Designing the Ecoplus PRT

When designing the Ecoplus PRT, the development team considered many possibilities before deciding on the final material selection. Their main areas of concern were finding a material that offered long-term resistance to hot water, excellent pressure resistance and an outstanding mechanical strength.

Having experimented with various traditional materials which, although effective, had their negative sides e.g. corrosion and excessive weight, the Ecoplus team became aware that Zytel® HTN was being used in the manufacture of automotive expansion tanks which indicated suitability in terms of high temperature, hot water and pressure resistance.

Ecoplus Limited made an approach to DuPont™ to discuss using DuPont™ Zytel® HTN high performance polyamide resin for the PRT material. Ian Welsh of DuPont™ Engineering Polymers, UK worked together with Ecoplus Limited in carrying out CAD analysis and moulding trials for prototype development. With the assistance of Dew Analysis (UK specialists providing analysis services for product development) and RAPRA (Europe’s leading independent plastics and rubber consultancy) the Zytel® HTN PRT prototype was subjected to a rigorous series of stress analysis and fatigue analysis tests, which it passed with excellent results. Another merit of Zytel® HTN is that it lent itself to the moulding process very well, as it can be moulded using relatively low temperatures (80-120°C) allowing standard moulding equipment to be used. If a competitive material such as a high temperature crystalline thermoplastic were used, it would require very hot, oil-heated tooling. 

Once the decision was made to use Zytel® HTN, the next step in the development process was to determine the optimal method of connecting the unit to the central heating pipes. The Ecoplus developers designed a unique over mould brass insert to be used with push-fit plumbing fittings instead of threaded compression fittings. Push-fit fittings were chosen as they eliminate the risk of stress cracks forming, which can happen when threaded compression fittings are screwed on too tightly.

Ecoplus Limited and DuPont™ Engineering Polymers are very proud of the unique design of the finished Ecoplus PRT, on which there are three patents pending.