- Inadequate hot water capacity, either through undersized hot water cylinder or insufficient flow rates from boiler
- Insulation to storage vessels or pipework deficient or omitted
- Incorrect or incomplete flues
- The homeowner is unable to efficiently operate their systems
It is imperative that the specification has taken into consideration the size, type and construction of the property, the number of rooms, how many people will occupy the property, the type of occupier (for example, young families or the elderly) and the number of draw-off points – basins, showers and baths. The system should then be designed to consider the needs of the home.
Hot water systems may have provision for storage or may be of an instantaneous type – for example, a combination boiler. Hot water cylinders, where installed as part of the system, must be of sufficient capacity to provide hot water for all residents' needs. The hot water system should be able to reheat water from 10°C to 60°C between 2.5 and 4 hours depending on the fuel being used. Hot water should not be stored above 65°C – 60°C is recommended. Flow rates at draw-off points will range from 0.1 to 0.3 litres per second at 40°C to 60°C, depending on the draw-off point.
Cold water storage should be between 100-150 litres. When providing a feed to a hot water cylinder, storage should be between 200-300 litres. Storage should be based on 90 litres per expected occupier.
Space heating systems should be able to maintain the heating within a dwelling between 16°C for landings and halls, to 18°C for bedrooms and 21°C for living rooms. This is based on an outside temperature of -1°C.
The lengths of pipe runs should be kept to a minimum to avoid heat losses. However, all hot water cylinders and the first 1 m of pipework from the cylinder should be insulated. All pipework and water storage tanks in exposed areas, that is, roof spaces, garages and in unheated voids, should be insulated to reduce heat loss and to prevent condensation and freezing.
It is vital that flues are correctly installed, not only for appliance optimum performance, but also, more importantly, for occupant safety. Flue positioning must ensure that harmful gases are successfully expelled from the home. All flues must be complete and operational before occupation.
The homeowner should be shown how to use their heating/hot water systems and other mechanical devices within their new home. This should be part of the handover process of the new home. Adequate instruction should be given both through demonstration and by providing the manufacturers' operating instruction manuals. These manuals advise on the maintenance regime necessary to validate manufacturers' warranties.
Q. How do you avoid leaking, noisy plumbing systems and damage to pipework and electrical cables?
- Incorrectly installed pipework and electrical cables
- Systems not tested or commissioned before handover
Gas appliances must only be installed by CORGI (Confederation of Registered Gas Installers) registered plumbers. Electrical installations should be installed by NICEIC (National Inspection Council for Electrical Installations) registered electricians.
The installation of pipes and cables through timber joists should be notched and drilled to avoid compromising the integrity of structural members.
Holes and notch sizes should be kept to a minimum. Provision should be made for expansion of water service installations where required. Pipes passing through timbers should be insulated to avoid noise through thermal movement.
Pipes, ducts and cables should be securely fixed to walls at suitable intervals to prevent sagging, using purpose-made support brackets or clips. Pipework should be arranged to prevent contact with electrical cables.
All joints in pipework should be carefully made to eliminate leaks. Proprietary plastic pipe systems should closely follow the manufacturer's installation methods.
Pipes should not be cast into walls or floors; the use of a proprietary accessible ducting system is strongly recommended. Plumbing runs should not be located in timber-frame external walls (so as to avoid inaccessibility and the risk of condensation occurring on the pipes).
Pipes behind dry lining should be placed either horizontally below the valves, vertically within the radiator width from ceiling to floor level or within 150 mm of a wall junction or door frame. Similarly cables should be positioned so that future damage is avoided. If pipes and cables are positioned outside these safe areas, then to avoid damage they should be mechanically protected.
Cables running in or covered by thermal insulation should be de-rated to reduce the risk of overheating. The current carrying capacity should be reduced by 50% when the cable is fully surrounded or by 25% when the insulation is one-sided.
Holes in ceilings, formed by the installation of recessed lighting and mechanical devices, such as extractor fans, should not undermine the structural integrity of the building fabric. Either reposition or fit proprietary devices to maintain sound insulation and fire separation layers, especially to separating floors and walls.
All mechanical systems within the new home should be fully tested and commissioned. Pipework and storage intended for the transfer and conveyance of water should be filled and tested both cold and under the intended heat load. Visual inspection of pipework should be made to ensure that no leaks are evident. Heating and ventilation systems should be balanced to ensure optimum performance. Ducts to ventilation systems shall be fully connected to avoid noise and complete extraction.