tekmar 365 User Manual

- Data Brochure

R

D 365

Mixing Control 365

WWSD

Power

Heat

UnOcc.

Demand

Switch

Max. or

Min.

Setpoint

105
(41)

Pump

is on

Return

Boiler

Pump

90

70

of full

50

output

%

30

10

R

R

LR 58233

E150539

70°F

70°F

(21°C)

(21°C)

35

35

105

(2

(2

(41)

)

)

Occupied

Unoccupied

Mixing Control 365

Variable Speed and 4-20 mA

Control is

maintaining

Minimum Return

System

Unoccupied

temperature

setting

Occupied

temperature

setting

Variable Speed

and 4-20 mA

operating level

Terminal Plugs:

Power and out-

put connections

The tekmar Mixing Control 365 is a microprocessor-based control with a 120 Vac output for operating
a variable speed injection pump. A 4-20mA output is available for operating devices such as a 4­20mA actuating motor, modulating gas valve, a mixing valve combination, or for operating a 4-20mA
motor drive for larger variable speed pumps. The variable speed pump or mixing valve regulates the
supply water temperature to a heating system based on the outdoor air temperature, and optionally,
the indoor air temperature. The system is shut down when there is no Heat Demand signal or when
the outdoor temperature is warm enough so that the system no longer requires heat (WWSD).

Outdoor Reset Strategy. . pg. 2
Variable Speed Pump . . . pg. 3
Sequence of Operation . . pg. 5

Installation . . . . . . . . . . . . pg. 7

Settings . . . . . . . . . . . . . . . pg. 11

Heating

is required

35
(2)

Occupied

Mixing Control 365

Variable Speed and 4-20 mA

Use Nº 20 AWG or larger copper conductors rated for at least 75°C and 300V.

12 3456

Heat

Dem

Dem Pmp

70°F

(21°C)

105
(41)

120Vac power

supply is on

70°F

(21°C)

35

105

(2)

(41)

Unoccupied

Power

System

N

L

Pmp

System is in

Warm Weather

Shut Down

7

Var.
Pmp

Power

Heat
Demand

Min.
Return

Pump

LR 58223

89

Boiler

90

70

50

30

10

R

switched to

Unoccupied

WWSD

UnOcc.
Switch

Max. or
Setpoint

Boiler

of full

output

%

Listed

5T62

R

E150539

Testing . . . . . . . . . . . . pg. 13

Error Messages . . . . . pg. 15

Technical Data . . . . . . pg. 16

Limited Warranty . . . . pg. 16

System is

Setpoint

123 4

Reset

60

Test

Manufactured
in Canada by

Power: 120V 50/60Hz 300VA
System pump: 120Vac 12A 1/3 hp, pilot duty 480VA 4A
Var pump: 120V 50/60Hz 2.2A 1/6 hp, internally fused
Relay: 120Vac 10A 1/4 hp, pilot duty 240VA 2A
Enclosed Energy Management Equipment

1000Ω max

Do not apply power here

13 14

12 15

10 11

Ret

UnO

4-20

Com

+

–

Sen

Control is

maintaining

Maximum Supply

Boiler on when 25% open
External Heat Demand
Zone Control

Indoor Sensor
Permanent Heat Demand
Boiler on when 10% open

2.0

0.4

3.6

Heating Curve

100°F

150

Minimum

Boiler Return

16 17

2K10K

Com Com

SenSw

Sen

RTU

Sen

150°F

100 200

Max./Setpoint

130 sec.

30 230Off

Motor Speed /

Pump Response

2093
1234567

18 19

Sup Out
Sen

Sen

Date

R

06/00

Boiler is on

Operating Mode
selector
switches

Heating Curve

Maximum

/Setpoint

Supply

Minimum
Boiler Return

Motor Speed

Test button and
LED to test main

S/N

control functions

Terminal Plug:
Sensor and
timer input

H1073

Input:
Heat Demand
signal.

Optional

120Vac
Power Supply

Output: Turn on

system pump

Output: Control

variable speed pump

Output:

Turn on boiler

OR

Output:

4-20mA device

M

Input: Return

Sensor 071.

Optional

Input:

Unoccupied

signal (030

Timer)

Optional

Input: Indoor

Sensor 074

Optional

Copyright © D 365 - 06/001 of 16

Input: Outdoor

Sensor 070

Included

Input: Supply Universal

Sensor 071.

