FASTflo LWH56, Installation Design Manual

Page: 12 / 24

Andrews WH & WHX Unvented System Kits
Fig No.9
If continuous flow water heaters are used on circulation systems or linked to a storage cylinder/buffer vessell
an unvented system kit is required to allow for expansion of the hot water system. The kit includes the
necessary safety devices required to conform to the current building regulations.
Three sizes of kit can be supplied and each contains a combined strainer/pressure reducing valve set to 3.5
bar, check valve, expansion valve set to 6.0 bar, tundish, 5 litre expansion vessel, wall bracket and hose.
When the system includes a storage cylinder/buffer vessel, a combined temperature/pressure relief valve
must be sized to suit the total input of all the water heaters installed (see table below).
This valve must be located at the top of the storage unit (see Fig. No. 10). In addition the size of the
expansion vessel must also be increased to suit both the storage cylinder plus the contents of the system
pipework (see expansion vessel table).
Unvented System Kit
Part No. Size
B235 3 /
4
inch dia.
B234 1 inch dia.
B276 1
1
/
4
inch dia.
Expansion Vessel
Part No. Size
C782 25 litre, 3.5 bar
C789 40 litre, 3.5 bar
E047 60 litre, 3.5 bar
C890 80 litre, 3.5 bar
Temperature and pressure Relief Valves Tundishes
Part No. Total Output Quantity & Size of Valves Part No. Size
C380 Up to 56kw 1 x 1 inch C384 1 inch - 1 1 /
4
inch
E242
Up to 112kw 1 x 1
1
/
2
inch
E326
1 1/2 inch - 2 inch
E242+C456
Up to 126kw 1 x 1
1
/
2
inch + 1 x
3
/
4
inch
E497
2 inch - 2
1
/
2
inch
E291
Up to 168kw 1 x 2 inch
E497
2 inch - 2
1
/
2
inch
E291+C380
Up to 224kw 1 x 2 inch + 1 x 1 inch
E497+C384
2 inch - 2 1 /
2
inch+ 1 inch - 1 1 /
4
inch