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SUPERSEDES: March 1, 2013
Plant ID# 9300-2871
PPLIC TION:
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
stencils and our highly
praised
Zone
Controls
Wiring Guide, scan the QR
code to the right or go to
our website:
http://www.taco-hvac.com.
CONTROL STR TEGY:
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.
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. s 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
temperature and supply water temperature. The reset ratio determines
the amount the supply water temperature is raised for every 1° drop in
outdoor air temperature, and it is determined from the starting point
and the system design conditions. In order for the control to automat-
ically determine the reset ratio, outdoor design conditions must be
established. This is usually the typical coldest outdoor temperature
or it can be set by using
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
R
W C R
TEMPERATURE
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
(1KΩ,
1
⁄
W)
2
may be needed
between W and C
terminals.
INPUT
120 VAC
N H
POWER
N
INPUT
H
(120 VAC)
ONE ZONE INSTALLATION W/O INDIRECT DHW
SH RE standards for Design Outdoor
See NOTE
OUTDOOR
SENSOR
BOILER
SUPPLY
SENSOR
W
SUPPLY
OUTDOOR
SENSOR
SENSOR
LED
INDICATORS
POWER
TSTAT
DHW
OVERRIDE
BOILER
6
RELAY
AMP
ZONE 1
120 VAC
N H
SYSTEM
CIRCULATOR
(OPTIONAL)
BOILER SUPPLY TEMPERATURE vs. OUTDOOR TEMPERATURE (°F)
90
80
EFFECTIVE: December 20, 2013
THERMOSTATS
(24VAC)
X
X
R W
C
ZONE 1 ZONE 2 ZONE 3
ISOLATED
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
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
AMP
INPUT
120 VAC
N H
POWER
N
INPUT
H
(120 VAC)
MULTI-ZONE INSTALLATION WITH ZONE CONTROL
AND WITH INDIRECT DHW
FOR OUTDOOR DESIGN TEMPERATURES
40
30
20
70
60
50
40
30
20
OUTDOOR TEMPERATURE (°F)
102-431
DHW
A
AQUASTAT
ZONE 3
PRIORITY
R W
C
R W
C
ON
OFF
LED
PRIORITY
INDICATORS
POWER
VALVE 1
T STAT 1
T STAT 2
VALVE 2
VALVE 3
T STAT 3
PRIORITY
ZONE 3
1 2 3 4
1
2
3
TACO 3 WIRE
ZONE VALVE
OUTDOOR
SENSOR
BOILER
SUPPLY
SENSOR
SUPPLY
OUTDOOR
SENSOR
SENSOR
LED
INDICATORS
POWER
TSTAT
DHW
OVERRIDE
BOILER
6
RELAY
ZONE 1
120 VAC
N H
SYSTEM
CIRCULATOR
(OPTIONAL)
210
0
10
-10
190
180
-20
170
-30
150
130
110
90
70
10
0
-10
-20
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Related Manuals for Taco FuelMizer SR501-OR-4
Summary of Contents for Taco FuelMizer SR501-OR-4
- Page 1 NOTE: Resistor TSTAT (1KΩ, ⁄ OVERRIDE may be needed OVERRIDE BOILER RELAY between W and C BOILER RELAY terminals. For information on Taco’s INPUT ZONE 1 INPUT ZONE 1 120 VAC 120 VAC Switching Relays (SR) 120 VAC 120 VAC including...
- Page 2 • The sensor is wall mounted and the wiring enters through the Instruction Sheet bottom of the enclosure. The hole for the cable entry must face Replacement sensors are available from Taco, Inc.: downward in order to prevent water from entering and filling the enclosure.
- Page 3 • The sensor should be mounted on a wall which best represents Low Voltage Connections – the heat load on the building (i.e. a northern wall for most build- Connect thermostat or zone control end switch to the R and W ings and a southern facing wall for buildings with large south thermostat terminals.
- Page 4 If in doubt as to whether a particular substance LL OTHER W RR NTIES, EXPRESS OR shipment (whichever occurs first). is suitable for use with a Taco product or part, or ST TUTORY, OR NY OTHER W RR NTY In order to obtain service under this warranty, it for any application restrictions, consult the OBLIG TION ON THE P RT OF T CO.