Included

OR

Input: 2k RTU

Optional

Outdoor Reset Strategy

Correct setting and shifting of the Heating Curve... the key to More Comfort and Energy Savings.

Heating Curve

As outdoor temperatures get colder, heat losses from a building increase, requiring the addition of more heat to prevent the indoor
air temperature from also getting colder. This tekmar reset control measures the outdoor temperature and as the outdoor
temperature gets colder, it balances the heat loss by making the heating supply water hotter.
The Heating Curve is used to calculate how hot to make the supply water at different outdoor temperatures. It is the number of
degrees the supply water temperature is raised for each degree that the outdoor temperature falls.

Setting the Heating Curve

Two examples of how the Heating Curve works are given in the following illustration.
—With a 2.4 Curve, the supply water temperature is raised 2.4 degrees for every degree of outdoor temperature drop.

If WWSD point = 70°F and Outdoor temperature = 30°F, then Supply temperature = 166°F

—With a 0.6 Curve, the supply water temperature is raised 0.6 degrees for every degree of outdoor temperature drop.

If WWSD point = 70°F and Outdoor temperature = 30°F, then Supply temperature = 94°F

• If the Heating Curve selected is too low;

able to raise the supply temperature high enough to keep the room
temperature warm during colder weather.

• If the Heating Curve selected is too high;

the building will overheat during colder weather.

Warm Weather Shut Down (WWSD)

At warm outdoor temperatures, the indoor space of a building gains heat
from the outdoors; additional heat is not required, and if the heating
system is running (even on standby), enough excess heat can be
produced to overheat the building, causing discomfort and wasting
valuable energy.

This control turns off the system pump and injection pump (or closes a
mixing valve), when the outdoor temperature is above the WWSD point.

As outdoor temperatures get colder, there comes a point where the heat
gain turns into heat loss; the heat loss causes the indoor temperature to
fall below the comfort level, and the heating system must be turned on to
start delivering heat.

To provide heat to the building, this control turns on the system pump and starts the injection pump (or opens the mixing valve),
delivering heat at the low output required by the Heating Curve near the WWSD point. If the outdoor temperature rises above the
WWSD point, the control shuts the system off again, and because the system was operating at a low heat output level, overheating
and temperature swings in mild weather are avoided.

When the system is operating near the WWSD point and the building is too cold;
When the system is operating near the WWSD point and the building is too warm;

3.0

WWSD

Point

will

shift

up and

down

with

shift of

Heating

Curve

(32)

3.6

Heating

Curve

Parallel Shift of Heating Curve

UP

DOWN

UP

90

70

(21)

50

(10)

Outdoor air temperature

2.4 2.0

DOWN

30

(-1)10(-12)

A very cool room temperature can shift the curve far enough up to bring the control out of WWSD at warm outdoor temperatures.
A very warm room temperature can shift the curve far enough down to put the control into WWSD at cool outdoor temperatures.

the heating system will not be

too much heat is delivered and

Shifting the Heating Curve

(a) Manually, at the control:

The Occupied and Unoccupied dials on this control can shift the WWSD
point up or down from 35 to 105°F (2 to 41°C).

(b) Automatically, using room temperature feedback:

In addition to a Supply Sensor and an Outdoor Sensor, this control can use
a tekmar 2k RTU, 10k Zone Control or 10k Indoor Sensor to provide room
temperature feedback for added comfort and system flexibility.

The control still calculates a desired supply temperature based on the

Supply water temperature

Heating Curve setting and the outdoor temperature.

If the air temperature in the room is too cold, the control will shift the Heating
Curve (and WWSD point)
room warms up again.

If the air temperature in the room is too warm, the control will shift the
Heating Curve (and WWSD point)

1.6

1.2

1.0

0.8

0.6

0.4

-10°F

(-23)°C

210
(99)

190
(88)

170
(77)

150
(65)

130
(54)

11 0
(43)

90

(32)

70

(21)

50°F

(10)°C

ture until the room cools down.

3.0

90

(32)

WWSD

Point

Heating

Curve

70

(21)

3.6

50

(10)

Outdoor air temperature

2.4 2.0

30

(-1)10(-12)

the WWSD point should be raised.

the WWSD point should be lowered.

up,

which raises the supply temperature until the

down,

which lowers the supply tempera-

1.6

1.2

1.0

0.8

0.6

0.4

-10°F

(-23)°C

210
(99)

190
(88)

170
(77)

150
(65)

130
(54)

11 0
(43)

Supply water temperature

90

(32)

70

(21)

50°F

(10)°C

Refer to the tekmar Essays E 001 and E 002 for more detailed information regarding control strategy and integration of control functions.

