Drip Legs and Sediment Traps
The drip legs and sediment traps in the home inspectors reports are a pain in the back side to most realtors. But they are a safety device designed to make the automatic operation of our water heaters that much safer. There is at least one YouTube Video (https://www.youtube.com/watch?v=fUkjXGfCLIM) by the MythBuster people, that shows just what can happen when a water heater explodes. At least 2 things need to go wrong with the unit for this to happen: 1. the gas control valve needs to malfunction and not shut off allowing the gas to continue into the burn chamber and heat the water beyond normal settings and 2. the TPR safety valve, on the side or top of the tank, needs to malfunction and stick closed allowing the excess pressure to build to the point of explosion, instead of being bled away through the TPR valve and its drain line.
Drip legs and sediments traps are actually two similar types of assemblies for two different reasons. We write up the missing drip legs/sediment traps as if it were a single unit. This is because a properly designed drip leg/sediment trap assembly can function for both purposes at once. I have been told, multiple times, that the natural gas supplied in our area of central Texas is both dry and well filtered, yet there is still the need for a drip leg (to catch any excess moisture in the gas) and sediment trap (to catch any small pieces of debris in the gas).
The SOP Doesn’t Ignore Safety
Drip legs/Sediment traps are one of the things affected by the new 2014 home inspection SOP. The new standards lean more to the performance of the structure, components, appliances and mechanicals in the home. But it does not ignore the building standards at the time of installation or the proper methods and materials of the installed component, appliance or mechanicals specifically when it comes to safety.
For example: A water heater that was manufactured and installed in 2005 and is performing as designed, it has a catch pan and drain line to exterior, the draft hood is properly placed and secured, the exhaust vent is attached, intact and supported properly BUT doesn’t have a drip leg/sediment trap assembly on the gas supply line would not have to be written up in a report. (I will tell you that many inspectors will continue to write it up however). This is because the code in 2005 didn’t require a drip leg/sediment trap on the gas supply line (as close to the unit as possible). BUT MANY manufacturers were beginning to put the drip leg/sediment trap requirement in their installation instructions for their water heaters at that time.
Is there anything in the process of installing mechanicals in a home that supersedes the building codes in place at the time of installation? YES!
If the manufacturer requires their units to be installed in a certain way, using certain materials and the installation of additional apparatus then code is superseded.
Sediment Trap in Manufacturers Instructions
So in the case of the mysterious drip leg/sediment trap assembly missing from the water heaters in the homes our clients wish to buy the inspector could, and many do, easily ignore code and go straight to the installation instructions for that water heater and cite the fact that it was installed improperly because the installation violates the manufacturers instructions (and therefore isn’t performing as it was designed to). So please, please, please don’t blame the inspector for something someone else didn’t do correctly. IN ADDITION many manufacturers plainly state in the installation instructions that the lack of a properly installed sediment trap COULD VOID the water heaters warrantee! So it is obvious that the manufacturer considers the sediment traps a necessary part of the performance of their water heaters.
But why do they consider them so necessary? Why is the sediment trap written into the building code? I’m glad you asked! Lets look at what the ‘commentary’, that accompanies the building code, has to say about them. (The commentary is an explanation of why the code exists).
“In addition to the code requirement, most appliance manufacturers require the installation of a sediment trap (dirt leg) to protect the appliance from debris in the gas. Sediment traps are necessary to protect appliance gas controls from the dirt, soil, pipe chips, pipe joint tapes and compounds, and construction site debris that enters the piping during installation and repairs. Hazardous appliance operation could result from debris entering gas controls and burners. Despite the fact that utilities supply clean gas, debris can enter the piping prior to and during installation on the utility side of the system and on the customer side. Sediment traps are designed to cause the gas flow to change direction 90 degrees at the sediment collection point, thus causing the solid or liquid contaminants to drop out of the gas flow.”
Should I Recommend a Sediment Trap Be Installed?
So if an inspector recommends someone to install a sediment trap on a 10 year old water heater, that is otherwise performing properly, aren’t they inadvertently introducing the possibility of the very dirt, soil, pipe chips, pipe joint tapes and compounds, and construction site debris into the gas supply line through that very ‘installation and repairs’ that otherwise isn’t be there?
On the other hand replacing an old water heater with a new one IS going to require the installation of a sediment trap. ANY water heater installed after 2006 SHOULD have a sediment trap installed and ANY water heater with manufacturer instructions requiring it should have a sediment trap as well. (2006 IRC Code SECTION G2419 (408) DRIPS AND SLOPED PIPING)
So what’s the bottom line? There isn’t a cut and dried bottom line, it will depend on your inspector. Anything before about 2006 is an ‘IF’-Y situation. But virtually all water heaters after 2006 should all have sediment traps installed, by code or manufacturer instructions.