RA Tech UK Ltd invests to give our customers the confidence that hotun products perform to the highest levels and now hotun hiflo has UKAS accreditation.

Since its inception, the hotun hiflo dry trap tundish has been and always will be all about regulatory compliance. The recent hotun hiflo UKAS accredition test has established that hotun hiflo can cope with a flow of 18L/min and goes on to flow just under 20L/min UKAS NSF flow test report To see who stocks our hotun products take a look at our store locator here

When we first started our hotun journey we knew we had to comply with water and building regulations. To enable our product to be successful, full compliance was essential.

Our website identifies all the requirements applicable to unvented water heater installations in question? Our introductory product, hotun, was, designed to fulfill the role of a convenient, cost effective and simple way of dealing with the Pressure relief valve (PRV) discharge from small (less than 15 liters) unvented hot water heaters. Routing the discharge to drain via hotun, stops odours coming back up from the waste pipe and also?provides a complaint air break to prevent backflow issues.

As we found out, small unvented cylinders do not flow much water even when manually opened. Therefor our original product, hotun, was designed for this and has a rated maximum flow of 12L/min Soon after its launch, the question from installers asked, was hotun suitable for boiler PRV applications? One of the UK’s largest boiler manufacturers approached us about the application of hotun on the boiler PRV.?Tests showed that hotun could not cope with a full bore flow from a boiler. So we developed hotun hiflo which took the flow volume from 12L/min up to approximately 18L/min.

In house testing of hotun products

To establish a “working” maximum flow rate, we carried out extensive in-house testing. The boiler manufacturers did their own testing of hotun hiflo and concurred that it was capable of dealing with the full flow of their products PRV discharge. Of course, on site D2 pipe configurations (of which we cannot control) could have an effect on flow. We are dealing with a gravity drainage type system and the more convoluted the route the less overall volume it can handle.

Independent testing

NSF International Laboratories, a well know accreditation company, who also carry our WRAS approval tests, carried out the independent tests. NSF established the test methods to ensure repeatable and verifiable results They put the product on a calibrated cold water test rig. The installed configuration of pipework? forms the base test and gives comparable results for future like for like product tests . For the results and conclusions please click on the link:

The future

We can now proudly say that hotun hiflo has independently proven to deal with the claimed 18L/m. New, 2nd generation hotun products are in the pipeline and we hope to make an official announcement soon as to their launch date We will continue to put in further R&D to develop our products and welcome any feedback or thoughts our customers may have about our products Please either send us an email to info@hotun.co.uk call us on 01332 702678?

Get In Touch

Registered Address

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

T: 01332 702678
E: info@ratechuk.co.uk



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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