hotun technical specifications

hotun technical specifications

On this page, you can download our printable versions of our hotun technical specifications for our;

1/ hotun dry trap tundishes (100C and SF ranges)

2/ hotun detect – in-tundish alarm unit

hotun dry trap tundish

To download a PDF copy of our hotun technical specifications sheet please click the button below:

Materials and testing

The manufacturing process for both hotun and hotun hiflo is certified to ISO 9001/2000 standards.
hotun 100 and all SF range tundishes are fully WRAS approved.


Materials Specifications

  • Body, large top hat washer, large plain washer
    Made from heat resistant Acetal Co-polymer Engineering Thermoplastic
  • Bolt
    Purpose designed made from cold formed A2 grade freshwater 302 Stainless Steel
  • Spring
    Bespoke designed made from A2 graded Freshwater 302 Stainless Steel to EN 13906; BS 1726 – 1: 2002; EN10270-3 1.4310 Austenitic 302
  • Diaphragm
    High grade EPDM rubber to BS EN 681-1
  • Plain M3 washer
    Made from A2 grade freshwater 302 stainless steel
  • Nyloc Nut
    Made from A2 grade freshwater 302 stainless steel.

Temperature Rating Specifications

hotun is rated for use and is suitable for:

  • use up to 120°C


All hotun tundishes are manufactured to conform with the following standards:

BS EN 12380 (2002) (Air Admittance Valves) (pressure testing)

WRAS Test Code 2 (Tundish with air break to drain facility)

BS EN 1451 ? 1: 2000 (Plastics piping systems for soil and waste discharge (low and high temperature) within the building structure.)

BS 6700: 2006. (Design, installation, testing and maintenance of services supplying water for domestic use)

BS EN 274-2: 2002 (Thermal Cycling test)

BS EN ISO 228-1 Threaded end connections

BS EN 1254-2. Compression end connections

Performance testing criterion:

All hotun tundishes have been tested to operate in accordance with the following test procedures

RA Tech UK Ltd has carried out the following tests to ensure that the product reaching the market is of a standard to conform to the requirements of the relevant British Standards and regulations.

  • Trigger point test – To allow a slow/low volume discharge from the pressure relief valve to pass through the device without letting foul air enter the space. The trigger point for hotun is between 5ml and 25ml of water. The actual figure differs because of standard manufacturing tolerances. Through the range it has been proved that the device holds a small quantity of water before discharging the liquid through to the waste discharge pipe.
  • Full volume discharge test – To establish the maximum flow rate that will pass through the device without backing up and flooding over.
  • For testing performance please view it on our UKAS accreditation testing documents
  • Thermal cycling test –  The device has been tested for temperature stability and performance when subjected to alternate volumes of water at 95ºC then 10ºC. The device remains effective after the test was finished
  • Drain test – Pressurize to 100mmWG: The tests passed if the pressure does not fall below 75mmWG after 5 mins. All hotun products passed this test.
  • Sanitary pipework test – Pressurise to 38mmWG: The test is passed if the pressure holds at 38mmWG for 3 minutes. All hotun products pass this test.

hotun detect – In-tundish water detection alarm system

To download a PDF copy of our hotun detect features overview please click the button below:

Features and benefits
Features and benefits of hotun detect
  • Instant, audible (72dBA) and visual alarm for PRV, T/PRV and water storage tank overflows
  • Operational Features:

Set up/unit on indication, alarm stage warning, one touch battery condition check, auto low power alert


  • Auto-mute/Auto reset operation with manual mute/reset override
  • Helps save water and energy to heat the wasted water
  • Specifically meets the criterion in G3 Guidance Document para 3.55 (where discharges from safety devices may not be apparent e.g. in dwellings occupied by people with impaired vision or mobility, consideration should be given to the installation of a suitable safety device to warn when discharge takes place, e.g. electronically operated)
  • Fitted within seconds on ANY hotun dry trap tundish
  • Can be used on ANY system where an active alarm warning might be useful e.g. cold water storage tank overflows
  • Promotes conversations about the benefit of regular maintenance before any unnecessary breakdown occurs
  • The staged warning gives the installer a better chance of achieving a first-time repair
  • Senses temperature of water in four stages (up to 20°C, 21-60°C, 61-85°C & >85°C) to aid with fault diagnosis
  • Battery operated (2032 coin cell – supplied with unit) – Requires no specialist electrical knowledge to fit

Get In Touch

Registered Address

RA Tech UK Ltd
6 Nottingham Road
Long Eaton, Nottingham, UK

T: 01332 702678



In one simple fitting, hotun solves the problem of compliantly running a PRV valve discharge from a pressurised hot water cylinder relief valve or boiler pressure relief valve to a local waste or soil pipe.

hotun combines a tundish and a non-return valve to make a dry trap tundish which acts as a visible early warning device and prevents foul odours from escaping from the waste/soil pipe.


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