a) All water heaters shall comply with
Appendix A.Table A (Approved Standards for Plumbing
Appliances/Appurtenances/Devices) and ASHRAE 90 Standards. Hot water storage
tanks shall meet construction requirements of ASME, AGA or UL listed in
Appendix A.Table A (Approved Standards for Plumbing
Appliances/Appurtenances/Devices), as appropriate. Hot water supply boilers
with heat input in excess of 200,000 BTU per hour, water temperature in excess
of 200 degrees Fahrenheit, or capacity in excess of 120 gallons shall also
comply with the requirements of 41 Ill. Adm. Code
120(Boiler and Pressure
Vessel Safety). Smaller water storage tanks that are not subject to ASME
requirements shall be constructed of durable materials and constructed to
withstand 150 psi. (See Appendix I.Illustrations L and M, for examples of
typical water heater installations.)
1) All
equipment used for heating and storage of hot water shall bear the marking of
an approved testing agency certifying that it has been tested and approved and
listed as meeting the requirements of the applicable standard. Listing by UL,
the Canadian Standards Association (CSA), or National Board of Boiler and
Pressure Vessel Inspectors, or the ASME Standard shall constitute evidence of
conformance with these standards.
2) Solar Hot Water Heat Exchangers
A) A hot water heat exchanger used in a
solar-heated system may be of single wall construction if a non-toxic transfer
fluid with no conditioning chemicals in the system is used.
B) A hot water exchanger used in a
solar-heated system using a toxic transfer fluid or having conditioning
chemicals in the system shall be separated from the potable water by double
wall construction that has an air gap vented to the atmosphere between the
walls.
3) A hot water
heat exchanger may be of single wall construction if a non-toxic transfer fluid
with no conditioning chemicals in the system is used.
4) A hot water heat exchanger operating at or
below 65 psi using a toxic transfer fluid or having conditioning chemicals in
the system shall be separated from the potable water by double wall
construction, with an air gap open to the atmosphere between the two
walls.
5) A hot water heat
exchanger shall not be permitted on any hot water boiler system operating in
excess of 65 psi or 250 degrees Fahrenheit, unless:
A) the heat exchanger is
double-walled;
B) the heat
exchanger has an air gap open to the atmosphere between the two walls;
and
C) the heat exchanger has a
pressure gradient monitor system with a "fail-safe to off" switch installed to
isolate the heat exchanger from the potable cold or hot water system. If
pressure on the potable water side reaches a pressure less than 20 psi above
the pressure of the transfer fluid or steam and a pressure-reducing valve is
installed on the inlet to the heat exchanger with a setting 20 psi lower than
the potable water pressure at the heat exchanger, an audible alarm shall be
activated and the heat exchanger shall be automatically shut off until the
alarm and heat exchanger can be reset manually.
6) Any boiler using toxic chemicals shall
have a label with a minimum size of 5 inches by 5 inches attached to the boiler
in a conspicuous place. The label shall read as follows:
WARNING
Chemicals and additives used to treat the boiler feed water
in this boiler are not approved for potable water. The steam or hot water
produced by this boiler is not potable. If the steam or hot water produced by
this boiler is used to heat water, the water will not be considered potable if
the steam and potable water are mixed.
7) Indirect, External, Submerged Coils.
Indirect, external, tankless or submerged coils used in heating water shall be
equipped with a thermostatic mixing valve or valves when not connected to a
storage tank. A pressure relief valve shall be installed on the cold water
inlet of the tank. A properly sized temperature and pressure relief valve,
based upon the energy input rating of the coils, shall be installed on the
tempered line with the temperature sensing element immersed in the tempered
water line as close as possible to the mixing valve.
8) Water Heaters Used for Space Heating. Any
water heater to be used for space heating, in addition to hot water supply,
shall conform to ANSI Z
21.10.1,
Z21.10.1a and Z21.10.1b and shall be constructed for continuous use, and the
piping for space heating shall be conducted to a proper terminal heating
device.
A) A thermostatic mixing valve,
conforming to ASSE 1017, shall be installed on the hot water line to the
plumbing fixtures. (The mixing valve shall be set to prevent temperatures
exceeding 120 degrees Fahrenheit from reaching the plumbing
fixtures.)
B) A single check valve
shall be installed in the cold water line supplying the water heater. This will
prevent hot water backing up from the heating unit to the plumbing
fixtures.
C) A properly sized and
approved expansion tank shall be located on the outlet side of the check valve
in the water heater's cold water supply, with no shut-off valve between the
heater and expansion tank.
