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Replacing or updating old plant room systems is a necessary evil for many local authorities looking to improve efficiencies and save on energy bills. The heating networks housed within historic council properties are often dated and inefficient, with many old open-spill, cast iron boiler systems having been in operation for decades without renewal
T
his was the case for Exeter City Council, which in 2015 commissioned North Somerset County Council to design, procure and install
on its behalf a refurbishment of the heating system at Exeter Civic Centre. Following nearly 40 years of use, the existing open vent heating system, which was supported by three cast iron boilers, was beginning to show its age. Both the chilled and hot water systems were experiencing premature failure and poor performance, so appropriate water samples were taken and a strategy was set to remedy the issues. The local authority called on the services of Phil
Shone, a local M&E consultant who had previously worked in partnership with the council on a number of projects. “We needed to move from an open to a sealed vent system, but due to the age of the system we had to approach with caution,” explains Shone. “We were very reluctant to aggressively flush the system as the feeling was it would likely do more harm than good. “The integrity of the network was at risk if we didn’t adopt the right approach, which we believed rested with a programme of consistent, long-term dirt separation and air removal via degassing, not heavy dosing,” he added. Following Shone’s recommendations, the three existing boilers, which were housed in one centralised plant room, were replaced with modern, energy efficient units, accompanied by Spirotech’s MA06A50W vacuum degasser and a BE150FM magnetic SpiroTrap dirt separator, to help ensure that the years of dirt (magnetic and non magnetic) build up was removed. Shone recommended products from Spirotech’s dirt separation and degassing portfolio following similar projects with the council to upgrade heating and cooling systems across its building stock. The issue of good water quality is paramount when working with modern, energy efficient boilers, as poor quality system fluid will have a detrimental effect on performance. Aluminium construction heat exchangers are particularly sensitive to poor quality water, and will eventually fail if steps are not taken to remove dirt and air. Through constant dirt separation, the magnetite and system sludge is removed so won’t hinder
March 2017
The efficiencies of the Exeter Civic Centre building have been transformed by assessing the needs of the system and installing a vacuum degasser and SpioTrap commercial sized dirt separator
boiler performance over the long term. The vacuum degasser will then work to extract air from the system, thus stopping the build up of air pockets, which affect performance and can cause noise. The reduction of air pockets also helps to improve system longevity by protecting the system from future corrosion problems.
Maintaining good water quality is an ongoing
consideration, and this is especially true when servicing and maintaining systems, as the introduction of any new liquid into the system must be properly treated and degassed, otherwise oxygen-rich liquids will give rise to associated problems. Air can also enter a system through a number of other factors like an expansion vessel being too small or located at the wrong point, an incorrect initial fill pressure, mistakes in system
design or pressure differences over regulating valves.
Such risks can be prevented through a good initial design; a key part of which is the recognition that water quality is at the root of a properly functioning system and must be treated as such for both new and retrofit installations to avoid premature system failure. Ted Watson, Spirotech’s area sales manager,
added: “We’ve worked alongside Phil and many other local authorities in the South West and Wales to help improve and update aged heating and cooling systems. We’re delighted that the installation at Exeter Civic Centre has been a success and that its investment in modern, efficient boilers is being protected and prolonged through correct system maintenance.”
www.heatingandventilating.net
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