The brief – to heat a large outdoor pool
We were asked to provide a solution for heating an extremely large 190,000L swimming pool with air source heat pump technology. The pool itself is located in Suffolk not far from our Brandon office so we were able to make site visits before, during and after installation.
The client wanted to heat the pool water to 29°C from April to October, this was particularly difficult given it was such a large outdoor swimming pool without an enclosure, the excessive heat loss at this water temperature presented the largest challenge.
The customer was extremely keen to use heat pump technology to ensure the low running cost of heating such a large swimming pool. Most air source heat pumps on the market are not capable of heating such large volumes of water, the limit is normally around 140,000L.
The solution – twin air source heat pumps
We proposed that given the space around the plant room we could use a twin heat pump solution, allowing us to increase the heat output capacity to overcome the heat loss and achieve the desired goal of heating this 190,000L swimming pool to 29°C.
The heat pump model we proposed was the 26kW Hydro-Pro 26T, the client had three phase electrics available on site.
Important considerations – key factors
Air flow – under normal conditions on a single heat pump set up, air flow is a critical consideration. With a twin heat pump installation it is even more critical that good air flow is achieved, if sited too close together each heat pump will lower the ambient temperature for the other heat pump, therefore additional space is required to ensure both heat pumps work efficiently.
Flow rate – for single heat pump installations flow rate control is very simple – one bypass kit will control the flow rate for the circuit. However with twin heat pumps the flow rate is much more difficult to control.
The final installation
Firstly we asked the customer to extend an existing concrete pad to accommodate the two new heat pumps. This would ensure sufficient airflow in the installation area, allowing the necessary distance required between the heat pumps to enable effective heating from both units.
However the spacing created an additional problem, water will always takes the course of least resistance, effectively meaning a higher flow rate to the nearest heat pump and reduced flow to the furthest heat pump.
We solved this by designing a pipework arrangement that was equal and symmetrical in length. This also means that if the flow rate changes the flow rate will increase or decrease equally across both heat pumps.
We also ensured that each heat pump had independent isolation valves, meaning a heat pump can be taken off the filtration circuit if required, without effecting the other heat pump.
With external pipework runs it is important to insulate pipework to reduce additional unwanted heat loss.
The heat pumps were commissioned and started at 7pm on a Thursday evening, the pool water temperature was reading 16°C and the outside air temperature was 14°C. The outside air temperature on the following days stayed at 14-16°C, by Sunday afternoon the family were enjoying swimming in the pool with the water temperature at 28°C. The client is naturally really pleased with the result and has been swimming every day since.
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We’re here to help
If you would like to talk to us about heating your pool using heat pump technology, please call us on 01842 819130.