D)
Valves (manual, automatic) supplying hot water to the heat transfer unit for
space heating shall have a minimum of a 1/8-inch orifice. This will prohibit
potable water from standing in the heat transfer unit when not in use. This
does not prohibit full shut off/isolation valves on either side of the pump
within a heat transfer unit, as needed, to permit the servicing of the
pump.
E) The water heater
instructions shall have a statement specifying that piping and components
connected to the water heater for the space heating application shall be
suitable for use with potable water, and the water heater shall not exceed a
developed length of more than 25 feet from the heating coil.
F) A statement specifying that toxic
chemicals, such as those used for boiler treatment, shall not be introduced
into the potable water used for space heating shall be included in the
instructions. A label with the following words shall be firmly attached to any
water heater used for space heating: "DO NOT INJECT TOXIC MATERIALS INTO THIS
TANK."
G) A statement specifying
that a water heater that will be used to supply potable water shall not be
connected to any heating system or components previously used with a
non-potable water heating appliance shall be included in the installation
instructions.
H) Each water heater
shall bear a statement on the rating plate as follows: "SUITABLE FOR POTABLE
WATER HEATING AND SPACE HEATING."
9) Point-of-Use Water Heaters. Point-of-use
water heaters shall meet the following requirements:
A) Non-storage and non-pressurized units
intended to deliver water temperatures exceeding 110 degrees Fahrenheit, or
with no mechanical or electrical temperature limiting device, shall have the
faucet located at least 3 inches from the 110 degrees Fahrenheit hot water or
cold water faucet. Faucet outlets shall have labels clearly and conspicuously
indicating extremely hot water. These units are exempt from the requirement
that a relief valve or valves be used to protect against excessive or unsafe
temperature or pressure.
B) Units
intended to deliver water temperatures 110 degrees Fahrenheit or less shall
have an internal burnout element. These units are exempt from the requirement
that a relief valve or valves to be used to protect against excessive or unsafe
temperature and/or pressure.
C) All
pressurized point-of-use water heaters, other than those in subsection
(a)(9)(A) or (B), shall be provided with proper temperature and pressure
relief.
10) Steam Heat.
All water heaters, including storage heaters, instantaneous shell and tube heat
exchangers, steam injection heaters and any other device using steam to heat
water for potable use, shall meet the following requirements:
A) All chemicals and additives used to treat
the boiler feed water in a boiler supplying steam to heat potable water shall
be approved for use with potable water. If approved chemicals and additives are
used with steam boilers generating at 15 psi or less, or are used with pressure
reducing stations with pressure relief valves set at 15 psi or less downstream
from the pressure reducing valves, single wall heat exchangers may be
used.
B) All steam heat exchangers
operating in excess of 15 psi but less than 50 psi shall be separated by double
wall construction, with an air gap open to the atmosphere between the two
walls.
C) All steam heat exchangers
operating in excess of 50 psi shall meet the following requirements:
i) The heat exchanger shall be
double-walled;
ii) The heat
exchanger shall have an air gap open to the atmosphere between the 2 walls;
and
iii) The heat exchanger shall
have a pressure gradient monitoring system with a "fail-safe to off" switch
installed to isolate the heat exchanger from the potable cold or hot water
system. If the pressure on the potable water side reaches a pressure less than
20 psi above the pressure of the transfer fluid or steam and a pressure
reducing valve is installed on the inlet to the heat exchanger with a setting
20 psi lower than the potable water pressure at the heat exchanger, an audible
alarm shall be activated and the heat exchanger shall automatically shut off
until the conditions resulting in an alarm are corrected and the heat exchanger
pressure gradient monitoring system can be manually reset.
D) The steam pressure to all the steam heat
injectors shall be 15 psi lower than the water pressure at the ejector. Steam
injection heaters shall be supplied with steam from a generator or boiler that
uses only United States Food and Drug Administration (FDA) approved additives
or chemicals.
E) The following
warning label with a minimum size of 5 inches by 5 inches shall be permanently
attached on the front of any boiler providing steam to direct-injection steam
hot water heaters:
"If the chemicals used to treat the boiler feed water in this
boiler are not approved for potable water, the steam produced by this boiler
cannot be considered potable. Therefore, if steam from this boiler is used to
heat water, the water shall not be considered potable and any cross-connections
between the hot water produced and a potable water supply must be provided with
a device to prevent the backflow of the non-potable hot water into the potable
water supply."