Install Instructions

35
5 System piping (continued)
See the * piping illustrations included in this section,
FIG.’s 5-2 thru 5-4 for suggested guidelines in piping the
Shield water heater.
*Please note that these illustrations are
meant to show system piping concept
only, the installer is responsible for all
equipment and detailing required by local
codes.
NOTICE
Piping components
Check valves:
Field supplied. Check valves are recommended for installation
as shown in FIG.’s 5-2 thru 5-4.
Water heater isolation valves:
Field supplied. Full port ball valves are required. Failure to
use full port ball valves could result in a restricted flow rate
through the water heater.
Anti-scald mixing valve:
Field supplied. An anti-scald mixing valve is recommended
when storing domestic hot water above 115°F.
Unions:
Field supplied. Recommended for unit serviceability.
Temperature and pressure relief valve:
Factory supplied on water heaters. The temperature and
pressure relief valve is sized to ASME specifications.
Water chemistry
The water must be treated if it is not between 5 to 25 grains
per gallon or above 350 ppm of total dissolved solids.
Hardness exceeding 25 grains or 350 ppm can cause non-
warrantable premature failure of the heat exchanger. Water
with a hardness of less than 5 grains per gallon will usually
have a pH which can be aggressive and corrosive causing
non-warrantable damage to the pump and associated piping.
Corrosion due to water chemistry generally shows up first in
the hot water system because heated water increases the rate
of corrosive chemical reactions.
The following chart (Table 5A) details the relationship of
water temperature and time with regard to scald injury
and may be used as a guide in determining the safest water
temperature for your applications.
APPROXIMATE TIME / TEMPERATURE
RELATIONSHIPS IN SCALDS
120°F More than 5 minutes
125°F 1 1/2 to 2 minutes
130°F About 30 seconds
135°F About 10 seconds
140°F Less than 5 seconds
145°F Less than 3 seconds
150°F About 1 1/2 seconds
155°F About 1 second
Table 5A Approximate Time / Temperature Scald Chart
The Shield water heater is designed for
heating potable water with a hardness
of 5 to 25 grains per gallon and a total
dissolved solids not exceeding 350 ppm.
NOTICE
Installation & Service Manual
No valves shall be placed between the relief
valve, heat exchanger, or tank. The relief
valve shall be piped to a suitable drain
as close as possible to the heater with no
reducing couplings or other restrictions.
The piping must be sloping away from the
heater at all times.
 CAUTION