TM
Installation & Service Manual
6System piping (continued)
The following chart (Table 6A) 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.
Table 6A Approximate Time / Temperature Scald Chart
APPROXIMATE TIME / TEMPERATURE
RELATIONSHIPS IN SCALDS
120°F | More than 5 minutes |
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125°F | 1 1/2 to 2 minutes |
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130°F | About 30 seconds |
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135°F | About 10 seconds |
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140°F | Less than 5 seconds |
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145°F | Less than 3 seconds |
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150°F | About 1 1/2 seconds |
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155°F | About 1 second |
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Piping components
Check valves:
Field supplied. Check valves are recommended for installation as shown in FIG.’s
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
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
NOTICE | 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. |
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
CAUTION
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.
The heater is equipped with 3/4" CPVC (SDR11) pipe and elbow connections. If local codes prohibit the use of CPVC, the CPVC pipe, elbow, and 3/4" NPT adapter can be replaced with a copper equivalent.
Corrosion due to water chemistry generally shows up first in the hot water system because heated water increases the rate of corrosive chemical reactions.
Delta T
If the temperature rise or difference between the HEX IN and HEX OUT is greater than 30°, scaling of the heat exchanger has already begun. A
See the *piping illustrations included in this section, FIG.’s
NOTICE | *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. |
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