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Tundra’s Tech Talk helps you learn how to fix you restaurant & food service equipment on your own – DIY. Ask one of our experienced technicians a question, or learn about other equipment we’ve already helped other readers with.

Replacing Gas Safety Valves

There are many different types of safety valves. These are the most common types:

  • FMDA
  • BASO
  • TS
  • Combination Type

1. The FMDA safety valve is the only type with the thermocouple permanently attached to it.  This means the thermocouple cannot be replaced; the entire safety valve must be replaced if the thermocouple fails.  The easiest way to identify an FMDA type safety is a ½” diameter red button on the bottom of the valve.  You must know the gas pipe size and if the pilot tube is an “in and out” or an “out only.”  An “in and out” safety valve has two threaded holes at the top of the part, one for gas for the pilot to come in and one for gas to go out.  An “out only” safety valve has just one threaded hole to connect gas for the pilot to.

Replacing Gas Safety Valves

FMDA Safety Valve

2. The BASO safety valve can vary in design depending on the piece of equipment it is on, so it is important to know the brand name, model and serial number of the piece of equipment to get the correct safety valve the first time.  The easiest way to identify a BASO valve is by the 15/16” diameter red pilot button.  The thermocouple is separate from the safety.

Replacing Gas Safety Valves

BASO Safety Valve

3. The TS type safety valve is the only one that can be rebuilt.  It is similar to the FMDA and BASO types in that it has “in and out” or “out only” pilot tubing, so you must know what is in your equipment.  A rebuilt kit is available in both and it is not necessary to replace the body unless it is damaged.  The body has no moving parts in it.  The easiest way to identify the TS safety is by the 5/8” diameter red button.  The thermocouple is also separate from this safety, similar to the BASO.

Replacing Gas Safety Valves

TS Type Safety Valve

4. Combination safety valves come in three different styles:

  • 120 Volt Type
  • Tubing Type
  • Millivolt Type or 24 Volt Type

A combination valve is a gas valve with the safety built into it.  Most combination valves are found in fryers.

Replacing Gas Safety Valves

Combination Safety Valve

How to determine which type you have:

  • If there are two wire leads coming out of the valve then it would be the 120 volt.
  • If the wire leads are screwed to the top terminal block, and two tubes are coming out of the top of the valve, it is the tubing type combination safety valve.
  • If the wires screw into a terminal block it would be a mulitvolt type.If you are not sure, just provide the brand name, model and serial numbers.

Every combination valve uses either a thermopile or thermocouple.  The most common is a thermopile, and there are two different thermopiles:

  • Screw-in type
  • Two-lead type

The screw-in type screws directly into the body and the two-lead type has a terminal block on the combo valve to directly screw into.

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Repairing Overhead Warmers

Repairing Overhead WarmersOverhead warmers are fairly simple devices.  They are typically used to keep food that is ready to be served warm before it goes out on the server’s tray.  Overhead warmers have three main parts:

1. Element
2. On/off switch
3. Infinite Control

Warmers come in different voltages such as 120V, 208V, and 240V, and they are made in different lengths.  Always remember that it’s crucial to have the correct voltage on the unit, because severe damage can happen when the unit is introduced to the wrong voltage.  There are two types of elements in most overhead warmers.

1. Cal-rod (metal) type
2. Quartz glass type.

These elements vary in wattage and length.  When replacing an element, it is helpful to provide the following information to ensure you get the correct element.

1. Overall length of the warmer
2. Model Number
3. Serial number
4. Voltage

This information can be found on the name tag that is attached to the warmer.

There are two ways to determine if an element is bad:

1. Visual Inspection. On the Cal-rod element, inspect the outside for burn marks.  On the quartz element, inspect the filament or wire coil inside the glass tube.  If it is separated in any way, it is burnt out.Repairing Overhead Warmers

2. Continuity Testing. A continuity tester can determine if an element is defective.  Remember to disconnect the power! For either element (cal-rod or quartz), first remove at least one wire connection or remove the element if it is a socket type.  If you have a Multi-Tester set your tester in the continuity position and touch the leads to the element.  If there is no digital read out on the display the element is no good.  If you’re using a lighted tester and the light does not light up, then the element is not good.  In either case, the element needs to be replaced.  The element is still good if you get a digital read out or the lights does light up.

Repairing Overhead WarmersOn/Off Switch

To test the on/off switch, disconnect at least one wire from the switch and perform a continuity test with the switch in the on position.  If you do not get a reading, then you need to replace the on/off switch.

Infinite Control

To test the infinite control, there are multiple wire connections on the back of the control.  These wire connections are marked as follows:  L1 and L2 are the power wires coming in the warmer.  H1 and H2 are the connections for the element wires.  On units with a pilot light there may be a HP connection or a P connection, P meaning pilot light connection.  Repairing Overhead Warmers

Disconnect at least one wire from any of the H connections and perform a continuity test across the H prongs with the control in the on position.  If you did not get a reading or light it is time to replace the infinite control.  On an infinite control make sure to determine if it is a  screw mount or nut mount before purchasing a replacement.  Screw mount controls screw into the overhead warming unit; nut mount controls bolt onto the unit.

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