[Code of Federal Regulations]
[Title 10, Volume 3]
[Revised as of January 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 10CFR435.109]
[Page 578-583]
TITLE 10--ENERGY
CHAPTER II--DEPARTMENT OF ENERGY
PART 435--ENERGY CONSERVATION VOLUNTARY PERFORMANCE STANDARDS FOR NEW BUILDINGS; MANDATORY FOR FEDERAL BUILDINGS--Table of Contents
Subpart A--Voluntary Performance Standards for New Commercial and Multi-
Family High Rise Residential Buildings; Mandatory for Federal Buildings
Sec. 435.109 Service water heating systems.
9.1 General
9.1.1 This section contains minimum and prescriptive requirements
for the design of Service Water Heating Systems.
9.1.2 A building shall be considered in compliance with this
section if the following conditions are met:
9.1.2.1 The minimum requirements of section 9.3 are met; and
9.1.2.2 The Service Water Heating System design complies with the
prescriptive criteria of section 9.4.
[[Page 579]]
9.2 Principles of Design
9.2.1 Showerheads shall be designed to provide and maintain user
comfort and energy savings. They should not use removable flow
restricting inserts to meet flow limitation requirements.
9.2.2 Point of use water heaters shall be considered where their
use will reduce energy consumption and is life cycle cost effective.
9.2.3 High temperature condensate, when returned to condensation
pump tanks or other vented tanks, will have a certain portion flashed
into steam, thus wasting energy. To conserve this energy, a heat
exchanger shall be considered for use in the condensate return line to
heat or preheat the service water, cool the condensate, and prevent
flashing.
9.2.4 Storage may be used to optimize heat recovery when the flow
of heat to be recovered is out of phase with the demand for heated
water, or when energy use for water heating can be shifted to take
advantage of off-peak rates.
9.3 Minimum Requirements
9.3.1 Sizing of Systems
9.3.1.1 Service water heating system design loads for the purpose
of sizing and selecting systems shall be determined in accordance with
the procedures described in chapter 54 of the ASHRAE Handbook, 1987 HVAC
Systems and Applications Volume, or a similar computation procedure.
9.3.2 Equipment Efficiency
9.3.2.1 All water heaters and hot water storage tanks shall meet
the criteria of Table 9.3-1. Where multiple criteria are listed, all
criteria shall be met. Where no criteria are provided, no requirements
need be met.
[[Page 580]]
Table 9.3-1.--Standard Rating Conditions and Minimum Performance of Water Heating Equipment
[January 30, 1989]
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Minimum performance
Type Fuel Storage Input rating Applicable test procedure ----------------------------------
capacity (gal) DOE rating Eff.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Storage water heaters......... Electric...... 120........... 12 kW.................... DOE Test Procedures, 1985 EF......................
Code of Federal gt;0.95-0.00132V........
Regulations Title 10,
Part 430.
.............. gt;120 (or)... gt;12 kW................. ANSI C72.1--1972.......... ........................ .......
Gas........... 100........... 75,000 Btu/h............. DOE Test Procedures, 1985 EF...................... .......
Code of Federal gt;0.62-0.0019V.........
Regulations Title 10,
Part 30.
.............. gt;100 (or)... gt;75,000 Btu/h.......... ANSI Z21.10.3-198 Gas ........................ Et
Water Heaters w/Addenda 77%
Z21.10.3a--1985.
Oil........... .............. 75,000 Btu/h............. DOE Test Procedures, 1985 EF...................... .......
50............ Code of Federal gt;0.59-0.0019V.........
Regulations Title 10,
Part 430.
.............. .............. 105,000 Btu/h............ .......................... gt;0.59-0.0019V......... .......
.............. gt;50 (or).... gt;105,000 Btu/h......... .......................... ........................ Ec
83%
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Table 9.3-1.--Standard Rating Conditions and Minimum Performance of Water Heating Equipment (Cont.)
[January 30, 1989]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Type Minimum performance
------------------------------------------------------------------------------------------------- Applicable test ------------------------------
Class Fuel Capacity Input rating procedure
--------------------------------------------------------------------------------------------------------------------------------------------------------
Unfired Storage................. 1................... All Volume......... All Inputs......... ....................... ...........
HL.........
6.5 Btu/h
ft\2\.
Instantaneous................... Gas................. ................... All Inputs......... ANSI Z21.10.3--1984.... Et......... ................
80%........
Distill Oil......... ................... All Inputs......... ....................... Ec......... ................
83%........
Pool Heaters.................... Gas/Oil............. ................... All Inputs......... ANSI Z21.56--1986...... Et......... ................
