Protection against thermal expansion

What is the purpose of a safety valve on a water heater?

To understand the purpose of the safety valve, here is a simple example. Several issues may arise, like an improper thermostat setting, an overheating element, too little water in the tank. In fact, all the previous points can lead to over-pressurization, namely excessive pressure in the equipment. This is where the safety valve comes into play. When the pressure in the tank is too high, the valve opens to release steam. This allows the excess pressure to escape and prevent all risks, like a ruptured tank or pipes. Therefore, the safety valve’s purpose is to prevent hazards.


Why is it necessary to have a protection device against thermal expansion?

First of all, let us define the terms “thermal” and “expansion.” The word thermal is an adjective that relates to heat and temperature. As for the word expansion, when an object expands, it grows from its original size. Now, let us explain why it is important to have a protection device against thermal expansion. In fact, protection against thermal expansion is required when the appliance has a check valve. This prevents backflows and reduces the pressure in the equipment.

To ensure protection against thermal expansion, it is important to measure the air pressure from inside the tank before its installation.

Here is the formula:


Here is the meaning of each abbreviation:

Pa: The level of air pressure the tank should have
Ps: The static pressure at the water inlet of the potable water supply system
 : Difference of height between the water inlet and the tank
 : Density of water measured at the initial temperature [cold water]
144: Conversion factor

In addition, it is important to specify that the air pressure needs to be adjusted before installing the tank since the weight of the water on the membrane may alter the measurement on-site.

Therefore, it is necessary to involve certified experts to prevent any excessive pressure risks. They will know how to guide you to prevent possible hazards. In fact, the advice of plumbers will ensure compliance with Québec standards. Moreover, plumbers have the necessary qualifications to check the existing plumbing system and provide the safe installation of a new water heater. Finally, their expertise will allow you to meet the requirements of the different standards and upgrade any type of plumbing system to achieve compliance.


Water Heater

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