Copyright © D 365 - 06/00 2 of 16

The tekmar Variable Speed Pump Output

Variable Speed Pump

When using a variable speed pump, the injection of high tempera­ture water into the lower temperature heating system loop should
be continuous and the volume of water injected should be varied
by speeding up (more heat) or slowing down (less heat) the pump
rotation speed. This is a flexible and inexpensive method of mixing
reset/setpoint control and can be used for a number of applications
on systems with a wide variety of flow rates.

Ideally, the variable speed pump should operate near 100 %
output during system design temperature conditions (when run­ning in mixing reset mode). Injection rates will vary with changing
high temperature loop water temperatures, and correct sizing of
the injection pump must take this factor into account. Plumbing
arrangements and pump sizing calculations are covered in more
detail in the Essay E 021.

Operation

The Mixing Control 365 has a 120Vac 50/60Hz output which has
been designed to directly power an injection pump at variable
speeds to control the rate at which hot water is added to the heating
system loop. The maximum drive capacity for this circuit is 1/6 hp,

2.2 Amp, 120Vac. There are a number of manufacturers produc­ing small circulators that can be operated by this 120Vac output.
A permanent capacitor, impedance protected pump motor (no
start switch) under 1/6 hp is required. Most small "wet rotor"
circulators have proven to be acceptable. Consult the accompa­nying Addendum for a list of the specific pumps tested and
approved by their manufacturers. As these companies test and
approve new products for use with the tekmar variable speed
output, the Addendum will be updated.

Larger pumps require that a compatible 4–20 mA motor drive be
used as an interface between the control and the pump motor.
Contact the pump manufacturer regarding compatible equipment
for specific pumps.

The variable speed (
the same time. If the 120Vac output is used and remote monitoring
is important, a remote read out via the 4–20 mA could be
connected. The 4–20 mA is proportional to the level of the variable
speed output.

Var Pmp

) and the 4–20 mA output operate at

Supply To Low

Temperature Loop

Return from Low

Temperature Loop

Supply To Low

Temperature Loop

Return from Low

Temperature Loop

Mixing Point

Crossover

Flow

Variable Speed
Injection Pump

Crossover

Flow

Variable Speed

Injection Mixing

Low Output

Mixing Point

Crossover

Flow

Variable Speed

Injection Pump

Crossover

Flow

Variable Speed

Injection Mixing

High Output

Supply From High
Temperature Loop

Return to High

Temperature Loop

Supply From High
Temperature Loop

Return to High

Temperature Loop

Variable Speed Pump Start Up

The control gives an initial 100% power output to the motor for
1/5 second to get it started up from a dead stop. This full power
output is required to get the pump motor turning. After the 1/5
second starting pulse, the control adjusts the pump speed to meet
the heating requirements.

The maximum

rate

at which the motor can change its speed from
0% output to 100% or from 100% output back to 0% output is set
by the "Motor Speed/Pump Response" dial. This dial should be set
according to system response times and will typically be set
somewhere between 30 and 50 seconds. Refer to the "Settings"
section, page 12, for more information.

% of Full Output

The control's variable speed output has been designed to provide
a linear GPM flow rate over the full operating range of the pump.
For example, when the "10 % of full output " LED is on, the control
will be running the pump to deliver 10% of its GPM output rather
than 10% of its rated rotational speed. As the above illustration
indicates, the % output of flow from the pump is directly propor­tional (within 10%) to the "% of full output" scale of the control.

Variable Speed & 4-20 mA Output Operation

100%

80%

60%

40%

Rated GPM of Pump

20%

90

70

50

30

10

20%

% of Full Output Display (Pump GPM output in %)

90

70

50

90

70

50

30

90

70

50

30

90

70

50

30

10

40% 60% 80% 100%

10

Note: Refer to Pump

Manufacturers' Specifications

10

for G.P.M. Output

30

10

Within 10%

(typical)

Copyright © D 365 - 06/003 of 16

Plumbing Arrangements

T

T

F

F

T

F

F

∆T

T

T

F

F

T

F

F

∆T

tekmar has developed two significantly different ways of piping variable speed injection pumps for small commercial and residential
hydronic heating systems. Each method has its advantages and disadvantages, and designers should read the tekmar essay E 021
thoroughly in order to correctly choose the best arrangement for their particular application.

