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Legionellae article

MikeyB Member Posts: 696
This months issue of Plumbing Engineer has an  Legionellae article by Ron George, check it out if you get this magizine.


  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    open systems anyone?

    The tide is shifting!
  • Bob Gagnon plumbing and heating
    Bob Gagnon plumbing and heating Member Posts: 1,361
    edited March 2011
    Copper Piping

    I think we may be killing the legionella inadvertently with our copper piping systems. I remember reading years ago that they found legionella in a large percentage of hot water tanks in this country, 20% or 25% if I remember correctly, yet they were surprised not more people were getting sick.

    I'm told that copper contains copper arsenic, an element that can kill viruses and bacterium. I saw a study from the EPA about a year ago that recommended restaurants, schools, and hospitals use copper surfaces for health reasons to kill bacterium and viruses. Some roofers use copper flashing on the north side of the roof to prevent mold and moss buildup and premature failure of the shingles. I have talked to some of the guys installing pex for domestic and many have noticed a reddish mold only in the hot water lines after time, and I saw on TV recently they were recommending a brass shower arm to kill the virus while showering. Mark E, does your hunting cabin have pex or copper piping?

    I read in Europe that they disinfect their PEX hot water systems monthly, I think we may be inadvertently killing the legionella in our hot water systems with copper piping. This seems like it would be easy to confirm by running legionella contaminated water through a copper pipe, and then testing the water. If 8,000 people are dieing annually, the CDC should be on this.

    The Plumber Protects The Health Of The Nation.

    Thanks, Bob Gagnon 
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    edited March 2011
    slight benefit with new pipes

    As soon as biofilms form, which is soon after copper lines are installed, there is no longer any benefit or bacterial kill-rate. The bugs live freely to replicate within the biofilms, which also protects them from chlorine, which does not penetrate biofilms well and is far too weak at 2- to 4-PPM anyway. Chlorine Dioxide, on the other hand, does penetrate biofilms and whack the bugs. As does copper/silver ionization, which offers a residual kill-rate. UV, by itself, doesn't work & needs ultrasonic bombardment upstream to break open the cysts of one-celled animals (trojan horses) within which legionella have set up a nursery that eventually bursts open spewing forth the offspring.

    It was disappointing to see that the list of approved methods includes ones that either don't work (chlorine) at concentrations found in potable systems or are weak players where eradicating the bugs is concerned. But, it's a huge step in the right direction.  
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840

    SOMEONE found the piles of bodies that Ms Smith and everyone else who was against us asked to see.... They were hiding right there, in the nursing homes and hospitals of America... mis labled as victims of bacterial pneumonia...

    Maybe all our efforts were not in vain Dave :-)

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    My cabin has PEX...

    I got rid of the tank style heater, and am using a flat plate heat exchanger that I maintain at 140 degrees F, reducing the potential bacteria count.

    The good news about having caught LP, is that there are no known cases of anyone ever having had caught it twice. It probably has a 100% mortality rate at that point.

    I am glad to see these folks at ASSE taking a position on this issue, but we (they and us) are still fighting a continuous uphill battle against the utility companies, the federal government and the legions of lawyers who want to keep the scalding potential low.

    Still good news nonetheless.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Jim Pompetti
    Jim Pompetti Member Posts: 552
    Radiant systems

    I have seen radiant and hot water systems ,tied into hot water systems . This has me concerned , I often warn people of the safety of such systems . What is your take on this?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    My take on this....

    As taught to my by the person I consider the key figure in pointing it out (Dave Yates) is that it is a deadly practice.

    I am personally aware of three people who have contracted LP from exactly these systems. Fortunately, they all three lived, but it proves a point. This practice is deadly and should be illegal. In fact, depending upon you interpretation, it IS illegal.

    But certain well connected internet peddlars with more money than common sense got their "system" approved under the code, and fought us tooth and nail when Dave and I approached the code authorities to have it banned. More power to them. I hope they can sleep well at night. I know I can...

    If you come across this in the field, recommend the installation of a flat plate heat exchanger between the heat source and the RFH to lessen the possibility of creating a leginonella farm.

    If they resist, have them sign a paper stating you warned them of the inherent dangers and move on to the next job.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • icesailor
    icesailor Member Posts: 7,265

    A question: What would purging the hot water system with hot water, over 140 degrees do for helping remove the problem?

