Identification of Critical Issues
Proactive Problem Solving
Ensuring Resident Comfort
Background
The new build development includes over 120 residential units along with some commercial units. A heat network provides heating and hot water via HIUs to residential units from an onsite centralised energy centre. The heat generation is managed by three gas condensing boilers, which are supported by two 1000L thermal stores to assist during peak demand times. FairHeat was engaged to oversee Building Management System (BMS) points and conduct a LTHW system Load Test in the Energy Centre.
Challenge
During the initial phase of system monitoring, FairHeat identified discrepancies in the Building Management System (BMS). Several sensors were either missing or not communicating effectively with the BMS. A subsequent dynamic Load Test, simulating peak demand conditions, further revealed that the network was delivering water at temperatures significantly below the desired levels. This test brought to light multiple design-related challenges, including issues with pump installations and thermal store discharge rates.
- Building Management System (BMS) Discrepancies: FairHeat identified issues with the BMS where several sensors were either missing or not communicating effectively with the system.
- Suboptimal Water Temperatures: A dynamic Load Test revealed that the network was delivering water at temperatures significantly below the desired levels.
- Pump Installation Issues: The network pumps were installed without Non-Return Valves on their outlets. This led to backflows when the pumps were deactivated, which could potentially damage the primary pumps and compromise the system's ability to maintain the desired differential pressure during Load Tests.
- Thermal Store Discharge Rates: The thermal stores had inlets and outlets that were not adequately sized. This design flaw limited their charge and discharge rates, preventing them from meeting the variable demands of the network.
- Boiler Sequencing Uncertainties: Due to the issues with the thermal stores' discharge, there were doubts regarding the boiler sequencing methodology. It was crucial to ensure that the boilers were functioning in alignment with their specified Description of Operation.
FairHeat Solution
One of FairHeat’s primary concerns was the installation of network pumps without Non-Return Valves on their outlets. This oversight led to a backflow through the main and auxiliary pumps when they were deactivated. The subsequent backflow not only increased the operational speeds of the jockey pumps but also posed a risk of damaging the primary pumps. This compromised the system’s ability to maintain the desired differential pressure during the Load Test. To rectify this, FairHeat recommended to install non-return valves on all the network pumps, ensuring a unidirectional flow and preventing any potential backflow.
Furthermore, it was observed that the thermal stores were equipped with inlets and outlets that were not adequately sized, thereby limiting their charge and discharge rates. This design flaw hindered the thermal stores’ ability to discharge at a rate fast enough to cater to the variable demands of the network. To address this bottleneck, FairHeat advised to replace the inlet and outlet pipes of the thermal stores with ones of appropriate dimensions, ensuring optimal flow rates.
Lastly, due to the aforementioned discharge issues with the thermal stores, there were uncertainties regarding the boiler sequencing methodology. It became imperative for the assigned contractor to validate and ensure that the boilers were functioning in alignment with their specified Description of Operation, guaranteeing optimal performance and efficiency.
Results
FairHeat’s involvement led to the identification of critical design and installation oversights that could have severely impacted the efficiency and reliability of the heat network. Recommendations were made to rectify these issues, including the installation of non-return valves on network pumps and modifications to the thermal stores’ inlet and outlet pipes. While remedial actions at this stage would incur additional costs and potentially delay the project’s completion, these measures were deemed essential to ensure the system’s long-term efficiency and reliability. The case underscored the importance of early expert involvement in such projects to pre-emptively identify and address potential challenges.
Early involvement allows for a thorough review of design plans, equipment specifications, and installation procedures. By catching potential oversights or inefficiencies at the outset, FairHeat can recommend adjustments before they escalate into more significant, costly, and time-consuming issues. This proactive approach not only ensures that the project adheres to best practices but also can lead to substantial savings in terms of time, resources, and finances. Moreover, early consultation can foster a smoother project execution, minimising disruptions and ensuring that the end result aligns with the project’s objectives and quality standards.
Load tests play a pivotal role in assessing the efficiency and reliability of heating systems. By simulating peak demand conditions, these tests provide an actual evaluation of how the system will perform when residents rely on it the most. Stable temperatures are crucial for resident comfort, especially during extreme weather conditions. Load Tests help in identifying discrepancies in temperature delivery, ensuring that residents receive consistent and optimal heating. Furthermore, Load Tests can uncover design flaws, equipment malfunctions, or installation oversights that might compromise temperature stability. By addressing these issues, projects can guarantee that residents enjoy a comfortable living environment, free from temperature fluctuations or heating disruptions.
Gain more insight on the impacts of building-level heat Load Testing on heat network performance in the following research written by Ryan Harris, Consulting Engineer at FairHeat.
