Stagnant Water during the Pandemic

Posted by Jonathan Zinser

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Due to the Coronavirus pandemic, our normal life has been interrupted. This means places that we frequent like hotels, malls, office buildings, dorms, etc. may have only sections of the building operating or closed completely. It may not come into mind for the normal person, but the impact that these closures have on HVAC systems cannot be understated. If the microclimates in these spaces are no longer controlled, then the water used will be stagnant.

Water stagnation can affect all types of HVAC and can cause differing amounts of damage to pieces of capital equipment. Stagnant water will also encourage the growth of biofilms – this can cause microbially induced corrosion, fouling, and a safe space for Legionella and other pathogens to proliferate. In closed loops, if boilers or chillers are not running, temperatures will not stay at their setpoints. Cooling towers’ disinfectant levels will diminish.

To reduce the possibility of long-term damage to your systems, these are some steps you can take as a building engineer, property manager, or owner:

 1. Keep hot water hot and cold water cold. These set points discourage microbial growth.
2. Cooling towers should be drained if not in use to prevent corrosion issues, biofouling, or Legionella bacteria proliferation.

3. Boilers should be placed offline following a wet or dry lay-up procedure to prevent corrosion issues – these could cause failure once boiler is returned to full operation.

4. Follow Water Management Plan protocols – including testing for disinfectant levels, periodic flushes, etc. – to reduce the potential for problems during this shutdown. Remember the risk associated with fixtures such as showers, fountains, misters, ice machines, eyewashes,

5. All chemical feeds need to be flow-interlocked to safeguard against chemical being fed into ‘dead water’ as neat chemical can cause corrosion to piping and equipment. Flow-interlocking also helps ensure that chemical is appropriately dosed or not dosed during all load conditions.

RMC can help provide consultation and services, contact us today.

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Topics: legionella, legionella risk minimization, Pandemic, Water Treatment, water management plan, HVAC, Stagnant, cooling


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