Microbiological Control and Energy Savings with Huwa-San Constant Dosing

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.

In July 2017 the two blending valves were bypassed, the calorifier temperature was reduced and a Huwa-San, silver stabilised hydrogen peroxide, proportional dosing system was installed.

Initially high level disinfection was carried out using Huwa-San at 500ppm peroxide to help clean the system and reduce biofilm. Huwa-San, 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 Huwa-San 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.