Reverse Injection

Reverse injection requires that the water from the boiler loop
is injected into the low temperature loop upstream of the
return to the boiler loop. Mixing occurs directly after the point
of injection. Since some of the mixed water is then returned
back to the boiler loop, higher injection flow rates are required
than in direct injection systems.

Pump Sizing

Reverse Injection

To calculate the required size of the injection pump:

F1 = System Supply flow rate in US GPM
T1 = Hot Loop (Boiler) supply temperature available
T2 = Low Temperature (System) Supply temperature
∆Ts = Low Temperature (System) temperature drop (T2 – Tr)

Note: All values are to be given at design conditions.

Maximum
Variable Flow

(Fv) =

F1 x ∆Ts
T1 - T2

Sample Calculation

Values at

Design

Conditions

Are:

T1 = Boiler Supply = 180°F
T2 = System Supply = 130°F

∆Ts = System ∆T = 25°F

F1 = System Flow = 10 GPM

r

1

∆T

s

Supply To Low

Temperature Loop

1 x ∆Ts 10 x 25 250

F

Fv = = = = 5 GPM

T1 - T2 180 - 130 50

"REVERSE" INJECTION

2

1

Variable

Speed

Injection

Pump

V

V

Supply From High

Temperature Loop

1

Direct Injection

Direct injection requires the water from the hot loop to be
injected into the low temperature loop so that the heat rise and
the mixing occur directly after the point of injection, down­stream of the return to the hot loop.

Pump Sizing

Direct Injection

To calculate the required size of the injection pump:

F1 = System Supply flow rate in US GPM
T1 = Hot Loop (Boiler) supply temperature available
T2 = Low Temperature (System) Supply temperature
Tr = Low Temperature (System) Return temperature
∆Ts = Low Temperature (System) temperature drop (T2 – Tr)

Note: All values are to be given at design conditions.

Maximum
Variable Flow

(Fv) =

F1 x ∆Ts
T1 - Tr

Sample Calculation

Values at

Design

Conditions

Are:

T1 = Boiler Supply = 200°F
T2 = System Supply = 120°F

∆Ts = System ∆T = 20°F

F1 = System Flow = 60 GPM
Tr = System Return = T2 – ∆Ts = 100°F

Fv = = = = 12 GPM

This example illustrates an important point to consider when designing variable speed systems. The hotter the maximum boiler supply
temperature is designed for, or the cooler the maximum system supply temperature is designed for, the less injection flow is required. Quite
large systems can be designed with relatively small injection pumps when this is kept in mind.

Supply To Low

Temperature Loop

2

1

∆T

s

F

1 x ∆Ts 60 x 20 1200

"DIRECT" INJECTION

1

r

Variable

Speed

Injection

Pump

V

V

T1 - Tr 200 - 100 100

Supply From High
Temperature Loop

1

For more details on variable speed pumping, refer to tekmar essay E 021

The variable speed injection pump should be sized for full load heat transfer at design conditions. Calculations reveal that in most typical
residential and small commercial applications the smallest circulators are of sufficient size and in many cases exceed the maximum
required GPM rating. If an appropriate pump size is not available, a larger pump may be used provided a balancing valve is included to
reduce flow through the transfer loop.

Copyright © D 365 - 06/00 4 of 16

Sequence of Operation

Zone Control

Boiler on when 25% open

External Heat Demand

Setpoint

123 4

When the Mixing Control 365 is powered-up, the "Power" light will come on and the control will turn on all
LEDs for five seconds. If no errors are detected, the control enters the operating mode.

Once in operating mode, the control determines whether to operate in Reset or Setpoint mode based on
the setting of the Reset/Setpoint DIP switch.

If the control is configured for Setpoint it will monitor:

• a Universal Sensor 071 to continually monitor the system supply water temperature.

•

Optionally,

a Universal Sensor 071 to continually monitor the boiler return water temperature.

If the control is configured for Reset it will monitor:

• an Outdoor Sensor 070 to continually monitor the outdoor temperature.

• a Universal Sensor 071 to continually monitor the system supply water temperature.

