Boiler Cleaning; Aquastat Switching Action Within L8124C Control; Aquastat Switching Action Within L8148A Controls; Adjustable Differential - Burnham V7 SERIES Installation & Operating Instructions Manual

AQUASTAT SWITCHING ACTION WITHIN L8124C
CONTROL
The switching action within the L8124C control has
three settings:
1. high limit
2. low limit

3. adjustable differential

HIGH LIMIT OPERATION —-
The high limit opens and turns off the burner when the
water temperature reaches the set point. The high limit
automatically resets after the water temperature drops past
the set point and through the 10°F differential.
Set the indicator at desired shutoff temperature.
LOW LIMIT OPERATION —-
On a temperature rise, with the adjustable differential
at the minimum setting of 10°F, the burner circuit (R-B)
breaks and the circulator circuit (R-W) makes at the low
limit set point. On a temperature drop of 10°F below the set
point, the R-B circuit makes and the R-W circuit breaks.
ADJUSTABLE DIFFERENTIAL —-
At any differential setting greater than 10°F, the R-B
make temperature and R-W break temperature will remain
the same-control setting minus 10°F. The R-B break and R-
W make temperature will be the set point temperature plus
the difference between the differential setting and 10°F.
A ll b oiler clea nin g mus t be comp le ted w ith burn er s erv ic e sw it ch turne d o ff. B oiler s
e quippe d w it h bu rner sw in g do or ha ve a pot ent ia l h az ard wh ic h c an ca use s ev ere prop ert y
da mage , per sona l injury or los s of lif e if ignor ed. B ef ore ope nin g s wing d oor, tu rn of f
se rvice sw it ch to boiler to prev en t a cc ide nta l firing of b urne r out si de the co mbus tion
c ham ber. B e s ure to t igh ten sw in g do or f ast ene r c omp let ely w he n s erv ic e is co mplete d.
(Non-Burnham Drawing
Copy from other Manual)
SECTION V: BOILER CLEANING
WARNING
EXAMPLE: Set point of 140°F; differential set at 25°F.
On a temperature rise, R-B will break and R-W will make
at 155°F. On a temperature fall, R-B will make and R-W
will break at 130°F.
Set low limit indicator at the minimum temperature
recommended for domestic hot water supply. This setting
must be at least 20°F below high limit setting to prevent
one switch from locking out the other.
Set the differential the desired number of degrees.
25°F differential gives longest burner cycles.
AQUASTAT SWITCHING ACTION WITHIN L8148A
CONTROLS
The switching action in the L8148A control has one
setting, the high limit. The switching relay is controlled by
the low voltage room thermostat. On a call for heat, the
relay contacts make to complete the line voltage circulator
circuit and also the burner circuit if the boiler water
temperature is below the high limit setting. The high limit
switch shuts off the burner if boiler water temperature
exceeds the high limit setting.
Set the indicator at the desired shutoff temperature.
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