Common Hot Water Cylinder Issues
A residential hot water cylinder is a relatively simple piece of technology, with a few moving parts and not a great deal that can go wrong with it. A reasonable expectation of service life for a hot water cylinder is around 20 years (provided you keep up with maintenance). We have seen hot water cylinders still going strong after 60 years!
If you do have a problem, we have written a guide of how to explain your issue to your plumber, using correct terminology and diagnosis so your plumber has a better chance of arriving with the correct gear to fix your problem. If you need hot water cylinder repairs in Auckland, look no further than Archer Plumbing Solutions Ltd for a fast, efficient and friendly fix.
First things first. Is it mains pressure or low pressure?
A majority of older houses (before 1990) have a low pressure cylinder, however the type of cylinder can be easily read off the tank. Another way to tell is if there is a disparity between the pressures of your hot tap and your cold tap. If you have a copper pipe through your roof, either with a valve on the end or not, you probably have a low pressure cylinder. This is important information for your plumber. Each cylinder has their own unique valves and unique problems.
1980s Low-pressure hot water cylinder
Issue: No hot water.
Is the water cold from the hot tap, or is there no water at all coming through the tap? If there is no water at all coming from the hot tap, is there any water coming from the cold tap?
If there is no water from either, this is usually a supply issue as opposed to a hot water cylinder issue.
Is there electricity getting to the cylinder?
Has the power been off to your house? Is the power still off? It’s worthwhile checking whether the circuit breaker for your hot water cylinder has popped, or on older houses, blown. This could be a quick fix for you. Note: if the circuit breaker pops again, it could be an indication of a more pressing problem. In this case, call an electrician to diagnose the problem.
Is the thermostat set correctly?
A thermostat set too low can mean cold/lukewarm water, or too high can lead to constant venting of hot water from the cylinder safety valves. Ensure the thermostat is set at an absolute minimum of 60 degrees, anything higher than 65 or 70 degrees is wasting you money on your power bill and increases the risk of scalding on an untempered tap. A temperature lower than 60 degrees can lead to the propagation of legionella.
Is there water constantly dripping from the copper pipes attached to the valves associated with the cylinder?
These valves are safety valves. They are to stop an over-pressure or over-temperature situation in your cylinder. Water dripping fast enough from these pipes can cause the cylinder to struggle to keep hot. It also means that this valve is not performing as required. You can replace these valves yourself, but it's advisable to get a qualified plumber to repair or replace these valves. Other common reasons that these valves can drip is a build up of limescale in the working parts of the valve, a faulty thermostat causing constant over-temperature, or a worn pressure relief valve.
Note: it is normal for these valves to drip a little water when it is heating. As water is heated the density is decreased meaning it takes up more space inside your cylinder. Therefore your cylinder needs to vent a little water to stop the pressure inside increasing to dangerous levels.
Could the element be faulty?
The element is the component that actually heats the water. Element failure is hard to diagnose yourself. You will need an electrician or competently trained plumber to check. Most, if not all, electricians are trained to replace an element.
Could the tempering valve be faulty?
This valve mixes hot from your cylinder and cold water to give you a safe water temperature in your bathrooms. These valves are predominantly on mains pressure cylinders. If there is hot water being supplied to the top of this valve, and there is no hot water, it sounds like this is your issue.
All you need to know about tempering valves here
Apex tempering valve. Note H denotes where hot water should be entering
Issue: There is a strange noise coming from my hot water cylinder
Strange noises are never good, so we need a little help to diagnose the problem.
Is there a hissing, knocking or banging coming from the cylinder itself?
This could be an issue with the safety valves on your cylinder. To be safe, turn off the power switch to your cylinder, then call us.
Is the strange noise only there when you are using a water fixture, or when turning on or off?
This could mean a few issues. It could just mean that some piping needs to be secured, or it could mean that a valve needs to be replaced or repaired.
Issue: There is water leaking from, or somewhere near, to the hot water cylinder.
How much water is leaking? Is the progress of the leak in the carpet/floor progressing quickly?
If it is progressing quickly and you fear further damage could ensue, switch off your water main, turn off the power to your hot water cylinder and turn on your hot tap for a couple of minutes (to reduce pressure from your cylinder) Then, give us a call.
A leak from your hot water cylinder can mean a few issues. The element could be leaking, a valve or connection could have a leak, the cylinder could be rusted. Some of these are quick and easy fixes; a rusted cylinder is a longer fix.
Issue: Smelly or discoloured water
To see if it’s an issue associated with the hot water cylinder, run the cold tap only for 1 minute. Is the water smelly and discoloured? If it is, this is a water supply issue, if not, it is more than likely a hot water cylinder issue.
Issue: Water too hot.
There are a few issues that this could be. This could be an issue with the thermostat, or an issue with the tempering valve. Call us to diagnose the issue.
Issue: Water keeps changing temperatures
Is someone else in the house using another tap/shower when this is happening? That could be the issue. Or it could be an issue with your tempering valve. Call us now to diagnose this issue.