10
A 511 - DTC 628 Eng.
06.12.05 LB
We reserve the right to make changes without notice
15. CONTROLS
The controller is able to control the modulating burner (E), the boiler shut-off valve (Y) if present and
the pump (M) for the boiler, manifold or heating plant.
15.
1
Control burner E
To control the burner the controller uses output switches 1-2 and 3-4 for burner modulation and
switch 11-12 for On-Off.
The controller compares the desired temperature (T°d) of the current mode with the temperature
measured by the boiler detector (B4) and produces the PI mode control action in relation to the
temperature deviation and the following parameters:
• Proportional Band: fixed value equal to detector measurement
range
• Integral Time: value fixed at 20 minutes
• Time for modulating actuator to go from minimum to maximum
power. Enables controller to calculate the control times “In-
crease and “Decrease”
• Temperature differential On-Off of modulating burner when it
is at minimum power.
In order to prevent a too rapid increase in desired boiler temperature from triggering the safety ther-
mostats, it is possible to program a maximum gradient for this temperature in C° per minute.
15.
2
Control shut-off valve Y
When several boilers use a single manifold it often happens that the boilers are shut off by valves
that allow isolating the unused boilers. DTC 628 can control the shut-off valve by means of SPDT
switch 5-6-7.
• Boiler valve : – MAN : valve is always open (6-7 closed; 5-7 open).
– AUT : the valve is closed (6-7 open; 5-7 closed) in Off mode and with desi-
red temp. zones = 0. It is opened (6-7closed; 5-7 open) in any other
mode.
• Delay Off : xx min
: delay in closing valve (after switching off burner) to avoid overheating
of boiler because of residual heat in the combustion chamber.
15.
3
Control pump for recycle boiler, manifold or heating plant M
The SPDT switch 8-9-10 can control :
- the boiler recycle pump
- the manifold pump (with several boilers use the switches of the various DTC 628 connected
together in parallel)
- the heating plant pump (Examples plants12.
1
).
• Pump Summer: NO: pump not used in summer; - YES: pump used in summer.
• Pump use program :
– 7DAY 1-2 : set in
M2.
9…15
– 24HOUR 1...7: set in
M2.
2…7
– FOLLOWS BOILER : follows program chosen in
M0.
2
– ALWAYS ON : pump always on
– ALWAYS OFF : pump always off
• Pump Delay Off :
– NO : pump switched off without delay.
– YES: pump switched off with delay of 5 minutes.
14.
7
CDB 301 automatic remote control
CDB 301 remote control permits changing the controller programming by the closure of external
voltage-free switches. e.g. boiler, with compensated control, which has to operate at higher tempe-
rature because of demand from DHW storage.
The functions are :
– Input CC - M
= boiler OFF with priority over all other programming.
– Input 1 - M
= not used
– Input 2 - M
= boiler controlled on FROSTPROT
– Input 3 - M
= boiler controlled on SETBACK 1 room temp.
– Input 4 - M
= boiler controlled on NORMAL 1 room temp.
– Input 5 - M
= boiler controlled at Fixed Temp. FIXED POINT 1
The input CC-M “OFF” has absolute priority over all the other programs and consequently when CC
is switched to M it does not matter if some other switch is closed.
All the other controls (2…5) are exclusive and two switches cannot be closed at the same time.
With all the switches open the controller programming is operative.
M1.
11
P u m p S u m me r : Y E S
F O L L O W S B O I L E R
M5.
2
O n - O f f d i f f e r e n t
b u r n e r : x x . x c
M5.
1
B u r n e r M o d u l a t i o n
t i m e : x x x s
M4.
6
B o i l e r v a l v e : A U T
D e l a y O f f : x x m i n
M4.
7
P u m p
D e l a y O f f : N O
M1.
14
S p e e d I n c r e a s e
D e s B o l T : 9 9 . 0 c / m