Outdoor Activity Centre Case Study
An outdoor activity centre had showers that were fed from a boosted hot and cold water system. The hot and cold systems were blended together by two centralised mixer valves. These each fed two banks of three showers and six single showers over two floors. There were difficulties achieving good circulation of the hot water system at the far points of the system and this was leading to low hot water temperatures to the mixers and poor flow through the showers.
The poor flow through the showers was an issue to the visitors using the Outdoor Activity Centre. Also the temperatures were out of specification for legionella control and therefore an alternative solution had to be found.
The possibility of removing the large blending valves and replacing with individual mixers was discussed but it was unsure if this would solve the circulation problem. The possibility of replacing all the showers with electric units was also discussed but this would be financially prohibitive. It was therefore decided to move to biocidal control of the system rather than using temperature control.
In July 2017 the two blending valves were bypassed, the calorifier temperature was reduced and a HuwaSan, silver stabilised hydrogen peroxide, proportional dosing system was installed.
Initially high level disinfection was carried out using HuwaSan at 500ppm peroxide to help clean the system and reduce biofilm. HuwaSan, was then continuously injected, via a water meter, into the system to give 10-15ppm as peroxide.
The system has now operated for over one year at 43°C with a constant dose rate of 10-15ppm peroxide. The system has been sampled from various points each month and there has been no legionella detected. There have been some low level general bacterial counts from the domestic hot water but these are showing a downward trend and are likely to match the cold water services counts of <10 cfu/ml in the next couple of months.
Installation of a HuwaSan dosing system has shown good microbiological control of the system, the showers are working well with good flow, and substantial energy savings, from the hot water system have been achieved. In addition there has been a reduction in the routine maintenance of the valves and shower heads and hoses.
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