tekmar 262 Installation

- Data Brochure	D 262
Boiler Control 262	12/08

The Boiler Control 262 is a micro processor based control designed to maximize the comfort and efficiency of a hydronic heating system. The control is designed to operate in two distinct modes.

MODE —1—(Two Stage Boiler & DHW) allows for the control of two separate on /off boiler stages (or one low / high fire) based on outdoor air temperature, control for indirect Domestic Hot Water (DHW) generation and a Setpoint load. For single zone temperature control with indoor temperature feedback, a Room Temperature Unit (RTU) or indoor sensor may be connected to the 262. Multiple zone temperature control is achieved by using either a conventional thermostat system or by connecting a tekmar Zone Control to the 262.

MODE —2— is designed specifically for dedicated DHW applications. In Mode 2, the 262 can stage and rotate two on / off boiler stages (or one low / high fire) in order to provide heat to a DHW storage system.

The 262 control includes a large Liquid Crystal Display (LCD) in order to view system status and operating information. The same LCD is used when setting up and installing the control. Standard features include Equal Run Time Rotation, intelligent boiler operation, digital temperature readouts, and pump exercising. With the addition of a monitoring feature, it is now possible to track pump and boiler running hours, DHW tank temperature, outdoor and system high and low temperatures, boiler firing cycles, plus many other useful items.

Several energy saving features have been incorporated into the 262 such as Warm Weather Shut Down (WWSD), DHW post purge, system setback, DHW priority and an automatic differential for boiler operation.

		Setback	Reset Ratio
View	Boiler Demand
	DHW Demand	None	Characterized
°F	Setpoint Demand		Heating Curve
	WWSD
1	Minimum	Operating Modes
	Maximum
		1 Two Stage Boiler & DHW
1 2		2 Two Stages for DHW
		See product literature
		INSTALLATION CATEGORY II
Menu Item		Made in Canada by
		tekmar Control Systems Ltd.
		tektra 929-03

Test

off not testing red testing red

For maximum heat, press and hold Test button for 3 seconds.

Meets Class B:

Canadian ICES

FCC Part 15

Note:	Boiler Control 262
	Two Stage Boiler & DHW / Two Stage DHW
Boiler, DHW, or setpoint
demand must be powered
with 20 to 260 V (ac)	1 2 3 4 5	6	7	8	9 10	11 12 13 14
before the boiler is able	Boiler Com DHW Setp	Power		Boil	DHW	Stage		Stage
to fire.	Dem Dem Dem	N	L	P1	Pmp / Vlv	1	1	2	2

Input

Boiler

Demand

signal

Input

DHW Demand

signal

Input

Setpoint

Demand

signal

Input

120 V (ac)

Power

Supply

Output

Boiler System

Pump

M
Output
DHW Pump OR	Output	Output
DHW Valve	Boiler	Boiler

	Power	115 V ±10% 60 Hz 900 VA
	Relays	230 V (ac) 7.5 A 1/3 hp, pilot duty 240 VA
	Demands	20 to 260 V (ac) 2 VA		Code
	Signal wiring must be rated at least 300 V.			Date
	Wiring must be rated 194°F (90°C) minimum
		Do not apply power
	15 16 17 18 19 20 21 22			H1109F
	tN1/ Com 10K UnO Com DHW Boil Out
	tN2	Sw
					Input
					Outdoor
					Sensor Included
				Input
				Universal
				Sensor Included
				Input
				Universal
				Sensor Optional
					Input
					tekmar
					Timer
					Input
				OR	Slab Sensor
!	OR	!
Menu Item		Menu Item
Input		Input		OR	Input
Room		Remote	Input		Indoor Sensor
Temperature		Display
Unit (RTU) Module (RDM)			Zone Control

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Copyright © D 262 -12/08

How To Use The Data Brochure

This brochure is organized into four main sections. They are: 1) Sequence of Operation, 2) Installation, 3) Control Settings, and 4) Troubleshooting. The Sequence of Operation section has four 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 refer to the sub sections that apply to your installation.

The Control Settings section of this brochure illustrates the menu screens that are built into the control. These menu settings are referenced to the specific section in the Sequence of Operation.

