Low Voltage Flush Valve Troubleshooting

[LightsOn81]

This will be a good bit for a “first“ post.

Im troubleshooting a Zurn flush valve on a urinal. When the flusher is connected to the low voltage power supply AND the urinal, it will not work.
When the flusher is disconnected from the urinal it works fine. When the flusher is connected to another urinal, the flusher works fine.

The flush valves are on their own circuit. Supply conductors are installed in EMT, EGC pulled and connected clean and text book. Transformer is mounted to a 4sq box per manufacturer instructions. Low voltage terminations are clean, in J Box. Total length of the low voltage cable is well within the allowable length.

I’ve taken the flush valve while energized and reconnected it to the urinal and I’ve watched the red LED indicator flicker and go out as I’ve tightened the nut down that attaches the flusher to the valve body.

I pulled new cable and get the same result.
the flusher has been replaced this is the second one. Same result.
i free aired the cable and have eliminated the possiblit’s of something in the wall or conduit.

I measured voltage and read 5 VDC on the valve body while the flusher is attached.

I wrapped the threads of the male connection side of the valve body with 33 to create a dielectric break and, now, the flusher will work but still read 3VDC on the valve body. Can’t leave the tape because the flusher will leak.
The chrome on the valve body and flusher both have what looks like the effects of electrolysis ( like someone wiped grease off and it left streaks) on both components.

the transformer supplying this urinal also supplies 4 other toilets and 1 urinal. Max on these toilets is 6. 1 feed off the transformer is spliced and goes 3 different directions. Only this urinal has an issue. There’s a total of 40 sensors in this building all installed the same way and this is the only place with an issue.

I think it’s a low impedance ground fault, as if the water supply to this toilet is touching something somewhere else (rebar, structural steel) and giving a shorter path to ground for the low voltage xfmr. Or a dielectric break (plastic valve installed in the cold water copper not allowing the voltage to go to ground on the cold water bond).

does anyone have any ideas how to determine what’s wrong and how to go about fixing this.

 

[hbiss]

Is this what you are working with? Note that it says that less than 7.4V can result in a malfunction of the units. You measure 5V. I would disconnect the low voltage leads from the power supply and check continuity to ground on both leads. Then check continuity to ground on each power supply LV terminal. Also, check that polarity is correct on each valve.

https://www.zurnproducts.com/downloads/dl/file/id/134889/product/4432/zems_is_install.pdf

-Hal

 

[LightsOn81]

Is this what you are working with? Note that it says that less than 7.4V can result in a malfunction of the units. You measure 5V. I would disconnect the low voltage leads from the power supply and check continuity to ground on both leads. Then check continuity to ground on each power supply LV terminal. Also, check that polarity is correct on each valve.

https://www.zurnproducts.com/downloads/dl/file/id/134889/product/4432/zems_is_install.pdf

-Hal

Thanks Hal. The 5VDC was on the actual piping not the wiring. The problems is that the flusher will operate when it is not attached to the toilet. It won’t work when it is attached

 

[curt swartz]

You mention moving the flush valve to a different toilet but I think you are only moving the actuator. The flush valve is the actual valve that connects the water supply to the toilet. The flush valve can be operated by a manual handle or and electric actuator.

Have you tried moving a know working actuator to the flush valve that is having the problem? Maybe the actuator is working fine but the flush valve is the problem? Have the plumber move a flush valve and actuator from a working toilet.

The metal water piping is required to be bonded to the building electrical system. An incidental contact with another grounded object is not a problem.

 

[LightsOn81]

You mention moving the flush valve to a different toilet but I think you are only moving the actuator. The flush valve is the actual valve that connects the water supply to the toilet. The flush valve can be operated by a manual handle or and electric actuator.

Have you tried moving a know working actuator to the flush valve that is having the problem? Maybe the actuator is working fine but the flush valve is the problem? Have the plumber move a flush valve and actuator from a working toilet.

The metal water piping is required to be bonded to the building electrical system. An incidental contact with another grounded object is not a problem.

Thanks Curt. We swapped actuators, double checked polarity and the only variable is toilet.
and you are right I’m calling the actuator the flush valve by mistake

 

[jim dungar]

Thanks Curt. We swapped actuators, double checked polarity and the only variable is toilet.
and you are right I’m calling the actuator the flush valve by mistake

If the problem stays with the actual mechanical valve - call the plumber.
If the problem follows the electrical actuators - get a new actuator.

Too many times everyone says it must be electrical, and we tend to believe them.

 

[LightsOn81]

If the problem stays with the actual mechanical valve - call the plumber.
If the problem follows the electrical actuators - get a new actuator.

Too many times everyone says it must be electrical, and we tend to believe them.

I agree Jim. We re down to commissioning the building and because electrical is so “mysterious” it takes a legal team to convince them it’s not us