Water Source Heat Pumps

What are the stages of a closed loop water source heat pump installation? 

A closed loop water source heat pump system will typically follow this process:  

1. Desktop study – the first stage of a closed loop water source heat pump system is to ascertain whether the water source has the capacity to supply the required thermal energy. This will involve calculating the volumetric heat capacity of the water body and also the replenishment rate. 
2. Design – once it is confirmed that the water source can supply the thermal energy for the proposed system, the design work starts. This will typically take 4-6 weeks and it is the most important step – mistakes during installation can usually be corrected but mistakes in the design of a system are much harder to resolve.
3. Site set up and planning – the third stage of installing a closed loop water source heat pump system is the site set up and planning which includes:
   • Setting up welfare and health and safety provisions on site
   • Setting out all trenches and groundworks accurately 
   • Double checking that you have sufficient capacity in your electrical supply for the heat pump system
   • Having a plan to deal with the spoil from the trenching and for reinstating the areas affected by groundworks. 
   • Attain planning permission for the system. Not all heat pump systems require planning but Ofgem make it a requirement of the Renewable Heat Incentive scheme that you send evidence of planning approval, or that planning isn’t required. 
   • Ensure that all health and safety measures are taken care of. This includes: risk assessment and method statements, fencing off dangerous areas, providing welfare facilities as required, and making sure all operatives are suitably qualified and wearing the correct Personal Protective Equipment (PPE)
4. Install the heat exchangers in the water source – the next step is to install the heat exchangers which will extract the heat from the water source. Sizing the heat source correctly is the most important part of designing a heat pump system. If you undersize the heat collector then you won’t be able to get enough heat to keep the heat pumps operating and this will lead to recurring faults and inadequate heating. For closed loop water source heat pump systems there are two options for extracting the heat:
   • An array of metal heat exchangers – these look like large radiators and are used most often in rivers and areas unsuitable for large arrays of pipework
   • An array of pipe heat collectors – these are comprised of multiple coils of plastic pipe secured to a metal frame and then connected to a manifold next to the water source. These are most commonly used in lakes and large bodies of water. 
5. Manifolding – Once the heat collectors are installed they need to be connected together to form a common flow and return. A manifold is used to bring all flow pipes together and all return pipes together. It is usually a good idea to also include flow regulators and isolation valves on the manifold too. Once the manifolding is complete, the main flow and return pipes are taken to the plant room ready for connection to the heat pumps.
6. Mechanical heat pump installation – The next step is to install the heat pump system. The mechanical installation happens first and includes all pipework, buffer vessel, valves, pumps, and the heat pumps themselves. This work is carried out by highly skilled and experienced engineers who will ensure that the installation is completed according to the design. 
7. Electrical and controls installation – Once the mechanical installation is complete we can start the electrical and controls installation. One of the most common reasons for faults and under performing systems is not setting the control strategy correctly and not making sure that the heat pump system interfaces correctly with the rest of the heating/cooling/hot water system.
8. Commissioning and testing – The commissioning and testing process should include:
   • Making sure the controls are set up correctly
   • Checking that the whole system is successfully tested under pressure
   • Flushing and filling the system thoroughly and properly
   • Making sure that all air is removed from the system
   • Making sure that the system controls are setting up as required by the owner and that the system is operating as it is meant to
   • Gathering all the information required for the Renewable Heat Incentive application
9. Handover – this stage includes demonstrating the system to the client and showing them the various parts of the heat pump installation. It also includes handing over the operation and maintenance manual for the system. 
10. Monitoring, servicing, and maintenance – the final stage is ongoing and involves:
    • Remote monitoring: we use remote monitoring to log all the parameters of the system performance. This enables us to pick up any faults in the system quickly and to make sure our engineers have everything they need to fix the problem when they get to site. Our monitoring service also includes the periodic remote reading and submission of heat meter data to Ofgem for the Renewable Heat Incentive scheme. 
    • Servicing: All heat pump manufacturers require the heat pump system to be regularly and correctly serviced for the manufacturers warranty to remain valid. Regular servicing is also important to maximise the heat pump longevity. Correct and preemptive servicing can add years to the life of your heat pump system. 
    • Maintenance: There are two types of maintenance that people require: emergency, and non-emergency. It is important that you have a servicing and maintenance contract with a company which understands your system and has the resources to react quickly to any problems that arise.