What ongoing maintenance is required for a mains pressure hot water cylinder?

As the owner of a shiny new hot water cylinder you are not devoid of responsibility to keep your asset running in tip-top condition.

There are a couple of valves that need to be exercised regularly, and a couple of things that are not essential, but are recommended to do.

This sequence should be completed every 6 months. If we have installed your cylinder, or worked on your house, we will automatically send you a reminder to do these things (unless you ask us to stop).

Firstly you need to exercise your temperature/pressure relief valve. This is usually on the top, or on the side, directly wound into the cylinder. All you need to do is lift the valve lever to let water out. This ensures that it will not be stuck shut when it is trying to relieve. This is the final safety valve on your cylinder, and is there to stop it turning into a bomb should you have runaway heating or something similar.

If there is a constant leak or the valve will not eject water, call us immediately as this is the backup safety device on your hot water cylinder. We will need the information from the cylinder data plate.

Example data plate

Secondly you need to exercise your cold water expansion valve, This is connected to the water inlet in some position. As shown in the video below, you action the knob one quarter turn to allow water to flow. This allows water to exit the system when there is an overpressure situation, such as when the cylinder is heating. When the cylinder is heating, the water expands, and exerts pressure. The cold water expansion valve relieves the pressure by ejecting cold water instead of heated water, thereby saving on electricity.

If this valve is constantly leaking, for days on end, this valve or valve insert needs replacing. Calls us for a speedy fix.

Recommended action is to check all the connections to see if there is a leak, or a siping water leak. Usually these tiny leaks can be fixed by tightening with a crescent wrench. Check the hot water outlet (usually on the top of the cylinder [on the side near the top for most outdoor cylinders]), Check the water inlet and the bungs (usually the lowest inlets). Check the valve connections.

If tightening these connections makes the leak worse, give us a call for a fast and efficient fix.

Another recommendation is to check around the cylinder to ensure that the bottom is not starting to leak. This should not be an issue with a correctly installed cylinder under 10 years old, but better safe than sorry,

Finally, check the temperature of water from the outlet using a point and shoot thermometer. The temperature should ideally be between 60°C and 65°C. Definitely not below 60°C (see our legionnaires article here) or anywhere near 70°C

If the temperature is too hot, or cold you may need to adjust the thermostat.

Then you should check your water temperature from the tap. This should not exceed 55°C in the bathrooms, but can exceed it in the kitchen and laundry. 

If your water is far too hot, or too cold from your taps, you can adjust the tempering valve. (see here for our tempering valve article)

That's it, you are done for another 6 months

If you want to have this done for you plus many other preventative maintenance tasks that will keep your house in tiptop shape, it may be worth subscribing to our preventative maintenance plan; the details are here