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  • From: "Lawrence F. London, Jr." <venaurafarm@bellsouth.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] any biologists out there?
  • Date: Sat, 19 Dec 2009 15:49:52 -0500

paul wheaton wrote:
When heating water with solar or the jean pain method or .... whatever
... it seems wise to consider legionnaires disease. But in order to
consider it, it seems we need to know the enemy. And we're coming up
short on a few things.
http://www.permies.com/permaculture-forums/2607_0/alternative-energy/alternative-hot-water-and-legionnaires-disease
The question is: what is the reproduction rate of legionella? Would
they reproduce faster in pond water than in, say, well water?
Distilled water?

Kevin Topek, in this list, might have an answer as he seems knowledgeable about health and safety issues. Misha Gale-Sinex, once in this forum (see the archives) and occasionally in sanet-mg list will probably have a quick answer for you. Of course, Google it.

I never thought about the possibly of legionella on the farm or homestead. How did this subject come up in the first place? If you're heating DHW for dish wash, heat, bathe etc. then it would seem the only issue would be getting water on you rather than in you or on washed dishes used wet or breeding in clothes as well as airborne pathogens from dried particles (does it need a moist environment to survive?) or from water vapor, humidity, condensation on objects and steam.

Do I assume correctly that it presents a risk from external contact
or only from internal contact, including breathing the contaminants as airborne dry particles or moist, in steam, mist, spray?

What environment does it need to survive and propagate? What nutrients does it need? Where is is usually found?

There is also the known risk of pathogens breeding in hot tub water.
The Japanese obviously figured out how to avoid this problem over the centuries of bath house use.

One way to avoid the problem, just as with common hot water heaters,
used, of course, for storage, long term, might be to use solar or Jean Pain apparatus to transfer heat to your DHW
by way of a heat exchanger located in the actual DHW storage tank, heating a continual source of clean water. Instead of running your clean cold water infeed through the actual heating apparatus you run it into your storage tank and heat it with a heat exchanger carrying hot water from the collector, recycling that fluid continuously while your pressurized DHW cycles from its source (city, cistern or well) through your storage tank to where you use it, never in contact with the heating equipment. Remember the sludge buildup inside conventional hot water heaters (minerals and microorganisms, if I am correct)? Most of this could probably be avoided using a heat exchanger as a DHW heat source.
Or just use hot water direct from the source for house or greenhouse heat.

Another option is using a solar closet, heating water in barrels located
in a super insulated room with hot air from a collector inside a glazed case. Cycle hot water from your Jean Pain equipment or solar collector through the barrels also. Extract the heat by way of a heat exchanger to generate DHW, stored in its own insulated tank or figure out a way to do demand batch DHW generation in a hot box of some sort. The heat exchanger itself, if it can contain an adequate volume of water, might serve that purpose by default. Google "solar closet" and "Nick Pine"
for more info on solar losets or read the Usenet newsgroup alt.solar.thermal or alt.energy.renewable. I have archives of saved Usenet posts on Nick and his solar closet technology here:
Top level directory:
http://www.ibiblio.org/ecolandtech/alternative-energy/
http://www.ibiblio.org/ecolandtech/alternative-energy/solar/
This is solar closet central:
http://www.ibiblio.org/ecolandtech/alternative-energy/solar/Nick.Pine/




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