Check controls, Pilots with thermocouple element, Bryant automatic pilot (d4) – Bryant 234B User Manual

Page 9

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SEP/02/2008/TUE 08:19 AM UTC TECH PUB

FAX No. 31 7 240 5662

P, 009

J'urthex change in gas xate can be accomplished if

necessary by changing the fiired orifice to the bur-
ners*

Propane Gas:

Propane gas units axe not equipped

with gas pressure regulators. Burner orifices are
sized to give the rated input at a manifold pressure

of 11" w.c. The only check for rated input is the
manifold.pressure.

CHECK CONTROLS

Bryant

Gas

Control

Valve: If not already checked

when .iighting the main burner, check" thè proper

opexa'Lon pof This valve. Move the thermòstaf to a
call for diedi position. Observe there-Iwiil^ jAbe an
approxitnetfe 30 'second delay for the vaTye; ip 'ppen.
Move the the mio stai to a satisfied position;, again,
the 30 second -delay before the'.val ve iQlphes,.T' .^^^^

Automatic Pilot';

Check 'the V

automatic pilot as fòliows;

1. Set the room thermostat bh tail'fpi heaf-

2. After burners have ignited, close the pilot gas

cock.

3. After pilot gas cock is closed, the gas valve will
close in approximately 1 minute. After the pilot gas

is shut off the monometal cools and returns

the

open position. This breaks the circuit to the gas

valve closing the gas valve.

PILOTS WITH THERMOCOUPLE ELEMENT

The D2 andTÌS gas :x-on|rolV.Mye;p^

with thermocouple elements.,

The pilot flame should surround the tip of -the ther
mocouple. It should also extend downward to include

3/8 VT

1/2." Ql.th§.Th??Lmpcoub^i^^^^ -Th£ flame mu St

not come in contact with any other part of. the ther
mocouple.

The thermocouple transforms heat energy from the

pilot flame into electrical energy. The current thus
generated is sufficient to operate the 100% shut-off
valve. The Bryant Diaphragm Gas Control Valve is

powered externally from the transformer, and oper
ates independently of the shut-off valve. When there

is a pilot flame, the current generated from the ther
mocouple holds thè 100% shut-off valve in the open
position and the gas control valve controls the flow

of gas. Should the pilot go out, there will

be no

cur

rent generated fay the thermocouple and the 100%
shut-off valve will close and no gas can flow to the

pilot.

If the pilot should go out, the electrical circuit to
the main gas valve will be broken and gas cannot
flow through the diaphragm valve. '

BRYANT AUTOMATIC PILOT (D4)

The pilot assembly includes a normally open switch

wired in series with the Bryant diaphragm gas con

trol -valve. The switch is at the free end of . the

monometal element assembled so that the fixed end
is positioned at the pilot flame. Heat applied to the
fixed end of the monometal element causes the free
end to move. This closes the switch and completes

the electrical circuit to the control valve. The cir

cuit will close within one minute. It will remain

^' closed aS long as there is iiori^al pilot flame. .While,

closedTbe ^bbilei tS riiidef tiie difieCf aj^Miiatic con
trol of the ioo^

ojpetating con

trol as long as the ;main gas manual shutpif vATve is

open. If the pilot .ilanie' g^

reason^ the

monometal element will cool and the free end will

move back to its original position. This breaks the

electric circuit and the Bryant diaphragm gas con
trol valve will close. This shuts off the gas supply
to the main burner.

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