Camus Hydronics Valiant FT VA0080, Manual

Page: 31 / 79

24
The two parameters above define the second reference
point to determine the slope of the Outdoor Reset Curve.
Figure 36: Outdoor Reset Curve Slope
The slope of the curve is determined by interpolation
between the first and second reference point. Changing the
Boiler Maximum and Boiler Minimum parameters of the
curve will only change the overall range of the curve and
not the slope of the curve. The slope can only be changed
by altering the parameters corresponding to the two
individual reference points above. The outdoor temperature
used for the CH_Setpoint calculation is measured once a
minute and averaged with the previous measurement. If an
‘open’ outdoor sensor is detected, the
CH_Setpoint
will be
equal to the
Design_Supply_Temp
.
Description Programming Instructions
• Boiler
operates at
variable
Setpoint set
by the outdoor
reset curve.
•
This mode will
only function
when an
outdoor
temperature
sensor is
connected.
•
Heat demand
is generated
when a relay,
such as one
connected to a
room
thermostat,
closes the
1) Place Remote/Local switch into
“REMOTE”.
2) On the digital display, follow the
previous instructions to enter into
the ‘Boiler Parameters’ settings and
set the CH Mode to 1.
3) Scroll down to parameters
‘Design
Supply Temp.’ , ‘Design Outdoor
Temp.’
,
‘Baseline Supply Temp.’
,
‘Baseline Outdoor Temp.’ and
adjust all the parameters required
to set the curve as previously
described.
Enable/Disable
contact.
4) The ENABLE/DISABLE contact on
Terminal Block 1 (TB1-2, TB1-4)
must be closed by a relay, such as
one connected to a room
thermostat to generate a Heat
Demand.
Some additional features of the Outdoor Reset are Warm
Weather Shutdown
,
Boost function
and
Calculated
Setpoint Offset
.
Figure 37: Outdoor Reset Warm Weather Shutdown
Warm Weather Shutdown: Warm weather shutdown is a
feature which shuts off the demand to the boiler when the
outdoor temperature reaches above the set
Warm_Weather_Shutdown tempe 1.8°F. Similarly,
when the outdoor temperature drops below the set
Warm_Weather_Shutdown temperature - 1.8°F, the heat
demand is re-enabled.
Boost Function: The outdoor reset boost function
increases the CH_Setpoint by a prescribed increment
(Boost_Temperature_Incr) if a call for heat continues
beyond the pre-set time limit (Boost_Time_Delay).
CH_Setpoint increases again if the call for heat still is not
satisfied in another time increment.
Setpoint Adjustment: It is possible to adjust the calculated
setpoint with parameter CH_Setpoint_Diff. The calculated
setpoint can be increased or decreased with a maximum of
50°F.
The CH setpoint limits (Reset_Curve_Boiler_Minimum and
Reset_Curve_Boiler_Maximum) are respected while
adjusting the setpoint.