    Maybe it hides in  a bio film but if the bio film is too hot, it can't. It would seem that is hospitals, which can generate large amounts of hot water, couldn't flush their hot water systems with ultra-hot water periodically.

    Just curious.
  • HDE
    HDE Member Posts: 225
    Going away?

    I'm all for dangerous systems going away but tell me then why manufacturers like Rinnai and Rheem are pushing Tankless heaters installed as open system combi's is drawing so much attention as the new green efficiency thing.

    Don't they understand the dangers they are promoting?
  • meplumber
    meplumber Member Posts: 678
    My $.02 worth.

    To answer Home Depot's question, they do it because they can and they make money at it.  There is no corporate responsibility anymore.  If it is profitable then they will do it.

    (Off soapbox now.)

    The bulk of our customer base is seasonal.  These are summer homes that are occupied from mid June to mid Sept.  Some stay till Thanksgiving.  Some of these homes are drained every fall, some aren't.  Regardless, it is our practice to set the hot water tanks at 140 deg and install a mixing valve.  Not negotiable in our books.  When I price a new home, even for a normal customer, I price a mixing valve on the hot water tank.

    For those that will scream about cost, if you do the math, you can normally downsize the tank by installing the mixing valve.  Because you are extending your storage capacity by storing at 140 versus 120.  Even if you can't, if you are losing jobs over the cost of a mixing valve then you have bigger problems.

    These mixed radiant/hot water systems must be made illegal where they aren't already. 
  • BobC
    BobC Member Posts: 5,401
    edited March 2011
    had it in Boston

    The Boston P&DC had a case of legionella about 5 years back, that individual was very sick but did recover. They traced the cause to some long plumbing stubs where water could sit for years and grow anything it pleased.

    That's when i started to bring water from home. one of the water bubblers that tested positive was about 10 ft from my workbench. maybe the two stiff glasses of bourbon I drank every night after getting home (about 11:30Pm killed it, who knows.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • scott markle_2
    scott markle_2 Member Posts: 611
    automatic periodic heating

    I have a hard time setting an indirect a 140f, just seems wasteful. Got to hand it to Viessman for incorporating a periodic disinfection cycle. I wish Tekmar included this feature.

    While I'v always questioned the hygiene of open systems, I'm not quite ready to set my (non- Viessman controlled) indirects at a 140. You can kiss high efficiency combustion goodbye at that temperature not to mention exacerbating standby losses.

    It certainly makes sense to avoid incubating pathogens, but these organisms are part of nature and it's unrealistic to believe we can completely eliminate our exposure. It's also important to keep some perspective on the actual risks. Fear is deeply connected to the unknown and unseen- Terrorists, Radiation, Germs etc.

    Don't these relatively low number of infections mostly effect immune compromised individuals?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    Define compromised immune systems...

    I had a minor head/chest cold when I contracted it. Have you ever had a chest/head cold?

    The CDC did a blood study a long time ago. A random sampling of blood found Legionella pathogens in over 90% of those tested. It's not a matter of IF we are exposed, it is a matter of our immune systems condition, and the degree of exposure.

    As for inefficiency of modcons when doing DHW, by using a reverse indirect, like a Turbomax, you only need to maintain a target boiler temperature 10 degrees F higher than your target DHW temperature, so in the case of 140, you'd need 150 degree boiler water, and at a 20 degree or better delta T, your return water temps keep your condenser in the condensing mode.

    I think that if you crunch the numbers, knowing what the standby losses are, raising the tank to 140 degrees is NOT going to cost that much more $. I think the study that Dave Yates did showed that with a conventional gas fired self contained water heater (typical energy hog) that the difference in cost of operation between 120 versus 140 was less than $2.00 per month. In my book, having almost DIED from this dreaded disease, 25 bucks a year is CHEAP insurance.

    The Europeans have recognized this deadly disease and are taking steps to limit its exposure, and the US should be no different, except that the lobbying powers of the HBA, and GAMA are stronger than the opposition, hence it is accepted in the current codes.

    As soon as someone gets the living crap sued out of them for exposure resulting in death (already going on across the pond) Americans will smarten up...

