INSTALLATION AND OPERATION INSTRUCTIONS
2-8
SL 30-175, SL 45-260 MODULATING GAS BOILERS
the boiler to fire using onward leads to the boiler’s dry contacts (use one of the
pairs marked “therm 1, 2 or 3” on the sensor Block terminal strip. gang such
leads in parallel from multiple zone valves for single connection to the boiler.
note that typical room thermostats simply provide a call for heat, they do not
control the circulating water temperature from the boiler in an open loop reset
system. adjustment of a room thermostat from 23°C to 30°C will make no further
difference to the delivered temperature if the floor slab has stabilized at the boiler
temperature served up by the reset curve.
Where outdoor reset is applied without the indoor sensor feedback option, some
manual adjustment may be required to achieve the desired comfort level. Fine
adjustment can be made at the keypad using the
Indoor Setpoint Temperature
variable, located as line 1 in the user screen. to increase heat (e.g. from 72°F to
73°) - move the indoor value upward (warmer) from the level otherwise chosen.
this shifts the position of the reset curve, will amend the boiler water temperature
by a similar amount. do not adjust the
Design Indoor Temp.
value - a movement
upward in concert with line 1 adjustment will have the effect of neutralizing the
intended effect.
An optional indoor temperature feedback routine can be activated (with field
installation of an indoor sensor, connected to the contacts located on the
controller) to automate adjustment of the outdoor reset routine.
the key inputs on initial set up are (1)
Design Outdoor Temperature
– the coldest
expected weather typically experienced at the installation site; (2) the
Design
Supply Temperature
– the desired boiler operating level to occur at that coldest
day; and (3) the
Design Indoor Temp.
- this is the value that anchors the reset
curve. the
Indoor Set Point Temp.
variable is the primary means for the user to
“bias” the outdoor reset routine to add or reduce heat.
if outdoor reset is selected and there is no signal received from the sensor,
the controller assigns a provisional 0°C value and will adopt the appropriate
temperature target from the relevant reset curve.
see
Section 2.7 Set Up & Load Definition
for activation procedure.
2.6.4 variable Speed Pumping
This section reserved
2.6.5 Temperature Setback
For heating loads declared as space Heating (e.g. with
Outdoor Reset
) and/
or
DHW (where a thermistor probe is used),
there are provisions for entering
temperature setback intervals. during the setback period, the boiler supply
water temperature target is adjusted from the pre-set fixed or floating (with
Outdoor Reset
) levels. there is a simultaneous movement in the
Indoor Setpoint
Temperature
or
DHW Tank Setpoint,
to yield a consistent spread and avoid
undesirable cycling. normally users would apply this feature to achieve fuel
savings during night-or-away hours. it is also possible to use the feature to
set forward (up) the temperature; this may be of use for certain commercial
applications where short-term high temperature dHW service is desired.
up to 56 events / week can be programmed for each eligible load – for example,
dHW can be set back twice and returned (twice) each day. the routine can be
applied by specific day (Mon-Sun).
the automated setback feature cannot be applied to setpoint loads, including
dHW with simple aquastat control. this is due to the lack of linkage with the
thermostat; setback without linkage could lead to unacceptable cycling.
access is via the
User Setup
screen.
Summary of Contents for SL 30-175
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