38
5
System piping
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.
Strainer:
Field supplied. Required to help eliminate debris from
causing damage to the heat exchanger. When installing in a
pre-existing system, it is recommended to install a filter in the
recirculation line capable of removing debris left in the system.
Building Recirculation Filter:
Field supplied as required (see Table 9C). When required,
helps to eliminate debris from causing damage to the heat
exchanger.
Water chemistry
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
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
NOTICE
The required temperature rise and the
standard circulating pump are sized based
on the heating of potable water with a
specified water chemistry. See Table 9A
in Start-Up Section for recommendations.
Check recirculation pump size to verify
it is sized for filter addition and upsize if
necessary.
⚠
CAUTION
