Install Instructions

C. BOILER CONTROL
1. Installation Location & Vent Material:
The P
UREFIRE
®
boiler allows the installer to input the
installation location and the vent material used. This
information is used to determine the suitable vent
temperature limit based on National Codes. Table 8.5
shows the vent temperature limit based on the
location and vent material.
The P
UREFIRE
®
control will reduce the boiler firing rate
if the vent temperature approaches the vent
temperature limit. If the vent temperature continues to
rise, the control will shut down the boiler.
2. Freeze Protection:
The P
UREFIRE
®
boiler control is intended to prevent
the central heating system from freezing. The default
temperature to activate this function is 50°F (10°C).
If the supply temperature drops to below the freeze
protection setpoint, the general pump and/or the CH
pump (depending on pump mode) will be activated. If
the supply or return temperature drops more than 9°F
(5°C) below the setpoint, the control lights the boiler
using the ignition sequence described in section 8.B.
The control will operate the burner at minimum
power until the both the supply and return boiler
temperature are more than 9°F (5°C) above the freeze
protection setpoint.
While this function is active the interface panel will
display the following:
3. Blower Postpurge Time:
The P
UREFIRE
®
boiler control allows the installer to
change the burner postpurge timing. This is useful
under extreme conditions where high winds and
unusual wind currents prevent proper purging of the
combustion chamber.
This parameter is adjustable from 30 seconds to 120
seconds with the 30 second minimum as its default. It
is important to note that increased purge times may
slightly reduce the boiler efficiency.
4. Additional Safety Functions:
The P
UREFIRE
®
boiler control is equipped with terminals
for either a low water cutoff or a flow switch. The low
water cutoff option is the factory default and a factory
supplied jumper is installed. This jumper is to be
removed if a low water cutoff or flow switch is installed.
Low Water Cutoff
: The installer can connect the
power supply wires for a probe-type low water cutoff
to terminal #19 (Hot) and #20 (Neutral) in the main
terminal box. The contacts should be wired to
terminals #9 and #10.
Flow Switch
: If a flow switch is used, simply wire the
contacts to terminals #9 and #10 in the main
terminal box.
D. CENTRAL HEATING
1. Heating Modes:
Table 8.1 provides an overview of the central heating
(CH) modes. The following are detailed descriptions
of the operation of these modes. In accordance with
Federal regulations under the Energy Policy and
Conservation Act of 2012, all boilers must be
equipped with a feature that saves energy by reducing
the boiler water temperature as the heating load
decreases. This feature may be equipped with an
override feature to allow the use of an external energy
management system that serves the same function.
Mode 0 – Indoor Thermostat
: This mode responds to
a thermostat contact closure between terminals #1 &
#2 in the electrical panel to target a fixed supply
(outlet) temperature selected in the User Menu. Based
on the Federal regulations this mode cannot be used
for space heating unless the boiler is the managing
boiler of a multiple boiler cascade system having a
total input of 300,000 btu/hr or greater.
Mode 1 – Thermostat and Outdoor Reset
: This mode
responds to a thermostat contact closure between
terminals #1 & #2 in the electrical panel to target a
temperature calculated by the control. In this mode,
the installer selects the temperatures which define the
target temperature based on the current outdoor
temperature. As the outdoor temperature increases,
the target temperature is decreased. Detailed
explanations of the operating principal and the
settings for this mode are provided below in
subsection 3.
The factory default settings will target a supply
temperature of 180°F when the outdoor temperature
drops to 10°F or below. The target supply (outlet)
temperature will be 70°F when the outdoor
temperature is 70°F.
Mode 2 – Permanent Demand and Outdoor Reset
:
Mode 2 operates much like Mode 1 except that no
thermostat contact closure is required between
terminals #1 & #2 in the electrical panel to operate
the boiler. The boiler will attempt to constantly
maintain the target temperature calculate by the
control. The factory defaults for this mode are the
same as in Mode 1. Details for outdoor reset are
covered in subsection 3 below.
A contact closure between terminals #1 & #2 will
result in a target temperature setback of 18°F. This
feature may be used in conjunction with a timer or
switch for unoccupied setback periods.
42
BOILER CONTROL: INTERNAL WIRING & OPERATION
Table 8.5: Vent Temperature Limits
Vent Limit Temperature
Vent
Material
Location
U.S.A. Canada
PVC 190°F (80°C) 149°F (65°C)
CPVC 230°F (110°C) 190°F (80°C)
PP(s) 230°F (110°C) 230°F (110°C)