Posted on February 05 2020
A control stop is a device found within a closet or urinal flushometer that functions as an on/off valve. When properly installed, it operates by either enabling or disabling water from coming into the flushometer. A common misconception is that a control stop is a regulator. It is not. This is the job of the diaphragm. A control stop is exactly what it sounds like, either controlling or allowing water through the unit or stopping it from coming through.
How a Control Stop Works
A control stop functions like a check valve. It’s a spring-loaded mechanism that opens when pressure from incoming water is present, and it is closed when that pressure is not there. This means that the control stop disables water from moving in the wrong direction, so backflow does not occur.
The Wrong Way to Use a Control Stop
We often see the following scenario which is a perfect example of how not to use a control stop:
What NOT to do: A facility manager, let’s call him Jimmy, has a urinal that is designed for a 0.5 flush volume, but only has a 1.5 GPF diaphragm in stock. Instead of ordering the correct diaphragm for the urinal, he installs the 1.5 GPF diaphragm he has in stock. Then in an effort to make the flushometer function properly with an incorrect diaphragm, he attempts to use the control stop (incorrectly) like a regulator. To do this, he opens the control stop incorrectly by turning the slotted screw of the control stop so it opens only partially. This causes the control stop to not fully close or open, but remains partially open.
The problem with not opening a control stop fully: Not opening a control stop fully can cause the unit to overflow. It may not happen initially, which will lead the maintenance person to believe that their ‘jimmy-rigged’ fix works, but it will not work long term, and might not even work come morning. Why? Because the pressure within a building’s plumbing system fluctuates, with higher pressure often occurring at night, when the building experiences low or no use overnight. This pressure, without a control stop in the fully open position, will cause the flushometer to overflow the urinal with water. Other factors like different fixtures flushing at the same time will also affect water pressure to the flushometer as well, which is why a control stop cannot be used to regulate water. It needs to be fully opened so it can function as intended, as an on/off valve and nothing in between.
Left: Control Stop Closed. Right: Control Stop Opened
When the correctly sized diaphragm is used and the control stop is fully opened, then and only then will the flushometer function properly and reliably.
How Often Do Control Stops Need to Be Replaced?
There is no direct answer to how long a control stop should last or will last. How long a control stop lasts is dependent on a variety of factors including water quality, pressure, usage, water main breaks, and even the weather. The good thing is, when a control stop is no longer working, there will be tell-tale signs like the signs listed below in our troubleshooting control stops section.
Troubleshooting Control Stops
Flushometer Continuously Runs/ Valve Will Not Shut Off
One sign that a control stop is not fully opened is a unit that continuously runs. This occurs when a control stop does not open all the way when the unit is flushed, which then causes the water pressure to not be high enough for the diaphragm to function properly and reset. This causes water to continuously run into the unit. To fix this, the control stop needs to adjusted so it can fully open as intended. If the control stop is fully opened but still not functioning properly, the control and/or the diaphragm kit may also need to be replaced. The diaphragm will also need to be replaced if the wrong sized diaphragm was initially installed.
Control Stop No Longer Opens/Closes
If the control stop on your flushometer no longer opens or closes all the way, then the control stop needs to be replaced. This is the most common reason why a control stop needs to be replaced. It occurs for one of three reasons:
- The screw on the control stop is stripped. This happens because the metal screw goes into plastic.
- The rubber portion of the bottom of the control stop wears away and no longer seals the unit when in the closed position.
- The spring within the control stop breaks.
The image above illustrates how to open or close the stop valve
How to Adjust a Control Stop
Control stops are fairly easy to adjust. Read the directions below to learn how to adjust a control stop in a flushometer.
If a stop cap is present, you will first need to remove the stop cap. Below are directions from Sloan on how to properly remove a vandal resistant stop cap:
Use a large flat screwdriver as a lever to remove the cap from the control stop. Insert the screwdriver blade between the bottom edge of the cap and the flat surface of the control stop body as shown. Push the screwdriver handle straight back toward the wall to gently lift the cap. If necessary, work the screwdriver around the diameter of the cap until you can grasp the cap and lift it completely off the sleeve. The sleeve should remain attached to the bonnet of the control stop.
