Non-return Valve

Non-return valves (NRVs) protect a property from water flowing back towards it, especially in flood situations, when foul water can enter via toilets, sinks and other waste pipes.

The NRVs are easy to install - they can be simply pushed into the desired inlet in the property’s manhole chamber. Installation can be achieved in minutes, without any specialist expertise.

The NRV does not affect the usual flow of the pipeline, allowing water to be discharged as normal.

Benefits of the S1E NRVs:

  • Simple push-fit installation into existing manhole
  • Unobtrusive when installed
  • Two sizes available to suit DN100 and DN150 pipes
  • Universal for all pipe materials within the product’s size range
  • Can be installed in chambers with tight benching
  • Protects against back flow and pests, such as rats and other rodents
  • Stainless steel reinforced flap for added protection against rodent infestation
  • NRV100 WRc Approved

Installation Instructions

  1. When opening an inspection chamber or manhole the necessary safety precautions must be taken, especially lifting the manhole cover. This may take two people as it can be heavy.
  2. Once the manhole cover is lifted, the direction of flow should be determined. This can be determined by flushing a toilet in the property.
  3. A non return valve should be fitted to each of the flow pipes from the property.
  4. DO NOT install the NRV on the outlet of the chamber (where the water exits the chamber) as this will cause a blockage. Only install the NRV on the chamber inlets.
  5. Clean out any debris from the incoming pipes.
  6. Make sure the valve is positioned correctly in the pipe, with the flap position downwards and the hinge pivot point horizontal.
    1. 100mm version:The red locking tab must be positioned downward for normal use
    2. 150mm version: The locking latches must be positioned upwards for normal use.
  7. Push the NRV into the pipe inlet mouth. The NRV is fully in position once the plastic fin at the top touches the pipe or chamber wall.
  8. For maintenance use, the NRV can be locked closed, using the red tab on the front of the flap (100mm version) or the two latches at the top of the valve (150mm version). DO NOT over force upwards as this may cause damage to the unit.





1. The valve should be checked on regular intervals for efficient operation.
2. Check the valve flap opens freely and has not become dislodged or caught.
3. Clean out the valve of any debris that could affect the closing or sealing operation.


1. If the NRV is not installed and maintained in accordance with manufacturing instructions, the supplier assumes no responsibility for any damaged caused.
2. The NRV has been designed for domestic use and should be fitted as close to the property as possible.
3. The NRV has been designed to be fitted to one inlet, it should be not be fitted within a communal inspection chamber.

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