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How to set an impact sprinkler

Updated: 23 October 2026

The jet is hitting the fence, or the head is walking a full circle when you wanted a wedge beside the path. How to set an impact sprinkler is the pin, the two stops, and the screw that breaks up the jet, in that order. The head is already in the garden. This page does not rank the eight listings in the [impulse sprinkler comparison](/hub/garden-watering/impulse-sprinkler). If a temporary use ban is in force, setting the collars does not make a mains sprinkler lawful. Read the [sprinkler hosepipe ban](/hub/garden-watering/impulse-sprinkler/sub/impulse-sprinkler-hosepipe-ban) page before you open the tap. A qualifying purchase can earn a commission at no extra cost to you.

The jet is hitting the fence, or the head is walking a full circle when you wanted a wedge beside the path. How to set an impact sprinkler is the pin, the two stops, and the screw that breaks up the jet, in that order.

Our top picks

FANHAO FANHAO heavy-duty sled

Best overall

FANHAO FANHAO heavy-duty sled
7.1/10about £37.99
View offer
Gardena Gardena Comfort 8141-20

Rank 2

Gardena Gardena Comfort 8141-20
7.5/10about £25.55
View offer
Holzsammlung Holzsammlung ABS spike

Best value

Holzsammlung Holzsammlung ABS spike
6.4/10about £9.98
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On this page
  1. 1.The four controls on an impact head
  2. 2.Set the arc before you chase the distance
  3. 3.Shorten the jet without moving the sprinkler
  4. 4.When this is no longer a setting job

The four controls on an impact head

Most impact heads give you the same four jobs. The trip pin is a wire, a V-clip, or a flip-up lever. Up, it misses the stops and the head can travel the whole circle. Down, it strikes the stops and the head reverses, which is a sector. The collars are those stops. Slide them closer and the wedge gets narrower. The diffuser is a screw you wind into the jet so the stream frays and falls short. The deflector tips the jet up or down. Easy Garden Irrigation and Lawn Tiger's sheet use those names. Gardena's UK page uses a large knob for throw and a sector from 25 to 360 degrees. An arc aimed at the fence is still wrong after you have only shortened it.

Set the arc before you chase the distance

Start with the water off. Point the nozzle at the middle of the area you want wet. For a full circle, put the trip pin or V-clip up so it clears the collars. For a wedge, put the pin down and slide the collars to the two edges, such as the path and the bed. Closer collars mean a narrower slice. On a Gardena dial, turn toward the sector you want. The UK page's range starts at 25 degrees, so a very thin sliver may be narrower than the dial will hold. Turn the head by hand through the arc, still dry, and watch whether the nozzle clears the fence. Rain Bird says not to oil the head. A STYDDI review that oiled a stuck head is a complaint, not a step.
FANHAO FANHAO heavy-duty sled

Testsieger

FANHAO FANHAO heavy-duty sled
7.1/10about £37.99
View offer

Shorten the jet without moving the sprinkler

Once the arc clears the fence, wind the diffuser into the stream a small turn at a time. The jet should fray and land shorter. Wind it out and the stream reaches further. Tip the deflector down to pull the wet edge back from a path. FANHAO's bullets describe a diffuser from mist to jet. Mist is a shorter, wetter circle near the head, not a way to water the far corner evenly. Change one control, watch one edge for a minute, then change the next. An impact head wets a circle or a wedge. The dry corner of a long lawn is the wrong tool, which the buying guide covers.

When this is no longer a setting job

If the leaflet is tiny, use the four words anyway: pin, collars, diffuser, deflector. Do not drill the nozzle, and do not oil the bearing. A leak at the inlet looks like a setting fault. Water runs down the spike and the jet collapses. One FANHAO review seated the inlet washer with a spanner. Tighten the connector until the inlet is dry, then judge the arc again. Stop when the pin is down, the inlet is dry, and the head still parks on one side. That is pressure, debris, or a broken trip. Stop when the head ran for days and then seized. Collars will not restore a failed mechanism. The Water Supply (Water Fittings) Regulations 1999 require backflow protection on a hose union tap, and these sprinklers do not include that valve. A new tap is a plumber's job, not a trip pin.

Common questions

How do I get a full circle?
Lift the trip pin, V-clip, or flip-up wire so it misses the collars, then turn the head by hand through a full turn with the water off. On the Gardena Comfort, use the sector control toward 360 degrees.
How do I water only a wedge beside a path?
Put the trip pin down so it strikes the collars, and slide the collars to the two edges you want, such as the path and the bed. Closer collars make a narrower arc. Gardena's dial starts at 25 degrees on the UK page, so a thinner sliver may be beyond that model.
How do I shorten the jet?
Wind the diffuser screw into the jet so the stream breaks up and lands shorter. A deflector tipped down pulls the wet edge back without moving the sled. FANHAO's mist-to-jet wording is that screw. Shortening the jet does not move a wedge that is still aimed at the fence.
Should I oil it?
Leave the arm dry. Rain Bird's impact sheet lists lubricant as a cause of failure and tells you not to oil the head. A STYDDI review in which someone oiled a stuck head records a head that had already failed. Oil holds grit. Rinsing debris out is as far as a setting job goes.
Do I set it with the water on or off?
Set the pin and the collars with the water off, and prove the arc by turning the head with your hand. Trim the diffuser with the jet running, because you need to see where the drops land. If a hosepipe ban is in force, do not open the tap at all.
When is this no longer a setting job?
Stop when the pin is in the right place, the inlet is dry, and the head still will not finish the arc. That is pressure, a leak, debris, or a broken trip. Collars will not repair a mechanism that worked for days and then stuck. A new outdoor tap is a plumber's job under the water fittings rules.

Related pages

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Sources

Public UK sources listed in the research digest. amazon.co.uk prices, stars and review counts are the saved listing lines for these eight products. Last reviewed 22 October 2026.

  1. Gardena UK, Comfort pulse sprinkler 8141-20 (retrieved 22 October 2026)
  2. Water Industry Act 1991, section 76 (retrieved 22 October 2026)
  3. Water Use (Temporary Bans) Order 2010, article 3 (retrieved 22 October 2026)
  4. Water UK, hosepipe bans FAQ (retrieved 22 October 2026)
  5. Thames Water, temporary hosepipe ban (retrieved 22 October 2026)
  6. Water Supply (Water Fittings) Regulations 1999, Schedule 2 (retrieved 22 October 2026)
  7. Ofwat, water pressure (retrieved 22 October 2026)
  8. Easy Garden Irrigation, impact sprinkler guide (retrieved 22 October 2026)
  9. HydroSure 1/2 inch garden impulse sprinkler (retrieved 22 October 2026)