Garland GPD Series, Installation And Operation Manual

Document #:  G_GO_OM_PYRODECK_4606131 – 12/20

Page 9

Gas Pressure Adjustments

All GPD Series ovens are equipped with fixed orifices and 

cannot be adjusted for gas flow: If necessary, pressure 

adjustments can be made at the pressure regulator (located 

on the combination gas valve).

A pressure tap is supplied with the unit and it is installed 

on the manifold, downstream of the main valve. The gas 

pressure must be checked when the unit is installed, to 

ensure that the unit gas pressure is the same as specified on 

the rating plate.

Flame & Air Mixture Adjustment

After the pilot burner is ignited, when heat is desired, turn 

gas cock dial to “ON” position and set the thermostat dial 

to the desired temperature. The oven burner flame should 

always have a blue appearance. This indicates a good mixture 

of air and gas. When using LP gas the flame will have a blue 

yellow appearance. Follow steps 1 thru 4 to adjust the flame 

for good quality.

1.  Loosen the small knurled locking disk.

2.  Turn the large adjusting disk towards the air mixture 

throat to reduce the opening. This restricts the amount of 

air, causing the flame to turn yellow.

3.  Turn the adjusting disk gradually out, away from the air 

mixer throat, allowing more air into the air mixer until the 

yellow disappears and a sharp blue flame appears.

4.  When the flame turns blue and spreads out, turn the 

locking disk tight against the adjusting disk. There may 

be intermittent yellow-orange flame noticed. This is 

caused by dust particles burning in the Flame. Should the 

burners fail to light, check to see if there is a problem with 

any or all of the following.

ADJUSTMENTS

A.  The gas supply: If there are other gas appliances on the 

same supply line, shut them off temporarily and see if 

the flame comes back on, or if it fluctuates as other gas 

appliances are turned on and off. If so, it would indicate 

overloading of the gas supply or a faulty gas pressure 

regulator. You should contact a qualified service agency 

or the local gas company to check the gas supply.

B.  Dirty burner orifice or ports: With the oven cold, use a 

thin wire to check that the spud orifice (nozzle) is clear. If 

necessary, loosen and remove the spud. Be careful when 

cleaning not to enlarge the hole. Then, using a wire or 

thin nail, clear the burner ports of carbon deposits or 

other restrictions.

Periodically, after breaking the ovens in, check the burner 

flame and readjust the air mixture if needed. Black soot on 

the oven doors or in the burner compartment may indicate 

that not enough air is mixing with the gas. If this is the case, 

back off the air adjustment disk until the proper flame and 

color is set.

By-Pass Flame Adjustment

The by-pass in the thermostat is a small gas supply through 

the control that is independent of the dial setting. It is 

controlled strictly by the Adjusting Screw. This small gas 

supply maintains a minimum flame or the burner(s), helping 

to maintain the heat in the oven and assisting in recovery. 

This adjustment is best done when the oven is being heated 

for the day’s business. To adjust the by-pass flame follow 

steps 1 thru 4.

1.  Turn the oven on and set the thermostat to the desired 

temperature.

2.  Allow the oven to pre-heat until the burner flame begins 

to throttle down.

3.  At this point, turn the thermostat dial all the way down. 

This ensures that the thermostat is in the by-pass mode. 

There should now be a small steady flame remaining 

across the burner without flickering or going out.

NOTE: It may be necessary to turn the thermostat back up to 

relight the burner(s) if there is not flame present.

4. Using a small screwdriver, reach through the access hold 

on the control panel to the left of the thermostat knob. 

Turn the by-pass adjustment screw to raise or lower the 

by-pass flame as required. Counter-clockwise raises the 

flame, clockwise lowers the flame. Take care not to turn 

the screw out too far as that will allow gas to leak around 

the adjustment screw.

IMPORTANT: 

All gas burners and pilots need sufficient 

air to operate and large objects should not 

be placed in front of this oven, which would 

obstruct the airflow through the front. 

Objects should not be placed on main rear of 

oven while in use.