Have you ever looked at your gas furnace or gas water heater and wondered what the short piece of gas pipe going to nothing was for? Did the plumber possibly leave it in case you wanted to add to the line? It is actually a very useful component of the gas line known as a sediment trap.
Let's look at what the code says about sediment traps:
"Where a sediment trap is not incorporated as part if the appliance, a sediment trap shall be installed downstream of the appliance shutoff valve as close to the inlet of the appliance as practical."
We can see an example of this in the picture below.
The code also specifies some locations where sediment traps are not required: illuminating appliances (appliances that have a flame that is clearly visible during operation), ranges, clothes dryers, decorative vented appliances for installation in vented fireplaces, gas fireplaces and outdoor grills. The orientation of the sediment trap is also important. It must be vertical to function properly. We can see an improper horizontal installation below.
I frequently see appliances required to have sediment traps that aren't equipped with them. I find it odd since sediment traps have basically always been required. I even find them missing during new construction inspections. Apparently, not all installers and government inspectors are concerned with whether they are present or not. To be honest, I am not overly concerned with their presence either. However, I will note the lack of a sediment trap in the report.
If you look at your own appliances or a thorough home inspection report and see that there are missing sediment traps, don't be alarmed. Just consider having one installed the next time the unit is serviced or replaced. If you don't have the issue corrected, it isn't the end of the world. Think of a sediment trap as a cheap form of insurance for your gas appliances.
On a recent inspection, I came across an issue that I don't see often, yet it is one of the more potentially dangerous problems I see. The problem? Air conditioning ducts from the living space supplying air to the garage space. To understand the dangers of this issue, lets first look at what the building code says regarding garage HVAC systems:
IRC Section M1601.6- Furnaces and air-handling systems that supply air into living spaces shall not supply air to or return air from a garage.
This doesn't mean the garage space can't be heated and cooled. It is saying that the garage can't share an HVAC system with the rest of the home. The garage must have its own separate system. This makes sense when we think about it from a health and safety standpoint.
Think about all the things we typically store in our garages. Things such as lawn equipment, pesticides and herbicides, painting supplies, gas fired appliances such as water heaters, automobiles and much more. Let's focus on two of those things: items with combustion engines and gas fired appliances.
Combustion engines and gas fired appliances function by burning fossil fuels. This process results in products expelled as exhaust gases. Some of these products are inert, such as nitrogen, or harmless. such as water vapor. Exhaust gas also contains some products which can be extremely harmful to human health. one of those products is carbon monoxide.
Carbon monoxide is a colorless and odorless gas that displaces oxygen. It is an asphyxiant and is often referred to as the silent killer. The danger of carbon monoxide is that it binds to your blood cells just like oxygen does. Actually, carbon monoxide is 200 times more attractive to your blood cells than oxygen. Therefore, it will attach to the blood cell and block the oxygen from attaching. This will greatly inhibit the bloods ability to carry oxygen to the tissues.
When carbon monoxide poisoning occurs, the symptoms usually include headache and nausea. However, if the concentrations of carbon monoxide are high enough, you could become unconscious before you begin to notice any of the other symptoms. This is what makes carbon monoxide so dangerous.
When the ducts from the living space also extend to the garage, it provides a direct path for carbon monoxide to enter the home. If a car were left running in the garage (perhaps warming up on a cold morning) or if a gas fired appliance experienced a back draft situation, carbon monoxide could backfeed through the ducts into the home and create a potentially deadly situation. Your family's health and safety is my number one priority. It is for this reason that I will always call out ductwork shared between the living space and garage. I also recommend replacing (if one is already present) or installing a carbon monoxide detector upon moving into the home.
Colin is a Certified Professional Home Inspector as well as a licensed MS Residential Builder. He has been remodeling homes since he was 14 and even built his own house by hand from the ground up. Colin is also the owner of Wilson Home Inspections.
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