Which appliance connection requires a sediment trap in the gas supply piping when a trap is not built into the appliance itself?
- AA domestic clothes dryer
Clothes dryers appear on the code's exception list, so no sediment trap is required at that connection.
- BA residential gas range
Ranges and cooktops are specifically excepted from the sediment trap requirement in the fuel gas code.
- A storage-type gas water heater
- DAn outdoor gas grill
Outdoor grills are on the exception list along with other outdoor and decorative appliances.
Why C is correct
Water heaters are not among the appliances the code exempts, so a sediment trap must be installed unless the manufacturer built one into the appliance. The trap gives pipe scale, mill dust and moisture a dead-end pocket to drop into instead of letting them reach the gas control valve and the burner orifice.
What this question is testing
This checks whether you remember which appliances the code exempts from the sediment trap requirement, and whether you understand that the exemption list is short and specific.
On the job
A sediment trap is just a tee with a capped nipple hanging below the run, and it costs a few dollars, but it is one of the most commonly written-up items on a water heater or furnace change-out. Field crews sometimes install it horizontally coming off the side of the tee, which does nothing, because the pocket has to hang below the flow path for gravity to work. New black pipe carries a surprising amount of cutting oil and mill scale, which is why the trap matters most on brand new piping.
Memory technique
Range, dryer, grill get a pass; heaters and furnaces get the trap.
Exam tip
Memorize the short exception list. Anything not on it, especially water heaters and furnaces, needs the trap.
Where to look it up
Drips and sediment traps are IFGC Chapter 4, Section 408. UPC jurisdictions handle this in UPC Chapter 12 or NFPA 54, where the exception list is worded differently, so confirm against your adopted code.