tekmar 367 Zone Control User Manual
Page 4
4
ZONING OPERATION
The 367 can directly control the temperature of up to 6 One Stage heating zones or 3 Two
Stage heating zones or a combination of One Stage and Two Stage zones. In order to
measure the indoor temperature, each zone requires either an Indoor Sensor or a Room
Temperature Unit (RTU). With an RTU the desired zone temperature is set using the RTU
dial, but with an Indoor Sensor the desired zone temperature is fixed at 70
°
F (21
°
C). The
Max. Room dial prevents the desired zone temperature from exceeding a maximum value
(see Settings - page 9).
Common Blocks
The 367 has 3 common blocks for both the RTU inputs and the relay outputs. Each
common block has a terminal starting with
Com (Eg. Com Sen or Com 5-6 ). Each
common block can be used for either two One Stage zones or one Two Stage zone.
One Stage Common Blocks
If an RTU is connected to the lowest number in the common block, a One Stage common
block is created.
Example An RTU connected between the terminals
Com Sen — RTU 5 is used to control
the output relay
5, and an RTU connected between the terminals Com Sen —
RTU 6 is used to control the output relay 6.
Note If only one RTU is used, it must be placed on the lower number in the common
block. In the above example this would be
Com Sen — RTU 5 controlling output
relay
Com 5-6 — 5.
PID Zoning Logic
The 367 operation is based on a 15 minute cycle. During every cycle,
the control turns on each zone relay for a specific on time. The
required on time is calculated based on the PID response of the zone
during the previous 15 minute period. If the zone needs more heat,
the on time is increased and if the zone needs less heat, the on time
is reduced. In order to prevent short cycling, the 367 ensures that the
zone relays remain on or off for at least 3 minutes.
Two Stage Common Blocks
When the DIP switch is set to
One & Two Stage and a single RTU is connected to the
highest terminal number in the common block, a Two Stage common block is created.
The single RTU therefore controls two output relays: a
Lo stage relay and a Hi stage relay.
Example An RTU connected between the terminals
Com Sen — RTU 2 is used to
control the output relays
1 and 2. Relay 1 is the Lo stage output relay and relay
2 is the Hi stage output relay.
PID Zoning logic
The temperature within each Two Stage zone is controlled by
varying the on time of the output relays over a 15 minute period.
During light loads, the 367 cycles the
Lo stage relay on and off. As
the load increases, the
Lo stage relay on time increases until it
reaches a maximum of 15 minutes. The
Hi stage relay is then turned
on and its on time is increased as the load increases. When the
heating load decreases again, the on time of the
Hi stage relay is
reduced until the
Hi stage relay is turned off completely. The control
then starts to reduce the on time of the
Lo stage relay.
Zone Control Load Staggering and Synchronization
The 367 staggers the operation of the zones in order to achieve a steady load on the boiler while minimizing boiler running time and
preventing boiler short cycling. Multiple Zone Controls can be daisy chained together to increase the number of zones. Each of the
Zone Controls synchronizes its zone operating cycles based on the
Zo In input from the other Zone Controls. This results in a more
stable system flow rate and improved boiler operation.
Zone Control Operation with a tekmar Outdoor Reset Control
The 367 can provide indoor temperature feedback to a tekmar Reset
Control. When multiple Zone Controls are used, each Zone Control
sequentially passes the information to the tekmar Reset Control in
order to ensure the zone with the highest heat requirement is satisfied.
The
Heat Required light is turned on whenever the 367 is requesting
heat from the Reset Control.
70
Indoor Sensor
RTU
tekmar
Boiler or Heating System Control
LR 58233
E150539
LR 58233
E150539
tekmar
Zone Control
Relay On Time
Relay On Time
Relay On Time
Less Heat
More Heat
15 minute Cycle
H
C
R
Zone 5
Zone 6
H
M
M
Com
5-6
25
5
26
6
27
Com
Sen
11 12
RTU
5
RTU
6
13
15 minute Cycle
Lo Stage
Lo Stage
Hi Stage
Hi Stage
Lo Stage
Hi Stage
Lo Stage
Off
Off
Off
On
On
On
On
On
H
C
R
Lo
Stage
Hi
Stage
M
M
Com
1-2
19
1
20
2
21
Com
Sen
5
6
RTU
1
RTU
2
7