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Legionella Prevention Action Plan???

JUGHNE Member Posts: 10,897
So I convince this hospital that changing their HW system from steam indirect coil to condensing HW heaters would save money in operation and up grade their 1970's method/equipment. Part of this was me voicing a concern of Legionella possible in their 360 gallon 40 year old tank that was kept at a lukewarm 120 degrees. The Legionella concern was considered oh-hum...maybe.
So I change out the system to 2 HTP condensing water heaters.

One month later they tell me that there now must be a Legionella prevention plan in place.......(also jokingly accuse me of instigating this requirement).

Just changed out a WH for a nursing home and they too must have a plan. HTP Phoenix installed as for the hospital.

So for the hospital and the nursing home we have a tank heated up to 140/145 with temp valve set at 120.
Sounds good so far, the return is about 115. Recirc pumps run almost continually.
The logic is that the return water is sent back into the 140 tank to be cooked. The reality is that most of that water is sent thru the mixing/temp valve with a little 140 added to make the trip again at 120.
The faucet temp at the end of the circuit might be only 115-118.
The temp for the tub is again tempered down to 108-110.

Attached is a plan for prevention, does it seem to make sense?
I was surprised about the ice machine, but did read about this being a cause.


  • hot_rod
    hot_rod Member Posts: 20,725
    Ideally you would circulate 140F water to within a few feet of every HW fixture. in an old building that may not be doable.

    Also when the building is in anti legionella function, typically a 1 hour period, every HW faucet needs a point of use valve to protect anyone from using HW when it is at 140F.

    So not an easy upgrade some times.

    All sorts of solutions coming along, the Viega U fitting, some venturi fittings, like mono flow tees to push HW out all the end branches.

    There is a chemical solution accepted also.

    Here is a webinar I signed up for today.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JUGHNE Member Posts: 10,897
    Thanks, Hot Rod, I will pass that along to the staff.
    As many intentions of government regulatory processes go, to just have the plan and check the boxes off as required will prevent anything.

    As far as the 140 circulate temp that is easy for either of these institutions.
    However the hospital has 55 fixtures needing safe water temps, the nursing home has 40 fixtures. (this could be one floor of a large single hospital/institution) Out here these are really small sized facilities and that many point of use tempering valves would be a major outlay of cash. Even more so would be the constant testing of temps and plus then maintenance of devices as the smaller and cheaper they get the reliability goes down.
    Now you test a couple of sinks once a week. The master temp valve has a variety of built in safeties for fail safe operation that probably is not available in under sink units.
    With the 140 supply if one device failure went undetected you open yourself up to major liability.
  • hot_rod
    hot_rod Member Posts: 20,725
    Any under sink mixing valve will be a point of use type listing. it has a max setting of 120 and fails cold, so you would be safe with tat valve at fixtures.

    For a central mixed many are going with EMV electronic mix valves, better flow range both low and high, and with electronics it catalogs temperatures and times for record keeping.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JUGHNE Member Posts: 10,897
    Although perhaps not related to Legionalla;
    I did recall a posting by Hot Rod of a test instrument that would show both TDS and PH.
    Has anyone tried that, any comments, or any upgrades since?