SDC / DHC
Hydraulic Components
EN2H-0221GE51 R0808
133
Combined operation for 2-stage heat generators
•
As long as just one stage can meet the heat demand (stage II
inactive), stage I is switched according to switching
differential I.
•
As soon as stage 2 is needed to meet the heat demand,
switching differential I takes over the switching on and off of
stage II and switching differential II takes over the switching of
stage I.
i
a
1)
2)
3)
i
i
b
c
d
d
c
b
a
e
s
x
y
a
b
e
c
d
f
g
h
i
a Switch-off level stage I
g Area 1 high use (start-up),
coverage of heating demand at
full load (burner stages I and II)
b Switch-off level stage II
h Area 2 low use, coverage of
heat demand with partial load
(burner stage I only)
c Switch-on level stage II
i Area 3 increased use,
coverage of heating demand at
full load (both burner stages)
d Switch-on level stage I
x Boiler temperature
e Swap of switching
differential
y Time
f Theoretical
progression
with stage I alone
1) Temperature drop becomes slower after every switch-off of
stage II, as stage I provides support.
2) Switch-on level stage II is no longer reached, temperature is
reached from stage I.
3) Temperature drops due to increased heat demand under
switch-on level stage II.