Table of Contents

User Interface ..........................................	pg 2	Access Levels ................................................	pg 19
Description of Display Elements ............	pg 3	Control Settings .............................................	pg 20
Sequence of Operation ............................	pg 4	View Menu ...........................................	pg 20
Section A: General ........................	pg 4	Adjust Menu ........................................	pg 21
Section B: Boiler Reset.................	pg 6	Schedule Menu ...................................	pg 24
Section C: DHW ...........................	pg 10	Miscellaneous Menu ..........................	pg 25
Section D: Setpoint .......................	pg 13	RTU Menu ...........................................	pg 25
Installation ...............................................	pg 14	Testing and Troubleshooting ......................	pg 27
Electrical Connections..................	pg 14	Monitor Menu ......................................	pg 29
Testing The Wiring........................	pg 16	Error Messages ..................................	pg 31
DIP Switch Settings ................................	pg 18	Technical Data ...............................................	pg 36
		Limited Warranty ...........................................	pg 36

Reference Material: Essay E 003: Characterized Heating Curve and Reset Ratio

User Interface

The 262 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 262 uses four push buttons (Menu, Item, , ) for selecting and adjusting settings. As you program your control, record your settings in the actual settings column of the Adjust Menu. The table 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 that menu.

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.

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 / orbutton to make the adjustment.

Menu Item

Menu Item

Menu Item

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.

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Display

Item Field	Number Field
Displays an abbreviated	Displays the current value
name of the selected item	of the selected item

Menu Field

Displays the current menu

Status Field

Displays the current status of the control’s inputs, outputs and operation

	View			Boiler Demand
	Adjust			DHW Demand
	Monitor
		°F°C		Setpoint Demand
	Schd	min hr		WWSD
	Misc	sec
		UnOcc	Ovr	Minimum
		1		Maximum
		DHW
	12	!
				Buttons
				Selects Menus, Items and
				{adjusts settings
	Menu	Item

Symbol Description

				Burner	Ovr			Override
		1	2	Displays when the stage 1 and / or stage 2
								Displays when the control is in override mode.
				relay is turned on.
	1			Pump	!			Warning
				Displays when the boiler pump is operating.				Displays when an error exists or when a limit
								has been reached.
				DHW Pump				Lock - Unlock
								Displays whether the access levels are locked
	DHW Displays when the DHW pump is on.
								or unlocked.
				Boost	°F, °C, sec,			°F, °C, sec, min, hr
				Displays when the control is in boost after
				setback.	min, hr			Units of measurement.
	UnOcc			UnOccupied Schedule				Pointer
				Displays when the control is in unoccupied				Displays the control operation as indicated by
				mode.				the text.
	Occ			Occupied Schedule
				Displays when the control is in occupied mode.

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Copyright © D 262 -12/08

Sequence of Operation

Section A	Section B	Section C	Section D
General Operation	Boiler Reset	Domestic Hot	Setpoint
		Water (DHW)
Page 4 - 6	Page 6 - 10	Page 10 - 12	Page 12

Section A —General Operation

POWERING UP THE CONTROL

When the Boiler Control 262 is powered up, 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 and the LCD defaults to displaying the current outdoor air temperature.

MODES OF OPERATION (MODE)

The Boiler Control 262 has two operating modes. The mode of operation for which the control is to operate is selected in the Adjust Menu.

Mode 1 (MODE = —1—)

Mode 1 is designed for one or two stages of Heating, Domestic Hot Water (DHW), and Setpoint operation.

Mode 2 (MODE = —2—)

Mode 2 is designed for dedicated DHW operation. In this mode, the 262 controls one or two stages of heat for DHW generation (see Section C3 Dedicated DHW).

DHW

Pump

Boiler

Pump

Boiler

Sensor

STAGING

The 262 controls up to two stages in order to supply the required target temperature. After each stage is turned on in the firing sequence, the control waits a minimum amount of time before turning on the next stage. The minimum time between stages is the total of the fire delay (FIRE DLY) setting plus the minimum inter-stage delay selected by the boiler mass (Boil MASS) setting. After the minimum time delay between stages has expired, the 262 examines the control error to determine when the next stage is to fire. The control error is determined using Proportional, Integral, and Derivative (PID) logic.

Proportional - compares the actual supply temperature to the boiler target (Boil TRG) temperature. The colder the supply water temperature, the sooner the next stage is turned on.

Integral - compares the actual supply temperature to the Boil TRG temperature over a period of time.

Derivative - determines how fast or slow the supply water temperature is changing. If the supply temperature is increasing slowly, the next stage is turned on sooner. If the supply temperature is increasing quickly, the next stage is turned on later, if at all.

