Water heaters are strong pieces of equipment that last a long time. Unfortunately, this causes many homeowners to completely forget about them. While water heaters aren’t as troublesome as other appliances, when a problem does develop, it can be very serious.

Tpvalve

If the TPR valve constantly leaks or you notice any other problems with the valve or drainpipe, contact Service Champions to correct it. We have years of experience working with all types of water heaters and are happy to answer all your questions.

The other way to catch leaking water from the TPR valve is by collecting the water with a pan underneath the heater. Hopefully, this pan will have a hole that allows water to escape into a drain.

JavaScript seems to be disabled in your browser. For the best experience on our site, be sure to turn on Javascript in your browser.

Hot water tank pressurerelief valve

Assuming a 1.0 bar system pressure when the system is ‘cold’, the expansion vessel will normally be sized to ensure the running pressure at operating temperature rises by approx 0.5 Bar to 1.5 bar running pressure.  Therefore if the pressure vessel is installed at the top of the system the pre-charge pressure of the vessel will be equal to the ‘cold-fill’ pressure (1.0 Bar).  If the pressure vessel is installed at a lower point of the system the static pressure of the system above the vessel should be added to the pre-charge pressure.  E.g. if the static height of the top point of the system is 5 metres above the pressure vessel, the pre-charge pressure should be 1.0 bar + 5 metres = 1.5 bar.

This blog will give you a quick guide on how to size both expansion vessels for heating/cooling systems and potable pressure vessels.

A simple rule of thumb is 10% of the system volume – rounding up to the nearest vessel size. Allow for 10 litres per standard radiator and an additional 10 litres for a boiler. For example; a system with 10 radiators and a modern boiler would equate to an approximate system volume of 110 litres. 10% would equate to 10 litres – therefore using this calculation a 12 litre vessel would be suitable.

A little maintenance now will vastly improve the performance and safety of your water heater. Just set a little reminder every 6 months to perform some key maintenance tasks, such as testing the temperature and pressure relief valve.

Water heaterrelief valvedripping

The TPR valve is critical to the safety and proper operation of your water heater. This safety valve releases water and pressure if it becomes too high inside the tank.

Since the water heater tank holds about 50-100 gallons of water, any leak can cause a lot of property damage. You don’t want to come home to a flooded basement and then start thinking about water heater maintenance.

Both the above methods tend to slightly oversize the vessel capacity. Please see below table for more accurate selections:

Thermostatic mixingvalve

Copyright © 2024 Trade Pumps. All rights reserved. Tradepumps is a trading name of Dutypoint Ltd, a company registered in England and Wales No 09045694Registered office: Unit A, Quedgeley West Business Park, Gloucester, GL2 4PA, United Kingdom

Another ‘rule of thumb’ method of calculating vessel size is using the boiler KW size. The method used is to allow for 1 litre capacity per kW. For example; 7kW output would equate to an 8 litre vessel.

For instance, if there is a malfunction with the thermostat and the temperature gets too high, the valve will open to allow steam to escape safely. Water heaters can explode if the pressure gets too high and the valves do not work properly.

One of the most common problems with water heaters is leaking and defective TPR valves. Sometimes, debris, rust, corrosion, and freezing temperatures can cause the TPR valve to fail.

The ‘rule of thumb’ calculation is that the pressure vessel size is equal to 6 seconds of maximum flow. For example: if the design maximum flow rate of a booster set is 3 l/s – the required vessel size would be 18 litres.

Water heater pressurerelief valvefailure symptoms

While TPR valves are absolutely essential for safety purposes, they often leak with small surges in pressure. Since this is their purpose, there is no way to prevent the valve from leaking, however, a correct configuration will properly discharge the water outdoors.

Heating expansion vessels are selected and commissioned taking into account three system characteristics; maximum system temperature, system volume and static head above the vessel. The system volume and operating temperature range dictates the pressure vessel size and the static system head dictates the pre-charged pressure.  There are however a couple of quick simple methods to this – based on the assumption that the system is 82℃ / 71℃ flow and return and a system pressure up to 1.5 bar.

PressureRelief Valve

The selection and sizing of vessels is very important depending on the application type and system characteristics. Many a pump has failed due to too many starts because of incorrectly specified pressure vessels, and undersized expansion vessels can cause a range of failures.

It is important to remember here that on applications like this, the larger the vessel the smoother the system will run, and less energy will be required switching the pumps on and off. Additionally, if space is a constraint, vessels can be installed in tandem on a common manifold on the discharge pipework.

To calculate what size pressure vessels you will need for a pressure boosting system, the easiest method is by taking the design flow rate of the pump or pump system.