STA-RITE MAX-E-THERM 77707-1341 Service Manual Download Page 5

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Air/Fuel Ratio Adjustment

NOTICE: Do not

attempt to adjust the air/fuel mixture by

altering gas or air orifice sizes or by adjusting the gas input
to achieve a particular gas input rate (“clocking the
meter”), as the rate may vary depending on elevation and
local gas heating value.

Do not

attempt to adjust the gas input outside of the speci-

fied range.

Mixture Too Rich - (too much gas)

Symptoms:

A. CO

too high or

B. O

too low or

C. Burner emits a high pitched whine

Cure:

Call Sta-Rite for a 5%-decrease Propane orifice.
Repeat orifice installation, starting at Step 1, Page 2.
At Step 7, use the 5%-decrease replacement Propane
orifice which should be stamped as shown:

Model No.

Propane Orifice Marked

Orifice Size

SR/SRC200

.238

SR/SRC333

.332

SR/SRC400

.399

Mixture too Lean - (not enough gas)

Symptoms:

A. CO

too low or

B. O

too high or

C. Burner sounds rough and pulsating or exhaust has a

highly acrid odor.

Cure:

Call Sta-Rite for a 5%-increase Propane orifice.
Repeat orifice installation, starting at Step 1, Page 2.
At Step 7, use the 5%-increase replacement Propane orifice
which should be stamped as shown:

Model No.

Propane Orifice Marked

Orifice Size

SR/SRC200

.250

SR/SRC333

.348

SR/SRC400

.419

NOTICE:

If neither correction above produces satisfactory

combustion, consult your Sta-Rite distributor. The air/fuel
ratio is adjusted by replacing the gas orifice with an orifice
of the correct size.

Inlet Pressure:

Min./Max. . . . . . . . . . . . . . . . . . . . . . . . . . . 4" / 14" WC

Manifold Pressure:

(Referenced to blower inlet tap). . . . . . . . . . . . . . -0.2" WC

Required Gas Input (BTU/Hr):

Model SR/SRC200. . . . . . . . . . . . . . . . . 200,000BTU/Hr
Model SR/SRC333. . . . . . . . . . . . . . . . . 333,000BTU/Hr
Model SR/SRC400. . . . . . . . . . . . . . . . . 399,990BTU/Hr

Sequence Of Operation

For detailed information, please refer to Sta-Rite Pool/Spa
Heater Training and Service Manual, publication no.
S5066.
An electronic temperature sensing

thermistor

in the mani-

fold adapter inlet controls the heater operation. When the
inlet water temperature drops below the temperature set on
the

operating control

, the

burner controller

supplies

power to the combustion

air blower

through a series of

safety interlocks.

The interlocks consist of

• the

pressure switch (PS)

, which senses that the pump is

running,

• the

high limit switch (HLS)

, which opens if the heat

exchanger outlet temperature goes above 135°F (57°C),
and

• the

automatic gas shutoff (AGS)

switch, which opens if

the heat exchanger outlet temperature goes above 140°F
(60°C).

• the

stack flue switch

, which opens if the flue gas tem-

perature exceeds 500°F (260°C).

The

air flow switch (AFS)

senses the pressure drop across

the air metering orifice. As soon as there is sufficient air
flow, the AFS closes, closing the circuit to the

hot surface

ignition (HSI)

, which ignites the fuel mixture.

On a call for heat, the blower and HSI are energized. In
about 20 seconds, the gas valve opens and ignition occurs.
The HSI then switches to a sensing mode and monitors the
flame.

Parts List

Part Name

Qty.

Part No.

Gas Orifice - Propane (Kit 77707-1361)

42001-0361

Converts SR/SRC200NA to Propane

Gas Orifice - Propane (Kit 77707-1351)

42001-0351

Converts SR/SRC333NA to Propane

Gas Orifice - Propane (Kit 77707-1341)

42001-0341