
26
STRATA1
3 8 & 3 8 / 4 6 C O M B I
OS
S T
C
SV
IV
IV
IV
IV
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
IV
IV
PS
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 type 2
Typical single Strata 1 boiler installation serving domestic hot water (not Combi) and
heating where hot water has priority via a divertor valve. The in-built circulating pump
within the boiler is used to circulate the system (used only where system index resistance
< pump residual head - see page 24). Flow temperature to hot water is constant and flow
temperature to heating may be constant or weather variable.
17.0 hydraulic system design (contd)