Genesis approached Enerza Solutions to investigate and remedy a serious problem in regards to high return temperatures at their Stratford Halo site.
The site consists of 730 apartments over one 44 floor tower and 4 blocks at ground level of retail units and communal areas with a tenant gymnasium. It is supplied by a local district heating energy station which provides heat to various local developments in the Stratford area.
The challenge was to locate and remedy the riser bypasses in the DH system which were of poor quality and incorrectly specified causing the high return temperatures.
The high return temperatures would have resulted in heavy fines from the energy supplier.
The flow temperatures from the supplier were entering the site at 90C and returning at 88C, at the time there was no meaningful monitoring of the site supplying data for analysis to gauge the current and live site status. Additionally, the BMS onsite did not reflect the actual site and data was inaccurate.
Another challenge we encountered was that there were no site schematics available to work from so we had to work out the various hydraulic circuits and control strategy by inspecting the site.
A further issue was that the 730 heat energy meters onsite were installed in conjunction with a poor mbus network infrastructure which made reading the meters a manual process as remote reading was not reliable and was only picking up 10% of meters.
The objective was to lower the return temperature and get real-time and historic data to the site operation.
The first issues we found causing the main high return temperatures were:
Riser bypass valves were under specified on the original install, consequently the valves had failed in all risers causing a constant flow on the return instead of regulating on temperature. These needed changing first as this was having a masking effect on other potential issues downstream of the circuit.
The plant buffer vessel pipework needed modification to allow for correct buffer use rather than direct flow through the vessels.
The HIU units fitted onsite were suffering from a design fault where flow issues were being experienced causing loss of heat services to the tenants. Although this was then remedied by the manufacturer by installing bypass valves, these also failed causing constant flow.
We needed to re-establish communications and build a display/control dashboard on the Enerza/BMS cloud system to allow for accurate display of data and historical logging, with alarming and easy to use graphical display for O&M purposes and reporting for GHA.
Re-design and refit of the mbus metering backbone to enable and provide remote reading for the client. This involved having to initialise a master slave system over 7 x master/slave units to allow for remote reading.
Halo point monitoring example
Being able to monitor and control the site to pinpoint alarms and site failures and achieve steady running.
An increase in plant life expectancy/reducing breakdowns by avoiding irregular running cycles.
Being able to visualise the site and any alarms and issues from anywhere, with email alarms also sent on activation.
Having the ability to retrieve meter readings and bill some 800 tenants per annum over 750 apartments has generated a billing income of £600,000 per annum.
Dropping the return temperature by 10deg to Engie avoided heavy fines of at least £25,000 as well as relieving system stresses.