- Use your flat head screwdriver to either open (turn counterclockwise) or close (turn clockwise) the stop valve.
How to Replace the Control Stop
Follow the directions below to replace the control stop in your flushometer. The directions here are for a sloan flushometer, however, they most likely will not differ for other flushometers either.
- Gather the items needed to complete the replacement. You will need the following: the control stop repair kit, a flat blade screwdriver, a smooth jaw wrench, and a bucket.
- Turn off the water supply.
- Flush the valve to clear the flushometer of any remaining water in the unit with the bucket placed underneath.
- Remove the cap. (use directions from Sloan in the adjustment directions above if vandal proof cap is present)
- Use the smooth jaw wrench to remove the bonnet nut.
- Then remove the stem, along with the spring and the rubber button.
- Install the new control stop in the reverse order you removed the old control stop: First the button, then the spring, then the stem. It may be easiest to do this all together, by placing the constructed control stop into the opening altogether.
- Replace the cap nut and screw it back on and use the wrench to tighten it into place.
- Then use the flat head screwdriver and turn the screw in the center of the cap nut clockwise until it will no longer turn to close the stop valve.
- Turn the water supply back on, and test the unit to make sure the control stop in the correct setting. Adjust as needed.
- Replace cap.
How to Disable Water Flow Using the Control Stop
The control stop can be used to disable the water flow to the flushometer when servicing the rest of the unit. Simply remove the stop cap and turn the stop screw clockwise until it can't turn anymore. Flush any remaining water then complete your repairs. When finished servicing the unit, open the control stop again by turning the stop screw in the opposite direction until it can fully open once more.
Sloan Control Stop Repair Kits
Sloan control stops are available in two basic inlet sizes:
- 3/4” NPTF — Fits urinal flushometers (pre 2013)
- 1” NPTF — Fits water closet flushometers new urinal flushometers (post 2013)
In 2013, Sloan changed their flushometers so that all closet and urinal flushometers use the same control stop repair kit (Part #08032 / Sloan Model H541ASD). Closets always use this size, and new Sloan urinals made after 2013 use this size now as well. Older urinals use the ¾” stop assembly (Part #08033 / Sloan Model H543ASD).
If you are unsure whether your urinal flushometer was made before or after 2013, then you will need to shut off water to the restroom, remove the bonnet and pull out the control stop to see if it is a ¾-inch or 1-inch control stop.
Buy Sloan Control Stops Online
Stop Assembly - Repair Kit for 1" or 3/4"
Part Number: 08032
Sloan Model Number: H541ASD
Buy #08032 Online
The 08032 control stop assembly is by far the most common stop assembly purchased today. This is because Sloan consolidated all of it’s urinals (which use ¾” stops) into using the same body as the 08032. View in our online store
Stop Assembly - Repair Kit for 3/4"
Part Number: 08033
Sloan Model Number: H543ASD
Buy #08033 Online
The 08033 Sloan Control stop is used in old style sloan urinal flushometers. In 2013, Sloan switched their urinals over so they can use #08032, the same control stop used for closets. The 08033 unit is designed for use on Sloan urinal flushometers built prior to 2013. View in our online store
Stop Assembly Repair Kit - Old Style w/ Bonnet
For very old flushometers that were built in the 1950-1960’s and earlier, there is a different control stop repair kit. It can be purchased as a full kit with bonnet (listed below) or just the inner mechanisms (call to order). View in our online store
Part Number: #08718
Sloan Model Number.: H39ASD
Buy #08718 Online
Additional Flushometer Troubleshooting Resources
- Flushometer Repair Tool Quick Guide and Diagram
- Sloan Royal and Regal Flushometer Maintenance Schedules (w/Inside Look at Royal Units)
- Troubleshooting a G2 Flushometer (Video Guide)
- Sloan Optima Solenoid Replacement Guide
- Sloan Diaphragm Kit Guide
- Understanding Sloan Vacuum Breaker Repair Kits
- Sloan Complete Vacuum Breaker Replacement Guide