How To Look At A House
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What is a sediment trap or dirt leg?
Friday, June 29, 2018
A water heater or furnace sediment trap is a T-shaped pipe configuration designed to catch any debris in a gas line before it goes into the appliance. It is required by both the Florida Building Code (FBC) and International Residential Code (IRC) for any appliance that does not have one incorporated into it. Illuminating (lighting) appliances, ranges, clothes dryers, and outdoor grilles are exempt from the requirement.
Although it is part of the building codes, the sediment trap requirement is not enforced in some jurisdictions, and our local natural gas utility does not require a sediment trap when inspecting a gas system before turning on the service.
The sediment trap must be downstream from the shut-off valve and have a right angle change in the gas flow before the trap, like in the photo above, so the debris doesn’t bypass the dirt leg intended to trap it, along with a threaded nipple cap at the bottom for removal of any debris accumulation.
The Florida Building Code provides this diagram of a sediment trap.
Here’s an example of a sediment trap installed incorrectly below. The gas flow goes right past it.
And here’s an example of a water heater installation done without a dirt leg. This particular one was a job by a handyman that had several other defects and lacked a building permit.
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Here’s links to a collection of our other blog posts about PLUMBING:
• How can I protect my pipes to keep them from bursting during a hard winter freeze in North Florida?
• Why is the vacuum breaker at my hose faucet leaking, gushing water, or making funny sounds?
• What are the code requirements for plumbing vent terminations?
• What are the code requirements for layout of drain piping under sinks?
• Why is there sand in the bottom of my toilet tank?
• What causes a gurgling sound when a bathtub or sink drains?
• Are drop-in toilet bowl cleaner tablets safe?
• What can I add to my septic tank to help it work better?
• Why is there mold inside my toilet tank?
• What are the pros and cons of a wall-mounted toilet?
• Which plumbing fixtures require water shut off valves in a home?
• How can I tell if a house is connected to a septic tank system or sewer?
• Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water?
• Why is a backflow preventer required on lawn sprinkler systems?
• How can I locate my septic tank?
• Is a hot water faucet handle required to be on the left?
• Can you live in a house while the plumbing is being replaced?
• Why is the European-style bottle trap not approved by the plumbing codes in the U.S.?
• Why can't PVC be used for water pipe inside a house?
• What are the common problems to look for when the plumbing has been replaced in a house?
• What's that powdery crust on the pipe connections at the water heater?
• How can I tell what type of plumbing pipe I have?
• What causes low water pressure in a house?
• Should I call a plumber or septic tank contractor when my septic tank backs up into the house?
• How do I get rid of the sewer gas smell in my house?
• What are the pipes on my roof?
• Should I wrap the water heater with an insulation blanket?
• My water bill went way up last month. How do I look for a leak?
• Why does the water have a rotten-egg smell in some empty houses?
• What is an "S-Trap" under my sink? Why is it a problem?
• Where is the septic tank? Are you going to inspect it?
• What does polybutylene pipe look like? Why is it a problem?
• Which water pipes are an insurance problem and possibly uninsurable?
• Does a home inspector check the plumbing under the floor slab?
• Is it alright to disconnect the washing machine drain from the septic tank and divert it to the ground in the yard?
Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.
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