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Backwater Valve I needThe Mainline Fullport Backwater Valve installed on the main building drain allows for the free circulation of air & will protect the entire building from backflow with just the one valve.

Until recently most plumbing codes did not allow a backwater valve to be installed on a main-building drain. Municipal sewers exert both negative and positive air pressures, and a building’s venting system alleviates these pressure differences. Free circulation of air between a municipal sewer and a buildings venting system is essential for the proper flow of sewage. The only backwater valves available when the codes were originally written, were the “normally closed” design and these valves would not allow a free circulation of air between the building and municipal sewer.

The Mainline Fullport Backwater Valve features a ‘normally open’ gate design which makes the free circulation possible. The valve allows the free flow of air to vent through it, and at the same time in the event of a sewer back up, the gate floats into the closed position to protect the building from backflow.

Because of this normally-open technology, Special Changes to the National Plumbing Code of Canada were made to allow for main-building drain protection versus the old standard which restricted backwater valves to the branch line of the building drain only. Today, the plumbing industry has embraced this method of backflow protection and the Mainline Fullport Backwater Valve.

The Mainline Fullport Backwater Valve is a normally open backwater valve. It allows non-restrictive sewage flow from the inlet to the outlet side of the valve, through flow channels incorporated on the gate and body. (This superior design prevents sewage buildup in body).

Upon a quick reversal sewer backsurge, flow is diverted to the gates 45-degree wings (incorporated on the sides of the gate) – this causes an upward lifting action of the gate. Once the lift occurs, the reversal flow of water slams the gate into the closed position, isolating the entire plumbing system from backflow.
Upon a slow reversal backsurge, the gate is fitted with certified flotation devices that initiate the lifting of the gate. The reversal flow then pushes up on the bottom of the gate and closes it automatically isolating the system.

The Mainline Fullport Backwater Valve is also designed with a built in cleanout for the rodding of the building drain-sewer (first time ever in a backwater valve).

The Mainline Fullport Backwater Valve’s “normally open” design allows unrestricted sewage flow. Because of its Fullport design, it requires minimal homeowner maintenance when installed properly, and provides the best in backflow protection.

Installation of Backwater Valve

Prior To Installation
• Inspect unit through cleanout
• Check o-rings
• Make sure flotation devices are in place (one on each side of gate)
• Check the gate and ensure it moves freely.
Installation
• Allow maximum grade when possible – 4% or higher
• NOTE: min. grade must be at least 2% – 1/4 inch per foot
• Check grade with level by placing it on the bolts
• See arrows for direction of flow
• Do not install any fittings within 2 feet of inlet side of valve. This will ensure laminar flow through valve body
(as there is no control of fitting layouts, in retrofit installations this rule may be waived by the enforcing authority)
• Care should be taken when solvent welding pipe into valve. Ensure solvent does not enter the body as it
will affect the valve’s function
• Re-inspection of unit-remove sand, gravel, dirt or any other debris which may have entered the body and
hinge area upon installation
• Tighten cleanout
• Install Mainline Access Box

Testing the Unit

All backwater valves are factory tested through our certified quality control program. If you wish to test the backwater valves, follow these instructions.
1. Place a “Test Ball” through the cleanout plug on the body, downstream of the valve into the outlet
drainage piping leading away from the valve.
2. Inflate the test ball.
3. Through the cleanout opening, stretch a garden hose down to the “Test Ball” and begin filling the pipe with water.
4. Watching through the cleanout opening, you should see the gate rise intothe closed position. This means
the valve is closing properly. During a sewer back surge, back pressure will increase downstream of the
valve, and the gate will seat onto the valves o-ring, protecting the building from backflow.
5. Deflate the “Test Ball” to release the water. This will allow the gate to fall back into the open position.
WARNING
• Improper installation may result in valve failure
• Follow installation procedures carefully, with special care and attention to be taken when retrofitting valve
into existing systems
• Do not install if proper grade cannot be achieved

Retrofit Installation Of Backwater Valve

Failures may occur due to back grade on valves. In order to achieve grade in retrofit installations, an

installer must expose approx. 4-5 feet of piping. Often sewers are at a minimum, flat, or back grading. Since
there is 3⁄4 of an inch difference in height from inlet to outlet on your Mainline valve, it may be necessary to
adjust the grade on the piping leading up to the valve, to achieve required grade on the backwater valve
• In retrofit installations, always run and test all fixtures to ensure each one runs through the backwater valve,
and nothing remains unprotected
• Check that the sewer is unrestricted (roots, blockages, etc.) downstream of valve.
• Ensure weeping tiles (French drains) tie in downstream of valve
Testing the Unit
All backwater valves are factory tested through our certified quality control program. If you wish to test the
backwater valves, follow these instructions.
1. Place a “Test Ball” through the cleanout plug on the body, downstream of the valve into the outlet
drainage piping leading away from the valve.
2. Inflate the test ball.
3. Through the cleanout opening, stretch a garden hose down to the “Test Ball” and begin filling the pipe with water.
4. Watching through the cleanout opening, you should see the gate rise intothe closed position. This means
the valve is closing properly. During a sewer back surge, back pressure will increase downstream of the
valve, and the gate will seat onto the valves o-ring, protecting the building from backflow.
5. Deflate the “Test Ball” to release the water. This will allow the gate to fall back into the open position.
WARNING
• Improper installation may result in valve failure
• Follow installation procedures carefully, with special care and attention to be taken when retrofitting valve
into existing systems
• Do not install if proper grade cannot be achieved

