tekmar 263 Boiler Control - Manual (Page 7)

7 of 36 © 2009 D 263 - 03/09
ROTATION
The control’s Equal Run Time Rotation function is fixed at 48 hours. The
firing order of the boilers changes whenever one boiler accumulates 48
hours more running time than the other boiler. After each rotation, the
boiler with the 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 both
boilers receive equal amounts of use. When the Rotate / Off DIP switch
is set to the Off position, the firing sequence always begins with boiler
one and then boiler two.
Note: When using a single two-stage boiler, ensure that the Rotate / Off
DIP
switch is set to Off.
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.
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 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. If the heating system is causing the boiler(s) to be staged on and off in rapid succession, a higher Boiler Mass setting
will result in a decrease in the amount of cycling. Conversely, if the system is slow to respond to heat requirements, then decreasing
the Boiler Mass setting will increase the response rate by staging the boilers at a faster rate.
Lo (1)
The Lo 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 Lo Mass setting provides a fast staging rate of additional
on / off boiler stages.
Med (2)
The Med 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 small 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 staging rate of additional on / off
boiler stages.
Hi (3)
The Hi 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 Hi Mass setting provides a slow staging rate of additional on / off
boiler stages.
DIFFERENTIAL
An on / off heat source must be operated with a differential in order to prevent short cycling. With the control, either a fixed or an
auto differential may be selected. The boiler differential is divided around the boiler target temperature. The stage contact closes
when the supply water temperature is ½ of the differential setting below the boiler target temperature. Additional staging occurs if
the first stage is unable to raise the supply water temperature up to the boiler target temperature at a reasonable rate. As the supply
temperature reaches ½ of the differential above the boiler target temperature, stages are staged off.
Fixed Differential
If the user desires to have a fixed differential, this is set using the
Boiler Differential
setting in the ADJUST menu.
1 2
720 hours 672 hours
2 1
672 hours 720 hours
Stage Delay
Boiler 1
Contact Closes
Boiler 1
Fires
Fire
Delay
Fire
Delay
Boiler 2
Contact Closes
Boiler 2
Fires
Time
Tem
pe
ratu
re f
all
Te
m
pe
ra
tu
re
ri
se
Time
Desired temperature
160°F (71°C)
Differential
10°F (6°C) Boiler Off
Boiler On
155°F (68°C)
165°F (74°C)