Tuning is the process of balancing the gas and air ratio throughout the range of the equipment, from low-fire to high-fire.  Natural gas requires 10 parts air to 1 part gas for neutral combustion, propane requires 25 parts air to 1 part gas for neutral combustion.  The adjustment on combustion equipment will allow you to get adjust these ratios.

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.

Start with the FRG at about half (Factory setting), and the needle valve open just a few turns.   Air will need to be bled from the lines the first time, and the equipment will need to run through its startup sequence several times to do so.  Set the Watlow controller to manual and set to 70%

The blower will run for a 30 second purge, then the DSSOV(Dual Safety Shut-off Valves) will click open.  KDI Valves have indicators that turn red when the valves open.  Kromschroder have blue lights that indicate open.  When the valves open, use a MAP gas torch or similar inserted into the lighting hole to light the burners.  If the system does not start within the allotted time the valves close and an error is displayed on the MPA.  Press reset to begin the ignition procedure again.

When the Glory Hole is lit, adjust the needle valve to achieve a good neutral flame.  Change the blower speed on the Watlow Controller to 100%.  Adjust the needle valve again if needed.  Decrease blower speed to 50% and adjust the FRG as needed.  Decrease blower speed to 0% and adjust FRG as needed.

Change the Controller to Auto, and set the temp for 500F.  Let sit for an hour.  Repeat at 1000, 1500, and 2000.  Attened throughout the process to adjust gas/air ratio as needed.  Ratio changes at different temperatures, so focus on working temperature.

Turn the glory hole off by pressing the red “Off” Button.  To start again, press the “On” Button.  Glory hole controller can be left at working temp, it does not need to be ramped up or down.

Two Burner glory holes need to be lit at 70-100% blower speed.  The first bunrer lights the second burner and needs to be at high fire for this top happen properly.


Step 1 –On the Watlow controller, press the advance key until you see “CM1” or a percentage and  “AUto, MAn, or OFF” and set the control mode to manual .   Press the reset key, then set the output percentage in the lower display to 100%. This percentage directly reflects the Blowers speed.  100% is maximum, 0% is the lowest the blower can go without turning off.

Step 2 – Adjust the ALO or AOGC needle valve (located on the gas line just upstream of the burner). Clockwise (CW) rotation decreases gas while counter-clockwise (CCW) increases gas. Increase the gas until you see reduction flames coming out from under and around the door, then decrease the gas until these flames are only about 1” long and fairly difficult to see. The temperature should be rising very quickly at this setting

Step 3 – Adjust the controller output to 20% and again, look for reduction flames around the door. Adjust the proportionator spring stem screw CW for more gas and CCW for less gas. Once you see the reduction flames, decrease the gas until they disappear.

Step 4 – Adjust the controller output to 0% and adjust the low fire bypass on the side of the proportional regulator. Look for the reduction flames to appear, then make them disappear by decreasing gas. At this low output setting, the flames may take 15-20 seconds to build up while the door is closed. When you open the door, you may see a finger of a flame appear then go away. This is because the excess gas in the furnace found oxygenwhen you opened the door. Decrease gas using the bypass fitting screw until you can open the door after 15 seconds and not see that flame

Step 5 — If throughout the whole range there is either always too much gas, or too little, adjust the butteryfly valve.  The default is half open.  When the butterfly valve is changed, it has a drastic effect on the tuning.  Opening the valve allows more air, but also decrease the impulse line pressure, decreasing the amount of gas the proportionator lets through, and vice versa.  A small change to the butterfly valve makes a very large difference.  When a setting is found that puts the furnace into a good range for fine tuning with the other adjustments, the butterfly valve should be the last adjustment to be used.

Step 6 – Adjust the proportionator at other output levels such as 30% and 40%. Cycle back through 100%, 20% and 0%, making fine adjustments atthe same points you did in steps one through four.

Step 7 – Press the advance key and set the control mode to auto . Press the reset key and set a temperature set point in the lower display. The furnace should now be able to maintain this set point. Once the output percentage stabilizes with a furnace full of glass, you may have just a little more fine tuning to do for charging temps or squeezing temps, and you can use the same steps above, especially steps three through five.


Overview: Venturi systems work by generating negative pressure to entrain air to mix with the gas in the atmospheric injector.  The gas coming out of a small orifice pulls air with it  (Primary air), and mixes in the venturi and the piping to the burner. Air is pulled in again (Secondary when the flame comes out of the burner heard.

Therefore, there is no need for a combustion air blower. This is a very basic system that is most often controlled manually and used on simple equipment such as pipe warmers and garages. The gas pressure regulator maintains stable pressure over the operating range.

Most WDG venturi systems use a smart valve and ignitor combination.  A hot face ignitor will warm up and begin to glow.  The smartvalve allows a small amount of gas to the pilot burner, which is ignited by the hot surface.  A small thermocouple is heated by the pilot flame.  As along as this TC is above a certain temperature the system stays on.  If the pilot goes out and the TC cools down, the system will shut down and attempt to restart.  Once the pilot is lit, the main gas is allowed into the venturi, and then to the burner.  The pilot lights the main burner. 

Step 1 -Make sure the pipe warmer/garage isn’t closed off so much that it creates back pressure.

Step 2 -Make sure the burner head is about ¼” outside the wall of the pipe warmer. There should be ¼” around the burner head. This allows secondary air to be drawn in around the head to supplement the primary air drawn in by the injector.

Step 3 -Open the air shutter completely. The air shutter is a metal disc at the very end of the mixer, near where the gas is adjusted.

Step 4- Make sure the gas valve is shut so no gas is flowing to the burner.

Step 5 -Remove the large green acorn nut that covers the gas adjustment screw, then loosen the brass locknut on the gas needle valve.

Step 6 -Turn the needle valve clockwise until it is closed off completely.

Step 7 -Press the green “Push to Start” button to start the system. The button will illuminate, and the pilot will light.

Step 8—Shortly after the pilot lights you will hear the click of the main valves opening.  Once this happens, slowly open the needle valve until the burner lights and you achieve the desired flame characteristics.

Step 9 -If the Equipment doesn’t get hot enough, add more gas to the mixture. If it gets too hot, reduce the gas in the mixture

Step 10-  Close the air shutter down until you see the flame begin to go yellow, produce smoke, or the flame get fluttery.  Open the air until these effects just go away.

Step 11 — Adjust the pressure regulator as necessary to increase or decrease the temperature range.