Each stage has a minimum on time and a minimum off time.

	Boiler Contact Closes	#2
BoilerTemperature	Interstage Delay	Boiler	Boiler #2 Fires
	Boiler #1 Fires
	Boiler#1
	Fire	Fire
	Delay	Delay
		Time

FIRE DELAY (FIRE DLY)

The Fire Delay is the delay time that may occur between the time that the 262 closes a stage contact and the burner fires for that stage. This delay is usually the result of burner pre-purge or other forms of time delay built into the burner’s safety circuits.

BOILER MASS (Boil MASS)

The Boiler Mass setting allows the installer to adjust the control to the thermal mass of different types of heat sources used.

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	Boiler Contact Closes
	Boiler Fires
Temperature	Minimum On Time	Minimum	Minim
		Off Time
	Fire		Fire
Boiler
	Delay		Delay
		Time

Light (LITE)

The LITE setting is selected if the boiler(s) that is used has a low thermal mass. This means that the boiler(s) 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 minimum inter-stage delay for the LITE setting is two minutes.

Medium (MED)

The Medium setting is selected if the boiler(s) that is used has a medium thermal mass. This means that the boiler(s) 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 minimum inter-stage delay for the MED setting is four minutes.

Heavy (HEVY)

The Heavy setting is selected if the boiler(s) that is used has a high thermal mass. This means that the boiler(s) 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 minimum inter-stage delay setting for the HEVY setting is six minutes.

BOILER DIFFERENTIAL (BOIL DIFF)

An on / off heat source must be operated with a differential in order to prevent short cycling. With the 262, either a fixed or an auto differential maybe selected.

Fixed Differential

The boiler differential is divided around the Boil TRG temperature. The first stage contact will close when the supply water temperature is 1/2 of the differential setting below the Boil TRG temperature, and will open when the supply water temperature is 1/2 of the differential setting above the Boil TRG temperature. The second stage operates if the first stage cannot bring the water temperature up to the Boil TRG temperature.

Auto Differential (AUTO)

If the Auto Differential is selected, the 262 automatically determines the best differential as the load changes. This reduces potential short cycling during light loads.

STAGE 1&2 (STAGE)

The stage 1 and 2 setting may be selected to AUTO or OFF. When AUTO is selected, the stage is activated and the control operates the appropriate boiler. When OFF is selected, the control does not fire the stage.

ROTATION (ROTATE)

The ROTATE item is an adjustable setting that is factory set at 48 hours. The firing order of the boilers changes whenever one stage’s accumulated running time exceeds the other stage’s accumulated running time by more than the ROTATE setting. After each rotation, the stage with the least running hours is the first to fire and the stage with the most running hours is the last to fire. This function ensures that both stages receive equal amounts of use. When this item is set to the OFF setting, Stage 1 is always the first stage to fire.

BOILER PURGE (PURGE)

After the boiler demand is satisfied, the 262 continues to operate the boiler pump (Boil P1, terminal 8) for a period of time. The length of time that the boiler pump continues to run is adjustable (PURGE). This setting allows purging of any excess heat out of the boiler after the burner is shut off. This also helps to prevent the water in the boiler from flashing into steam after the boiler is shut off. The boiler pump continues to run either until the purging time has elapsed or the boiler supply (Boil SUP) temperature drops more than a differential below the boiler minimum (Boil MIN) setting.

SETBACK (UNOCCUPIED)

Off
Differential	On
Time	HeatingLoad
1	2
720 hours	672 hours
2	1
672 hours	720 hours
	or

To provide greater energy savings, the 262 has setback capability. With setback, the supply water temperature in the system is reduced when the building is not used (AWAY) or when the building is UnOccupied. By reducing water temperature, air temperature in the space can be reduced even when thermostat(s) are not turned down. This feature is enabled by setting the Setback / None DIP switch to the Setback position, and providing either an external signal or an internal override.

Note: AWAY does not require the DIP switch = Setback.

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External Unoccupied

An external signal can place the 262 into an UnOccupied mode. Any time the UnO Sw (18) and the Com Sen (19) 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 262 adjusts the supply water temperature based on the UnOcc setting made in the control.

Internal Overrides (OVERRIDE)

The 262 has a number of setback overrides that are selected through the Schedule (Schd) Menu. These setback overrides have priority over any external setback signal. Any time an override is in effect, the Ovr segment is displayed in the LCD.

