The tekmar Boiler Control 265 can control the supply water temperature on up to three modulating boilers based on outdoor
temperature or setpoint requirements. The control can be set to control up to two modulating boilers based on outdoor temperature
or domestic hot water requirements. A large easy to read display provides current system temperatures and operating status. The
control has outputs for a primary pump, individual boiler pumps, and either a combustion air damper or an alert.
Additional functions include:
• Outdoor Reset
• Sequential or Parallel Modulation
• Installer and Advanced access levels
• Primary pump output
• Individual boiler pump outputs
• Pump purging
• Boiler demand for space heating loads
MenuItem
Boiler Control 265
Three Modulating Boiler & DHW / Setpoint
Do not apply power
1
2
3
4
5
Input
Universal
Sensor
Included
Input
Universal
Sensor
Included
Com
Boil
Boil
Out
–
Sup
Ret
6+7
UnO
+
Sw
Boiler Demand
DHW / Setpoint Demand
WWSD
Modulation
Boiler Output (x10,000 BTU/hr)
External Input Signal
Offset / Priority Override
8
9 10 1112 13
Mod2 mAMod1 mA
–+–+–
Prim
Mod3 mAPowerBoiler Boiler
L14N
P1
• DHW demand for domestic hot water loads
• Setpoint demand for setpoint loads
• 0 – 10 V (dc) BAS / EMS input
• Test sequence to ensure proper component operation
• Setback input for energy savings
• CSA C US certified
• Pump exercising
Parallel
Alert
Boiler
Pump 1
CA.
Exercise
Sequential
Off
Boiler
Pump 2
External Input
Advanced
Installer
Stand Alone
Made in Canada by
tekmar Control Systems Ltd.
Power 115 V ±10% 60 Hz 600 VA
Relays 230 V (ac) 5 A 1/3 hp, pilot duty 240 VA
Demands 20 to 260 V (ac) 2 VA
Signal wiring must be rated at least 300 V.
15 16 17118119220221 22 23 24 25 26 27 28 29
C.A./
Alert
Boiler 3 /
DHW
Soft Stop
Off
Boiler
Pump 3
Test
Dem
Boil
Rotate
Fixed Lead
First On / Last Off
First On / First Off
not t
off
red testing
red tes
For maximum heat,
press & hold T
3 seconds.
Meets Class B:
Canadian ICES
FCC Part 15
30
31
Com
Setp/
Dem
DHW
esting
ting paused
est for
Date Code
H2037B
Note:
Boiler, DHW,
or setpoint
demand must
be powered with
20 to 260 V (ac)
before the boiler
is able to fire.
This brochure is organized into four main sections. They are: 1) Sequence of Operation, 2) Installation, 3) Control Settings, and
4) Testing and Troubleshooting. The Sequence of Operation section has seven sub-sections. We recommend reading Section A:
General of the Sequence of Operation, as this contains important information on the overall operation of the control. Then read the
sub sections that apply to your installation.
The Control Settings section (starting at DIP Switch Settings) of this brochure describes the various items that are adjusted and
displayed by the control. The control functions of each adjustable item are described in the Sequence of Operation.
Table of Contents
User Interface ..................................................Pg 2
The 265 uses a Liquid Crystal Display (LCD) as the method of supplying information. You use the LCD in order to setup and monitor
the operation of your system. The 265 has four push buttons (Menu, Item, ▲, ▼) for selecting and adjusting settings. As you
program your control, record your settings in the ADJUST Menu table which is found in the second half of this brochure.
Menu
All of the items displayed by the control are organized into various menus. These menus
are listed on the left hand side of the display (Menu Field). To select a menu, use the
Menu button. By pressing and releasing the Menu button, the display will advance to
the next available menu. Once a menu is selected, there will be a group of items that can
be viewed within the menu.
MenuItem
Item
The abbreviated name of the selected item will be displayed in the item field of the
display. To view the next available item, press and release the Item button. Once you
have reached the last available item in a menu, pressing and releasing the Item button
will return the display to the first item in the selected menu.
