Do you know the proper way to size a P trap on an HVAC unit? The pull of the water to the drain has to exceed the sucking of the supply fan (“negative pressure”). Rule of thumb… add 2.5” to the static pressure before the fan (return and internal to the unit) and that's the long end (closer to the drain of the unit.
P-traps come in two standard sizes: 1 ¼ inches for bathroom sinks or 1 ½ inches for kitchen sinks. Larger sizes—up to 2 inches in diameter—are reserved for showers and toilets.
Each “P” trap shall have a water seal of not less than 2 inches and not more than 4 inches and shall be set true to its seal. (6) Size. Traps shall be not less than 1 1/4 inches in diameter. A trap shall not be larger than the waste pipe to which it is connected.
A rule of thumb that incorporates pipe size is to choose liquid lines to handle a velocity of 1.5 +d/10 where “d” is the pipe diameter, inches. This gives 1.6 m/s for 1-inch and 2.5 m/s for 10-inch piping, and about 20 kPa/100 m pressure drop.
The general rule of thumb is to maintain a velocity below 5 ft/s (1.5 m/s). Gravity (g) and the slope of the pipe. An increase in slope decreases the pressure due to gravity. Pipe Diameter (D): The larger the pipe diameter is, the slower the flow velocity will be.
Here are the average water flow rates based on typical municipal water lines: ½-inch pipe: 50 gallons per minute. ¾-inch pipe: 110 gallons per minute.
The purpose of a p-trap is to trap water and prevent insects and sewer gasses from escaping out of the drain. If dry, the p-trap cannot perform its function correctly. To eliminate odors coming from a dry p-trap, pour half a gallon of water into the trap to restore the barrier.
A P-trap is not necessarily better when it's larger. The size should match the sink's drainpipe to ensure a proper seal and efficient drainage. A P-trap that's too large might not seal correctly, leading to sewer gas leaks. A smaller one might not allow water to flow freely, causing blockages.
The vertical distance from the fixture outlet to the trap weir shall not exceed 24 inches (610 mm), and the horizontal distance shall not exceed 30 inches (610 mm) measured from the centerline of the fixture outlet to the centerline of the inlet of the trap.
Plumbing codes expressly prohibit the use of double traps.
When the trap is too deep, liquid may flow through it too fast, which can lead to siphoning of the trap seal and sludge buildup. The drain connection at the wall is too high on this sink, resulting in a 9-inch-deep trap seal — 5 inches deeper than is allowed by code.
Disadvantages of P-Traps
One common issue is that the water seal can be protected if properly maintained or if there are blockages in the drainpipe. This can lead to the escape of sewer gases and unpleasant odors. The trap is regularly inspected and cleaned to ensure its proper functioning.
If traps have a size stamped on them, this will tell you if they are allowed or not. If traps don't have a size stamped on them, measure them at the widest point across the open jaws, at right angles to the pivot points (hinges).
Pour some baking soda down your drain and then pour boiling water down after. Sometimes this will clear the clog. Use a plunger on your sink drain to try to force the clog out of the trap.
Kitchen sink P-Traps come in 1-1/2” standard size, while bathroom sinks use P-Traps of 1-1/4” standard size. The traps also come in different material types such as propylene, ABS, brass (chrome-plated or natural), and PVC. You should use the material that is currently in place when replacing a P-Trap.
Do you know the proper way to size a P trap on an HVAC unit? The pull of the water to the drain has to exceed the sucking of the supply fan (“negative pressure”). Rule of thumb… add 2.5” to the static pressure before the fan (return and internal to the unit) and that's the long end (closer to the drain of the unit.
As we previously mentioned, it is a law in the United States that every shower has a P-trap. In addition to this rule, P-traps must be no more than 5 feet away from the shower drain. Ideally, it should be as close to your shower inlet as possible.
Running your sink obviously flushes water through the trap and down into the drain line. However, when you shut the faucet off, a small amount of water always remains inside the bend at the bottom of the P-trap. This water acts as a barrier that seals off the pipe so that the smelly sewer gases can't escape.
The bend in the p-trap collects water in the curve, creating a 1-½-inch to 2-inch water seal at the weir, preventing sewer gasses and odor from entering the home.
The experts are Moore Home Services recommend that you clean your P-trap once every 3 months.
When it comes to Shower Heads, you'll typically find 2.5 GPM, 2.0 GPM, 1.8 GPM and 1.5 GPM. If you're looking for the most pressure, go for the 2.5 GPM Flow Rate, unless you are restricted because you reside in California, Colorado or New York. Again, this has been the Maximum Flow Rate since 1992.
A 1" (ID) pipe at 60 psi will deliver 47 GPM. The piping loss in your scenario is negligible and not a consideration in almost every application.