Temporary (TMPY)

If a temporary OVERRIDE is selected, the 262 operates in the selected override mode for 3 hours. Once over, the control reverts to the previous operation.

Permanent (PERM)

If a permanent OVERRIDE is selected, the 262 operates in the selected override mode until a new OVERRIDE is selected.

18	19
UnO Com
Sw

Timer Switch

Schd
UnOcc	Ovr

Away (AWAY)

If the AWAY override is selected, the 262 operates with a fixed WWSD of 62˚F (17˚C) and a fixed room temperature of 62˚F (17˚C). Any DHW demand is ignored. The setpoint operation is not affected by the AWAY override.

EXERCISING (EXERCISE)

The 262 has a built in pump exercising function. The exercising period setting is adjustable and is factory set at 70 hours. If a pump output on the control has not been operated at least once during every exercising period, the control turns on the output for 10 seconds. This minimizes the possibility of the pump seizing during a long period of inactivity.

Note: The exercising function does not work if power to the control or pump(s) is disconnected.

Section B —Boiler Reset (Mode = —1—)

Section B1

General Boiler

Operation

Section B2

Alternate Boiler

Demands

Section B1 —General Boiler Operation

BOILER DEMAND

A boiler demand is generated by applying a voltage between 24 and 240 V (ac) across the Boil Dem (1&2) terminals. Once voltage is applied, the Boiler Demand pointer is displayed in the LCD. If the 262 is not in WWSD, it closes the Boil P1 contact, which starts the boiler pump and the control turns on the boiler pump segment in the LCD. The 262 calculates a Boil TRG supply temperature based on the outdoor air temperature and settings. The 262 then fires the boiler(s), if required, to maintain the target supply temperature.

CHARACTERIZED HEATING CURVE OR RESET RATIO

The 262 has two methods of varying the supply water temperature based on the outdoor air temperature. The installer can select either a Characterized Heating Curve or a Reset Ratio.

Characterized Heating Curve

The Characterized Heating Curve is the most accurate method of controlling the supply water temperature based on outdoor air temperature and optionally indoor 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, convection and conduction, the supply water temperature must be controlled differently. Once the control is told what type of terminal unit is used, 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.

Reset Ratio

The Reset Ratio method of controlling the supply water temperature is based solely on the outdoor air temperature. This method does not take into account the type of terminal unit that the heating system is using and therefore is not as accurate as a Characterized Heating Curve.

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BOILER START (Boil STRT) (RESETRATIO)

The Boil STRT temperature is the boiler supply water temperature that the heating system requires when the outdoor air temperature equals the OUT STRT air temperature setting.

OUTDOOR START (OUT STRT) (RESET RATIO)

The OUT STRT temperature is the outdoor air temperature at which the control provides the Boil STRT supply water temperature to the system.

OUTDOOR DESIGN (OUT DSGN)

(RESET RATIO & CHARACTERIZED HEATING CURVE)

The OUT DSGN 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 heat loss calculations for the building.

BOILER DESIGN (Boil DSGN)

(RESET RATIO & CHARACTERIZED HEATING CURVE)

The Boil DSGN temperature is the supply water temperature required to heat the boiler zones when the outdoor air is as cold as the OUT DSGN temperature.

	Boil MAX	210
Boiler Reset		(99)
Ratio	Boil DSGN	190
		(88)
		170
Boil MIN		(77)
		150
	Boil SETB	(66)Temperature
		130
		(54)Water
	OUT DSGN	110
Boil STRT		(43)Supply
		90
		(32)

OUT STRT					WWSD Occ									70
								WWSD Unocc						(21)
80	60			40					20			0		-20
(27)	(16)			(5)				(-7)				(-18)		(-29)

Outdoor Air Temperature

BOILER MINIMUM (Boil MIN)

(RESET RATIO & CHARACTERIZED HEATING CURVE)

The Boil MIN is the lowest water temperature that the control is allowed to use as a Boil TRG temperature. During mild conditions, if the 262 calculates a Boil TRG temperature that is below the Boil MIN setting, the Boil TRG temperature is adjusted to at least the Boil MIN setting. During this condition, if the boiler is operating, the Minimum pointer turns on in the LCD while the Boil TRG or the Boil SUP temperature is viewed. If the installed boiler(s) is designed for condensing operation, set the Boil MIN adjustment to OFF.

