The hotun approach to product development

Why develop an already good product?

From this

The hotun 100 range

To this

hotun sf range of dry trap tundishes

The hotun SF range

A Blog by Russell Armstrong (the inventor of the hotun dry trap tundish)

When I first started on product development for hotun, it was with one application in mind, that of connecting the PRV discharge from a small unvented hot water cylinder to a local waste pipe or drain, little did I know about the possibility and wide & varied applications there were going to be!

Investment – faint heart does not win fair maiden

Once the design had been tested with 3D technology prototypes, we proceeded (at some considerable expense), to commission the relevant tooling & IP protection. For a one-man band plumber, such as myself, this was a huge investment. In fact, I could have brought a modest-sized house in my local city (Derby) for the money I put into our first product. So I put what was, in effect, our life’s savings (myself, wife and a loan from my parents) into the venture.

I assure you this is not for the faint-hearted!

Within weeks of launch, I was asked by an installer in Scotland, if hotun was suitable for boilers? The long and short of it was a split decision by two boiler manufacturers. Luckily for me, it was Worcester Bosch who said my idea had potential and could they test hotun for use on their boilers

hotun 15/22 hw100C

Product Development – Upgrading

The hotun (15/22) did not cope with the full flow! We found that due to its design it would pass comfortably 12 liters per minute & at a push 16LPM but not the 18LPM that came out of the Worcester boiler.

Undaunted, I went away to develop hotun and came up with hotun hiflo (15/32). In our extensive tests, we found that the hiflo unit could easily cope with 18LPM and went upwards of 20-22LPM at a steady state full flow volume.

The two most important aspects of the performance of our dry trap tundishes were, could it handle trickle flow (valve opens to let water pass into the waste pipe) and did it cope with water at full bore discharge, because that was part of the regulatory criterion.

hotun hiflo 15/32 hhw100C

Therefore we had a resounding yes from Worcester Bosch, who then stated that they would accept hotun hiflo for use with their boilers!

Happy days? – You would have thought so

However, plumbers do not appear to be happy to accept your first offerings at face value. Right from launch, the market had taken our concept and were already giving us feedback about our products, some in a constructive manner others less so. That being said we knew there were several points that would take us forward if only we could incorporate them to achieve the following design & business elements

  1. They worked better than existing
  2. Still looked aesthetically pleasing (for a tundish!)
  3. Could still be easily manufactured
  4. The manufacturing cost was within reasonable limits so as to be affordable to the end user


What we achieved (and it took some 18 months of development work) is a remarkable collaboration with one of the UK’s best-known push fit range of pipe connectors, JG Speedfit. They were more than delighted to be associated with our product and gave us permission to use their “Speedfit technology” branding.

We looked extensively at flow dynamics both on the inlet and outlet side to see what could be done to improve flow.

With the “100” range we stated clearly that our units would flow 12 & 18LPM respectively and gave guidance as to what that meant but were pushed from day one to do more. The plumbers out there were putting our products on PRV’s that discharged almost 25LPM! So they demanded more from the hotun (which is an absolute compliment when you think about it, considering that before we came along they had no other single product to do the job!)

Onwards & Upwards

Be that as it may, plumbers shouted to us to be better, if 12/18 was good, 25 would be better! Please give us more & more. It is a testament to our success that the product had found a good market and rather than say it was a rubbish product, they just wanted it to be better

Unfortunately, due to reasons of confidentiality, we couldn’t tell people about our development plans, no manufacturer would. We said we were listening and that, when the time was right, we would bring something to the market. It’s an interesting dichotomy, having introduced an invention that grabbed the market by storm, got everybody excited about the new possibilities, they demanded that it could still be better.

Funnily enough, we agreed that things could be better. If we could achieve this 25LPM landmark, our product would have an immediate wider appeal. However the market was impatient for the new product, but they didn’t understand how long it takes to go from iteration 1 to iteration 2

When you change things everything has to be re-tested, that costs money, lots of it and as an embryonic company money was in short supply, this delayed things, so much so that although we had tested and developed our new range, the cost of tooling would have to wait and wait it did (frustratingly for us)

But as the infographic (below) shows the wait and product was worth it. With flows up from 12 & 18 to 16 & 25LPM with an additional 22/32 (hotun XLSF) added into the range at a rated flow of an incredible 40LPM we now boast a market leading range of dry trap tundishes that will cope with almost every application that there is out there! (well in the domestic to medium commercial market place)

Are we pleased with this?

Hell yes!

What were we asked and what did we achieve?

We were asked to;

  1. Include a nut & olive on the 22mm outlet version
  2. Provide an inlet connection
  3. Improve flow to cope with ANY application
  4. Give alternative (less expensive) options for connection to the discharge
  5. Keep the costs of the unit affordable to the end user (and from a supply chain point of view keep margins)

What did we achieve?

