Dimplex EDL200UK-630RF, Installation And User Instructions Manual

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7
Pre-Installation
5.8 Building Regulation G3 Discharge
Requirements
As part of the requirements of Building Regulation G3
this product is factory fitted with a T&P valve, which
complies with BS EN 1490. Any discharge from a water
heater system should be conveyed to where it is visible,
but will not cause danger to persons in or about the
building. The tundish and the discharge pipes should be
fitted in accordance with the requirements of
Building Regulation approved document G3, (England
and Wales), Part P of Northern Ireland and Standard
4.9 of Scotland.
5.8.1 Discharge Pipe D2
Dimplex strongly recommends the use of metal
pipework only and Dimplex does not take responsibility
for any damage caused from discharges.
The discharge pipe D2 should 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 9m long, i.e. for discharge pipes
between 9m and 18m the equivalent resistance length
should be at least two sizes larger than the nominal out-
let size of the safety device; between 18m and 27m at
least 3 sizes larger, and so on; bends must be taken into
account in calculating the flow resistance. See
Figure 2, Table 2 and the worked example.
5.8.2 Worked Example
Figure 2: Typical discharge pipe arrangement
If required, precautions can be taken to minimise
effects of water hardness, i.e. installation of water con -
ditioner or water softener. These devices should be in-
stalled in hard water areas where high water
storage temperatures are required, i.e. greater than
60°C storage temperatures, particularly when water
hardness exceeds 200ppm. Should the water heater re-
quire de-scaling, this must be performed by a
qualified technician.
Table 2: Discharge
Value
outlet
size
Minimum size
of discharge
pipe before
tundish (mm)
Minimum size
of discharge
pipe after
tundish (mm)
Maximum
allowed length
of pipe after
tundish (m)
Length to be
subtracted for
each elbow or
bend
(m)
G1/2 15 22 9 0.8
28 18 1.0
35 27 1.4
G3/4 22 28 9 1.0
35 18 1.4
42 27 1.7
G1 28 35 9 1.4
42 18 1.7
54 27 2.3
Dimplex recommend an annual maintenance
inspection is carried out on the water heater. In hard wa-
ter areas this should include inspection of the
immersion heater, [above 120ppm or 120mg/l]. A local
water treatment company should be able to offer free
water quality testing. The heating elements may require
periodic de-scaling. The installer should do this as part of
a maintenance agreement.
- The cold water inlet pipework should have at least an
inside diameter of 19mm and should meet the
requirements of the water regulations for the supply
of wholesome water.
Note: An alternative approach for sizing discharge pipes
would be to follow Annex D, section D.2 of BS 6700:2006
+ A1:2009).
- The cold water supply to the water heater must come
directly from the cold water mains after the mains
stop valve to the property.
This example is for a G½ temperature relief valve with
a discharge pipe (D2) having 4 No. 22mm elbows and
length of 7m from the tundish to the point of discharge.
The discharge pipe (D2) from the Tundish should:
- “have a vertical section of pipe at least 300mm long
below the tundish before any elbows or bends in the
pipework and be installed with a continuous fall of at
least 1 in 200 thereafter.”
The following instructions have to be followed when
installing the cold water mains supply to the water
heater:
Minimum dynamic pressure 150Kpa (1.5 bar)
Maximum inlet supply pressure 1200Kpa (12 bar)
Minimum flow rate 15l/min
Max. chlorine content 250mg/L
Max. water hardness 200mg/L
For satisfactory and safe performance of the water
heater the water supply must meet the following
criteria:
5.7 Cold Water Supply
The discharge pipe (D2) should be made of:
- “metal; or other material that has been demonstrated
to be capable of safely withstanding temperatures of
the water discharged and is clearly and permanently
marked to identify the product and performance
standard”
From Table 2, the maximum resistance allowed for a
straight length of 22mm copper discharge pipe (D2) from
a G½ temperature relief valve is 9.0m. Subtract the re-
sistance for 4 No. 22mm elbows at 0.8m each = 3.2m.