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

1/ hotun dry trap tundish

To download a PDF copy of our hotun technical specifications sheet please click the link above:


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

RA Tech UK Ltd has carried out the following tests to ensure that the product reaching 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 accreditation page
  • 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 – Presurise 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.

2/ hotun detect – In-tundish water detection alarm system

To download a copy of the features and benefits sheet please click on the link above

Please click the link to download a printable PDF copy of our hotun detect  a copy of hotun detect Installation and Maintenance Instructions

RA Tech UK hotun detect features and benefits

Features and benefits of hotun detect

  • An audible and visual alarm of the relief valve passing water, indicating something is wrong with the system
  • 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)
  • Helps save water and energy to heat the wasted water
  • 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
  • Simple hook-on design can be easily fitted or retrofitted to ANY hotun dry trap tundish
  • Requires no specialist electrical knowledge to fit
  • Battery operated (2032 coin cell – supplied with unit)