Victorum Exhaust Air Heat Pump Installation Guide
41
Victorum PrePlumb
Temperature & Pressure Relief Valve
Connect the tundish and route the discharge pipe which must be routed in accordance with Build-
ing Regulations - Part G3 of schedule 1.
When operating normally water will not be discharged from the temperature and pressure relief valve.
Water discharge from the temperature and pressure valve will only occur under fault conditions. The
tundish is pre-fitted as shown below.
The discharge pipe (D2) coming from the tundish should terminate in a safe place where there is no
risk to persons near the discharge, be of metal and:
•
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. discharge pipes
between 9m and 18m equivalent resistance length should be at least two sizes larger than the
nominal outlet size of the safety device, between 18 and 27m at least 3 sizes larger, and so on.
•
Bends must be taken into account in calculating the flow resistance. Refer to Table 1 and the
worked example. An alternative approach for sizing discharge pipes would be to follow BS6700
Specification for design, installation, testing and maintenance of services supplying water for
domestic use within buildings and their curtilages.
•
Be installed with a continuous fall. The discharge must be visible at the final point of discharge.
Image below shows the position of the tundish outlet.
G1/2
G3/4
G1
Min. size of discharge pipe D1
15mm
22mm
28mm
Min. size of discharge pipework D2
from tundish
22mm
28mm
35mm
28mm
35mm
42mm
35mm
42mm
54mm
Max. length of straight pipe (no bends
or elbows)
Up to
9m
Up to
18m
Up to
27m
Up to
9m
Up to
18m
Up to
27m
Up to
9m
Up to
18m
Up to
27m
Deducts the below from the maximum
length for each bend or elbow in the
discharge pipe
0.8m
1m
1.4m
1.0m
1.4m
1.7m
1.4m
1.7m
2.3m
Sizing of copper discharge pipe (D2) for a temp, relief valve with a G1/2 outlet size (as supplied)
TABLE 1