The items can be quickly scrolled through by holding the Item button and then pressing
the ▼ button. To rapidly scroll through the items in the reverse order, hold the Item button
and press the ▲ button.
Adjust
To make an adjustment to a setting in the control, begin by selecting the appropriate
menu using the Menu button. Then select the desired item using the Item button. Finally,
use the ▲ and / or ▼ button to make the adjustment.
Additional information can be gained by observing the Status field of the LCD. The status
field will indicate which of the control’s outputs are currently active. Most symbols in the
status field are only visible when the VIEW Menu is selected.
The following defined terms and symbols are used throughout this manual to bring attention to the presence of hazards of various risk
levels, or to important information concerning the life of the product.
- Warning Symbol: Indicates presence of hazards which can cause severe personal injury, death or
substantial property damage if ignored.
INSTALLATION
CATEGORY II
- Double insulated
- Local level, appliances
Sequence of Operation
Section A
General
Operation
Page 4 - 6
Section E
Setpoint
Operation
Page 16
Section B
Boiler
Operation
Page 6 - 10
Section F
External
Input Operation
Page 17 - 18
Section C
Outdoor
Reset
Page 10 - 12
Section G
Pump
Operation
Page 18 - 19
Section D
DHW
Operation
Page 13 - 15
Section A: General Operation
POWERING UP THE CONTROL
When the control is powered up, all segments in the LCD are turned on for 2 seconds. Next, the control displays the control type
number in the LCD for 2 seconds. Next, the software version is displayed for 2 seconds. Finally, the control enters into the normal
operating mode.
BOILER TARGET TEMPERATURE
The control operates up to three modulating boilers to control the supply water temperature to a hydronic space heating system
or setpoint. When using the control to provide Domestic Hot Water (DHW) requirements, only two modulating boilers can be
operated. The supply water temperature is based on boiler reset, an external 0 – 10 V (dc) signal, DHW requirements, or a
setpoint temperature.
Design SupplyDesign Supply
Boiler Reset (Stand Alone)
When a boiler demand signal from the heating system is present,
the control operates the boiler(s) to maintain the supply temperature
based on the outdoor air temperature and the Characterized Heating
Curve settings. Refer to section C.
When a DHW demand is present, the control operates the boiler(s)
to maintain the supply water temperature at least as hot as the DHW
exchange setting. Refer to section D.
Decreasing Outdoor Temperature
Increasing Water Temperature
Setpoint
When a setpoint demand signal is present, the control operates the boiler(s) to maintain the supply water temperature at least as
hot as the Setpoint setting. Refer to section E.
External Input 0 – 10 V (Dc) or 2 – 10 V (Dc)
When an external input signal is present, the control converts the signal to a target supply temperature. The control operates the
boiler(s) to maintain the required supply water temperature. Refer to section F.
To provide greater energy savings, the control has a setback feature. With setback, the
supply water temperature in the system is reduced when the building is unoccupied. By
Com
2
1
Boil
Boil
Ret
Sup
–
5
4
3
UnO
Out
Sw
+
reducing the supply water temperature, the air temperature in the space may be reduced
even when thermostat(s) are not turned down. Any time the UnO Sw (5) and the Com (1)
terminals are shorted together, the control operates in the unoccupied mode. When in the
unoccupied mode, the UNOCC segment is displayed in the LCD. The control adjusts the
supply water temperature based on the UNOCC settings in the control.
Timer Switch
COMBUSTION AIR OR ALERT CONTACT
The control has an isolated contact that can be used as either a combustion air damper contact or an alert contact. This selection
is made using the C.A. / Alert DIP switch.
Combustion Air (C.A.)
When the DIP switch is set to C.A., terminals 15 and 16 can be used as a switch to operate a combustion air damper. This contact
closes prior to the first boiler operating on the control. The amount of time that the contact closes prior to the first boiler firing is
set using the combustion delay setting.
The combustion air contact remains closed for a minimum of 15 seconds after the last boiler is turned off.
Alert
When the DIP switch is set to Alert, terminals 15 and 16 can be used as a switch to operate an alert circuit. This contact closes
whenever an error message is present on the control display. When the alert contact is activated, refer to the Error Messages
section of this brochure to determine the cause of the alert. Once the fault has been fixed, pressing either the Menu, Item, ▲ or ▼
button will clear the alert.
