Paragraph 3.60 of the Approved Document allows safety relief discharge pipes to connect to a soil stack if it can safely resist the temperature of the water discharged. Which materials are considered to be suitable?

Metal pipework, such as cast iron, is suitable.
For smaller hot water systems, BRE Information Paper 8/07 indicates that discharges can be made to PVCu stacks, provided that:
relief discharge is from domestic unvented hot water storage systems only – not combi boilers or sealed system boilers.
storage volumes do not exceed about 210 litres.
stacks are fully ventilated (ie. no stack cap or air admittance valve).
pipework complies with BS EN 1329-1:2000 or BS 4514:2001.

Paragraph 3.60 of the Approved Document says that if a discharge pipe is connected to a soil stack the discharge pipe should be either polybutalene or cross linked 8 polyethylene. Does this mean a polypropylene discharge pipe cannot be used?

As stated in its Introduction section, the guidance in the Approved Document is intended to provide advice on how to comply with the requirements set out in the Building Regulations and that “there may well be other ways of achieving compliance with the requirements”. The Department’s view is that it would be acceptable, subject to also complying with subparagraphs a, b and d of 3.60, for these pipes to be polypropylene to BS EN 1451-1, as recommended in BRE Information Paper 8/07.

Does an overheat cut-out in an indirectly heated vented system have to be non-self-resetting in the same way as energy cut-outs do in directly-heated vented systems and in unvented systems?

No, sub-paragraph 3.13a simply requires that in a vented hot water storage system, “for all indirect heat sources, an overheat cut-out to disconnect the supply of heat to the storage vessel in the event of the stored water overheating” is incorporated.

This is because, for indirect heat sources on vented systems, water overheating is more likely to be for operational reasons, for example, on solar-powered systems because of a very hot day and little hot water use. In such circumstances, self-resetting reduces the inconvenience to users, by resuming normal operation as soon as the operational circumstances change, without compromising safety. However, for direct heat sources, for example, electric immersion heaters, overheating associated with such devices is likely to be due to a failure of the device and the use of a non-self-resetting device would draw attention to the problem.

Do these requirements apply to small water heaters such as water heaters of less than 15 litres that were previously exempt?

Yes, the provision applies to all hot water systems. However, to reflect the lower risk associated with such a system, the work is not notifiable to the building control body nor is there a requirement for a certificate to be produced that states the work complies with the Building Regulations (unless the associated electrical work is notifiable for the purposes of Part P).

G3 – Hot Water Supply and Systems: What are the controls on the hot water supply and hot water systems?

With regard to supply, the provision requires that heated wholesome water (or softened wholesome water) is provided to any washbasin or bidet provided in or adjacent to a room containing a sanitary convenience, to any washbasin, bidet, bath or shower in a bathroom and to any sink provided in any area where food is prepared. In relation to hot water systems, the provision extends the scope of the previous safety regime to all types of system (not just unvented ones). This includes new guidance in the Approved Document to ensure that all parts of the system are capable of resisting the effects of temperature and pressure. In particular, this introduces guidance to ensure cold water cisterns supplying and receiving water from hot water cisterns are properly supported, following tragedies resulting from just such failures.

In addition, it also introduces a provision that all new homes (including those created by a change of use) have the temperature of the hot water supplied to a bath limited to no more 7 than 48°C. It’s likely that this will normally be complied with by the fitting of a thermostatic mixing valve (TMV).

When do I have to complete the Water Calculator?

We envisage that the Water Calculator will be completed initially when fittings and appliances are specified during the design stage and then revised if those fittings subsequently change. However, the provision does not require this, simply that a notice is given to the building control body within five days of the completion of work (or, where the building control body is an approved inspector, not later than the date on which the initial notice ceases to be in force under regulation of the Building (Approved Inspectors etc) Regulations 2010 if that is earlier). The regulations require only that the notice states the potential consumption, however, we envisage that, in practice, a copy of the completed calculation table will be submitted to the building control body.

G2 and Regulations 36 and 37 of the Building Regulations 2010 – Water Efficiency: What water efficiency targets now have to be met?

This introduces a minimum water efficiency standard into the Building Regulations for the first time for new homes. It requires that the average water usage of a new home (including those created by a change of use) is no more than 125 litres per person per day or 110 litres/person/day if required as part of the planning permission Estimated water usage must be calculated in accordance with the methodology set out in Appendix A of Approved Document G, unless ‘deemed to satisfy’ fittings described in Approved Document G are used.