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Is Your Swimming Pool Heater Not Heating? Troubleshooting Tips

Why Your Swimming Pool Heater Isn’t Heating and How to Fix itThere’s nothing worse than jumping into your pool and realising it’s ice cold. If your swimming pool heater has suddenly stopped working, don’t panic; most of the time, the fix is easier than you think.

Whether you’ve got a gas heater, solar setup, or one of the newer pool heat pumps in Sydney, this guide will help you figure out what’s going on and what to do next.

At Thermo Pools, we’ve seen every type of heating issue. So here’s what to check before you call for help.

1. Start With the Basics

First things first: Start with the basic things to check, as most people forget them when their Swimming Pool Heater doesn’t work. It’s basic, but do check it.

  • Is your pool heater switched on?
  • Is the thermostat set high enough to actually heat the water?
  • Is your filter clean and allowing enough water to flow?
  • Is the pool pump running at the same time as the heater?

If any of these are off, the heater won’t work. Sometimes, it’s just a timer setting or a filter that needs cleaning.

2. Poor Water Flow Could Be the Culprit

If water isn’t flowing properly, your swimming pool heater might shut itself off for safety. Low flow can be caused by a few things: clogged filters, stuck valves, or even air bubbles in the system.

If you’re using one of the best swimming pool heaters, like the ones we supply at Thermo Pools, you’ll often get a warning or error code on the display when there’s a flow issue. That’s your cue to check for blockages or pump problems.

3. Using a Heat Pump? Check the Conditions

Pool heat pumps in Sydney work great most of the year. But when the air temperature drops too low, they’ll slow down or stop altogether.

If your heat pump isn’t turning on:

  • Check the outdoor temperature. If it’s under 10°C, the unit might be in defrost mode.
  • Make sure the fan is spinning; no fan means no airflow.
  • Reset the system. Sometimes, all it needs is to be switched off and back on again.

Brands like Oasis include digital displays with error codes that tell you exactly what’s wrong.

4. Got a Gas Heater?

Gas heaters are fast and powerful, but they’re not without issues. If you’ve got one and it’s not heating:

  • Make sure the gas supply is on and working.
  • Check the igniter or pilot light.
  • Look for any signs of corrosion or wear.

Keep in mind that gas heaters need regular maintenance. And if your unit is more than 8–10 years old, it might be time to look at replacement options.

5. Solar Heating Systems

Solar heating system

Pool solar heating is fantastic when the sun’s out. But it’s not perfect.

If the weather’s been gloomy, don’t expect your solar panels to do much. Also, check that your water is actually circulating through the solar pipes. Sometimes, valves or pump timers aren’t set correctly, and water bypasses the system.

For a more consistent setup, many Sydney pool owners pair solar with a swimming pool heater or heat pump. That way, you’ve got backup when the sun isn’t enough.

6. Electrical Issues

Modern heaters have a lot of electronics, especially the newer inverter models.

If your heater’s screen is blank or the controls aren’t responding, you might have an electrical issue. This could be something simple, like a tripped breaker, or something more complex, like a blown fuse inside the unit. In most cases, this is where you stop and call a licensed technician. Never open a unit yourself, especially if it’s under warranty. Swimming pool heater repair is something better left to the pros.

7. What Does It Cost to Repair or Replace a Heater?

Let’s talk numbers. A quick fix like cleaning filters or replacing a thermostat won’t set you back too much, maybe a couple hundred bucks.

But bigger issues like a failed compressor, ignition system, or heat exchanger? That’s when it starts adding up.

Here’s a rough guide:

  • Minor repairs: $150–$300
  • Major part replacements: $500–$1,500
  • New heater (installed): $3,000 and up

Thermo Pools offers the best swimming pool heaters in the market. You need to get quality heat pumps in order to minimise the maintenance. It’s a wise decision to focus on quality as swimming pool heater repair costs are significantly higher if the pump is not of good quality.

8. When to Call in the Experts

Tried everything, and it’s still not working? Time to call someone who knows what they’re doing.

We recommend professional help if:

  • There’s a gas smell
  • The unit is tripping your breaker
  • Error codes keep coming up
  • The heater is more than 10 years old

Swimming pool heater installation and repairs are best handled by certified pros. That’s where we come in. At Thermo Pools, our team handles everything from diagnostics to full replacements, and we make sure your pool stays warm when you need it. Our experts know how to install swimming pool heat pumps in the right way to get the best results. 

Get Your Pool Heating Back on Track – No More Cold Surprises!

There’s no need to stress if your swimming pool heater isn’t working. Start with the basics, check your system step by step, and if it’s still acting up, give us a call.

