BOILERS & HOT WATER


When designing and installing hot water systems to meet building and water regulaons, the topic of the safe and visible discharge of relief valve water can pose some challenging quesons. Russell Armstrong, managing director at RA Tech UK, discusses the key quesons and consideraons


ne of the most common questions asked by engineers at all levels is; “can I compliantly discharge a boiler pressure relief into an internal waste pipe and if so, how should I do it?” The answer to the first part of the question comes as a simple “yes”; this is a widely accepted method for unvented cylinders and is also quickly becoming the method for boilers.


Best practice


It is the second part of the question that perhaps seems a little harder to answer. Key to the uncertainty on the routing of boiler relief valve discharge internally into a waste pipe or soil stack is that unlike G3 guidance for unvented cylinders, there is no comparable industry recognised direction for boilers. Ultimately, if G3 guidance is followed for a boiler install, then this is the best practice approach. The main difference for engineers to be aware of relates to the characteristics of the hot water discharged from the relief valve. Boiler relief valve discharge rates are significantly lower and of a more intermittent nature to than that of an unvented cylinder relief valve under operation caused by temperature. And, while the suitability of the chosen material for the waste and soil pipe system for receiving high temperature discharges is paramount


in both installations, there may be more material options available for boiler applications due to these different characteristics.


BSEE


Solving challenging installations O


Single product solution


One of the major benefits to engineers of routing boiler relief valve discharge internally into a waste pipe or soil stack, is the time and cost saving it provides. Traditional methods involve routing the pressure relief valve discharge through the building to an external termination point where provision would then need to be made for external access. Alternatively, in high-rise buildings the discharge may be routed through an internal service void to basement level where it would be terminated over an open-trap gulley. In either case, keeping the termination point inside, near the boiler, reduces the materials required and the time needed to install the system.


Installers have a number of tundishes, dry traps and pumps at their disposal to comply with water regulations, but recent innovations have introduced single product solutions which further the time and cost saving.


Dry-trap tundishes, such as the hotun, enable the compliant routing of discharge water from a relief valve to a local drain or waste pipe while providing backflow prevention and guarding against the risk of odours in a single product.


Provided there is an accessible soil stack located near the boiler bringing the point of discharge safely and visibly back inside via a dry-trap tundish offers a convenient, compliant and cost- effective solution.


Simplifying previously complicated installations is why the hotun has become a hugely useful product for engineers and installers. The focus on compliant installation is also why its officially accepted for use with boilers, water heaters and cylinders from the UK’s leading manufacturers.


www.hotun.co.uk


uOne of the major benefits to engineers of roung boiler relief valve discharge internally into a waste pipe or soil stack, is the me and cost saving it provides


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BUILDING SERVICES & ENVIRONMENTAL ENGINEER APRIL 2019 7


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