A modern, properly installed fireplace should not require a mantle to catch smoke; they are purely decorative. I believe Nathan was referring to the glass doors and metal screen that an indoor fireplace does require to be safe. Also that the inspector may have been referring to the surround (protects the walls around the fireplace and is often topped by a decorative mantel); the masonry directly adjacent the fireplace, on the walls and including a section of the floor.

The white mantle is decorative. The exposed hearth and the tile surround are functional.

In order to lower the risk when using your fireplace, you should:

Keep all combustibles a safe distance away from the hearth.

Use a fire screen to prevent sparks.

Install a spark arrester at the top of the flue to guard against roof fires.

Keep a fire extinguisher handy.

Install smoke detectors on every level of your home. You should also have a carbon monoxide detector.

Code -rumford.com (note, masonry fireplace; for steel-box construction consult the manufacturer)

R1001.11 Fireplace clearance. All wood beams, joists, studs and other combustible material shall have a clearance of not less than 2 inches (51 mm) from the front faces and sides of masonry fireplaces and not less than 4 inches (102 mm) from the back faces of masonry fireplaces. The air space shall not be filled, except to provide fire blocking in accordance with Section R1003.13.

Exceptions:

2. When masonry fireplaces are part of masonry or concrete walls, combustible materials shall not be in contact with the masonry or concrete walls less than 12 inches (305 mm)from the inside surface of the nearest firebox lining.

3. Exposed combustible trim and the edges of sheathing materials such as wood siding, flooring and drywall shall be permitted to abut the masonry fireplace side walls and hearth extension in accordance with Figure R1003.12, provided such combustible trim or sheathing is a minimum of 12 inches (305 mm) from the inside surface of the nearest firebox lining.

4. Exposed combustible mantels or trim may be placed directly on the masonry fireplace front surrounding the fireplace opening providing such combustible materials shall not be placed within 6 inches (152 mm) of a fireplace opening. Combustible material within 12 inches (306 mm) of the fireplace opening shall not project more than 1/8 inch (3.2 mm) for each 1-inch (25.4 mm) distance from such an opening.

Under my interpretation of #4, the mantle pictured is to close to the edge of the fireplace (~8") to stick out so far (~4"). It isn't the best picture to show a safe fireplace. Merely, it does a good job showing a useless mantle. It lacks doors and a screen but at least they attempted to keep combustibles (drywall) one foot from the opening in every direction.

It's difficult to help you troubleshoot a device, without a bit more information about it. Since you're not giving us much, I'll try to give general advice.

Depending on the system, there's a few things that could be wrong.

Gas Valve Closed

This would affect every type of gas fireplace.

Test:

1. Locate the gas valve.
2. Turn on the switch.
3. Listen for the valve to open.

If you hear the valve open (click, clank, clunk, etc.), but don't hear or smell gas. The valve may be off.

Most gas valves are quarter turn ball valves, so you can tell when they're open simply by looking at the knob. The knob should have an arrow, handle, or other linear feature on it. This feature should be aligned with (parallel to) the pipe, when the valve is open.

Solution:

Turn on the gas.

No Gas

If you get your gas from a tank or bottle, you'll want to make sure you have gas.

Test:

Similar to above, except that the valve will be open.

Solution:

Fill the tank.

Bad Switch

Since the system relies on a switch to know when to turn on, a bad switch could be devastating.

Test:

1. Label and remove the wires from the switch.
2. Test continuity across the switch, in both positions.

When the switch is toggled on way, you should measure infinity (or not hear a beep). When the switch is toggled the other way, you should get a measurement (or hear a beep).

Solution:

Replace the switch.

Pilot Not Lit

If your system requires a pilot, and it's not lit. You can flip the switch all you want, you'll never make fire.

Test:

1. Look at the pilot.

If you see a flame, it's lit.

Solution:

Light the pilot.

Bad Flame Sensor

Fireplaces use flame sensors (thermocouples, thermopiles, etc.), to determine if there's a flame. If the sensor goes bad, the system will not hold the gas valve open.

Test:

1. Disconnect the thermocouple from the system.
2. Set multimeter to measure DC millivolts (mV).
3. Connect the black lead to the button of the thermocouple.
4. Connect the red lead to the copper part of the thermocouple.
5. Heat the thermocouple with a torch.

As the thermocouple heats, you should get a reading on the multimeter.

Solution:

Replace the flame sensor.

Bad Gas Valve

If the system is getting all the right signals, but the gas valve is not opening. It could be a bad valve.

Test:

See test for Gas Valve Closed. You won't hear the valve open. You'll have to be sure the valve is getting the signal to open, so make sure all other items check out first.

Solution:

Replace the valve.

Depending on the type of fireplace, the ignition sequence will be a bit different. using the typical sequences below, you might be able to narrow down where the problem is.

Typical Gas Fireplace Ignition Sequence

Pilot

• Switch is flipped
• If pilot is lit (checked via a thermocouple or other flame sensor).
  • Open main burner gas valve.
  • Wait (There may be an adjustable timeout, or a hard set timeout).
  • If main burner lit (check via another thermocouple or other flame sensor).
    • Leave main gas valve open.
  • Else
    • Close main gas valve.
    • Purge system (in the case of a fireplace, this is likely a timed wait).
    • Retry ignition (this may happen 0 to many times, depending on the system).
• Else
  • Do nothing

Electronic Ignition with pilot

• Switch is flipped
• Open pilot gas valve.
• Initiate electronic ignition device (spark gap, hot surface, etc.).
• Wait.
• If pilot flame sensed.
  • Open main burner gas valve.
  • Wait.
  • If main burner flame sensed.
    • Hold main gas valve open.
  • Else
    • Close main gas valve.
    • Purge system.
    • Retry ignition.
    • If no ignition after retries
      • Close pilot gas valve.
      • Lockout (this may require something to be physically reset, or a simple timed lockout).
• Else
  • Close pilot gas valve.
  • Purge system.
  • Retry ignition.
  • If no ignition after retries
    • Close pilot gas valve.
    • Lockout.

Electronic Ignition

• Switch is flipped
• Open main burner gas valve.
• Initiate electronic ignition device.
• Wait
• If flame sensed.
  • Hold main gas valve open.
• Else
  • Close main gas valve.
  • Purge.
  • Retry.
  • Lockout.