Stephanie Allchurch, Product Development Manager at Altecnic, a member of the Hot Water Association, takes a closer look at G3 compliance.
Many engineers are experienced in installing both boilers and hot water cylinders. However, due to the strict safety requirements for an unvented water heating system, it is a legal requirement for plumbing and heating engineers to have a G3 qualification if they want to install unvented hot water cylinders.
The guidance to G3, which can be found in the Building Regulations, explains in full what electrical and water safety controls are necessary to demonstrate compliance.
The installation must be carried out by a competent person. This is defined as a person who has undergone the required training and can has demonstrate competence, through attaining the G3 unvented qualification, supplying evidence of ability, and through prior experience and knowledge.
Once proven, the person may join an independent competent person scheme which includes insurance liability, code of conduct, and a complaints procedure. Membership of a competent person scheme also removes the need for the installer to notify individual installations directly with Building Control.
Prevention of stored water reaching 100°C
The unvented water heater should have two independent safety controls:
Provision of safe discharge from safety valves
Any safety valve fitted to the unvented water heater must be plumbed to deal with any discharging water from the valves should they:
They must also:
The guidance to G3 includes information on the correct sizing and installation of discharge pipes.
Following installation, an unvented water heater must:
Why is G3 compliance so important?
With no expansion control on an unvented system, if the cylinder is continually heated or over-pressurised and has none of the required safety or control devices as prescribed in G3 or the Water Regulations, the cylinder could reach a point where it will discharge steam or rupture. Therefore, installation by a competent person who has been trained and understands the requirements, along with the correct controls, is vital for a safe install and continued use.
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