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Hydraulic Valve

for use with a urinal-flushing cistern, no mains or battery power required

Price(s) From
£ 230.40
Price (incl. VAT)

Hydraulic Valve

for use with a urinal-flushing cistern, no mains or battery power required

Price(s) From
£ 230.40
Price (incl. VAT)

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Product Information

The Hydraulic Control Valve is an automatic urinal flush control valve. The valve uses a unique and simple mechanism which prevents water waste by ensuring that the auto-flush cistern is only filled, and can only flush, when the washroom is used.

The Cistermiser Hydraulic Control Valve consists of three main elements:

  • An adjuster (restrictor) screw which can be set during installation to determine the volume of water discharged into the cistern at each operation by altering the duration of the ‘open’ period.
  • A hydraulic accumulator which, if fully charged, will maintain an equal supply-pressure on both sides of the diaphragm. When pressure on the inlet side is reduced, as other services are used, the pressure imbalance causes the diaphragm operated valve to open.
  • A diaphragm operated valve which, when opened, allows water to pass to the urinal cistern.

The installer or user can adjust the time the valve remains open and therefore how long the cistern takes to fill and how much water is used. When the washroom is not being used the water supply pressure remains constant and the valve remains closed, preventing water passing into the cistern.

The cistern can therefore only flush during periods when the washroom is in use, eliminating unnecessary water consumption and cost.

Two types of Hydraulic Control Valve are available:

  • The Standard (STD) model is suitable for supply system pressures of between 0.5 and 6.0 bar.
  • The Low Pressure (LP) model is suitable for supply system pressures of between 0.3 and 0.5 bar (tank-fed systems, 3 to 5 metres head).

For use in buildings where the washrooms are vacant for long periods, an optional Hygiene Flush Attachment is available to ensure a regular flush cycle every 12 hours to prevent washroom odours. The bypass screw should be set to permit a slow drip into the cistern to initiate a flush approximately every 12 hours.  For correct operation it is essential that the siphon of the auto flushing cistern does not leak.

81mm W x 116mm H x 81mm D
Water supply - Standard model
Suitable for supply system pressures of between 0.5 bar and 6.0 bar (typically either mains water or tank-fed systems above 5 metres head).
Water Supply - Low Pressure model
Suitable for supply system pressures of between 0.3 and 0.5 bar (typically tank-fed systems between 3 metres and 5 metres head).
1/2" BSP (15mm)
Operating sensitivity
15% of supply pressure
Product Features
Automatic urinal flush control valve - for use with cistern
Unique hydraulic mechanism - no electrical supply or batteries required
Industry leader with more than half a million valves already installed
"Fit and forget" quality and reliability
Reduces water consumption and washroom odours
Standard and Low Pressure models are WRAS approved to ensure compliance with the Water Regulations

The Cistermiser Hydraulic Control Valve is installed on the supply pipe to the urinal cistern. The valve is activated by short-term pressure drops created by use of taps or WCs on the same supply.  The valve is normally closed; when it is activated it opens and water passes to the urinal cistern until the pressures on both sides of the diaphragm are equalised.  When the cistern is full, the auto-siphon will flush.

Here is a selection of documents, designed to ease specification and installation:

Technical Datasheet

Hydraulic Control Valve

Download PDF
Product Brochure

Commercial Washroom Product Brochure

Download PDF
Installation Guide

Hydraulic Valve

Download PDF
Installation Guide

Hydraulic Valve (pre-June 2018 incl. HSLP model)

Download PDF
Specification Wording

Cistermiser & Keraflo Specification Wording

Download PDF
Specification Catalogue

Cistermiser Specification Catalogue

Download PDF
Cistermiser Standard Valve Installation

Hydraulic Control Valve

Cistermiser IRC and STD valves

Hydraulic Control Valve

BIM objects are available for download from the NBS National BIM Library, in both Revit and IFC formats.

Click here to view Cistermiser products on the National BIM Library

Warranty Cover

Parts only warranty (no labour) for equipment purchased in the United Kingdom, Ireland, Isle of Man and the Channel Islands. Components of the unit which are proven to be faulty or defective in manufacture will be exchanged or repaired.

Warranty Period

1 Year from Date of Manufacture

Extended Warranty Period (available on Registration)

3 Years from Date of Installation


Extended Warranty Terms

To register and qualify for Extended Warranty cover, the Cistermiser product must be correctly installed with the Commissioning Checklist fully completed as itemised in the Installation Guide (included with the product), to demonstrate compliance with the product installation instructions.