Boil Min + 1/2 Boiler Differential

e

r

tu

ra

e

Boil MIN

p

m

e

r

T

e

at

il W

Bo

Boil Min - 1/2 Boiler Differential

Pointer On

BOILER MAXIMUM (Boil MAX)

(RESET RATIO & CHARACTERIZED HEATING CURVE)

The Boil MAX is the highest water temperature that the control is allowed to use as a Boil TRG temperature. If the control does target Boil MAX, and the Boil SUP temperature is near the Boil MAX temperature, the Maximum pointer turns on in the LCD while the Boil TRG or the Boil SUP temperature is viewed.Atnotimedoesthecontroloperatetheboiler(s)above248˚F (120˚C).

Boil Max + 1/2 Boiler Differential

							e
							r
							tu
						a
						r
					e
					p
				m
				e				Boil MAX
				rT
			te
		a
	W
l
Boi					Boil Max - 1/2 Boiler Differential
Pointer On						Pointer On

WARM WEATHER SHUT DOWN (WWSD) OCC & UNOCC

(RESET RATIO & CHARACTERIZED HEATING CURVE)

When the outdoor air temperature rises above the WWSD setting, the 262 turns on the WWSD pointer in the display. When the control is in Warm Weather Shut Down, the Boiler Demand pointer is displayed if there is a demand. However, the control does not operate the heating system to satisfy this demand. The control does respond to either a DHW Demand or a Setpoint Demand and operates as described in Section C.

BOILER SETBACK (SETBACK) (RESET RATIO)

The boiler SETBACK is the amount that the boiler supply water temperature is reduced when the 262 is placed into an UnOccupied mode, using an internal or an external setback as described in Section A. This setting is only available if the Reset Ratio DIP switch is selected and Setback / None DIP switch is set to Setback.

BOILER INDOOR (Boil INDR)

(CHARACTERIZED HEATING CURVE)

The Boil INDR is the room temperature used in the heat loss calculations done for the building. This setting establishes the beginning of the Characterized Heating Curve for the boiler zones. This single setting replaces the Boil STRT water temperature and OUT STRT air temperature settings used by the Reset Ratio.

						210
				Boil MAX		(99)
Boiler Characterized			Boil DSGN			190
	Heating Curve					(88)
						170
						(77)
	Boil MIN					150
						(66)
						130Temperature
			OUT DSGN			(54)	Water
		WWSD Occ				110
							Supply
		WWSD Unocc				(43)
						90
Boil IND						(32)
		Boil ROOM Occ				70
						(21)
		Boil ROOM UnOcc
						50
80	60	40	20	0	-20 (10)
(27)	(16)	(5)	(-7)	(-18)	(-29)

Outdoor Air Temperature

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ROOM OCC & UNOCC (ROOM)

(CHARACTERIZED HEATING CURVE)

The ROOM is the desired room temperature for the boiler zone(s) and it provides a parallel shift of the Characterized Heating Curve. The room temperature desired by the occupants is often different from the designed indoor temperature (Boil INDR). If the room temperature is not correct, adjusting the ROOM setting increases or decreases the amount of heat available to the building. If the Setback / None DIP switch is set to Setback, a ROOM setting must be made for both the Occupied and UnOccupied modes.

TERMINAL UNITS (TERMINAL)

When using a Characterized Heating Curve, the control requires the selection of a terminal unit. The terminal unit determines the shape of the Characterized Heating Curve according to how the terminal unit delivers heat into the building space. The 262 provides for selection between six different terminal unit types: two types of hydronic radiant floor heat, fancoil, fin– tube convector, radiator, and baseboard.

Hydronic Radiant Floor (HRF 1)

HRF 1 is a heavy, or high mass, hydronic radiant floor 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.

Hydronic Radiant Floor (HRF 2)

HRF 2 is a light, or low mass, hydronic radiant floor system. Most commonly, 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 subfloor and the surface. This type of radiant system has a relatively low thermal mass and responds faster than a high mass system.

Fancoil (COIL)

HRF 1

HRF 2

COIL

A fancoil terminal unit or air handling unit (AHU) consists of an hydronic heating coil and either a fan or blower. Air is forced across the coil at a constant velocity by the fan or blower and is then delivered into the building space.

