Utica Boilers UB95M-200 Verweisanleitung

the term “differential” is also referred to as “hysteresis.”

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Parameter 22 is the “On” differential. the water tem-

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perature must be at least Parameter 22 less than the 
calculated setpoint temperature for the boiler to turn on.

Parameter 23 is the “Off” differential. When the boiler is 

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firing, the water temperature must rise at least Param-
eter 23 above the calculated setpoint temperature for 
the boiler to turn off.

See Figure #4 for an explanation of the “On” and “Off” 

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differentials of the boiler control. note that the differ-
entials are greater when a heat call starts or stops, as 
shown. the differentials decrease with time until they 
equal Parameters 22 and 23.

the factory default setting for Parameter 23 is 4° F.  

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this works well for most applications.

For low mass systems (fan coil), performance can be 

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improved by increasing Parameter 23. this compen-
sates for the quicker system temperature response of 
low-mass systems.

When setting Parameter 23, make sure that Parameter 

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23 plus Parameter 4 is not over 193° F to avoid possible 
nuisance lockouts.