Boiler Alert
The control can monitor the boiler supply temperature and provide an alert if the temperature does not increase within a certain
amount of time. The amount of time can be set using the Boiler Alert setting. This alert can be used to determine if the boilers
have failed to fire. To reset the alert, press and hold the ▲ and ▼ buttons for 5 seconds while in the VIEW menu.
ROTATION
The control includes an Equal Run Time feature which changes the firing
order of the boilers whenever one boiler accumulates 48 hours more
running time than any other boiler. After each rotation, the boiler with the
12
least running hours is the first to fire and the boiler with the most running
hours is the last to fire. This function ensures that all of the boilers that
are being rotated receive equal amounts of use. When the Rotate / Off
720 hours672 hours
DIP switch is set to the Off position, the firing sequence always begins
with lowest boiler to the highest boiler.
Fixed Lead Rotation
21
In some applications, it may be desirable to have the first boiler fire first
at all times while the firing sequence of the remaining boilers is changed
using Equal Run Time Rotation. This rotation option is selected by
672 hours720 hours
setting the Fixed Lead/Off DIP switch to the Fixed Lead position.
First On / Last Off or First On / First Off
When using the Fixed Lead rotation option, a selection must be made between First On/LastOff and First On/FirstOff
using the DIP switch. When First On / Last Off is selected, the lead boiler is always modulated first and shut off last. When
FirstOn/FirstOff is selected, the lead boiler is always modulated first and shut off first. This DIP switch is only read by the control
when the FixedLead/Off DIP switch is set to Fixed Lead.
Resetting the Rotation Sequence
To reset the rotation sequence, set the Rotate / Off DIP switch to the Off setting for 5 seconds and then return the DIP switch to
the Rotate setting.
RUNNING TIMES
The control displays the accumulated running time of each boiler in the VIEW menu.
Resetting the Running Times
To reset the running time for each boiler, select the appropriate running time in the VIEW menu. Next press the ▲ and ▼ buttons
simultaneously until CLr is displayed.
The control has a built-in exercising feature that is selected through the Exercise / Off DIP switch. To enable the exercising feature set
the Exercise/Off DIP switch to Exercise. If exercising is enabled, the control ensures that each pump is operated at least once every
3 days. If a pump has not been operated at least once every 3 days, the control turns on the output for 10 seconds. This minimizes
the possibility of the pump seizing during a long period of inactivity. While the control is exercising, the Te st LED flashes quickly.
Note: The exercising function does not work if power to the control or pumps is disconnected.
FACTORY DEFAULTS
The control comes preset with several factory defaults. These defaults are based on the terminal unit selection (see section C).
To fine-tune building requirements, these defaults may be changed.
To reload the factory defaults listed in the ADJUST Menu, power down the control and wait for 10 seconds. Power up the control
while simultaneously holding the Menu and ▼ buttons. An E01 error occurs forcing the installer to go through the ADJUST menu
to ensure the settings are correct.
Section B: Boiler Operation
Section B1
Boiler
Modulation
Section B1: Boiler Modulation
MODULATION
The control provides three modulating output signals, three boiler enable contacts, and three boiler pumps contacts to operate up
to three modulating boilers. The boiler enable contact may not be required, depending on the make and model of the boiler(s).
The control operates a boiler by first closing the boiler pump contact. The boiler enable contact is closed next and then the control
provides a modulating output signal to the boiler.
The modulation output signal is then modulated from the minimum modulation using Proportional, Integral and Derivative (PID)
logic in order to satisfy the boiler target temperature.
SEQUENTIAL MODULATION
The control offers a sequential modulation option. This is selected by setting the
Sequential/Parallel DIP switch to Sequential. Sequential modulation should be used on
boilers that are more efficient when operating at high fire.
SEQUENTIAL MODULATION
100%MODOFF
In sequential modulation, the first boiler is turned on and is modulated to satisfy light loads.