Fin-tube Convector (CONV)

A convector terminal unit is made up of a heating element encased in fins. This type of terminal unit relies on the natural convection of air across the heating element to deliver heated air into the space. The amount of natural convection is dependant on the supply water temperature to the heating element and the room air temperature.

Radiator (RAD)

A radiator terminal unit has a large heated surface that is exposed to the room. A radiator provides heat to the room through radiant heat transfer and natural convection.

CONV

RAD

Baseboard (BASE)

A baseboard terminal unit is similar to a radiator, but has a low profile and is installed at the base of the wall. The amount of heat transferred by radiation from a baseboard is greater than that from a fin-tube convector.

BOILER TARGET TEMPERATURE (BOIL TRG)

(RESET RATIO & CHARACTERIZED HEATING CURVE)

BASE

The Boil TRG temperature is determined from either the Characterized Heating Curve or the Reset Ratio settings and the outdoor air temperature and optionally indoor temperature feed back. 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 displays “- - -” in the LCD.

BOILER OPERATION

When the 262 determines that boiler operation is required, the Boiler stage contact(s) (11 and 12 and/or 13 and 14) close. While the Boiler contact(s) is closed, the burner and stage segment in the LCD is displayed.

BOILER PUMP (P1) OPERATION

The Boiler Pump contact (P1, terminal 8) closes whenever there is a Boiler demand and the 262 is not in WWSD. If 10K = INDR or SLAB, the control receives a boiler demand and the Boil TRG temperature is below the Boil MIN setting, the boiler pump may continue to operate after the boiler demand is removed. For boiler pump contact operation during either DHW and / or Setpoint operation, refer to the DHW, and Setpoint Section D.

Soft Start (SOF STRT)

The SOF STRT function allows the 262 to slowly ramp the water temperature up to the required supply temperature. By allowing the temperature in the system to be adjusted slowly, the control reduces any thermal expansion noises and stresses that may be caused by a quick change in supply water temperature.

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Boosting (BOOST)

When the control changes from the UnOccupied to the Occupied mode, it enters into a Boosting mode. In this mode, the supply water temperature to the system is raised above its normal values for a period of time to provide a faster recovery from the setback temperature of the building. The maximum length of the Boost is selected in the user interface. This setting is only available if a Characterized Heating Curve is selected; It is not available for a Reset Ratio or if a tekmar Zone Control is used.

Typical settings for the Boost function vary between 30 minutes and two hours for a building that has a fast responding heating system. For a building that has a slow responding heating system, a setting between four hours and eight hours is typical. After a Boost time is selected, the setback timer must be adjusted to come out of setback some time in advance of the desired Occupied time. This time in advance is normally the same as the Boost setting.

Water Temperature

Boost

Self Adjusting

Water Temperature

Boil TRG (Occupied)

Boil TRG (UnOccupied)

UnOcc to Occ

Boost setting - 20 minutes to 8 hours

Time

If the building is not up to temperature at the correct time, the Boost setting should be lengthened and the setback timer should be adjusted accordingly. If the building is up to temperature before the required time, the Boost setting should be shortened and the setback timer should be adjusted accordingly. If the system is operating near its design conditions or if the supply water temperatures are being limited by settings made in the control, the time required to bring the building up to temperature may be longer than expected.

Section B2 —Alternate Boiler Demands (Mode = —1—)

In addition to using conventional thermostats to provide a boiler demand as described in Section B1, the 262 can use a number of other methods to provide a Boiler Demand.

10K INDOOR SENSOR (10K = INDR)

Set the 10K item to INDR to add an indoor sensor for temperature control of a single zone boiler system. The indoor sensor is connected to the Com and 10K terminals (16 and 17). In addition, power must be applied to the Boiler Demand terminals (1 and 2) as described in Section B1. With the indoor sensor connected, the 262 is able to sense the actual room temperature. With this information, the 262 provides a more constant water flow through the system. At the same time, indoor feedback fine tunes the supply water temperature in the system to prevent over heating or under heating. To adjust the room temperature for the zone, use the ROOM Occupied or UnOccupied setting in the Adjust menu at the control.

tekmar Indoor Sensor

tekmar 262 Control

10K BOILER ZONE CONTROL (10K = ZoIn)

Set the 10K item to ZoIn to add indoor temperature feedback control of multiple zones. Control of the zones is provided by connecting a tekmar Zone Control to the Com and 10K terminals (16 and 17) of the 262. The zone control provides its own internal Boiler Demand to the 262. In this case, there is no need to provide an external Boiler Demand as described earlier in Section B1. The zone control is capable of automatically adjusting the Boil TRG temperature to improve building occupant comfort and system performance.