•

Optionally,

•

Optionally,

a Universal Sensor 071 to continually monitor the boiler return water temperature.

the indoor temperature can be monitored through the use of:
(a) - a tekmar 2K RTU or 10K Indoor Sensor 074 (DIP switch in "Indoor Sensor" position) or;
(b) - a tekmar 10K Zone Control (DIP switch in "Zone Control" position)

• While monitoring all of these temperatures, the control recognizes the following temperature conditions
and inputs and will respond as described. During operation, the lights of the control will indicate
operational status as illustrated.

Heating Operation (Reset Mode)

Selector Switch = Reset

When the control is in the reset mode, its main function is to reset the supply water
temperature based on the changing outdoor temperature.

External Heat Demand signal

Selector Switch = External Heat Demand

A heat demand signal is caused by either 24 or 120Vac applied to terminals

Heat Dem — Heat Dem

(1 and 2).

AND/OR

An active (calling for heat) 10 K Zone Control connected
to terminals

Com Sen — 10K Sen

(14 and 15).

Setpoint

123 4

Boiler on when 25% open
External Heat Demand

Zone Control

4-20

+

1110

Com –Ret

Reset

12 13

Sen

UnO

Sw

123 4

14

Com

Sen

?

Power

Heat
Demand

Min.
Return

Pump

90

70

50

30

10

Setpoint

Reset

Indoor Sensor
Permanent Heat Demand
Boiler on when 10% open

15

16

10K

2K

Sen

RTU

%

17

Com

Sen

WWSD

UnOcc.
Switch

Max. or
Setpoint

Boiler

of full

output

123 4

12

Heat

Dem Dem

18 19

Sup

Sen

Test

Out

Sen

Permanent Heat Demand signal

Selector Switch = Permanent Heat Demand

A heat demand signal is continuously present unless a10K Zone Control is connected to terminals

Com Sen — 10K Sen

(14 and 15).

(If a10K Zone Control is connected, there will only be a heat demand

present when it calls for heat)

Occupied/Unoccupied dial function

With no indoor air temperature feedback, the control will monitor the outdoor and supply
temperatures. The Occupied and Unoccupied dial settings become the WWSD points.
When in Occupied mode and the outdoor temperature is warmer than the setting of the
Occupied dial, the control enters WWSD. When switched into Unoccupied mode –
(short circuit) terminals

UnO Sw — Com Sen

(13 and 14) together by a switch or isolated timer

Connect

relay contacts (tekmar Timer 030) – the "UnOcc. Switch" light will come on, the Occupied dial
will become inactive and the Unoccupied dial will become active

as the control starts to

operate at the temperature of the Unoccupied dial setting.

Indoor Sensor 074 function

Selector switch = Indoor Sensor

The control will monitor the indoor, outdoor and supply temperatures, and shift the Heating Curve
(and the WWSD point) up or down to fine adjust the system supply water temperature whenever
the room temperature is different than the setting of the Occupied dial. When switched into
Unoccupied mode, the "UnOcc. Switch

" light will come on, and the control will operate at the

temperature of the Unoccupied dial setting.

2K RTU function

Selector switch = Indoor Sensor

The control will monitor the indoor, outdoor and supply temperatures, and shift the Heating Curve
(and the WWSD point) up or down to fine adjust the system supply water temperature whenever
the room temperature is different than the setting of the RTU dial. The Occupied and Unoccupied
dials are not functional. A Setback RTU 308 must be used if Unoccupied schedules are desired.

tekmar Zone Control function

Selector switch = Zone Control

The control accepts a zone input signal from a tekmar 10K Zone Control which monitors the
indoor temperature of all zones – as well as the outdoor and supply temperatures – and shifts the
Heating Curve (and the WWSD point) up or down to fine adjust the system supply water
temperature for whichever zone requires the hottest supply water. The Occupied and Unoccu­pied dials are only functional if an external heat demand is given and the dial setting is higher than
the zone control desired temperature.

4-20

+

12

1110

Com –Ret

Sen

Reset

Reset

Setpoint

Reset

13 14

UnO SwCom

123 4

123 4

123 4

Copyright © D 365 - 06/005 of 16

123 4

Sen

Indoor Sensor

Permanent Heat Demand

Boiler on when 10% open

15

16

10K

2K

Sen

RTU

Indoor Sensor

Permanent Heat Demand
Boiler on when 10% open

Indoor Sensor

Permanent Heat Demand
Boiler on when 10% open

Boiler on when 25% open
External Heat Demand

Zone Control

17

Com

Sen

18

Sup

Sen

19

Out

Sen