Once the first boiler does not have enough capacity to satisfy the load, the first boiler
reduces its modulation to provide a smooth transition when the second boiler fires at low
fire. The first boiler then modulates up to maximum modulation as the load increases. Only
then is the second boiler able to increase its output as the load continues to increase.
When the third boiler is required, the second boiler reduces its modulation to allow the
third boiler to operate at low fire. As the load continues to increase, the second boiler is
modulated to its maximum and then the third boiler is modulated. The operation is reversed
Boiler 1Boiler 2Boiler 3
when shutting off the boilers.
PARALLEL MODU L ATION
The control offers a parallel modulation option. This is selected by setting the
Sequential/Parallel DIP switch to Parallel. Parallel modulation should be used on boilers
that are more efficient when operating at low fire.
In parallel modulation, the first boiler turns on at low fire and begins to increase its
modulation. Once the first boiler’s output is greater than the combined output of the first
and second boiler’s low fire, the first boiler is modulated down to low fire and the second
boiler is fired at low fire. The two boilers now modulate together. Once the two boiler’s
combined output is greater than the combined output of all three boilers operating at low
fire, the first and second boilers are modulated down to low fire, and all three boilers are
operated at low fire. The boilers are then modulated as the load increases. The operation
is reversed when shutting off the boilers.
The modulation output (Mod 1, Mod 2, and Mod 3) for each boiler can be adjusted from a 4 to 20 mA output range to a 0 to 20 mA
output range using the Boil Modulation 1, Boil Modulation 2, or Boil Modulation 3 setting. The resulting modulation output signal
can be converted to a 0 to 5 V (dc), 1 to 5 V (dc), 0 to 10 V (dc), and 2 to 10 V (dc) output using external resistors. The modulation
output signal can be converted to a 0 to 135 Ω (W R B) output using a 0 - 135 Ω Converter 005. Refer to the Modulation Output
section in Step 4 of the Installation section.
MINIMUM MODULATION
The minimum modulation defines the minimum output signal from the control to the boiler burner. It is based on a percentage of
the control’s output signal range.
The minimum modulation setting for boilers with power burners is typically set to 0%.
For boilers with electronic operators, the boiler’s input signal range may not match the output signal range of the 265 control. The
Minimum Modulation setting limits the control output range in order to match the boiler’s input range.
To calculate the Minimum Modulation, use the following formulae:
MINIMUM MODULATION
For 4 to 20 mA:
Minimum Modulation =
4 - 20 mA
4 mA – Boiler’s Minimum Input Signal
For 0 to 10 V (dc):
Minimum Modulation =
0 – 10 V (dc)
0 V (dc) – Boiler’s Minimum Input Signal
For 2 to 10 V (dc):
Minimum Modulation =
2 – 10 V (dc)
2 V (dc) – Boiler’s Minimum Input Signal
x 100%
x 100%
x 100%
Control's
Output
Signal
Range
Minimum
Modulation
100%10 V (dc)10 V (dc)
Boiler's
Input
Signal
Range
18%
0%0 V (dc)
1.8 V (dc)
Boiler's Minimum
Input Signal
Example 1:
A boiler requires a 1.8 V (dc) signal to fire the boiler at low fire. The boiler can be modulated to 10 V (dc) where it reaches high fire.
This means the boiler’s input signal range is 1.8 to 10 V (dc). The 265 control has an output signal range of 0 to 20 mA which can be
externally converted to 0 to 10 V (dc) using a 500 Ω resistor (Refer to Modulation Output section in Step 4 of the Installation section).
To make the two signal ranges the same, the Minimum Modulation required is:
0 V – 1.8 V
Minimum Modulation
0 V – 10 V
=
x 100% = 18%
Example 2:
If the boiler’s input signal range is 6 to 20 mA the required Minimum Modulation is:
Minimum Modulation =
4 mA – 20 mA
4 mA – 6 mA
x 100% = 13%
MAXIMUM MODULATION
The maximum modulation defines the maximum output signal from the control to the boiler burner. It is based on a percentage of
the control’s output signal range.
The maximum modulation setting for boilers with power burners is typically set to 100%.