10K SLAB SENSOR (10K = SLAB)

Set the 10K item to SLAB to add a slab sensor for temperature control of a single zone system. The 262 can use a slab sensor to control the actual slab temperature. A slab sensor is placed in the slab and connected to the Com and the 10K terminals (16 and 17). Power must be applied to the Boiler Demand terminals (1 and 2) as described in Section B1. With the slab sensor connected, the 262 will limit the supply temperature in order to maintain the slab sensor between the SLAB MIN and SLAB MAX settings. This application is available only when

Boil MIN is set to OFF.

Slab Min (SLAB MIN)

tekmar Zone Control

tekmar Slab Sensor

tekmar 262 Control

tekmar 262 Control

The SLAB MIN sets the minimum allowed core temperature of the slab as long as the control is not in a WWSD. Caution should be used when adjusting the SLAB MIN setting as this may lead to overheating of the zone during mild conditions. If the AWAY setting is selected in the Schedule menu, the 262 ignores the SLAB MIN setting.

Slab Max (SLAB MAX)

The SLAB MAX sets the maximum allowed core temperature of the slab. If the slab is to be maintained at a fixed core temperature, set SLAB MAX and SLAB MIN items to the same setting.

ROOM TEMPERATURE UNIT (RTU) (10K = NONE)

If the system consists of a single zone, temperature control of that zone can be provided by using an RTU. The RTU is connected to the Com and tekmar NetTM tN1 / tN2 terminals (15 and 16). In addition, power must be applied to the Boiler Demand terminals (1 and

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2) as described in Section B1. With the RTU connected, the 262 measures the actual ROOM temperature. Indoor temperature feedback fine tunes the supply water temperature in the system to prevent over heating or under heating. The RTU allows the user to adjust the desired room temperature at the RTU. Remote sensor capability is also available through an RTU. See the Data brochure for the RTU you are connecting.

Section C —Domestic Hot Water (DHW) and Setpoint (Mode = —1—)

Section C1	Section C2	Section C3	Section C4
General Domestic	DHW Priority	DHW with Low	Dedicated
Hot Water (DHW)		Temperature	DHW
Operation		Boilers

Section C1 —General Domestic Hot Water (DHW) Operation (Mode = —1—)

DHW DEMAND

A DHW demand is generated on the 262 by using one of two methods: either an external DHW demand from an aquastat or an internal demand from a 10K tekmar sensor. If an external and internal demand is present simultaneously, the control stops operation of the DHW.

External Demand (DHW SENS = NONE)

The 262 registers an external demand for DHW when a voltage between 24 and 240 V (ac) is applied across the Com Dem and the DHW Dem terminals (3 and 4). A DHW aquastat or setpoint control is used as a switch in the DHW demand circuit. Once the 262 detects a DHW demand, the DHW Demand pointer turns on in the LCD and the control operates as described below.

Internal Demand (DHW SENS = DHW)

The 262 registers an internal demand for DHW when a sensor is connected across the Com and the DHW terminals (19 and 20). The DHW TANK setting is used to set the desired indirect DHW tank temperature. When MODE –1– is selected, if the temperature at the DHW sensor drops 3˚F (1.5˚C) below the DHW TANK setting, the DHW Demand pointer turns on in the LCD and the control operates as described below.

An advantage to using the DHW sensor is that the control can display the current DHW TANK temperature and record the highest and lowest DHW TANK temperatures. Also, the 262 can control the DHW temperature with more accuracy than when using an aquastat.

DHW DEVICE (DHW THRU)

Once the 262 receives a DHW Demand, the sequence of operation depends on the type of DHW device selected. The DHW device is selected using the DHW THRU item in the Adjust menu.

DHW Pump (DHW THRU = PUMP)

If PUMP is selected as the DHW device, the 262 assumes that the DHW pump provides adequate flow through both the DHW tank heat exchanger and the boiler(s). To provide heat to the DHW tank, the 262 closes the DHW Pmp / Vlv contact (9 and 10) and operates the boiler(s) to provide a sufficient boil supply temperature to the DHW tank. If using a primary loop with the DHW tank piped in primary / secondary, select DHW VALV.

