20
ITT LWCO - Electrical Connections
5.3.2
– High Limit
A high limit aqua-stat control is located at the back of the
appliance and the control bulb is installed in a dry well in the heat
exchanger header outlet. The setting of this control limits
maximum discharge water temperature. A manual reset high limit
will have a red reset button which must be pushed whenever
water temperature has exceeded the set point of the manual
reset limit. The temperature of the water in the tank must drop a
minimum of 15°F (8.3°C) below the setting of the high limit control
before the reset function can be activated. Whenever an
appliance is supplied with both an auto reset and manual reset
high limit always set the auto reset limit 10
ºF
(5.5°C) below the
manual reset limit to prevent nuisance tripping
.
5.5
– Expansion Tank
Systems with a backflow preventer (BFP) on the incoming water
connection must be supplied with expansion tanks (i.e.
diaphragm or bladder type) suitable for potable water
applications, to accommodate thermal expansion of stored
water. Some jurisdictions will require an expansion tank in all
cases. Expansion tanks must be installed on the building side of
the BFP.
Expansion tanks must be sized to accommodate at least the
volume of water in the water heater, but should also be able to
accommodate system piping volume. Expansion tank suppliers
have tank size calculators available.
