The manufacturing process for both hotun and hotun hiflo is certified to ISO 9001/2000 standards.
hotun is 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:

• Continuous applications of up to 95⁰C

• Intermittent use of up to 110⁰C

• Occasional use of up to 120⁰C


As there are no other products like hotun on the market, RA Tech UK Ltd have identified several different, but relevant, British Standards upon which to base our own in house testing.

To ensure fair and impartial verification, the tests have been repeated and independently verified by the University of Derby and the Institute for Innovation in Sustainable Engineering.

RA Tech UK Ltd have identified the following Standards upon which to base an acceptable and fair evaluation to establish its position in the market place;

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

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. This has been established as 12 l/min for hotun and 18 l/min for hotun hiflo. The 12 l/min is similar to many standard tundishes on the market (at 13 l/min) and will accommodate all under-counter (< 15litre) unvented water heater discharge rates and most larger unvented water heater discharge rates. Please check with manufacturer specifications to establish exact discharge rates expected for each installation. • Thermal cycling test – The device has been tested for temperature stability and performance when subjected to alternate volumes of water at 95⁰C then 10⁰C. The device remains effective after the test was finished • Drain test – The product passes the test if the pressure does not fall below 75mmWG after 5 mins. hotun passed this test. • Sanitary pipework test – The product was pressurised to 38mmWG and held the pressure at 38mmWG for 3 minutes. This is a pass on this test. [/av_textblock]