  1. All models (100 & SF) with a 22mm outlet now come with a nut & olive supplied as standard
  2. The SF range has an inbuilt speedfit connection (we still sell the threaded inlet 100 range for those that dont want speedfit)
  3. We improved flow from 12 & 18 LPM to an incredible 16, 25 & 40 LPM respectively
  4. The outlet on our unit is now compatible with industry standard push fit waste systems (as well as universal compression, it is after all universal for a reason!)
  5. The new product range sells, at a merchant near you, for between £18 & £21

Have we achieved our goals?

Well, only you can decide. All we can say is that we are pleased with the outcomes

hotun 100 & SF range selection table

The market spoke, we listened, we developed!

#hotun – Not just a tundish

hotun sf range of dry trap tundishes

RA Tech UK Ltd announces new appointment

Andy Pattison joins

RA Tech UK Ltd


Business Development Director

3 January 2019

Following a significant period of growth, RA Tech is very pleased to announce the appointment of Andy Pattison as Business Development Director 

Andy brings a wealth of experience and industry knowledge to the RA Tech team, having spent more than 30 years working in heating and renewables, in sectors covering installations, maintenance, sales and manufacturing.

RA Tech Managing Director, Russell Armstrong, says: “The recent changes we’ve made to our business and distribution model helped us end the year on a high and open up many opportunities for 2019. Andy has worked for some of the industry’s best-known names such as Help-Link UK, HomeServe and Kingspan and we believe his experience will help further strengthen our market position.

“We’re delighted that Andy has chosen to join us, it gives further credibility that our company future, vision, products and plans are a compelling story able to attract someone of his caliber and standing in the industry”

Andy adds: “This is a really exciting time for me to be joining Russell and the RA Tech team. Since Russell invented the hotun, the product range has been incredibly well received by installers, and the team has made outstanding progress getting the products stocked nationally by major distributors and merchants. Sales are continuing to grow every month and I’m looking forward to working with the team to build on this success.”

RA Tech UK Ltd, the creator of simple and long-term solutions that solve common heating and plumbing problems has seen considerable growth in sales over the last six months, the product remains a firm favorite of many installers, we get many installers wanting to add their projects featuring the hotun dry trap tundish on to our hotun gallery


hotun sf range of dry trap tundishes

The New hotun SF range is launched

The New hotun sf range is launched

5 November 2018

RA Tech UK Ltd, the creator of simple and long-term solutions that solve common heating and plumbing problems, has unveiled the next generation of its best-selling hotun dry trap tundish

The new hotun sf range has been designed to make installation achievable in just a few seconds, with the addition of industry-leading JG Speedfit Technology.

The revolutionary hotun was invented in 2015 by RA Tech Managing Director and experienced plumber, Russell Armstrong, to easily enable installers to discharge unvented water heaters and cylinders Temperature and Pressure Relief Valves, and boiler Pressure Relief Valves, compliantly to a local waste or soil pipe. It also eliminates the risk of odours returning from the foul drain.

Officially accepted for use with boilers and cylinders from the UK’s largest manufacturers, the award-winning hotun dry trap tundish has benefitted from further development. The new range provides a simple solution for boilers, plus small and large unvented cylinders, offering 15mm and 22mm pushfit sizes on the inlet and 22mm compression and 32mm pushfit on the outlet.

All models are WRAS approved and independently tested for flow rate by UKAS test house Kiwa. As well as coping with trickle and low volume flow discharges, the range now boasts flow rates of 16LPM for hotun sf (15/22), 25LPM for the hotun hiflo SF (15/32) and 40LPM on the hotun xlsf 22/32 model, so there will always be a model that will suit a full flow discharge for your application.

Russell Armstrong says: “The hotun is a compact, open-sided tundish that cleverly incorporates a unique and patented in-built non-return valve. It’s an incredibly useful product for any installer to have in their armory, and the development of the new hotun sf range with push-fit fittings now makes it even quicker and easier for installers to use.”

To find the WRAS certificate click here WRAS certificate SF range 29187

For the UKAS KIWA test results click here

Ella Gibson Rides to Victory

RA Tech are proud to sponsor #TeamGBTX transplant cyclists and Ella Gibson has just ridden to Gold in the British Transplant Games in Birmingham

Read, in her own words, her story

All we can say is what an amazing young lady, what fortitude and what a result!

Go Elle Go

Ella’s saviour and living donor – Her Mum!


Ella Gibson Story

Please if you are not already signed up to the organ donation list and this story has inspired you and it only takes a few minutes please follow this link

hotun history cabinet

hotun hiflo UKAS accreditation

hotun hiflo UKAS Accreditation

hotun hiflo UKAS accreditation tests

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.

hotun hiflo UKAS accreditation logo

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 here

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 call us on 01332 702678