Other tests can be carried out as required.
Commissioning closed systems and water quality considerations
When a new heating or cooling system is first charged, the water used for filling the tanks will usually be taken directly from the mains water supply.
Therefore, the closed system will contain the same levels of bacteria and minerals as are found in mains water.
These levels, particularly the mineral components are not the same across the country and will depend on both geography and where the water is drawn from.
Additionally, the expected levels of bacteria in mains water can typically be anywhere between 10 and 100 cfu per ml of water.
Testing water for bacteria in closed systems
There are many different types of bacteria found in mains water. Enterobacter, Klebsiella and Citrobacter might be found but are very unlikely to live and grow within a closed system.
However, as they die off, they can provide a food source for other types of bacteria.
Other species of bacteria which might cause problems in closed heating and cooling systems include Pseudomonas, Flavobacterium, Acineobacter and Aeromonas.
These types of bacteria rarely grow into sufficient numbers to cause problems in a drinking water supply.
However, in a closed system they can quickly form slime and cause biofilm to form on internal system surfaces including pipework, pumps and heat exchangers.
Iron, sulphite oxidising bacteria and sulphite reducing bacteria are also sometimes present in mains water.
Iron bacteria feeds off anything ferrous, and can be a cause of corrosion.
Red, orange or yellow coloured water is often a clear sign that iron bacteria is present.
A black slime in the system is a signal that sulphite oxidising bacteria are present. If a foul smell is present in addition to the slime, the problem may be sulphite reducing bacteria.
This type of bacteria is highly corrosive and can cause serious damage.
Biofilm problems in closed water systems
When a new closed system is first commissioned and brought in to service, slime or biofilm forming bacteria is often the first type to take root.
It can coat surfaces with layers of biofilm, which then provide a “hide-out” for other bacteria to start to grow too.
Soon, as the bacteria begins to build-up it will start to have an impact on the thermal efficiency and general operation of the closed heating or cooling system.
The layers of bacteria act as an insulation restricting heat transfer efficiencies and also affect the hydrology.
If the biofilm is allowed to grow unchecked, the oxygen levels within the system will become depleted.
This in turn allows the growth of potentially damaging bacteria which don’t need oxygen to thrive, such as the sulphite reducing bacteria (SRB).
If water levels in a closed system need to be occasionally topped up with water from an open header tank, then the number of bacteria can be even higher.
This is due to the way in which the water is being stored.
If bacteria is not dealt with correctly using specialist closed system water treatment chemicals called biocides, then eventually the entire system may fail… at best its reliability and thermal effectiveness will be compromised.
It is equally important to treat the system correctly.
Some of the chemicals commonly used to treat water can actually become a bacteria foodstuff if it is not added at the right concentration.
How to sample water in closed systems
There are no hard and fast rules about how often the water sampling of closed systems should be carried out.
The frequency will often depend on the design of the system, whether water quality problems are suspected and its life-cycle stage.
Whatever the type of system (heating, chilled or cooling) or its age, operators should have a detailed plan for the sampling and analysis of the water inside the closed system.
The plan should be reviewed frequently as requirements change.
When preparing a sampling plan for closed system water testing, operators should refer to the guidelines produced by both the British Standards Institute (BSI) and the Building Services Research and Information Association (BSRIA).
Appropriate safety precautions should also be followed during the sampling procedures.
Although you will need someone within the organisation to take the samples of water from the closed system, it is unlikely you will have access to the type of specialist laboratory facilities required to carry-out the range of micro and chemical tests specified by BSRIA 50/2015.
Closed system water analysis of this nature is best carried out by the specialists such as Water Treatment Services.
Taking water samples from a closed system
Once a suitable sampling point has been identified it should be thoroughly flushed before taking any water samples.
The water samples, once collected should be suitably referenced, timed and dated so they can be identified, they should then be sent to the laboratory for analysis.
Once the full suite of water tests has been completed you will receive a report detailing the results.
As part of the sampling process there should also be a system for recording and tracking results to allow for comparison over time.
In addition to closed system testing for bacteria which can corrode heating and cooling systems, our laboratories can also check for legionella, metals and other contaminants where these are of concern.
Expert BSRIA closed system water testing for heating, chilled and cooling facilities
Contact Water Treatment Services today to find out more about ourBSRIA closed system water testing and laboratory analysis services for the pro-active management of closed heating, chilled and cooling installations.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specialists we can offer professional, cost effective water treatment solutions across the whole of the UK and Internationally.
Contact us today for more information or for your FREE, no obligation quote.