24 to 240 V (ac)

3	4
ComDHW
Dem Dem

Aquastat

19	20
Com DHW

DHW

Storage Tank

Pump

Valve

P

DHW Valve (DHW THRU = VALV)

If VALV is selected as the DHW device and there is a DHW Demand, the 262 closes the DHW Pmp / Vlv contact (9 and 10) and the Boil P1 contact (7 and 8). The boiler pump provides flow through the DHW tank’s heat exchanger once the DHW valve is opened. The 262 operates the boiler(s) to provide a sufficient boiler supply temperature to the DHW tank.

BOILER TARGET DURING DHW GENERATION (Boil TRG)

The Boil TRG temperature during DHW operation depends on whether an external or internal demand is present. The DHW demand overrides the reset water temperature.

External Demand (DHW SENS = NONE)

If the control receives a DHW demand through an external device such as an aquastat, the Boil TRG temperature is at least as hot as the DHW heat exchanger setting (DHW XCHG).

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Internal Demand (DHW SENS = DHW)

If the control receives a DHW demand from a DHW sensor attached to the Com Sen and the DHW 10K terminals (19 and 20), the Boil TRG temperature is at least as hot as the DHW TANK setting plus 40˚F (22˚C).

DHW DURING UNOCCUPIED

The DHW operation during an UnOccupied period depends on the type of DHW demand that the 262 is receiving and the type of setback that is being used. For this function to operate, the control must have the Setback / None DIP switch set to Setback.

External Demand (Aquastat )

If an external DHW Demand is used, the control can either continue operation of the DHW system as it would during the Occupied period or the control can ignore a call for DHW as long as the control is in an UnOccupied mode.

Internal Demand (Sensor)

If an internal DHW Demand is used, a DHW TANK Unocc temperature can be set. This is the temperature that the tank maintains as long as the control is in an UnOccupied mode.

Away

If the AWAY setting is made in the Schd menu, any DHW Demand is ignored and the tank cools off. Note: AWAY does not require the DIP switch = Setback.

Section C2 —DHW Priority (Mode = —1—)

DHW PRIORITY (DHW PRI = BOIL)

It is often desirable to limit or even stop the flow of heat to the heating system when the DHW tank calls for heat. This allows for a faster recovery of the DHW tank. If DHW PRI is set to Boil, the boiler pump (P1) is turned off on a call for DHW. This setting is available only if DHW THRU = PUMP has been selected as the DHW device. If a valve is used as the DHW device, DHW priority can not be used. Caution should be taken to ensure that the flow rate of the DHW pump is adequate for both the DHW tank and the boiler(s), as this will be the only pump providing flow through the boiler(s).

DHW PRIORITY OVERRIDE

To prevent the building from cooling off too much or the possibility of a potential freeze up during DHW priority, the 262 limits the amount of time for DHW priority. As the outdoor air temperature becomes colder, the length of time that the 262 provides DHW priority is reduced. Once the allowed time for priority has elapsed, the 262 overrides the DHW priority and operates DHW and heating simultaneously.

CONDITIONAL DHW PRIORITY

If the boiler supply temperature is maintained at or above the required temperature during DHW generation, this indicates that the boiler(s) has enough capacity for DHW and possibly heating as well. As long as the boiler supply temperature is maintained near its target, DHW and heating occurs simultaneously.

DHW

P1

Increasing Time

DHW priority demand time limit

Increasing Air Temperature

Outdoor air temperature

DHW POST PURGE

After the DHW Demand is removed, the 262 performs a purge on the boiler(s). The 262 shuts off the boiler(s) and continues to operate either the DHW pump or the DHW valve and the boiler pump. This purges the residual heat from the boiler(s) into the DHW tank. The 262 continues this purge for a maximum of four minutes or until the boiler supply water temperature drops 20˚F (11˚C) below the DHW Boil TRG temperature. The 262 also stops the purge if the boiler supply temperature drops below the current Boil TRG temperature.

DHW MIXING PURGE

After DHW operation, the boiler(s) is extremely hot. At the same time, the heating zones may have cooled off considerably after being off for a period of time. To avoid thermally shocking the boiler(s) after DHW priority, the 262 shuts off the boiler(s), but continues to operate the DHW while restarting the heating system. This allows some of the DHW return water to mix with the cool return water from the zones and temper the boiler return water.

P

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