U.S. Boiler Company PVG3, Installation, Operating And Service Instructions

41

IX.  OPERATION (continued)

E.

  CHANGING THE ADJUSTABLE PARAMETERS

To adjust parameters such as High Limit Setpoint and 

High Limit Differential:
1.  Access the adjustment mode by pressing and 

holding the Up 

ñ

, Down 

ò

, and 

“

I

”

 keys 

simultaneously for three (3) seconds.  This 

procedure is intended to discourage unauthorized 

changes or accidental changes to limit settings.

2.  Press the 

“

I

”

 key to display available Adjustment 

Mode options. Select an option.

Adjustment Mode Options

HL_

140-220°F

Adjust High Limit Setting

dF_

10-30°F

Adjust High Limit Differential

Or_

0-10 minutes

Circulator Overrun Time 

PP_

2-20 minutes

Circulator Pre-purge Time 

St_

140-180°F

Start Temperature

Pt_

On

 or 

off

Priority time

dh_

dh

 or 

tt2

DH Terminal Function

rst

Reset Lockout

f-C

F

 or

 C

Select degrees F or C Mode

bac

Back to Operating Mode

3.  Press the Up 

ñ

 and Down 

ò

 keys to adjust the 

displayed item to the desired value.

4.  To return to the normal operating mode from 

the Adjustment Mode, when the “

bAc

” option is 

displayed, press either the Up 

ñ

 or Down 

ò

 key.  

If no keys are pressed, after five (5) minutes the 

control will automatically return to the Operating 

Mode.

F.

  MORE INFORMATION ABOUT ADJUSTABLE 

PARAMETERS 
1.  High Limit (

HL_

)

  The control is factory programmed with a High 

Limit Setpoint of 180°F.  The burner turns 

“off” when the boiler water temperature (

bt

) 

is above this value.  The High Limit setpoint is 

adjustable between 140° and 220°F.  The Operating 

Setpoint (

SP

) will equal the High Limit Setpoint.

2.  Differential (

df_

)

  The control is factory programmed with a Differential 

of 15°F.  The Differential is the number of degrees 

the boiler temperature must decrease below the 

Operating Setpoint before the boiler can restart.  The 

differential is adjustable between 10° through 30°F.

3.  Circulator Overrun Time (

OR_

)

  The control is factory programmed with a Circulator 

Overrun Time of 0 minutes.  Circulator Overrun Time 

(also called “circulator off delay” or “circulator post 

purge”) continues circulator operation after a call for 

heat has ended, sending excess heat from the boiler 

into the system.  Ensure system piping and zone 

panel settings allow water flow to the priority zone 

after the call for heat ends.  The  Circulator Overrun 

Time is adjustable between 0 through 10 minutes.

4. Circulator Pre-purge Time (

PP_

)

  When the boiler is warm (boiler water temperature 

higher than 140°F (adjustable using Start Temperature 

parameter)) and there is a thermostat call for heat, the 

system circulator is started and boiler firing is delayed 

Circulator Pre-purge minutes.  If the temperature drops 

below 140°F or there is a DHW call for heat the boiler 

is started without delay.  Additionally, the boiler is 

started without delay if the thermostat call for heat is 

initiated when the boiler water temperature is less than 

140°F.  This feature helps save energy by satisfying 

home heating needs with residual boiler heat rather 

than cycling the boiler.  The Circulator Pre-purge 

time has a factory setting of 2 minutes and is field 

adjustable between 2 and 20 minutes.  Refer to Table 13.

5. Start Temperature (

St_

)

Call for 

Heat 

Source

DHW 

Terminal 

Selection

Boiler 

Temperature

Burner Status

TT = on

-

<140

Start with no delay

TT = on

-

>140

Start after 2 minute delay

DHW = on

tt2

<140

Start with no delay

DHW = on

tt2

>140

Start after 2 minute delay

DHW = on

dh

<140

Start with no delay

DHW = on

dh

>140

Start with no delay

Table 13:  Circulator Pre-purge Time example,

               (

PP_

 = 2 minutes)

  Amount of “Heat available”  is calculated by taking 

the difference between measured boiler water 

temperature and the Start Temperature setting.  Useful 

“Heat Available” is dependent on the type of heating 

emitter installed in the home.  Heat emitters require a 

certain minimum temperature to operate effectively.  

Our default settings reflect cast iron radiators.  Fan 

Coils may require a start temperature setting of 

180°F or 160°F before providing heat to the home. 

The Start Temperature has a factory setting of 140°F 

and  is  field  adjustable  between  140°F  and  180°F.

6. Priority Time (

Pt_

)

  When the Priority Time parameter is set to “on”  and 

Domestic Hot Water (DHW) call for heat is “on” the 

DHW demand will take “Priority” over home heating 

demand. During Priority Time the system circulator 

will be forced “off”.   Priority Time ends and the system 

circulator is released to service home heating demand 

when Domestic Hot Water call for heat is over.  When 

Priority Time parameter is set to “Off” the DHW call 

for heat does not force “off” the system circulator.  The 

Priority Time has a factory setting of “On” and is field 

adjustable between “On” and “Off”  Refer to Table 14.