Flow Switch Problems

Lakewood Instruments Flow Switch

I get several calls per month on Flowswitch operation. Typically, I hear “my controller shows no flow, but there is plenty of pressure in the line”, or “my controller shows flow, but the system is shut down”. Our Flowswitch does not operate on pressure, only by the flow of water in the plumbing assembly.

When it comes to pressure in the line vs flow in the line, think of a garden hose. There is plenty of pressure in the hose when the water is turned on, but there is no flow until the handle on the nozzle is activated. Pressure will not raise the float.

The flowswitch requires a minimum of 1GPM of flow and a maximum of 5GPM of flow to operate correctly. Less than 1GPM is not enough to raise the Flow Float. More than 5GPM can damage the float causing it to deform and get jammed into the Flow Sight. This will cause a false “FLOW” reading on the controller when no flow is present.

What can cause Flowswitch “no flow” issues?

If there is a blockage in the line downstream of the flowswitch, there is no flow and the flow switch cannot operate correctly. The result will be a “no flow” alarm. If there is a blockage upstream of the switch, or if an upstream valve is closed, there will be no flow through the plumbing, This will also cause a “no flow” alarm.

What can cause a false flow reading?

The most common cause of a false flow reading is a buildup of scale in the plumbing assembly. Use a small bottle brush on a monthly basis to clean the interior of the plumbing.

Another cause is a chemical reaction with the backflow prevention o-ring. This is located inside the plumbing where the flow float is seated. If chemicals have interacted with the o-ring, it will need to be removed or replaced.  Call our tech support department for further direction.

Another of a false flow reading is if the flow float becomes deformed. It will no longer drop down into the plumbing. Replacing the flow float will solve this problem. Call our customer service department for the part number and price.

If none of these steps fix the issue, it may be time to replace the magnetic reed switch in your plumbing. Remove the reed switch from the back of the plumbing. Hold the flow float directly against the reed switch. If the flow light does not come on, the reed switch has failed open. If the flow light is on even after the switch has been removed from the plumbing, then the switch has failed closed. Call Customer Service for part numbers and pricing.

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