legionaires disease

[R1976]

Hi,

Has anyone ever been asked about legionella bacteria in air conditioning fan coils. These bacteria can be lethal in cooling towers and water systems and I wonder about the affect of the bacteria in basic fan coil units. If water sits in the drip tray and the unit switches to heating then there is a temperature range where they could grow and possibly be evaporated into the air that is blown out by the unit. When they are breathed as an aerosol they get into the lungs. :eek:

Also, guidance is around that states that humidifiers are systems which have a possible risk and they should be cleaned and disinfected every six months and risk assessed every two years. I don't see any site wher this is being done to air conditioning humidifiers.

Any thoughts on this?

[raz5]

Legionella occurs above 20C but is eradicated at above 60C it rarely occurs on copper as copper is an antibiotic it loves ferrous material and plastics. it is spread as you correctly say by the atomization of infected water droplets. If you are using heat pumps in AC systems as opposed to cooling then obviously there can be a risk. Regular preventative maint on the filters will prevent any bacteria breeding. Use an evp coil disinfectant and you will be fine .
We have a routine of 4 weeks cleaning filters, might sound over the top but our customer is insistant on this plus we all have to have acop L8 knowledge

HTH :)

[multisync]

We have always adivsed customers that L8 does not relate to standard splits or heat pumps.

[R1976]

Hi guys,

I was reading a copy of L8 yesterday but I believe this is just classed as guidance. In heating the temperature can be above 60 degrees but there is still a risk for a short time at lower temps as the heat builds up, especially if water has sat in the drip tray for some time. Air could pass over the water and evaporate it into the room. A lot of drip trays are plastic and have slime or bio film in them which is a nutrient source for the bacteria.

Is anyone out there disinfecting humidifiers and the ductwork off the plant?

[raz5]

We always disinfect our coils, and clean the filters. We have to go on a course for l8 in multiocupancy buildings. Just because no one has yet been infected due to heat pumps doesnt absolve them from infection. Were ever you have long time stood water at the right temp you have the risk .. This is what we are taught by the experts so we do not want the court case :eek:

[R1976]

Yes, court cases. Now there's a thought.

The law has recently been changed to convict people on manslaughter charges relating to legionaires disease, there are a number of people killed in the UK each year and hundreds of cases where people have contracted milder forms like pontiac fever. If ancompany runs a maintenance contract then are they responsible?

[multisync]

Can someone explain how a standard wall mount split can get the necessary criteria for growing conditions?




21 Legionella bacteria are common and can be found naturally in environmental water sources
such as rivers, lakes and reservoirs, usually in low numbers. Legionella bacteria can survive
under a wide variety of environmental conditions and have been found in water at temperatures
between 6°C and 60°C. Water temperatures in the range 20-45°C seem to promote growth.
The organisms do not appear to multiply below 20°C and will not survive above 60°C. They
may, however remain dormant in cool water and multiply only when water temperatures reach a
suitable level. Temperatures may also influence virulence; legionella bacteria held at 37°C have
greater virulence than the same legionella bacteria kept at a temperature below 25°C.


This was taken from the Barrow incident and again relates to the cooling towers.

Can anyone here give a link to a specific case where an air conditioner related outbreak has occurred where the cooling tower wasn't the culprit?

Seems a bit of scaremongering ?

[multisync]

http://www.cdc.gov/legionella/patient_facts.htm

Where do Legionella bacteria come from?

The Legionella bacteria are found naturally in the environment, usually in water. The bacteria grow best in warm water, like the kind found in hot tubs, cooling towers, hot water tanks, large plumbing systems, or parts of the air-conditioning systems of large buildings. They do not seem to grow in car or window air-conditioners.

http://www.goodgearguide.com.au/article/203443/air_conditioners?pp=2
Can a home unit cause Legionella? Legionella is not something you can contract from domestic air conditioning. The majority of cases are caused by incorrect cooling tower maintenance. Cooling towers are used in commercial air conditioning to cool water condensers and in industries to cool recirculated water.

http://www.public.health.wa.gov.au/cproot/1451/2/Legionnaires_Disease.pdf


Refrigerated air conditioners such as domestic refrigerated/reverse cycle integrated and split systems remove
heat and moisture from air without using water. They do not cause Legionnaires´ disease.

[Prince Vaillant]

QX60 has been developed to help with situations like this.

"QX-60 has been shown to be effective against a long list of micro-organisms that includes such feared names as Legionella, P. aeruginosa, E. coli, E. hirae, S. aureous, A. Niger and C. albicans."

More info can be found here (http://www.ryanairconspares.com/evaporator-cleaner-disinfectant-with-qx60-p-177.html)