St James Primary School, Elstead, Surrey — removal of the school’s biomass boiler installation and its associated equipment, and replacement with gas-fired condensing boilers, a new flue system, new plant room equipment and new controls, over a two-month programme.
Taking a biomass installation out
This project is unusual in the ComGas portfolio because the main task was removal rather than replacement.
Biomass plant occupies a building differently from gas plant. It is physically larger, it carries associated equipment beyond the boiler itself, and it leaves behind services, supports and a flue arrangement sized for a different fuel. Decommissioning it and clearing the space is a substantial part of the work before any new plant can be positioned.
The two-month programme at St James reflects that. It is the longest of the school plant room projects in this portfolio, and the difference is almost entirely in the strip-out.
Reinstating a gas-fired plant room
With the biomass boiler and its equipment removed, the plant room was rebuilt around gas-fired condensing boilers. The existing gas service was modified to suit, a new flue system was installed, and new plant room equipment and controls were installed and commissioned.
Changing the fuel changes the flue. A flue arrangement built for biomass cannot be carried over to condensing gas plant, which runs at lower flue-gas temperatures and produces condensate, so a new flue system formed part of the installation rather than an adaptation of what was already there.
Scope of works
- Strip-out and disposal of the existing plant room equipment
- Removal of the biomass boiler and associated equipment
- Modifications to the existing gas service
- Installation of new gas-fired condensing boilers
- Installation of a new flue system
- Installation of new plant room equipment
- Design and installation of new controls
- Pre-commission cleansing
- Testing and commissioning
- Builders work in connection with the mechanical installation
- Provision of record documentation
Why a school changes route
Schools that installed biomass a decade or more ago now hold assets that are approaching or past the end of their practical life, and the decision at replacement is not automatically to install the same thing again. Fuel handling, storage, servicing access and the availability of parts all weigh differently in a primary school than they did at the time of the original installation.
ComGas does not take a fixed position on which route is right — it depends on the building, the existing services and what the school is able to operate and maintain. At St James the outcome was a return to gas-fired condensing plant.
Handover
The system was cleansed, tested and commissioned, and record documentation was provided on completion.
Boiler replacement, fuel-route changes and plant room installations of this kind form a large part of the work ComGas carries out for schools across Surrey and the surrounding counties. Where a low-carbon route is the right answer for a site, that work sits within our renewable and low-carbon heating capability.
