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Bacteria and space heating systems using
domestic water heaters.
"Infectious diseases caused by pathogenic bacteria, viruses,
protozoa and helminths are the most common and widespread
health risk associated with drinking-water."
source:
World Health Association
"Like many microorganisms,
legionella bacteria have the ability to anchor themselves to
the interiors of pipes, faucets and shower heads. Once
attached, the bacteria replicate in a sticky substance
called a biofilm. As water flows past, it dislodges some of
the biofilm, dispersing bacteria throughout the water
system."
Source: Mayo Clinic
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Government and Association
Statements |
Alberta Government
requirements for combination heating systems
Alberta Government requirements for the design of hydronic
heating systems
CIPH Information Bulletin on the use of Water Heaters
MCA
Saskatchewan, Requirements for Water Heaters Used for
Combination Heating Systems
B149.1 Gas Installation Codes of Practice - SASKPower Gas
Inspection Division
Part 890 Illinois Plumbing Code, Section 890.1220 Hot Water
Supply and Distribution
Contact us to
add your AHJ statement here...
Myth Buster Episode
Water Heater Explosion
Most radiant heating systems operate within 95 deg F to 125 deg
F, which is also hospitable for the colonization
of pathogens. This is why the prudent HVAC designer will offer other
choices which may not be as low cost as an open system but they
will be safer. |
Our Current Position Statements on:
1. Using Hot Water Heaters as Boilers
2. Open Direct Systems used for space
heating
Definition of open direct system: one where the water used for space
heating is also used for bathing, cooking, cleaning and for
consumption.
1. Using Hot Water Heaters as Space Heating Boilers
We are not aware of any jurisdiction in North America which permits domestic water heaters furnished with relief valves rated above 30 psi to operate as stand alone space heating devices. We will be happy to acknowledge any written proof offering a different position.
We are not aware of any water heater manufacturer which furnishes its product with relief valves rated above 30 psi to recommend its product be used as a stand alone space heating appliance. We will be happy to acknowledge any written proof offering a different position.
We are aware of the availability of water heaters manufactured and rated for dual purpose which may or may not be permitted in one's municipality.
It is important to mention:
1. The availability of dual purpose products does not necessarily mean it's acceptable
by all jurisdictions across the country.
2.The availability of these products and their acceptance by
some jurisdictions does not imply zero risk.
We are aware that any field
alteration of a factory certified product to circumnavigate local codes or knowingly using a water heater for something other than what it was otherwise intended exposes one to liability issues which in the event of illness, injury or death could give cause for
criminal charges.
Some parts of North America also hold past property owners
(seller) liable to new owners (buyers) for components, systems, and assemblies which did not meet local codes and standards
at time of the sale.
Sample statements from authorities having
jurisdiction:
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United States
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Canada.
Our position at www.healthyheating.com is to contact a lawyer
specializing in negligence and the insurance company that underwrites ones home owner policy to see what they are prepared to cover
- particularly if ones decision contravenes local codes, standards and manufacturers recommendations.
Read this article by Dave Yates
2. Water Heaters for Space Heating
in an Open Direct System
Areas of concern: water stagnation, bacteria, cross contamination,
operating temperatures, need for sterilization vs. scald risks.
Suggested studies:
The
Precautionary Principle
If you are browsing the internet asking people for their
opinions on open systems and specifically the potential for Legionella, here
is our position:
Legionella and countless other
bacteria can
be a health risk in plumbing and
HVAC systems - this, no one of any credibility debates.
With regards to getting advice on
Legionella and designing
plumbing and HVAC systems - we say it’s probably unwise to ask a
lawyer, doctor or insurance agent on how to design, specify and
install HVAC and plumbing systems; likewise it’s probably unwise
to rely on a do-it-yourselfer, contractor, distributor or
manufacturer for advice on waterborne
pathogens when it affects ones
health, insurance and legal liabilities.
A
professional would be obligated by their
Code of Ethics to state, " hey Jill and Jack
homebuyer, I am not qualified in matters of medicine,
microbiology, industrial hygiene, law and
insurance as it relates to recommending water heaters for use in
open system for space heating, as such I am ethically bound to
recommend prudence." This is an application of
the
The Precautionary Principle.
Our position at
www.healthyheating.com is:
...if a space heating load is low enough to be serviced by a single water heater furnished with an internal or external heat exchanger isolating the potable water from the space heating fluid, then we would find this as an acceptable
first solution for combined indirect heating systems provided the equipment
and system meet all local code requirements established by the jurisdiction having authority.
If a jurisdiction allows combined open direct systems then know water maintained continually above 60 deg
C (140 Deg F) has a bactericidal effect, BUT also be aware that
at these temperatures there is the potential for harm via
scalding of unprotected skin. Additionally, know that these
higher temperatures are often above what may be necessary for
radiant floor heating.
Therefore taking the risk of an open systems requires the
addition of scald protection valves for thermal safety of
occupants and quite possibly the addition of a temperature
control valve for the radiant floor systems.
Finally any dual purpose open system should also have a timed
flush and purge process with fail safe controls on the entire
system to ensure fluid volume in the space heating system is
treated to a high temperature at least once in a 24 hour period.
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