What To Do If Your Rheem Hot Water System Is Not Working

There’s nothing quite like a freezing shower to remind you how much we rely on our hot water systems. If you’re standing there wondering why a Rheem hot water system not working has suddenly become your morning reality, you’re not alone – but you’re not without a few things to try, either.

You love reliable hot water – and that’s probably why you installed a Rheem! It’s one of Australia’s most trusted and recognised hot water brands, with decades of proven reliability across gas, electric, solar, and heat pump models. But even the most dependable system can hit a snag – especially if it’s been a few years since installation, or the weather, water pressure, or power supply throws it a curveball.

Our exclusive guide will walk you through common Rheem hot water system troubleshooting steps based on real information from Rheem’s own manuals, fault code references, and our own hands-on service experience. Whether you have a storage tank unit, a continuous flow gas or unit, a heat pump, or a solar-boosted system, we’ve broken it all down so you can get to the bottom of it fast.

Let’s find out what’s going wrong with your Rheem – and what you can do next:

1. Identify your system type

First things first – know your unit. Rheem has several types of water heaters:

• Continuous flow (gas)
• Electric storage
• Gas storage
• Solar systems (with or without gas/electric booster)
• Heat pumps
• Instantaneous (or continuous flow) water heaters.

Every model has its quirks, but they all have one thing in common – if something goes wrong, Rheem tries to make your life easier by starting with a clearly displayed fault code.

So before you panic, check the screen or monitor on your unit or controller. If there’s a number flashing, that’s your clue.

2. Look for an error code

As we’ve just said, if you see a code, that’s good news – because it’s not a guessing game anymore. This little code will help you or your plumber find the fix faster.

A few key examples:

11 = ignition failure

12 = flame failure

14 = overheat

79 = fan motor fault.

These are straight from the Rheem water heater troubleshooting manual, and often indicate specific faults that need checking. For continuous flow models, error codes appear on the controller screen or diagnostic display.

If you’re on LPG and see error 11, for instance, the fix could be as simple as checking the bottle level and restarting the unit.

3. Restart your system

Sometimes, especially for gas models, restarting can fix a minor hiccup. To safely reset your system:

• Turn off the power at the wall or GPO.
• Wait 10 seconds.
• Turn the power back on.
• Reopen the hot tap.

This can often clear non-critical issues in many Rheem gas hot water system not working scenarios. But if the code comes back right away, it’s time to call in help.

4. Check basic power and gas

If your screen is blank, or there’s no hot water at all:

• Check the unit is plugged in and switched on.
• For solar or electric systems, check the circuit breaker.
• For gas systems, make sure your gas supply hasn’t been interrupted
• For LPG users, check the bottle and regulator.

These checks rule out a surprising number of calls where the issue wasn’t with the unit itself, but the power or gas supply.

5. Continuous flow/instant unit? Check your flow rate

One of the most common Rheem continuous hot water troubleshooting calls we get is for fluctuating temperature – or no hot water at low flow.

Why? Because continuous flow units require a minimum water flow rate to activate. If you’ve got water-saving taps or showerheads, you may be below that threshold – especially with new installations.

SOLUTION: Open the tap fully.

If that works, you might need to change the aerator or restrictor on your tap.

6. Solar unit? Check the booster and weather

If your particular Rheem solar hot water troubleshooting situation involves lukewarm or cold water, consider the weather. Cloudy days or a string of rainy mornings can reduce solar collection.

Most systems include a booster (gas or electric). Make sure:

• The booster is switched on
• The timer (if fitted) is correctly set
• You’re using enough booster time to meet your daily needs
• If your booster is on but water is still cold, it may be a failed thermostat, element, or controller.

7. Heat pump? Listen for operation and look for lights

With Rheem heat pump water heater problems, a common issue is a flashing light on the control panel. This could mean anything from defrost mode to a fault with a sensor.

If you don’t hear the fan or compressor running, or the light keeps flashing in a specific pattern, it may need a service call. You’ll find the fault explanation in your specific Rheem owner’s guide.

8. Water leaking? take a closer look

Not all leaks mean disaster! For storage tanks, the temperature pressure relief valve (TPR) is designed to release a small amount of water during heating.

But:

• If it’s more than a bucket a day
• If it’s leaking constantly
• If water is leaking from fittings or joints …

Then it’s time to act. We often find that an everyday Rheem hot water not working report turns out to be a slow hot water leak that’s been ignored too long – leading to corrosion or electrical failure.

9. Check the controller or thermostat setting

For Rheem systems with controllers (like the ones installed in kitchens or bathrooms), make sure the temperature isn’t set too low. For storage models, especially electric ones, the thermostat could be faulty or set incorrectly.

Rheem instant hot water not working quite well enough? If you have warm but not satisfyingly hot water, check if a child-safe or extra temperature limiter has been activated.

10. Call a Rheem-specialist plumber

Sometimes, the issue will be beyond DIY – and that’s ok.

Checked all the basics and you still have a Rheem hot water heater not working? It’s time for a licensed plumber to inspect the system. Here at Fix-It Right Plumbing, we’ve been analysing fault codes, testing components, and making safe and approved repairs for years. From flow sensors to gas valves to thermistors and beyond, we know our way around all Rheem units.

So, whether you need a hot water replacement in Melbourne, expert hot water repairs in Geelong, or help with hot water systems in Canberra, the friendly team at Fix-It Right Plumbing can be at your door fast with the right equipment and specialist know-how.

Call now for help with your trusty Rheem

They’re great units from a great brand – until you have a Rheem hot water system not working, of course! No one likes to be left in the cold, but a bit of basic troubleshooting can go a long way. Just remember never to push your luck with electrical or gas components, because that’s pretty risky.

Give us a shout for help with your Rheem – we’ll Fix-It Right, the first time.