Technical information

25. Hot water production
25.1 Combi Type ’S’ Tap boiler
The appliance is provided with an integral
hot water store that keeps a limited quantity
of hot water water at a pre-set temperature
(tap boiler set-point, T
tap boiler
).
This means that hot water is always
available. As soon as the temperature in
the tap boiler falls below T
tap boiler
- 5 °C, the
burner ignites and functions on low load.
The status display shows ‘d’. As soon as the
water temperature increases above 93 °C,
the burner is switched off.
The pump continues to circulate water
through the hot water circuit.
The burner will again be ignited in order to
heat the contents of the tap boiler when the
return temperature falls below 70 °C.
If the temperature in the tap boiler is higher
than T
tap boiler
, the heating demand will be
removed and the overrun function for hot
water operation will be activated (30
seconds continuous pumping through the
hot water circuit). During this period the
status display shows ‘h’.
T
tap boiler
can be set with the aid of the keys
on the display.
25.2 General operation
For hot water operation the burner is
activated by means of a sensor that is fitted
in the hot water cylinder which measures
the temperature of the cold water supply
t
cold
.
The will be a burner demand for hot water
production in the following cases:
t
cold
< T
boiler
- 5 °C
t
cold
falls more than 50 °C/min
As soon as one of the foregoing conditions
is satisfied, the burner will be ignited. The
status display shows ‘d.’. The burner
modulates the return temperature to a value
that is dependent on the pre-set water
temperature (T
set point
) chosen by the user.
The burner will be switched off when:
- T
return
> T
set point
+ 5 °C
- t
set point
has increased by 10 °C
- t
set point
> T
boiler
+ 5 °C
If the burner no longer burns while there is
still a heating demand, the appliance will
continue to circulate water through the hot
water circuit until the return temperature
falls below
T
set point
- 0 °C. The status display shows ‘d’.
If t
cold
is higher than T
tap boiler
-5 °C, the
heating demand will be removed and the
overrun function for hot water operation will
be activated (30 seconds continuous
pumping via the hot water circuit).
During this period the status display shows
‘h’.
25.3 Pump operation
The pump has two speeds: low (1750 rpm)
and high (2200 rpm). Normally the pump
runs at low speed. When a value for
∆
t of
30 °C is reached, the pump switches to high
speed. Only when
∆
t is smaller than 10 °C
does the pump switch back to low speed.
Page 38 ECO HOMETEC
(
UK
)
LTD
.