For boilers with electronic operators, the boiler’s input signal range may not match the output signal range of the 265 control. The
Maximum Modulation setting limits the control output range in order to match the boiler’s input range.
To calculate the Maximum Modulation, use the following formulae:
A boiler’s input signal range is 2 to 9 V (dc). The 265 control has an output signal range of 2 to 10 V (dc). To make the two signal
ranges the same, the Maximum Modulation required is:
Maximum Modulation =
2 V – 10 V
2 V – 9 V
x 100% = 88%
Example 2:
If the boiler’s input signal range is 6 to 19 mA the required Maximum Modulation is:
Maximum Modulation =
4 mA – 20 mA
4 mA – 19 mA
x 100% = 94%
MINIMUM BOILER OUTPUT
In order to accommodate different boiler capacities in the same system, a minimum boiler output for each boiler can be set. This
allows the control to properly operate the boilers using either sequential or parallel modulation. The minimum boiler output range
is from 10,000 BTU / hour to 19,990,000 BTU / hour.
Each boiler typically has a rating plate that specifies the minimum output. This information is also available in the boiler manual. The
Minimum Boiler Output setting has units of 10,000 BTU / hour. Divide the minimum output rating by 10,000 and enter the number
as the Minimum Boiler Output setting.
For example, if a boiler has a minimum output of 20 MBH:
Minimum Boiler Output =
10,000
20,000 BTU/hr
= 2 x 10,000 BTU/hr
MAXIMUM BOILER OUTPUT
In order to accommodate different boiler capacities in the same system, there is a maximum boiler output for each boiler. This
allows the control to properly operate the boilers using either sequential or parallel modulation. The maximum boiler output range
is from 10,000 BTU / hour to 19,990,000 BTU / hour.
Each boiler typically has a rating plate that specifies the maximum output. This information is also available in the boiler manual.
The Maximum Boiler Output setting has units of 10,000 BTU / hour. Divide the maximum output rating by 10,000 and enter the
number into the Maximum Boiler Output setting.
For example, if a boiler has a maximum output of 100 MBH:
Maximum Boiler Output =
10,000
100,000 BTU/hr
= 10 x 10,000 BTU/hr
MOTOR SPEED
The Motor Speed is the amount of time the boiler requires to go from 0%
modulation to 100% modulation. The control includes a Motor Speed
setting for each individual boiler.
Gas valve actuating motors have a design time from fully closed to fully
opened which can be found in the manufacturer’s manual. The Motor
Speed should be set to this time.
The Motor Speed setting for a Variable Frequency Drive (VFD) is the
amount of time required to go from a stopped position to 100% fan
speed. Since a VFD has a very quick response rate, it may be necessary
to increase the Motor Speed setting in order to increase the stability of
the boiler modulation.
BOILER MASS
The boiler mass setting allows the installer to adjust the control to the thermal mass of the type of heat sources used in the
application. There is a boiler mass setting for each boiler. The modulation of the boiler can become unstable if the incorrect Boiler
Mass setting is chosen. A key sign of the boiler modulation being unstable is the flame will continue to increase and then decrease
in short periods of time. By choosing a lower boiler mass setting, the boiler response will become more stable.
Lo (1)
The Lo setting is selected if the boiler that is used has a low thermal mass. This means that the boiler has a very small water
content and has very little metal in the heat exchanger. A boiler that has a low thermal mass comes up to temperature quite
rapidly when fired. This is typical of many copper fin-tube boilers.
The Lo mass setting provides a fast response to the heating system.
The Med setting is selected if the boiler that is used has a medium thermal mass. This means that the boiler either has a large
water content and a low metal content or a low water content and a high metal content. This is typical of many modern residential
cast iron boilers or steel tube boilers.
The Med mass setting provides a moderate response to the heating system.
Hi (3)
The Hi setting is selected if the boiler that is used has a high thermal mass. This means that the boiler has both a large water
content and a large metal content. A boiler that has a high thermal mass is relatively slow in coming up to temperature. This is
typical of many commercial cast iron and steel tube boilers.
The Hi mass setting provides a slow response to the heating system.