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • ttekushan_3
    ttekushan_3 Member Posts: 953
    I would add

    that the normal background level of legionella is not the problem. Thats why we don't have problems with the cold water supply.

    We create the problem by interfering with nature by actively heating the water just enough, to a temperature that promotes the rapid propagation of the critters. After cultivating this bloom we then store it for the first hapless shower-goer. The shower head dispensed "legionella concentrate" aerosol is the problem.

    We need to solve this problem since this is one of those we have created to begin with. Since the solution is so simple, it seems to me that it bears doing.
  • Gordy
    Gordy Member Posts: 9,537
    Contracting Legionellla

     The real hazard to it is how it gets into the lungs. Aspiration. Steamy hot shower with an economizer head that really disperses the water. Drinking a Legionellla laced glass of water, and it going down the wrong pipe etc.. Then your immune system must be weak. Through illness, age, medications, treatments for other illness etc.

     The real issue here is who wants to not condone the very systems, and practices that create a harbor for the little suckers Not to debate whether there is a problem, or whether or not certain plumbing heating practices contribute to its existence. Because there is a problem, and certain practices are the problem, It all starts with education, and proper prevention with in the trades dealing with the systems it multiplies in.

     If you ask an average person on the street about how legionella is contracted, and from where they do not have a clue. Let alone the odds go up when you are in a hospital...a place where people go to get well.

  • Ex Maine Doug
    Ex Maine Doug Member Posts: 162
    Baltimore and LD

    St. Joseph's med center twice already

    Others listed here

  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    edited March 2011

    show me the bodies - ahhh, that old chestnut

    Some reading for those interested! It was a bit more than 10-years ago that I discovered the information (more like getting smacked upside my head!) while researching information about using water heaters instead of boilers for hosting a gig at Area51HVAC.com - a subject sure to incite strong feelings. I never in my wildest dreams suspected/expected to be stopped dead in my tracks by what was revealed. In fact, I was sure it wasn't "hard" evidence and set out to find credible evidence to the contrary - a search that has lasted for more than a decade without one single shred of credible evidence to support open-direct cross-connected potable/hydronic systems as being "safe" from bacterial amplification. The plain truth, it seems, is that they are the Field-of-Dreams you-build-it-they-will-come perfect-storm of amplifiers. But, what the hey-ho do I know, I'm just a guy who stumbled onto evidence that was there all the time.

    Took a lot of flack in the beginning, but over the years those who have bothered to read & research on their own (as I encourage all to do) with an open mind unbiased by sales/profits have virtually all arrived at the same conclusion. Google any combination of things and you'll find tons of rock-solid data/evidence regarding warm potable water systems and bacterial amplification.   

    Think of a residential hot water system as being three distinct parts: Point of Source (water heater); Distribution System (network of piping); and Points of Use. The cheapest least expensive solution to Legionella bacterial amplification requires heat pasteurization by elevating the storage temp to 140F or above to hold down the number of bugs; ASSE listed scald-guard mix vlv to flat-line the outlet temp; constant circulatuion with min of 124F at the return (this can be done without compromising the ASSE temp setting). The distance from hot recirc to Points of Use should be short.

    Nosocomial (hospital) vs. Community Acquired (home)







    From Robert Bean's web site:

  • icesailor
    icesailor Member Posts: 7,265
    140+ Degrees in water heaters/Storage tanks:

    I have (for quite some time) been adding Sparco/Honeywell mixers to water heaters so I can run them hotter and temper the hot down to legal levels. The AMX-101 unit has a check on the cold water side and you do not need a heat trap. Though I always install one. I've been concerned about LP for years.

    In MA, we are required to set the limit stops on shower valves to limit it to code temperature, 120 or 125 degrees. I set them to a temperature that I know that someone can not stand without scalding themselves. I use only Symmons S96-* valves and set the limit stop so that the handle stops pointing to 1:00 O'clock. Never had a complaint.

    I read an article a ways back about women getting sick from some bacterium in aerosol showers that get into lungs. Women were more sensitive. They hadn't really identified the bacterium. It must be LP. If you set the DHW in the tank to 140 degrees, and turn the valve to as hot as you can get it through the shower head, you should be able to improve the situation.
This discussion has been closed.