Testing the Unit

All backwater valves are factory tested through our certified quality control program. If you wish to test the backwater valves, follow these instructions.
Place a “Test Ball” through the cleanout plug on the body, downstream of the valve into the outlet drainage piping leading away from the valve.
Inflate the test ball.
Through the cleanout opening, stretch a garden hose down to the “Test Ball” and begin filling the pipe with water.
Watching through the cleanout opening, you should see the gate rise intothe closed position. This means the valve is closing properly. During a sewer back surge, back pressure will increase downstream of the valve, and the gate will seat onto the valves o-ring, protecting the building from backflow.
Deflate the “Test Ball” to release the water. This will allow the gate to fall back into the open position.

Maintenance

Backwater valves are mechanical devices sitting in a sewage environment, and regular inspections are required. To ensure the satisfactory performance of the backwater valve follow the procedures listed below.
1. Remove the cleanout plug on the top of the valve and do a visual inspection.
2. Take a flashlight or trouble light to properly see inside the valve body.
3. Inspect for debris build-up on the body, gate and beneath the gate.
4. If debris build-up is found flush clean.
5. Inspect o-ring and replace if necessary.  The valve’s gate seals against an o-ring on the body ( in the closed position).
6. Ensure gate freely moves up and down.
7. Reinstall cleanout plug.
On models fitted with closed cell polyethylene floats, check the condition of floats and replace as necessary. * Note: these floats are located on both sides of the gate and are protected from sewage contamination by the sidewalls of the gate and body (longlife cycle, impervious to sewage). CSA certified floats.

Bolted Cover
If damage is found on the gate, or a more thorough cleaning of the valve is required, remove the bolted cover.
Important: if you have difficulty maintaining these backflow devices, contact your plumber. If you wish to test the unit under a backflow condition refer to Installation for instructions.

How to choose which Backwater Valve I need?

New Homes:

Basement Applications

If you have a basement the most popular backwater valve used is the “Mainline Fullport Backwater Valve”.
This valve is typically installed on the Main-Sewer line entering the building and protects the entire building

If you have a basement the most popular backwater valve used is the “Mainline Fullport Backwater Valve”.

This valve is typically installed on the Main-Sewer line entering the building and protects the entire building from backflow; it comes only in a 4-inch DWV size, ABS or PVC. The valve has clear lid for ease of maintenance and incorporates a built-in Main-Sewer cleanout. This valve is used to protect half the homes using backwater valves in Canada and in certain US States. CSA and UPC certified
On-Slab Applications or deep burials
The Extendable “Adapt-a-Valve” backwater valve is ideal for exterior installations, deep burials and commercial applications. This valve simplifies backwater valve installation, on standard backwater valves you typically need expensive vaults and access boxes which are heavy and do not provide adequate access to service valves buried deeper than 24-inches. With the Extendable “Adapt-a-Valve” you eliminate the need for expensive vaults and access boxes and saves labor. The extendable valve body feature makes servicing of the valve easy at any depth. The valve comes in both 3 and 4-inch sizes. Popular choice for on-slab buildings with exterior installations, commercial CSA and UPC certified
Retrofitting Valves in existing Systems
Before selecting the valve you use, you must know the limitations of all backwater valves. Every valve on the market has a step down design, meaning the outlet is lower than the inlet. This difference in elevation may result in back grading of the valve which in turn dictates the amount of maintenance a valve requires. Check with your Contractor which valves works best for you!
“Mainline Fullport Backwater Valve” is the most popular retrofit valve we manufacture the elevation difference is 3/4″ between inlet and outlet. Installation into retrofit systems has been successful one with this valve with approximately 4,000 valves installed. Generally the 3/4″ difference is made up by the contractor by slightly raising 3-4 ft. of piping leading up to the valve on the inlet side. Depending on your piping grade determines whether or not you need to raise the piping leading up to the valve.
“Adapt-a-Valve” This valve is difficult to retrofit into a system if you are not replacing the sewer lateral. The 3-inch “Adapt-a-Valve” has a 1-inch difference between inlet and outlet and the 4-inch “Adapt-a-Valve” has a 1 3/4-inch difference between inlet and outlet. Generally this valve cannot be used in a retrofit system unless #1 You are replacing the entire line (lateral) outside the building where you can make up the height differences or: #2 You are installing it at the property line where you can generally make up the difference where it ties into the city sewer.
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