DIFFERENTIAL
A modulating boiler must be operated with a differential while operating in low fire. The boiler differential is divided around the boiler
target temperature. The boiler starts at low fire when the supply water temperature is ½ of the differential setting below the boiler
target temperature. The boiler is shut off in low fire as the supply temperature reaches at least ½ of the differential above the boiler
target temperature. With the control, either a fixed or an auto differential may be selected.
When the boiler is modulating above low fire, the differential does not apply. Instead, the modulation output signal is determined
using Proportional, Integral and Derivative (PID) logic in order to satisfy the boiler target temperature.
Desired temperature
Fixed Differential
If the user desires to have a fixed differential, this is set using the
boiler differential setting in the ADJUST menu.
160°F (71°C)
Boiler Off
Boiler On
165°F (74°C)
Time
e
r
u
t
a
r
e
p
m
e
T
155°F (68°C)
e
s
i
r
T
e
m
p
Differential
10°F (6°C)
e
r
a
t
u
r
e
f
a
l
l
Auto Differential
If the Auto Differential is selected, the control automatically determines
the best differential as the load changes. This reduces potential short
cycling during light load conditions.
BOILER MINIMUM
The boiler minimum is the lowest temperature that the control is allowed
to use as a boiler target temperature. During mild conditions, if the control
calculates a boiler target temperature that is below the boiler minimum
setting, the boiler target temperature is adjusted to at least the boiler
minimum setting. During this condition, if the boiler(s) is operating, the
minimum segment is turned on in the display when viewing either the
boiler supply temperature or the boiler target temperature. Set the boiler
minimum setting to the boiler manufacturer’s recommended temperature.
BOILER MAXIMUM
The boiler maximum is the highest temperature that the control is
allowed to use as a boiler target temperature. If the control does target
the boiler maximum setting, and the boiler temperature is near the boiler
maximum temperature, the maximum segment will be turned on in the
display while either the boiler target temperature or the boiler supply
temperature is being viewed. At no time does the control operate the
boiler(s) above 248°F (120°C).
The Fire Delay is the time delay that occurs between the time that the
control closes a boiler enable contact to fire a boiler and when the boiler
fires at low fire.
STAGE DELAY
The stage delay is the minimum time delay between the firing of stages.
After this delay has expired the control can fire the next stage if it is
required. This setting can be adjusted manually or set to an automatic
setting. When the automatic setting is used, the control determines the
best stage delay based on the operation of the system.
Boiler 1
Contact Closes
Fire
Delay 1
Boiler 1
Fires
Stage Delay
Boiler 2
Contact Closes
Fire
Delay 2
Time
Boiler 2
Fires
Stage Delay
Boiler 3
Contact Closes
Fire
Delay 3
Boiler 3
Fires
SOFT STOP
It is possible to thermally shock a boiler when it is shut off at high fire. The Soft Stop feature forces the boiler to modulate down to
minimum before turning off. This is designed to prevent large volumes of cold air being introduced into the combustion chamber of
the boiler when it is shut off. This can occur in applications where the burner includes a fan.
Once all demands are removed, the control allows for the firing rate to be modulated down to the MIN Modulation setting prior to
turning off the burner. This feature is enabled by setting the Soft Stop/Off DIP switch to the Soft Stop position. If the Soft Stop/Off
DIP switch is in the Off position, the control turns off the boiler at the current firing rate once all demands are removed.
COPY BOILER 1 SETTINGS
Many boiler installations will have multiple identical boilers. To reduce the number of settings required, the settings of boiler 1
(Fire Delay, Boiler Mass, Motor Speed, Minimum Boiler Output, Maximum Boiler Output, Boiler Modulation, Minimum Modulation,
Maximum Modulation, and Purge Boiler Pump) are copied to boiler 2 by setting the Boiler 2 setting to CP1. Likewise, setting Boiler 3
to CP1 copies the settings of boiler 1 to boiler 3. Boiler 2 and Boiler 3 settings are set to CP1 by default.
The setting of CP1 allows the control to enable the boiler similar to the setting of Au (automatic). If a boiler is set to OFF, the control
disables that boiler.