Each Commissioning Checklist activity should be dated and additional warranty details provided to enable registration: product serial number, installation date, installation site address and the installer’s name and contact details.

Extended Warranty can be registered online (via the Warranty section of this website) or by completing and returning the Commissioning Checklist from the Installation Guide (included with the product) to this address: Cistermiser Ltd, Unit 1, Woodley Park Estate, 59-69 Reading Road, Woodley, Berkshire RG5 3AN.


Product FAQs

We’re here to Help!

I have completed the installation but there seems to be a continuous flow of water through the new valve. Why is that happening?

Things to check:

  • You may have installed the valve in reverse.

Solution: Remove the valve and fit with arrow (located at the base of the valve) in the direction of the water flow.


  • The water pressure could be too high for the valve; which may crush the bellows.

Solution: Purchase a valve that is suitable for your water pressure.


  • The valve is possibly being triggered by a drop in pressure from another room.

Solution: Change the pipework or change the valve to a Cistermiser IRC which can be powered by either batteries or mains electricity.

The valve looks to be permanently closed since I completed the installation! What can I do?

Things to check:

  • The cause could be the water supply.

Solution: Ensure that the water supply is turned on and is reaching the valve.


  • There could be a restriction on the outlet of the pipework into the cistern.

Solution: The pipework after the valve should have no other valves or petcocks fitted and should be open ended. Anything that has been fitted after the valve can cause back pressure which will stop the valve from opening.


  • There is probably no draw-off point. Is there a draw-off point that will activate the valve on a common 15mm supply pipe?

Solution: Change the pipework or change the valve to a Cistermiser IRC which can be powered by either batteries or mains electricity.


  • The water pressure could be too low for the valve.

Solution: Change the valve to one that is suitable for the water pressure on site.


  • The valve is not vented.

Solution: The valve does need to be vented as per the commissioning instructions – trapped air will cause a malfunction.


  • The restrictor screw adjustment is incorrect.

Solution: The restrictor screw should be approx. 3.5 turns STD and LP (Low Pressure) valves and 2 turns for HSLP (High Sensitivity Low Pressure) valves below the level of the main valve on initial installation (not flush or across the valve body).


  • The sensitivity screw adjustment on the HSLP (High Sensitivity Low Pressure) valve is incorrect.

Solution: Unscrew the brass cap then turn the screw anti-clockwise to increase the sensitivity.


  • Pipework problems. Is all pipework between the draw-off point (which is activating the valve) and the valve 15mm? If the pipework is larger than 15mm then the ability to detect a pressure drop will be reduced.

Solution: Change the pipework or change the valve to a Cistermiser IRC which can be powered by either batteries or mains electricity.


  • The valve is installed too far away from the draw-off point. Note: The valve must be no further away than 5m from the draw-off point.
    Distance reduces the ability of the valve to sense pressure changes.

Solution: If possible move the valve/draw-off point closer together. Change the pipework or change the valve to a Cistermiser IRC which can be powered by either batteries or mains electricity. 


  • Check the draw-off points used to activate the valve. Are the taps mixer or aerated? Such taps do not always register a significant pressure drop and may not activate the valve.

Solution: Purchase a Cistermiser IRC valve which does not rely on pressure drops and can be powered by either batteries or mains electricity.


  • Check that the Water supply is pressurised or pumped. A supply that immediately makes up a pressure loss as services are used, reduces the capability of the valve.

Solution: Install a Cistermiser IRC.

The flow through the valve is not enough / or too great! How can I adjust the flow?

Things to check:

  • The restrictor screw adjustment could be incorrect.

Solution: Turn the restrictor screw clockwise to increase the volume of water allowed through with each activation of the valve and anti-clockwise to decrease. If this has no effect then a Cistermiser IRC valve, which does not rely on pressure drops, should be installed. The IRC can be powered by either batteries or mains electricity.



I think either the valve is faulty or there is an installation problem! What should I do?

Things to check:

  • You have tried the above FAQs and the valve is still not working properly.

Solution: Remove the pipework from the outlet side of the valve, put your thumb over the outlet and activate the draw-off. If you feel a slight suction there may be a fault with the valve and you should contact Cistermiser Ltd.  Call our Customer Services Team on 0118 969 1611 for advice.



  • The valve is leaking.

Solution: The leak is coming from the join with the pipework. The bonded seal may have slipped out during the installation. Ensure that the bonded seal is fitted before tightening pipework.



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Whether you need help with product support or installation advice, our dedicated support staff are on hand today.

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