Gas Riser Diagram – The Pipes Must Be Sized Correctly
A gas riser diagram is a three-dimensional drawing showing gas lines that will supply gas to gas-burning appliances in a home or commercial building. The pipes supplying the gas to each appliance must be sized correctly. If not, the appliance will not burn efficiently and could be starved for fuel.
How is a Gas Riser Diagram Created?
The first step is to list all of the gas appliances and then find out the Btu input listed by the manufacturer. This information is needed to start to size the main trunk line that leaves the natural gas meter or the pressure regulator on a propane (LPG) system.
The next step is to draw the pipes on a plan as a plumber would install them on the job. You must do this so you know the exact length of the pipe from the meter to all the appliances.
Who Can Draw A Riser Diagram?
I draw gas diagrams each week. I love doing it. CALL ME if you want me to draw yours. 603-470-0508.
I only charge a fraction of what you’ll pay a mechanical engineer to draw one. As of 2023, my price is just several hundred dollars.
My guess is the base price an engineering firm would charge would be about $1,000.00 or $1,500.00.
I’ve been a master plumber since 1981 and draw them for much cheaper than a mechanical engineer.
How Long Does it Take to Draw One?
It usually only takes four or five days to draw a drawing that will pass the smell test at the building department. If you try to do it yourself, there’s a very good chance you’ll get the calculations wrong and your plan might be rejected. If you do get the drawing wrong and the pipes are not sized correctly, your
A loop vent is a special pipe configuration that is used when a sink is not located against a wall. Sinks in islands need a loop vent or otherwise, the vent pipe would pierce the countertop and proceed to the ceiling much like a brass fireman’s pole. No one wants that look in a kitchen!
A typical vent pipe for a sink that’s on a wall is hidden inside the wall. The vent pipe travels up the wall and usually connects with other vent pipes. These pipes are collected into one and that pipe exits the roof.
Since most kitchen sinks are located centered on a window, this sink vent pipe can almost always be found in the wall cavity on either side of the window.
Why Does a Sink or Plumbing Fixture Need a Vent?
Vent pipes supply needed air into the plumbing system from the roof vent pipe. Each time water or solid waste enters a drain pipe, it pushes the air that was in the pipe moments before toward the sewer or septic tank.
This air must be replaced and it’s achieved by the vent pipe. You may think that vent pipes work like a smoke stack exhausting sewer gas. The opposite is true. Air travels down the pipes from the roof into the system.
What Size Pipes Are Needed for a Loop Vent?
You must use a minimum of 2-inch pipe for the actual drain stack and vent pipes. The branch arm pipe from the sanitary tee to the sink p-trap must NOT exceed 1 and 1/2 inches.
Where Does A Loop Vent Get Its Air?
The loop vent borrows air from the drain pipes in the plumbing system. When water starts to flow from the sink into the drain pipes, gravity pulls it to the bottom of the horizontal drain pipe. Air can flow back across the top of the flowing water to feed air back into the loop vent.
Since a 1 and 1/2-inch drain pipe was used for the sink, it’s impossible for that pipe to deliver enough water to fill a horizontal 2-inch drain pipe. This is why there’s always enough air in the system to satisfy the need.
Is a Pressure-Relief Vent Required?
To the best of my knowledge, only the city of New Orleans requires a pressure-relief vent. This dry vent is located just above the vent wye on the vent side of the loop vent. The pressure-relief vent then travels upwards until it exits the roof on its own or is connected to other dry vents within the system.
You may need a riser diagram to get a plumbing permit. They’re a very good idea because they prove to the plumbing department that you have a clear idea of the correct pipes to put in your home.
Who Draws Riser Diagrams?
I happen to draw them. I love doing it. I’ve been a master plumber since 1981 and to me drawing a riser diagram or plumbing isometric drawing is like solving a crossword puzzle. Call me now if you want me to draw your riser diagram in days: 603-470-0508
What do Riser Diagrams Show?
A riser diagram for plumbing drain, waste, and vent (DWV) piping shows:
all drain pipes
all waste pipes
all fixture vent pipes
the building drain
code-approved pipe connections
How Long Does it Take to Draw One?
I can draw a riser diagram in as little as 24 hours if you have an emergency. Otherwise it normally takes five business days. Other mechanical engineers might take weeks to produce this drawing.
Are Building Drain Layouts Important?
Yes, a building drain layout is very important. Non-plumbers almost always install the wrong fittings that cause serious clogs.
I offer DIY phone coaching. I’ve helped many homeowners over the phone install all the pipes in their homes. My favorite job was helping Zoe, a 28-year-old woman, in New Mexico with all the plumbing in her rural new home.
You can hire me for 15 minutes at a time and do either a voice or video call. Using video, I can see exactly what you’re up against to give you the best advice.