Universal Gas Valves

Written on: September 14, 2020 by Timmie McElwain

The importance of universal controls cannot be emphasized enough. The ability to carry one control that covers a multitude of applications makes the service technician’s job a lot easier. There are other control systems that also have universal controls that can be used. We are seeing electronic fan timers with a universal board that replaces many controls. We will be discussing some of those in later articles. There are also universal integrated furnace controls. Keeping truck stock simple and convenient is what it is all about.
Honeywell’s VR8345M Universal Electronic Ignition Gas Control (Figure 1) is used in gasfired equipment with capacities up to 300 cubic feet per hour at a one-inch water column pressure drop for natural gas. The VR8345M will operate with direct spark ignition (DSI), hot surface ignition (HSI) or intermittent pilot ignition.

The control includes a manual valve, two automatic operators, a pressure regulator, pilot adjustment, pilot plug and ignition adapter. It is also:
• Compatible with hot surface pilot, intermittent pilot and direct spark ignition.
• Replaces virtually any IP, HSI or DSI gas control.
• For use with 24 VAC heating appliances that burn natural or manufactured gas or liquefied petroleum (LP) gas (it includes a converter kit to adapt from natural gas to LP gas).
• Compact to fit into tightly packed, high efficiency heating equipment.
• Works with virtually all residential equipment and all but the largest commercial equipment, with a regulation capacity range of 30,000 to 415,000 BTU per hour natural gas (48,600 to 672,300 LP gas).
• All adjustments and wiring connections are accessible from the top of the control.
• Has a straight-through body pattern.
• Includes 1/8-inch NPT inlet and outlet taps on top of the gas control to aid the adjustment of gas pressure in problem installations.
• The 3/4-inch x 3/4-inch inlet and outlet fit easily on high capacity systems, as well as others, using 1/2-inch reducer bushings.
• A 4-inch swing radius allows easy rotation into position inside the tightest furnace vestibules.
• It can be installed at any angle, including vertically between 0–90° from the upright position.
• Its clearly marked, keyed terminal block allows quick attachment of wires and IP/DSI/HSI jumper. A keyed jumper cannot be incorrectly inserted.
• The internal inlet screen blocks contaminants in the gas line from entering the valve.

• Has a -40°F to + 175°F (-40°C to +79°C) temperature range standard.
• Features a standard opening.

There is a cross-reference available online that gives the cross-reference for Honeywell valves, which replace White-Rodgers, Robertshaw and Honeywell valves. The VR8345M- 4302 replaces all of them. Be sure to make note of the footnotes that follow the cross-reference.
In Figure 2, the procedure for applying pipe dope isshown along with the table “NPT Pipe Thread Length in Inches” which is the requirement for NPT (National Pipe Thread) thread length in inches for different size pipe. Teflon tape should not be used at the gas valve as pieces of the tape may break off and end up inside the gas valve.
It should be noted that for Figure 2, the table NPT Pipe Thread Length in Inches applies to all connections of piping to gas valves.

Figure 3 illustrates the requirement for a sediment trap with all gas valve installations. The valve comes with a plug in the pilot tubing outlet for use with DSI and HSI. When using the valve on intermittent pilot, the plug must be removed.

Figure 4 gives a top view of the control for ease of locating inlet and outlet pressure tap, pilot adjustment and pressure regulator adjustment.

Figure 5 shows the proper use of wrenches when installing the valve. These procedures apply to all gas valve installations, not just Honeywell.

Figure 6 shows the installation of pilot tubing into the valve. It is important to always replace the nut and ferrule and use new ones.

Figure 7 shows the installation of the pilot tubing into the valve for intermittent pilot applications.
Figure 8 shows the adapter installation required when using the valve for HSI or DSI applications. The adapter only plugs in one way so you can’t make a mistake. The pilot gas plug must be in place when using the valve on direct burner applications.
This ends Part 1. The next issue will pick-up with universal gas valves operation in various applications. ICM