Nelson Service & Support
Nelson 700 Series (All Models 700 & 760) Horse & Livestock Waterers
Dripping & Overflow – Nelson 700 Series Automatic Waterers
A water that drips when it should be completely shut off most likely has sand or other settlement in the control valve. Other causes could be an obstruction which interferes with movement to the pivot beam or the control valve could be out of adjustment. Check the easy ones first to look for an obstruction. To look for an obstruction, start with the cover and drinking bowl removed. Double check that the cross-beam screws are tight. The counterweight must be securely mounted on the pivot beam. Next examine the brass pivot shaft. If a Qatar key is missing and the brass pivot shaft is out of position reposition the shaft and replace the key.
Check the position of the beam lock lever making certain it does not interfere with the movement of the pivot beam or drinking bowl. Finally check the instructions below the drinking bowl that prevents the free movement on the beam or the drinking bowl. The brass shut off valve on the water supply line is usually the obstruction. Inspect the water supply line for interference with any moving parts. Be careful not to bend the cooper tubing moving the water supply line. Remove the cover and drinking bowl to adjust the control lever.
Then using a corner screwdriver turn the control valve adjustment screw until a very small stream flows from the waters spout tube and breaks up into drops about three inches below the two outlet. Then turn the control valve adjustment screw a quarter turn counterclockwise. This will cause water to stop flow-ing and your adjustment is completed. If the water is still dripping you need to remove the inline filter and the control valve, because a torn or missing inline filter can result in sediment traveling downstream to the control valve. To remove the filter for inspection you need to shut off the electric power to the water and shut off the water supply at the brass shut off valve.
Next unfasten the flare fitting connecting the brass shut-off valve to the copper water supply tube. Then remove the nylon water filter located just inside the copper water supply tube. A tool such as a pocket knife or needle nose pliers may be required. Now if you see settlement you need to clean and replace the filter. Also inspect the filter carefully for tears and if torn replace the filter. Next remove the control valve to inspect for sediment and more involve parts, with the power and water still off remove the lead weight. Then remove the cotter pin from the tapered end from the brass pivot shaft and slide the shaft out. The pivot beam and cage may then be removed as a unit. Remove the brass hex nut that secures the control valve to the bracket.
Next unfasten the water supply hose and the copper water spout tube from each end of the control valve. Unscrew the valve cap from the bottom of the control valve to remove the valve stem and stain-less steel spring. Now rinse the individual valve components thoroughly with water. Sediment impeding the control valve may not be visible. Inspect the valve body by holding it up to the light. Examine the valve body for cracks.
A black O ring is located on the valve cap at the base of the threats. Closely examine the cavity the valve stem occupies. It should be smoothed, replace if there are any nicks or gouges. A small black O ring is located below the head of the steam. Before reassembling the control valve, lubricate the valve stem with a little amount of petroleum jelly. It’s important to tighten the brass screw at the end of the valve stem. Insert the stem followed by the spring into the valve body. Tighten the valve cap with your hands. Do not use a wrench. Nelson sells individual valve components or the entire balance replacement parts. Refer to your parts list when ordering parts.
When replacing the control valve make certain water flows through the valve in the proper direction. Otherwise it will not shut off. Connect the water supply tube to the import of the control valve and the copper water spout and the copper water spout tube to the out port. When reassembling the pivot beam to the cage to the cross beam, it is much easier to insert the brass pivot shaft with the lead weight in control valve adjustment screw removed. Now adjust the control valve and your problems with drip-ping and overflow should be fixed.