35 JULY 2026 WorldWide Drilling Resource® The Great Refrigerator Ice Maker Filter Caper by Britt Storkson Owner, P2FlowLLC Most modern refrigerators have ice makers and use water filters to remove dirt and debris that could be a problem. Most have a light to indicate the water filter in your refrigerator/ice maker needs replacing. Typically, the indicator light is a red LED (light emitting diode). The “red” light (they use color red to imply urgency - like something really bad is going to happen if you don’t replace it RIGHT NOW!) So how does the refrigerator computer know when to turn that light on? In almost every case they use elapsed time . . . meaning how much time has elapsed since the filter was last changed. This elapsed time function is created by a spring-loaded switch that resets (clears/sets back to zero) a timer the refrigerator computer maintains for this purpose. After a certain time passes, the timer triggers (turns on) the change filter light. This means you may be gone on a long vacation and not use your refrigerator ice maker (not run any water through the filter) and the light will still turn on. When you change the filter, you move the switch which signals to the computer to reset the time back to zero and start over. Since in most cases elapsed time is not a good indicator, then what’s the correct way to determine if the filter is clogged? For any filter, there is a pressure drop or loss from inlet to outlet when the water is flowing through it. There’s zero pressure loss when the water is static or not flowing through the filter. How much pressure loss from inlet to outlet is a good indicator of how dirty or plugged up the filter is. The filter inlet pressure minus the filter outlet pressure (called pressure differential) when the water is flowing, indicates how plugged up the filter is. Also, the higher the rate of flow (gallons per minute), the higher the pressure differential will be. So to get it right, first we need to determine there is water flow before we measure the pressure differential. That’s usually done with a propeller type of device that starts spinning when the water flows through it. These propeller flow sensing devices are widely used in water meters in general, and tankless water heaters in particular, to turn on the heater when it senses a fluid flowing through it. Often, the flow meter has magnets on the propeller tips which pass by a sensor in the flow meter body, which generates pulses the computer monitors. The greater the number of pulses over a given time frame, the greater the water flow is. So the pressure loss across the filter relative to the rate of flow is a good indicator of how plugged up the filter is. To make a comprehensive filter status indicator, one must have two pressure sensors - one upstream of the filter and another downstream of the filter - and a flow meter to indicate when the water is passing through the filter. Then one needs a computer control to monitor the flow meter and both pressure sensor. One must then determine what conditions (flow rate and pressure differential) constitute a plugged filter condition. When those conditions exceed those metrics, then the computer turns the filter plugged light on or starts a flush cycle. One could also develop different level indicators from slightly plugged to fully plugged with perhaps eight or ten levels in between. This type of filter monitoring is widely used in industry and often done manually using two mechanical gauges and some way to ensure there is flow through the filter. Simply observe the pressure differential when the fluid is flowing through the filter and note the pressure difference. As for me and my refrigerator filter, I don’t use either practice since the filters for our refrigerator are very expensive - something like $58.00 each. And, of course, there’s only one place you can buy them from as they won’t fit any other model refrigerator. So what I do is run with the existing filter and don’t change it until it won’t pass water anymore. I know the filter has been fully utilized and don’t spend the money on a new filter unless I absolutely have to. Britt Britt Storkson may be contacted via e-mail to michele@worldwidedrillingresource.com For more information call: (270) 786-3010 or visit us online: www.geothermalsupply.com All New! Atlantis-Pro Vault • Traffic-Rated Capable • Simple installation • Trouble-free operation RE: “Billy Bob” Smith Article [Are Idiots Making the World Less Safe?, page 39, April 2026 WWDR] Billy Bob,To answer a couple of your questions: • Best By date - It is most important to things like meat and dairy. If it smells funky, toss it. Eggs are okay to use as fried or scrambled until pull date. Okay to use in baking for a while after pull date. Cereals, flour, etc. - If there are weevils in it, toss it. Try a couple of pieces - If too stale, buy new package. • Using credit vs. debit cards - Credit cards usually have more protection. • Safety - Carry a knife in a velcro closure case on your belt. The sound of it opening is distinctive. Years ago, I was in downtown Portland in the early evening. Three guys across the street were eyeing me. The sound of my knife case opening made them think otherwise. • On a plane - Yell as loud as you can. Sit down, stay seated. Listen to flight crew's instructions. Tom, Oregon Reader’s Response
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