If required, each of the three modulating boilers can have individual boiler settings. This allows for three different type, size,
and make of modulating boilers. To select individual boiler settings for boiler 2, set Boiler 2 to Au (automatic). Likewise, to select
individual boiler settings for boiler 3, set Boiler 3 to Au (automatic).
Section C: Outdoor Reset
Section C1
Boiler Reset
(Stand Alone)
Section C1: Boiler Reset (Stand Alone)
Boiler Reset operation only applies when the Stand Alone / External Input DIP switch is set to
Stand Alone.
BOILER DEMAND
A boiler demand is required in order for the control to provide heat to the heating system. A boiler
demand is generated by applying a voltage between 24 and 230 V (ac) across the Boil Dem
and ComDem terminals (29 and 30). Once voltage is applied, the Boiler Demand pointer is
displayed in the LCD. If the control is not in Warm Weather Shut Down (WWSD), the control
closes the primary pump contact. The control calculates a boiler target supply temperature
based on the outdoor air temperature and the characterized heating curve settings. The control
then fires the boiler(s), if required, to maintain the target supply temperature.
The control varies the supply water temperature based on the outdoor air
temperature. The control takes into account the type of terminal unit that
the system is using. Since different types of terminal units transfer heat
to a space using different proportions of radiation, natural convection
and forced convection, the supply water temperature must be controlled
differently. Once a terminal unit is selected, the control varies the supply
water temperature according to the type of terminal unit. This improves
the control of the air temperature in the building.
OUTDOOR DESIGN TEMPERATURE
The outdoor design temperature is the outdoor air temperature that is
the typical coldest temperature of the year where the building is located.
This temperature is used when doing the heat loss calculations for the
building. If a cold outdoor design temperature is selected, the boiler
supply temperature rises gradually as the outdoor temperature drops.
If a warm outdoor design temperature is selected, the boiler supply
temperature rises rapidly as the outdoor temperature drops.
BOILER DESIGN TEMPERATURE
Boiler Characterized
Boiler Characterized
Heating Curve
Heating Curve
BOIL MIN
BOIL INDR
80
(27)
60
(16)
Outdoor Air Temperature
OUT DSGN
WWSD OCC
WWSD UNOCC
ROOM OCC
ROOM UNOCC
40
(5)
BOIL DSGN
20
(-7)
BOIL MAX
0
(-18)
The boiler design supply temperature is the supply water temperature
required to heat the building when the outdoor air temperature is as cold
as the outdoor design temperature.
BOILER INDOOR DESIGN TEMPERATURE
The indoor design temperature is the room temperature that was used in the original heat loss calculations for the building. This
setting establishes the beginning of the characterized heating curve.
Supply Water Temperature
ROOM
The ROOM setting is the desired room temperature for the building and provides a parallel shift of the heating curve. The room
temperature desired by the occupants is often different from the design indoor temperature. If the room temperature is not correct,
adjusting the room setting increases or decreases the amount of heat available to the building. A room setting is available for both
the occupied (day) and unoccupied (night) periods.
BOILER TARGET TEMPERATURE
The boiler target temperature is determined from the characterized heating curve settings and the outdoor air temperature. The
control displays the temperature that it is currently trying to maintain as the boiler supply temperature. If the control does not
presently have a requirement for heat, it does not show a boiler target temperature. Instead, “– – –” is displayed in the LCD.
TERMINAL UNITS
The control provides for a selection between six different terminal unit types: two types of radiant floor heat, fancoil, fin-tube
convector, radiator and baseboard. When a terminal unit is selected, the control automatically loads the design supply temperature,
maximum supply temperature, and minimum supply temperature. The factory defaults are listed below. These factory defaults can
be changed to better match the installed system.
This type of a hydronic radiant floor is embedded in either a thick concrete or gypsum
pour. This heating system has a large thermal mass and is slow acting.
Low Mass Radiant (2)
This type of radiant heating system is either attached to the bottom of a wood sub-floor,
suspended in the joist space, or sandwiched between the sub-floor and the surface.
This type of radiant system has a relatively low thermal mass and responds faster than
a high mass system.