Hot Water Cylinder Repairs and Replacements

One of the most common questions we get asked about hot water cylinders is, how do I know whether I should repair or replace my hot water cylinder?

There are quite a few things we factor into the decision, and we’ll ask you the following questions before helping you decide whether it is best to repair or replace your hot water cylinder.

What is wrong with your hot water cylinder?

You might not know exactly what’s wrong with it, but we start by finding out what has made you suspect your hot water cylinder isn’t working properly. If you hear hissing, banging or other strange noises coming from it, we can sometimes diagnose the problem simply from your description.

Specific, common sounds often indicate it just needs a replacement part. If you hear a knocking or banging noise, there may be an issue with how the pipework is fixed or there may be damaged valves. These things can usually be fixed without replacing your hot water cylinder.

If your hot water cylinder is leaking water, or if all of a sudden you have no hot water, we’ll need to know a few other things, starting with the age of your hot water cylinder. Sometimes a change in water temperature may mean there is a fault with the thermostat or element.

We can replace just the broken part if the cylinder is still not very old. If there is water leaking (more than the usual amount from the release valve), there may be a faulty valve that can be replaced. Or there may be a crack in the tank, which is rare, but does happen over time (particularly if it has been relocated or if you live in an earthquake zone).

How old is your hot water cylinder?

A general rule of thumb is that a hot water cylinder should last about 15 years. Most major manufacturers, including Rinnai and Rheem, have a 10-year warranty on their products. If your hot water cylinder is less than 10 years old, we’ll almost always consider repairing it instead of replacing it. A problem that arises with a cylinder that is less than 10 years old is usually a sign that there is a part that needs replacing (as mentioned above), not the entire hot water heating system.

If your hot water cylinder is between 15 and 20 years old (or older), we’ll most likely recommend replacing the hot water cylinder. This will, of course, depend on how much use it has seen. A household with only one or two people in it may have a hot water cylinder that lasts a lot longer than a hot water cylinder in a household of five people, for example. This is purely because of use and wear and tear.

Once a hot water cylinder is over 15 years old, though, there may be more than one issue or part that needs replacing. We can come and have a look at it and see what condition the rest of the components and valves are in, and whether they are likely to need replacing any time soon. We’ll look at all of these things, along with the related costs, and help you make the best decision on whether to repair or replace it.

Is a hot water cylinder still the best option for your household?

If your hot water cylinder needs several parts repaired or replaced, or if you decide that the whole hot water cylinder needs replacing, it may be a good time to evaluate whether a hot water cylinder is the best option for providing hot water to your household.

This may be a good time to move away from a hot water cylinder to a continuous flow hot water system. This decision depends on a few things, such as the size of your household and how much hot water you require.

If things like instant hot water, unlimited hot water, and saving money in the long run are attractive to you, it may be time to look into a gas continuous flow system. This is a gas system that essentially generates hot water on demand, with no cylinder to store hot water. If you’d like to know more about continuous flow hot water systems, give us a call or read more about instantaneous gas hot water here.

Factors that may affect your decision to repair or replace your hot water cylinder

Sometimes we diagnose a problem with a hot water cylinder and see that the options to repair or replace it are evenly weighted. That is, sometimes a few components have started to wear out or stop working altogether, and the repair costs are getting close to the cost of a new system altogether. Here we need to look at a few other determining factors with you.

The first thing to think about is whether you’re going to stay in the property for much longer. If you’re thinking of putting the house on the market any time soon, then think about whether you want to spend the money on a new hot water cylinder or just replace the parts and live with it until you sell. Alternatively, if you replace the hot water cylinder you can then market the property with that as a featured advantage – and it may help increase the asking price.

You might also factor into the decision whether the property is your own home or a rental property. If you have tenants in a rental property that are repeatedly calling you to complain about having no hot water or hearing odd noises coming from the hot water cylinder cupboard, then it’s probably worthwhile to replace the system (if it’s more than 10 years old).

Now might also be a good time to stop and think about whether your water usage is likely to change in the near future. Families and households go through stages, and these stages affect your water use. If you’re about to have a baby, you’ll soon be running the bath every night. If you have children who are about to enter the teen years or who are about to start playing more college sport, the frequency of showers in your household will likely be about to change.

If you’ve just renovated and now have a part of your home that is a rental unit, you’ll likely need more hot water for the additional residents. If you’re nearing retirement age or about to become an empty nester, your water use may be about to decrease. If you’ve just installed a water tank, again, your water use will likely change. There are a number of things that affect your hot water use and what the best water heating system is for your home. If you’d like to review the options, please get in touch with us for a no-obligation chat.


There are a number of plumbing and drainage companies in Auckland, so why choose Sumich?

Founded by owner-operator Chris Sumich in 1991, Sumich Plumbing & Drainage has one of the most experienced teams operating in Auckland. Our team has a combined experience of over 100 years and we’ve seen a comprehensive range of scenarios and solutions over the years. Clients trust us to give honest, transparent advice and service.

As registered members of the New Zealand Plumbers, Drainlayers & Gasfitters Association, we are professional, licensed Auckland plumbers for all of your plumbing, drain laying, gasfitting and heating needs. Give us a call to see how we can help.