Leaky Valve Heads Dribble Water Constantly
If you continue to see water draining or dribbling out of the sprinkler heads after the zone has shut down it usually means one of a couple things. It is either just low-head drainage, which is just the water left in the lateral line draining out to the lowest sprinkler heads after the valve has shut down, or you have a valve that is not shutting down completely.
If it is low-head drainage the water should stop after 2 - 10 minutes, depending on several factors such as the grade or slope of the landscape and how large the zone is. Low head drainage can be solved by installing sprinkler heads with built-in check valves that will stop the drainage of water after the valve has shut down. You could also install a check valve at a higher elevation point on the lateral line for that particular zone.
However, low head drainage is actually necessary for indexing valve systems, but not needed for electric valve systems. The reason why it is needed for indexing valve systems is that the index valve must have the pressure of water relieved to be able to switch to the next zone. I'm not saying that 100% of the water needs to be drained out, especially on a flat yard, but on a sloped yard some of the water does need to drain. An electric valve system does not need to have the water drained out of the lines, the electric valves will start and stop the flow water and the timer will tell it to open or shut.
Rain Bird makes sprinkler heads with built-in check valves called S.A.M. heads which stand for "Seal-a-matic". The heads will pop up with the flow, pressure, and force of an active zone, but will stop the slow drainage of water when the zone shuts down.
If your property is fairly level and/or the water continues to leak out for more than 10 minutes, then you may have a valve that is stuck open or not shutting down all the way. This is more noticeable on pressurized systems such as those systems using city water or those built with a pressure tank. To solve this problem you must locate the bad valve and replace the diaphragm or the whole valve. If you have the same brand and model you can get away with just removing & replacing the "guts" from the valve. If you don't have the same valve, you will have to dig a pit and cut the PVC to replace the entire valve.
Scott
http://www.autolawnsprinklers.com
If it is low-head drainage the water should stop after 2 - 10 minutes, depending on several factors such as the grade or slope of the landscape and how large the zone is. Low head drainage can be solved by installing sprinkler heads with built-in check valves that will stop the drainage of water after the valve has shut down. You could also install a check valve at a higher elevation point on the lateral line for that particular zone.
However, low head drainage is actually necessary for indexing valve systems, but not needed for electric valve systems. The reason why it is needed for indexing valve systems is that the index valve must have the pressure of water relieved to be able to switch to the next zone. I'm not saying that 100% of the water needs to be drained out, especially on a flat yard, but on a sloped yard some of the water does need to drain. An electric valve system does not need to have the water drained out of the lines, the electric valves will start and stop the flow water and the timer will tell it to open or shut.
Rain Bird makes sprinkler heads with built-in check valves called S.A.M. heads which stand for "Seal-a-matic". The heads will pop up with the flow, pressure, and force of an active zone, but will stop the slow drainage of water when the zone shuts down.
If your property is fairly level and/or the water continues to leak out for more than 10 minutes, then you may have a valve that is stuck open or not shutting down all the way. This is more noticeable on pressurized systems such as those systems using city water or those built with a pressure tank. To solve this problem you must locate the bad valve and replace the diaphragm or the whole valve. If you have the same brand and model you can get away with just removing & replacing the "guts" from the valve. If you don't have the same valve, you will have to dig a pit and cut the PVC to replace the entire valve.
Scott
http://www.autolawnsprinklers.com
posted by Irrigationman at
6:37 AM
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