One of the biggest challenges in design and construction of a home’s drainage system is the treatment of the gases that are produced in the septic tank. Regardless of whether the application is in masonry or light construction such as sheetrock.
Every drainage and residual water flow falls because of gravity and goes straight to said tank, generating bad odors and gases that could be explosive when confined and in large concentrations (as in the case of methane). These gases usually return by the effect of pressure generated by themselves and tend to go out of sinks, washbasins and bathtubs creating bad odors and even explosion hazards. This is the reason why P traps are placed. The purpose of the P sink trap is to allow the natural flow of water because of gravity and to avoid the return of the gases with a natural seal that’s formed on the curvature of the sink trap.
When this seal breaks because of high pressure from the gases, these penetrate since they are not channeled to the exterior. At this point it’s where the ventilation from the home’s drainage is placed.
The drainage’s ventilation is always placed and channeled just before the sink trap with PVC pipes and a T shaped PVC pipe. The central outlet from the T shaped part in PVC connects with the outlet from the sink trap, then both of the outlets are placed, one end downwards to channel the residue water and the other upwards to channel the returning gases.
The most common cases where we find these situations are in the kitchen area. Generally, in the kitchen area there’s always a window, this represents a challenge when it comes to channeling the drainage’s ventilation given to the need of going around the window to place it vertically.
Knowing the information mentioned before, we’re ready to know how to ventilate a sink underneath a window, which is one of the most common situations in these type of installations.
It’s important to keep in mind that installation will be made within the walls and around the window that’s placed above the sink.
Next you will see a series of steps to follow on how to ventilate a sink beneath a window:
Step 1:
Once we have our sink trap located, we need to measure 3.5 feet from the center of the curve until the sanitary T pipe. This will be the distance for our drainage and its ventilation.
Step 2:
Measure from the sanitary T pipe vertically towards the window, leaving a 2 feet allowance and cutting the PVC pipe with this measurement. Said pipe has to have the same diameter as the T pipe to be able to join them. The recommended diameter for the installation is ½ inches.
Step 3:
Join the horizontal tube with a sanitary L pipe and the previous pipe, using contact cement. Set the tube to the surface in at least 2 places, this fixation can be done with anchors and the appropriate screws for the wall’s surface.
Step 4:
Measure horizontally with a ¼ of an inch inclination for every foot and respecting the 2 foot allowance from the window (this slope is necessary to make the ventilation system more efficient). Cut the tube with this measurement.
Step 5:
Join the horizontal tube with a sanitary L pipe and the previous pipe using contact cement. Fix the tube to the surface in at least 3 places, this fixation can be done with anchors and the appropriate screws for the wall’s surface.
Step 6:
Measure vertically from the end of the horizontal tube to the roof’s outlet. This end has to have at least a 2 feet overlap. Cut the tube with this measurement.
Step 7:
Join the vertical tube with the horizontal tube with a sanitary L pipe using contact cement (at this point the vertical tube has to be placed 2 feet away from the window). Fix the tube in at least 3 places, this fixation can be done with anchors and the appropriate screws for the wall’s surface.
In the tube’s part that overlaps the roof it is imminently necessary to seal correctly around the tube and the roof (it can be used a special foam to seal holes or some mechanic addition for this application) and on top of the tube there needs to be applied protection to avoid solid waste from entering the tube or ventilation system.
Conclusion
In conclusion, to be able to ventilate a sink beneath a window, we need to keep in mind that we’re going to install the pipes around the window with the appropriate pipeline for said installation, separating the pipeline 2 perimetral feet from the window. The whole ventilation system goes from the sink trap, then up to the inferior part of the window, then to the horizontal par, giving it a ¼ inclination for every foot, then it goes up through the roof.
On the exterior part of the roof, create a perfect seal between the walls of the hole and the pipes (it can be used a special foam to seal holes or some mechanic addition for this application). Lastly, on top of the tube, place a bell end pipe to protect the ventilation system from solid waste and to stop the rain from entering the pipes. We need to take into consideration that throughout the pipelines there must be fixations that hold them to the wall and that the union between every part needs to be with PVC cement.
Always remember that to be able to make the fixation, the contact cement must be in liquid form (not dry). And on the other hand, the cuts of the tubes will be made with an electric or manual saw.
