Tower Bridge - Replacement of Heating System

The City invites Tenderers to submit a Selection Questionnaire for the provision of Replacement of Heating System at Tower Bridge, Tower Bridge Rd, London SE1 2UP.

Tower Bridge is a Grade 1 listed structure and important asset for the City of London Corporation providing a valuable contribution to London and the nation. As well as being an operational bridge facilitating over 700 bridge lifts a year there is a successful tourism, events and educational offering which fully supports the existing strategies, programmes and projects of the City of London and City Bridge Trust.

Tower Bridge is a combined bascule and suspension bridge; it consists of two bridge towers tied together at the upper level by two horizontal walkways. The bridge deck is accessible to both vehicles and pedestrians, whereas the bridge's twin towers, high-level walkways and Victorian engine rooms form part of the Tower Bridge Exhibition.

A fully detailed specification of works and design drawings will be produced for the proposed work, to enable a competitive tender to be sought. The form of contract will be the JCT2016 Intermediate Form of Contract without Contractor's Design Portion.

The Works.

The existing heating system comprises 4 gas fired boilers (2 in each pier underneath the Bridge) which feed a mixture of underfloor heating in the towers and radiators in on the high level walkways. The majority of the steel distribution pipework dates back to the 1980s and is well past its life expectancy, it runs within inaccessible vertical risers through the exhibition space.

The existing heating system is to be stripped out and removed, with the exception of the underfloor heating system, which is to be retained and chemically cleaned and flushed.

It is proposed to install new bespoke non-condensing boilers, delivered to site in kit form and built in situ. These boilers would be sized to heat all areas of the towers simultaneously and new structural platforms will have to be constructed to accommodate the additional heating plant provision. The single existing heating circuit would be replaced with two new LTHW heating circuits, namely 1) a reduced temperature 50°C circuit to serve the underfloor heating and 2) a higher temperature 80°C circuit serving the walkways and the additional radiator and radiant heating circuits. All associated plant including pumps, valves pressurisation units, expansion vessels will be replaced The existing heating controls no longer provide effective control of the system and will be replaced with a new automatic control system. The new automatic controls will need to integrate with Schneider Continuum new motor control panels located in each plant room.

The vertical risers will be dismantled to facilitate the installation of the pipework and re-built once the new pipework is installed. The draughts reported on the 4th floor/ walkways would be eliminated by the introduction of draught lobbies at both North and South Towers.