Worked Example - Dimplex ECS150HP40A-580 Installation And User Instructions Manual

4.4.2 Worked Example

This example is for a G½ temperature relief valve
with a discharge pipe (D2) (as fitted on 125 to
300L cylinders) having 4 No. 22mm elbows and
length of 7m from the tundish to the point of
discharge.
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 resistance for 4 No. 22mm elbows
at 0.8m each = 3.2m.
Therefore the maximum permitted length
equates to 5.8m, which is less than the actual
length of 7m, therefore calculate the next largest
size.
Maximum resistance allowed for a straight length
of 28mm copper discharge pipe (D2) from a G½
temperature relief valve is: 18m
Subtract the resistance for 4 No. 28mm elbows
at 1.0m each = 4m
Therefore the maximum
equates to 14m.
As the actual length is 7m, a 28mm (D2) copper
pipe will be satisfactory.
 Where a single common discharge pipe
serves more than one system, it should be
at least one pipe size larger than the largest
individual discharge
connected.
 The discharge pipe should not be connected
to a soil discharge stack unless the soil
discharge stack
withstanding temperatures of the water
discharged, in which case, it should:
 contain a mechanical seal, which allows
water into the branch pipe without allowing
foul air from the drain to be ventilated
through the tundish.
 there should be a separate branch pipe with
no sanitary appliances connected to it.
 if plastic pipes are used as branch pipes
carrying discharge from a safety device,
permitted length
pipe (D2) to
is capable of safely
Pre-Installation
they should be either polybutalene (PB) or
cross-linked polyethylene (PE-X) complying
with national standards.
 be continuously marked with a warning that
no sanitary appliances should be connected
to the pipe.
4.4.3 Termination of Discharge Pipe
 "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."
Examples of acceptable discharge arrangements
are:
 "to a trapped gully with the end of the pipe
below a fixed grating and above the water
seal;
 downward discharges at low level; i.e. up to
100mm above external surfaces such as car
parks, hard standings, grassed areas etc.
are acceptable providing that a wire cage or
similar guard is positioned
contact, whilst maintaining visibility; and,
 discharges at high level: e.g. into a metal
hopper and metal downpipe with the end of
the discharge pipe clearly visible or onto a
roof capable
temperature discharges of water and 3m
from any plastic guttering system that would
collect such discharges."
Note: As the discharge would consist of
high temperature water and steam, asphalt,
be
roofing felt and non-metallic rainwater
goods may be damaged by such discharges.
4.5 Limitations
 The heat pump must be specified correctly,
to ensure it is compatible with the model of
cylinder installed. This is to prevent the heat
pump
domestic hot water.
 The heat exchangers in this range of
cylinders have been specifically designed for
heat pump applications. Great care must be
taken if using these cylinders with other heat
sources, due to the heat exchange capacity
of the product.
of withstanding
malfunctioning when
to prevent
high
preparing