78%c.......
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Notes for Table 9.3-1:
Terms Defined:
1. EF = Energy factor, overall heater efficiency by DOE Test Procedure Et = Thermal efficiency with 70 deg.F, eT Ec = Combustion efficiency, 100
percent--flue loss when smoke = 0 (trace is permitted) HL = Heat loss of tank surface area V = Storage volume in gallons
[[Page 581]]
9.3.2.1.1 Exception to section 9.3.2.1
(a) storage water heaters and hot water storage tanks having more
than 500 gallons of storage capacity need not meet the heat loss (HL)
requirements of Table 9.3-1 if the tank surface area is thermally
insulated to R-12.5 and if a standing pilot light is not used.
9.3.2.2 Heat Traps. Storage water heaters not equipped with
integral heat traps and having vertical pipe risers shall be installed
with heat traps on both the inlet and outlets. The heat trap shall be
installed directly, or as close as possible to the outlet fittings.
Circulating systems need not employ heat traps.
9.3.2.2.1 A heat trap may take the form of a bent piece of tubing
that forms a loop of 360 degrees; an arrangement of pipe fittings, such
as elbows, connected so that the inlet and outlet piping make vertically
upward runs just before turning downward to connect to the water
heater's inlet and outlet fittings; a commercially available heat trap;
or any other type that effectively restricts the natural tendency of hot
water to rise in the vertical pipe during standby periods.
9.3.2.2.2 When the water heater outlet is directly horizontal out
of the tank, or is piped with an elbow on the vertical outlet and then
downward, this piping arrangement itself is effectively a heat trap and
a separate heat trap is not then needed.
9.3.3 Piping Insulation
9.3.3.1 For circulating systems, piping insulation shall conform to
the requirements of Table 7.3-1 or an equivalent level as calculated in
accordance with Equation 7.3-1.
9.3.3.2 For non-circulating systems, the first 8 ft of piping from
a storage system that is maintained at a constant temperature shall be
insulated in accordance with Table 7.3-1, or an equivalent level as
calculated in accordance with Equation 7.3-1. Systems without a heat
trap to prevent circulation due to natural convection shall be
considered circulating systems.
9.3.4 Controls
9.3.4.1 Temperature. Service water heating systems shall be
equipped with temperature controls capable of adjustment from 90 deg.F
to a temperature setting compatible with intended use, except for
systems serving residential dwelling units may be equipped with controls
capable of adjustment down to 110 deg.F only. (See ASHRAE Handbook,
1987 Systems and Applications Volume, Chapter 54, Table 3).
9.3.4.1.1 Where temperatures higher than 120 deg.F are required at
certain outlets for a particular intended use, separate remote heaters
or booster heaters shall be installed for those outlets unless it can be
shown by calculation that either energy is not saved by the application
of this requirement or that the total cost over the life of the
equipment is not reduced.
9.3.4.1.2 Circulating Hot Water Systems and Heated Pipes. Systems
designed to maintain temperatures in hot water pipes, including
circulating hot water systems and heat tape on water pipes, shall be
equipped with automatic controls that can be set to turn off the system
when hot water is not required.
9.3.5 Equipment and Control Requirements for the Conservation of Hot
Water
9.3.5.1 Showers used for other than safety reasons shall limit the
maximum hot water discharge to 2.75 gpm when tested according to ANSI
A112.18.1M-1979, ``Finished and Rough Brass Plumbing Fixtures''. The
designer shall evaluate the use of lower flow showerheads than 2.75 gpm,
particularly for heavily used facilities. Removable flow restricting
inserts shall not be used in showerheads to meet this criterion. When
flow restricting inserts are used as a component part of a showerhead,
they shall be mechanically retained at the point of manufacture.
[Mechanically retained means a pushing or pulling force to remove the
flow restricting insert at 8 pounds or more.] This requirement shall not
apply to showerheads that will cause water to leak significantly from
areas other than the spray face, if the flow restricting insert were
removed.
