Install Instructions
46
EMP
Installation & Service Manual
109529-03 - 11/19
Dial Setting Feature Options Description
Default 
Setting
1 Thermal Pre-Pruge
OFF 
ON
Purge Inactive
Purge Active
OFF
2 Fahrenheit or Celsius
F
C
Degrees Fahrenheit
Degree Celcius
F
3
LWCO Manual or 
Automatic Reset
A
b
Automatic Reset
Manual Reset
A
4 Circulator Options
A
b
c
Circulator operation on TT call only
Circulator operation on ZC/ZR call only
Circulator operation on call from either
A
5 Circulator Hold Off
ON
OFF
Circulator Hold Off - Active
Circulator Hold Off - Inactive
ON
6
Not available on this 
control
7
Not available on this 
control
8 Well Type
A
b
Hydrolevel Electro-Well
Standard Immersion Well
A
9 High Limit Differential
10
20
30
10 Differential
20 Differential
30 Differential
10
dEF
Restore Factory De-
faults
Y
N
Restore Defaults
Do Not Restore Defaults
n
NOTE: If the HydroStat is factory-equipped on a boiler, some options may be set differently from the 
default settings. Not all features are available on older HydroStat models.
   d. Reset LO TEMP and HI TEMP settings to 
   desired temperatures.
 8.  Restore Factory Default Settings
  To restore all features to the factory   
  default settings (see following chart for   
  default settings)
  a. Turn the LO TEMP dial to access   
   the Program Mode - indicated in the  
   display as Pro
  b. Turn the HI TEMP dial to select feature 
   dEF
  c. Push the Test/Setting Button to Y
   to reset all features to the default   
   settings
  d. Reset LO TEMP and HI TEMP settings 
   to desired temperatures.
   9.  LED Legend and Test/Settings Button
  a. TEMP ACTIVE Indicates that the   
   Fuel Smart HydroStat control is   
 powered and that the temperature   
   function is active.
  b. TEMP HI TEMP Illuminates when   
   the boiler water temperature reaches 
   the high limit setting. It will remain   
   lit until the water temperature falls   
   10. The Fuel Smart HydroStat   
   prevents burner operation while this  
   LED is on. See Differential     
   explanation.
  c. LWCO ACTIVE Indicates that the low 
   water cut-off (LWCO) function of the   
   Fuel Smart HydroStat is active. When the 
   control is installed with a Hydrolevel   
 Electro-Well
TM
, this LED will be on at all 
   times when the control is powered.   
   IMPORTANT: If the control is installed with 
   a well other than the Elctro-Well
TM
, this LED 
   will no illuminate indicating that the control 
   is not providing low water cut- off   
   functionality.
  d. LWCO LOW WATER Indicates that   
   the boiler is in a low water condition.  
 The HydroStat control will prevent burner 
   operation during this condition. If the  
   LOW WATER light is blinking, the   
   control has been programmed to provide 
   lockout protection in the event a low water 
   condition is detected (see Manual Reset 
   Low Water Cut-Off). Pressing the TEST/ 
   SETTINGS button will reset the control.
IMPORTANT: The system must be checked by a 
qualified heating professional prior to resuming 
operation.
9 Operating (continued)










