
28
STRATA1
3 8 & 3 8 / 4 6 C O M B I
OS
S T
C
SV
IV
IV
IV
IV
DOC
DOC
DOC
LSV
DOC
Divertor
Valve
Strata 1- 38 Boiler
Condense
Waste
Expansion
Vessel
Calorifier/Indirect
Hot Water Cylinder
Filling
Point
CWM
DOC
Strainer
Heating Load
AAV
Heating Pump
2A Max.
Vertical
Low Velocity
Mixing Header
Max Velocity 0.5m/s
IV
IV
PS
Strainer
IV
IV
OS =
Outside air temperature sensor. Used where
direct-on-boiler weather compensated flow
temperatures are required.
C =
Room controls, either RE2132 modulating room
unit from MHS Boilers or a room thermostat.
S/T =
Hot water temperature controls, either: “S”, an
HWS temperature sensor from MHS Boilers or
“T”, a cylinder thermostat.
PS =
Low water pressure cut off switch.
Divertor valve must be so installed to spring
return to heating.
Divertor valve will require SPDT
relay if not spring return.
System pump to be no greater than 2 amps.
system type 4
Typical Single Strata 1 boiler installation serving heating & domestic hot water (not
Combi). Hot water is priority and is served via a divertor valve and the boiler's in built
circulating pump where index loss through HWS primaries is less than boiler pump residual
head*. Heating circuit index loss exceeds boiler pump residual head* and is served via a low
velocity mixing header and a separate pump. Heating flow temperature may be
fixed/constant or weather variable.
* See page 24
17.0 hydraulic system design (contd)