Taco Comfort Solutions FuelMizer SR501-OR-4 Instruction Sheet

SUPERSEDES: March 1, 2013
A Taco Family Company
Plant ID# 9300-2871
APPLICATION:
The SR501-OR is a microprocessor-based control designed to regulate
the supply water temperature of a single boiler, based on the outdoor
temperature. The SR501-OR is a boiler reset control and switching relay
in one unit. The SR501-OR is ideal for retrofit application, but may also
be used in new installations as well.
The SR501-OR includes functions such as automatic reset ratio calcu-
lation, warm weather shut down (WWSD), minimum boiler temperature
setting, and boiler differential setting. The control also has boiler sensor
and outdoor sensor error checking.
For information on Taco's
Switching Relays (SR)
including catalog sheet,
instruction sheets, Visio sten-
cils and our highly praised
Zone Controls Wiring Guide,
scan the QR code above or
go to our website:
http://www.TacoComfort.com.
CONTROL STRATEGY:
Outdoor Reset:
In order to properly control a hot water heating system, the heat sup-
plied to the building must equal the heat lost by the building.
• The heat supplied to a building is proportional to the temperature of
the supply water and the surface area of the heating element. A
small surface area such as baseboard radiators requires a higher
water temperature than a larger surface area such as radiant floors.
• The heat lost from a building is dependent on the outdoor tem-
perature, as well as other factors. As the outdoor temperature
drops, the building heat loss increases.
Reset Ratio:
Operation of a hot water heating system can generally be improved by
modulating the supply water temperature as the outdoor temperature
changes. Using this approach, the heat lost from the building is
matched by the heat input to the building. The SR501-OR boiler reset
control utilizes a reset ratio to set the relationship between outdoor tem-
perature and supply water temperature. The reset ratio determines the
amount the supply water temperature is raised for every 1° drop in out-
door air temperature, and it is determined from the starting point and
the system design conditions. In order for the control to automatically
determine the reset ratio, outdoor design conditions must be estab-
lished. This is usually the typical coldest outdoor temperature or it can
be set by using ASHARE standards for Design Outdoor Temperature
for specific geographic locations.
Instruction Sheet
FuelMizer SR501-OR-4 Switching Relay with Outdoor Reset
®
24 VAC
THERMOSTAT
BOILER
CONTROL
OFF ON
SW1
DESIGN OUTDOOR
X X W C R W
R
TEMPERATURE
OUTDOOR
FOR 180°F SUPPLY
BOILER TSTAT DHW
TEMPERATURE
0
-10 10
ONE ZONE
-20 20
SWITCHING RELAY
POT1
-30 30
WITH OUTDOOR RESET
OFF 40
NOTE: Resistor
1
(1KΩ, ⁄ W)
2
may be needed
6
between W and C
AMP
terminals.
INPUT
120 VAC
N H
POWER N
INPUT
H
(120 VAC)
ONE ZONE INSTALLATION W/O INDIRECT DHW
See NOTE
OUTDOOR
SENSOR
BOILER
SUPPLY
SENSOR
SUPPLY
SENSOR SENSOR
LED
INDICATORS
POWER
TSTAT
DHW
OVERRIDE
BOILER
RELAY
ZONE 1
120 VAC
N H
SYSTEM
CIRCULATOR
(OPTIONAL)
BOILER SUPPLY TEMPERATURE vs. OUTDOOR TEMPERATURE (°F)
FOR OUTDOOR DESIGN TEMPERATURES
90 80 70
EFFECTIVE: December 20, 2013
THERMOSTATS
(24VAC)
X X R W C R W C
ISOLATED ZONE 1 ZONE 2 ZONE 3
END SWITCH THERMOSTATS
EXISTING
ZONE VALVE CONTROL
24 VAC ZONE VALVES
ZONE 1 ZONE 2
PUMP END ZONE 3 PUMP
SWITCH END SWITCH
1 2 3 4 1 2 3 4
X X N/O COM N/C
JUMPER
1
3 & 4
2
2 WIRE ZONE VALVE 3
(NO END SWITCH)
TACO 3 WIRE
MUST USE JUMPER
ZONE VALVE
BOILER
CONTROL
OFF ON
SW1
DESIGN OUTDOOR
X X W C R W
R
TEMPERATURE
OUTDOOR
FOR 180°F SUPPLY
SENSOR
TEMPERATURE BOILER TSTAT DHW
0
-10 10
ONE ZONE
-20 20
SWITCHING RELAY
POT1
-30 30
WITH OUTDOOR RESET
OFF 40
6
AMP
INPUT ZONE 1
120 VAC 120 VAC
N H N H
N
POWER
INPUT
(120 VAC) H
MULTI-ZONE INSTALLATION WITH ZONE CONTROL
AND WITH INDIRECT DHW
40 30
20
60 50 40 30 20 10
OUTDOOR TEMPERATURE (°F)
102-431
DHW
A
AQUASTAT
ZONE 3
PRIORITY
R W C
ON
OFF
LED
PRIORITY
INDICATORS
POWER
T STAT 1 VALVE 1
T STAT 2 VALVE 2
T STAT 3 VALVE 3
PRIORITY
ZONE 3
1 2 3 4
1
2
3
TACO 3 WIRE
ZONE VALVE
OUTDOOR
SENSOR
BOILER
SUPPLY
SENSOR
SUPPLY
SENSOR
LED
INDICATORS
POWER
TSTAT
DHW
OVERRIDE
BOILER
RELAY
SYSTEM
CIRCULATOR
(OPTIONAL)
210
0
10
-10
190
180
-20
170
-30
150
130
110
90
70
0 -10 -20