Eco Hometec EC 25 COMPACT Technical Manual - page 22
12. Hot
water
output
12.1
Combi Type ’S’ Tap boiler
The appliance is provided with an integral
hot water store that keeps a limited quantity
of hot water at a pre-set temperature.
This means that hot water is always
available. As soon as the temperature in
the tap boiler falls below 5 °C below set
point the burner ignites and functions on low
load.
12.2
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.
When the heating demand is removed, the
pump continues to run for the pre-set
overrun time, at the end of which it is
switched off.
12.3
Hot Water Cylinder
A hot water cylinder boiler can be directly
connected to the EC25HS. The cylinder
temperature can be regulated by means of
a thermostat or an NTC temperature
sensor. When an NTC-sensor is used, the
appliance will modulate during the boiler
heating cycle. In the following process
description it is assumed that regulation
takes place by means of an NTC-sensor.
13. Safety
devices
13.1
Flow protection
The appliance is provided with a water
pressure sensor that is used in combination
with the supply and return sensors to
protect the appliance.
For every burner start, the pump is stopped
and after a 2 second delay the static system
pressure is measured. Hereafter the pump
is restarted at high speed. The fan runs and
the pre-ignition phase begins.
At the end of the pre-ignition phase the
system pressure is measured again.
The following situations are possible:
Pressure difference < 0.06 bar:
1.
Air in the appliance
Pump or pump connection is broken. The
control system switches to the pump test
phase, in which the pump is switched on for
30 seconds and then off for 30 seconds.
During this test phase the control system
waits until a sufficient pressure difference is
created. The display shows ‘P’ continuously
and all heating demands are disregarded.
Pressure difference > 0.44 bar:
Too little flow. In this case the control
system also switches to the pump test
phase. During this test phase the control
system continues to wait until the pressure
difference is between 0.06 and 0.44 bar.
Pressure difference > 0.06 and < 0.44 bar:
The burner ignites and the flow monitoring
is taken over by the supply and return
sensor logic.
The pump is forced to switch over to low
speed until there is an increase in
temperature. In this way the pump is tested
at both speeds: high speed with the aid of a
pressure difference, low speed by means of
a temperature increase.
If, when the burner is ignited, the pressure
rises or falls by more than 0.1 bar within 4
seconds, then the burner will be switched
off. The control system then switches to the
pump test phase until sufficient pressure
difference has been created.
For central heating and hot water operation
the appliance modulates back when
∆
T >
40 °C. The
∆T regulation in the programme
functions as follows:
∆T
< 32
complete capacity
utilization
32 <
∆T < 40 capacity is reduced linearly
to low load at 40 °C
40 <
∆T < 45
low load
> 45
Off
Page 22
ECO HOMETEC
(
UK
)
LTD
.