Safety Device Discharge Arrangements (G3); Electrical Connection - Mitsubishi Electric ecodan EHPT20Q-VM2EA Installation Manual

4
Installation

4.4 Safety Device Discharge Arrangements (G3)

The following instructions are a requirement of UK Building Regulations
and MUST be adhered to. If you are in any doubt please seek advice from
local building planning office.
1. Connect the tundish and route the discharge pipe as shown in Figure 4.4.1.
2. The tundish should be fitted vertically and as close to the safety device as
possible and within 500 mm of the device.
3. The tundish should be visible to occupants and positioned away from electri-
cal devices.
4. The discharge pipe (D2) from the tundish should terminate in a safe place
where there is no risk to persons in the vicinity of the discharge, be of metal
construction and:
A) Be at least one pipe size larger than the nominal outlet size of the safety
device unless its total equivalent hydraulic resistance exceeds that of a
straight pipe 9 m long i.e. discharge pipes between 9 m and 18 m equivalent
resistance length should be at least two sizes larger than the nominal outlet
size of the safety device, between 18 and 27 m at least 3 sizes larger, and so
on. Bends MUST be taken into account in calculating the flow resistance.
Refer to Figure 4.4.1, Table 4.4.1 and the worked example. An alternative
approach for sizing discharge pipes would be to follow BS 6700: 1987 specifi-
cation for design installation, testing and maintenance of services supplying
water for domestic use within buildings and their cartilages.
B) Have a vertical section of pipe at least 300 mm long, below the tundish before
any elbows or bends in the pipework.
C) Be installed with a continuous fall.
D) Have discharges visible at both the tundish and the final point of discharge
but where this is not possible or is practically difficult there should be clear
visibility at one or other of these locations. Examples of acceptable discharge
arrangements are:
Metal discharge pipe (D1)
pressure relief valve to tundish
Safety device
(e.g. pressure
relief valve)
500 mm maximum
Tundish
300 mm
minimum
Metal discharge pipe (D2) from tundish,
with continuous fall. See Point 4.D i-iv,
Table 4.4.1 and worked example
Valve outlet Minimum size of Minimum size of discharge
size discharge pipe D1 pipe D2 from tundish
G 1/2 15 mm 22 mm
28 mm
35 mm
G 3/4 22 mm 28 mm
35 mm
42 mm
G1 28 mm 35 mm
42 mm
54 mm
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i. Ideally below a fixed grating and above the water seal in a trapped gully.
ii. Downward discharges at low level; i.e. up to 100 mm above external
surfaces such as car parks, hard standings, grassed areas etc. are accept-
able providing that where children may play or otherwise come into contact
with discharges a wire cage or similar guard is positioned to prevent contact,
whilst maintaining visibility.
iii. Discharges at high level; e.g. into a metal hopper and metal down pipe with
the end of the discharge pipe clearly visible (tundish visible or not) or onto a
roof capable of withstanding high temperature discharges of water and 3 m
from any plastic guttering system that would collect such discharges (tundish
visible).
iv. Where a single pipe serves a number of discharges, such as in blocks of
flats,the number served should be limited to not more than 6 systems so that
any installation discharging can be traced reasonably easily. The single
common discharge pipe should be at least one pipe size larger than the
largest individual discharge pipe (D2) to be connected. If unvented hot water
storage systems are installed where discharges from safety devices may not
be apparent i.e.in dwellings occupied by blind, infirm or disabled people,
consideration should be given to the installation of an electronically operated
device to warn when discharge takes place.
Note: The discharge will consist of scalding water and steam. Asphalt,
roofing felt and nonmetallic rainwater goods may be damaged by
such discharges.
Discharges MUST be positioned in a frost-free location.
Worked example: The example below is for a G½ pressure relief valve with a
discharge pipe (D2) having 4 No. elbows and length of 7 m from the tundish to
the point of discharge.
From Table 4.4.1: Maximum resistance allowed for a straight length of 22 mm
copper discharge pipe (D2) from a G½ pressure relief valve is: 9.0 m subtract
the resistance for 4 No. 22 mm elbows at 0.8 m each = 3.2 m. Therefore the
maximum permitted length equates to: 5.8 m. 5.8 m is less than the actual
length of 7 m, therefore calculate the next largest size. Maximum resistance
allowed for a straight length of 28 mm pipe (D2) from a G½ pressure relief valve
equates to: 18 m
Subtract the resistance for 4 No. 28 mm elbows at 1.0 m each = 4 m. Therefore
the maximum permitted length equates to: 14 m. As the actual length is 7 m, a
28 mm (D2) copper pipe will be satisfactory.
Discharge below fixed grating
(Point 4.D gives alternative points of
discharge)
Fixed grating
Trapped gulley
<Figure 4.4.1>
Maximum resistance allowed, expressed as a Resistance created by
length of straight pipe (no elbows or bends) each elbow or bend
Up to 9 m 0.8 m
Up to 18 m 1.0 m
Up to 27 m 1.4 m
Up to 9 m 1.0 m
Up to 18 m 1.4 m
Up to 27 m 1.7 m
Up to 9 m 1.4 m
Up to 18 m 1.7 m
Up to 27 m 2.3 m
<Table 4.4.1>
4
Installation

4.5 Electrical Connection

Breaker abbreviation Meaning
ECB Earth leakage circuit breaker for booster heater
TB1 Terminal block 1
TB2 Terminal block 2
⑥
⑦ ① ② ④③ ⑤
⑦ ① ②⑥ ④③ ⑤
and run wires shown as
e a r t h
TB1
TB2
cable longer than
① ②
ECB
ECB
CAUTION
-
This product contains
-
electrically grounded / earthed in order to discharge any possible static elec-
The outdoor unit can only be powered via Cylinder unit.
terminals as indicated in the figures to the
left
① 〜 ⑦
A Locally supplied wiring should be inserted through the inlets situated on the
B Wiring should be fed down the left hand side of the control and electrical box
C
control board
③
④
⑤
⑥
cable
...①
D
①
cable
E Connect the outdoor unit – cylinder unit connecting cable to TB2 ...②
②
unit cable
Connect the power cable for the booster heater to ECB ...⑦
⑦
cable for Booster heater
*1
n completion of wiring, ensure main controller cable is connected to
the relay connector
WARNING
When confirming the operation of the ECB, make sure that the ECB can
be turned ON/OFF by the power lever before pressing the test button.
If the ECB cannot be turned ON/OFF by the power lever, stop using the
ECB and replace it.
ensure you are
on the
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