to those areas, or floor elevations where insufficient water
A/E shall obtain, from the water utility purveyor, seasonal
pressures may be experienced/expected utilizing the Low
cold water service temperatures supplied by the water
HGL. Outlets on floor elevations or areas that can be
utility purveyor (past three year minimum preferred).
served with the required pressures provided at Low HGL
Low temperature (lowest of past three years) seasonal
shall not be pumped. The entire water service shall not be
cold water service temperatures shall be utilized in
pressure boosted if only portions of the building systems
calculation and application of water heating, water
require pressure maintenance boosting.
heating energy source (steam, heating hot water, gas),
and for make-up to the water heating energy source.
The water service supply source (utility) low hydraulic
Preheating of domestic cold water supply to the domestic
grade line (Low HGL), low head elevation of water source
water heater and cold water make-up to water heating
tank or pump, adjusted for friction and head losses/gains,
energy source shall be considered utilizing steam
shall be utilized for determining available water source
condensate or heating hot water return.
pressure, pump suction calculations and selection. The
water service supply source (utility) high hydraulic grade
Instantaneous water heaters are not permitted as a
line (High HGL), high head elevation of utility service
primary source. For incidental use, sporadic equipment
water supply source tank or pump, plus booster pump
demands, or remote individual fixtures (i.e. lavatory, sink,
shut-off head for boosted systems (system maximum
shower, service sink), the use of instantaneous water
working pressure), adjusted for static pressure head
heaters is permitted. Point of use instantaneous water
losses/gains, shall be utilized for determining maximum
heaters are permitted for use at emergency fixtures to
system working pressures.
supply "tepid water" immediately at the emergency
fixture or group of emergency fixtures.
Domestic Hot Water Service. Domestic potable hot water
Domestic hot water supply temperatures shall be
shall be generated by water heaters utilizing natural gas,
generated and stored at a minimum of 60.0C (140F),
electricity, or steam as the energy source. Selection shall
and tempered to deliver 51C (124F) to outlets, where
be supported by an economic evaluation incorporating
permitted by state code. Hand washing, lavatory, sink and
first cost, operating costs and life cycle costs in
similar fixtures accessible to the disabled, elderly, or
conjunction with the HVAC energy provisions.
children shall be tempered to deliver 29C (85F)- 63C
Cold (or preheated) water supply to water heaters shall
(109F) water temperatures at the fixture or group of
include service valve, check valve, expansion tank (sized
battery fixtures. Bathing and showering fixtures (except
for expansion of storage capacity only), 27'' heat trap,
emergency showering) shall be tempered to deliver
mixing valve by-pass primer, and hot water return
"tempered water" 29C (85F) - 49C (120F) water
connection as a minimum. 27'' trap height minimum
temperatures at the fixture or group of battery fixtures.
shall be provided at water heater cold water inlets for
Individual fixture or battery thermostatic mixing valves
energy savings.
shall be provided where distributed, or zone, outlet
temperatures may exceed 51C (124F). Hot water supply
Cold water temperatures supplied from the utility source
to dishwashers shall be at 60C (140F), and the
vary in temperature by season and regional location. The
160 F A C I L I T I E S S T A N D A R D S
FOR THE
PUBLIC
BUILDINGS
SERVICE
5.18 Plumbing Systems
Revised March 2005 PBS-P100
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