Closed System Thermal Expansion - Bosch Tronic 3000T ES 2.5 Installation Manual And Operating Instructions

The supplied temperature and pressure relief valve is marked
with a maximum set pressure (150 psi) that does not exceed
the marked maximum working pressure of the water heater.
▶ Install the valve in the opening provided and marked for this
purpose in the water heater.
▶ Orient it or provide tubing so that any discharge from the
valve will exit within 6 inches above, or at any distance
below, the structural floor, and cannot contact any live
electrical part. The discharge opening must not be blocked
or reduced in size under any circumstances.
National Plumbing codes may require a drain pan for the water
heater installation. Failure to install one is the sole
responsibility of owner and/ or installer. Reference UPC
(Uniform Plumbing Code), or IPC (International Plumbing
Code).
3.3

Closed system thermal expansion

Periodic discharge of the temperature and pressure relief valve
or failure of the element gasket may be due to thermal
expansion in a closed water supply system. The water utility
supply meter may contain a checkvalve, backflow preventer or
water pressure reducing valve which will create a closed water
system.
During the heating cycle of the water heater, the water expands
causing pressure inside the water heater to increase. The
temperature and pressure relief valve may discharge hot water
under these conditions which results in a loss of energy and a
build-up of lime on the relief valve seat.
To prevent this from
recommendations:
1. Install a diaphragm-type expansion tank that is suitable for
potable water on the cold water supply line. A minimum 0.5
gallon expansion tank should be used.
Contact the local water supplier or plumbing inspector for
information on how to control this situation. Do not plug the
temperature and pressure relief valve.
Tronic 3000T – 6 720 801 072 (2018/04)
happening, there are two
Installation instructions
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