VM2HB does not include following pressure relief valve.
item
Pressure relief valve (1.0 MPa (10 bar))
Install a pressure relief valve (1.0MPa (10 bar)) on the local piping connected to the cold water inlet.
A pressure relief valve should be installed between the pressure reducing valve and the cylinder unit (see Figures 3.6, 3.7 and 3.9).
Note: It is essential no check valve or isolation valve is fitted between the cylinder unit connection and the 10 bar pressure relief valve accessory (safety matter).
The connection size is G1/2" (the drain connection size G3/4").
The cold water inlet can be identified on the diagram label on top of the cylinder unit.
<Accessory location>
The pressure relief valve accessory pack can be found inside the cylinder unit, taped to the base.

Piping diagram for 2-zone temperature control

Connect the pipe work and field supplied parts according to the relevant circuit diagram shown in Section 3. Technical Information, of this manual.
For more details on wiring, refer to "5.3 Wiring for 2-zone temperature controls".
Note: Do not install the thermistors on the mixing tank. This could affect correct monitoring of flow and return temperatures through each zone.
Install the Zone2 flow temp. thermistor (THW8) near the mixing valve.

4.4 refrigerant Pipework

refer to the outdoor unit installation manual.
Match the outer diameter of the refrigerant pipe between the outdoor unit and cylinder
unit with that of the refrigerant pipe on the outdoor unit.
If they do not match, connect the following adapter to the refrigerant pipe on the cylinder unit.
Connected pipes
Model name
diameter (mm)
PAC-SH50RJ-E ø15.88 → ø12.7
PAC-SH30RJ-E ø9.52 → ø6.35
15
Connection Connection
size type
G 1/2 Female
15 mm Compression
15 mm Compression
Quantity
1
diameter A diameter B
(mm) (mm)
ø15.88 (5/8 F) ø12.7 (1/2 F)
ø9.52 (3/8 F) ø6.35 (1/4 F)
eHPt20X-VM2HB (for UK)
DHW
2
6
Other models
The expansion vessel on the sanitary water side shall
be installed as necessary in accordance with your lo-
cal regulations.
Expansion relief valve
(sanitary water side)
DHW
<Figure 4.3.6>
A
<Cylinder unit side>
<Figure 4.4.1>
Cold water inlet
PRV (primary) to discharge to
safe & visible location
Tundish
Cold water inlet
B
<Extension pipe side>