9.3.5.2 Lavatories in public restrooms, with the exception of
lavatories for physically handicapped persons, shall be equipped with
devices that:
9.3.5.2.1 Limit the flow of hot water to either:
(a) A maximum of 0.5 gpm;
[[Page 582]]
(b) 0.75 gpm if a device or fitting is used that limits the period
of water discharge, such as a foot switch, fixture occupancy sensor; or
(c) 2.5 gpm if equipped with a self-closing valve;
9.3.5.2.2 Either be equipped with a foot switch or occupancy sensor
or similar device or limit delivery with a self-closing valve or a foot
switch to a maximum of 0.25 gallons of hot water for circulating
systems;
9.3.5.2.3 Limits delivery with a self-closing valve or a foot
switch to a maximum of 0.50 gallons for non-circulating systems; and
9.3.5.2.4 Limits the outlet temperature to a maximum 110 deg.F.
9.3.6 Swimming Pools
9.3.6.1 Pool Heaters. All pool heaters shall meet the criteria of
Table 9.3-1 and be equipped with a readily accessible ``on-off'' switch
to allow system shut-off without adjusting the thermostat setting and,
when applicable, allow restarting without manually relighting the pilot
light.
9.3.6.2 Pool Covers. Outdoor heated swimming pools shall be
equipped with a pool cover. However, pools deriving over 70% of the
energy for heating from non-depletable sources or from recovery of
energy that would otherwise be wasted (computed over an operating
season) need not be equipped with pool covers.
9.3.6.3 Time Switches. Time switches shall be installed on all
swimming pool pumps and all electric swimming pool heaters. These
switches shall allow for the shutdown of heaters during hours of peak
utility demand except as is necessary in peak period operation to
maintain water in a clear and sanitary condition in keeping with
applicable public health standards.
9.3.6.3.1 Exceptions to section 9.3.5.3:
(a) Where public health standards require 24 hour operation of
pumps; and
(b) Pumps are required to operate solar pool heating systems.
9.4 Service Hot Water Heating Systems--Prescriptive Compliance
Alternative
9.4.1 Combination Service Water Heating/Space Heating Equipment
9.4.1.1 Water heaters used for combination service water and space
heating shall meet the appropriate minimum efficiency requirements of
both section 8.3 and 9.3.
9.4.1.2 Combination space heating and service water heating
equipment shall only be used when at least one of the following
conditions is met:
9.4.1.2.1 where the annual space heating energy use is less than
50% of the annual service water heating energy use;
9.4.1.2.2 where the energy input or storage volume of the combined
boiler or water heater is less than twice the size of the smaller of the
separate boilers or water heaters otherwise required;
9.4.1.2.3 where calculations show that the combined system uses no
more energy than separate systems that meet the requirements of sections
8.3 and 9.3; or
9.4.1.2.4 where the input to the combined boiler is less than
150,000
Btu/h.
9.4.1.3 Combination function equipment (space heating, service
water heating, cooling, etc.) shall comply with minimum efficiency
requirements in accordance with nationally recognized test procedures.
Where such procedures are not available for particular equipment
designs, compliance shall be determined based on the function
representing the maximum annual energy consumption, using data provided
by equipment and component manufacturers.
9.4.2 Additional Equipment Efficiency Measures
9.4.2.1 Electric Water Heaters. In applications where water
temperatures not greater than 145 deg.F are required, an economic
evaluation shall be made on the potential benefit of using an electric
heat pump water heater(s) instead
[[Page 583]]
of electric resistance water heater(s). The analysis shall compare the
extra costs of the heat pump unit with the benefits in reduced energy
costs, less increased maintenance costs, over the estimated service life
of the heat pump water heater.
9.4.2.1.1 Exception to section 9.4.2.1:
(a) Electric resistance water heaters used in conjunction with site-
recovered or non-depletable energy sources or off-peak heating with
thermal storage.
9.4.2.2 Gas-Fired Water Heaters. All gas-fired storage water
heaters that use indoor air for combustion or draft hood dilution and
that are installed in a conditioned room shall be equipped with a vent
damper unless the water heater is already so equipped. Unless the water
heater has an available electrical supply, the installation of such a
vent damper shall not require an electrical connection. The vent damper
shall be listed as meeting appropriate ANSI standards and shall be
installed in accordance with manufacturer's instructions and local
codes.
9.4.2.2.1 Exception to section 9.4.2.2:
(a) where the cost of the damper exceeds the value of reduced energy
costs over the damper's lifetime.
9.4.3 Use of Waste Heat, Solar Energy, and Thermal Storage
9.4.3.1 An evaluation shall be made of the potential for the use of
condenser heat, waste energy, solar energy, or off-peak heating with
thermal storage to reduce water heating energy cost.
9.4.3.2 Storage shall be used to optimize heat recovery when the
flow of heat to be recovered is out of phase with the demand for heated
water, or when energy use for water heating can be shifted to take
advantage of off-peak rates.
[54 FR 4554, Jan. 30, 1989, as amended at 55 FR 23869, June 12, 1990; 59
FR 18294, Apr. 18, 1994]