We’ve got options for every pool, pool heaters, heat pumps, solar heating systems, and more. Whether you need a quick repair or a brand-new setup, Thermo Pools can help you find the right fit.

Warm pool days don’t have to wait. Contact us or call on (02) 88 50 40 30 for expert advice or visit our profile for more product updates.
Pool Heating Specialist

TESTIMONIALS

What clients say

Cannot recommend Thermo Pools highly enough. Sunny and Kirsty are incredibly professional and the job was completed to perfection. We were so impressed we are now getting Sunny back to tile our pool.
Anna Butler
2 months ago
Brilliant service! Thank you!
Steve Walkerden
3 months ago
Thermopools have been a breath of fresh air during our pool renovation. When so much has gone wrong with other aspects, they've come through with honest advice, reliability, and dependability. Thank you Sunny and Kirsty!
Benjamin Barrera
3 months ago
Honestly Sunny cares and always answers the phone at any time. One of the best trades I’ve ever worked with. Years later and still communicates and helps if you have any questions, even small ones.
Sam Saad
3 months ago
We had a Solar Pool Heating solution installed by Thermo Pools over seven years ago and it has been going strong ever since. At the start of this season, the system would not kick on for some reason and it turned out to be a faulty controller and pump. Thermo Pools were prompt at determining the issue and providing repair services at a reasonable price. As we go into the current season of using our pool I am happy that we chose Thermo Pools when we did.
Bill Wright
4 months ago
We highly recommend Sunny as an exceptionally knowledgeable and dedicated professional. He went above and beyond in installing the Thermotube system, which heats our pool significantly faster than the traditional solar system we have had before. The system is compact, efficient, and far neater in appearance than our older style conventional system. What truly sets Sunny apart is his extraordinary level of care, dedication, and helpfulness. He took the time to understand our circumstances and tailored his approach to accommodate our needs—something we have never experienced before. His professionalism and genuine compassion made the entire experience outstanding. Sunny also offers pool repairs and deep cleaning of the pool. He will be undoubtedly the first professional we turn to, to complete this work. Many thanks Sunny.
Kristine Celestin
5 months ago
Sonny and Thermo Pools have been fantastic to deal with and the pool heating system they offer is effective and long lasting. We have the same system that we installed in 2008 and it's still going strong. Can't recommend them highly enough!
Ros Harvey
5 months ago
Jeff Buchan
5 months ago
Had a small leak from solar, one phone call and he was out the next day thks
kim kogias
5 months ago
I can highly recommend Sonny and Thermo Pools product. Our system failed and he was the only operator willing to come and help with issue. Professionally diagnosed problem and fixed..we new due to leaks eventually system would need replacing. We were then hammered with large hail Now the roof needed to be replaced. Sonny worked in with roofers and solar was installed the day after roof. Amazing effort just before Christmas. He also sorted the old thermostat and wiring.This is the third rubber on roof and I can already tell its far superior. Pool reached 30 degrees in approximately 4 hours. Previously it took at least 2 weeks to get to this temperature. Sonny was a pleasure to do business with. He is proffessional. I couldn't be happier. Many thanks again.
Cheryl Potocki
5 months ago
Great service from Sunny and Thermo Pools ! Would also like to give a shout out to theirThermorush panels, they have proved to be 2 x 3 times more efficient than our old panels.WOW! Work far better than expected, We made a great decision choosing Thermo Pools!!
Sarah Conlin
6 months ago
Allen Stutchbury
6 months ago
We had a very good experience dealing with Sonny as he replaced our old solar roof collector.
Tim Somerville
6 months ago
Our experience with Thermo Pools was first class. Sunny was very prompt in providing us with a quote and followed up with a visit to ensure our measurements were correct and we had sufficient roof space to install the solar tubing. The installation was done soon after we accepted our quote and Sunny explained the workings of the solar system to us. Thermo Pools were very professional in their communications and we have no hesitation in recommending their services. Our new system is functioning well and as promised by Sunny.
Chris Sherrah
6 months ago
Sunny said he was busy but he fit me in for a repair, and found a problem I didn't know about, which he fixed too! And, he did a small extra-curricular job for us while he was up his ladder. I definitely recommend Sunny!
Shane Martin
6 months ago
I want to commend Sunny from Thermo Pools for his exceptional service in replacing our solar heating. His professionalism, promptness, and attention to detail were outstanding. Sunny's expertise and dedication make him a reliable technician, and I highly recommend him for solar/pool heating repairs and installation. He consistently goes above and beyond to ensure customer satisfaction. If you need high-quality service with a professional touch, Sunny from Thermo Pools is the person to call.
George John
6 months ago
Excellent service, on time, efficient and will continue to be my preferred supplier in the future. Sincere thanks.
Anthony Ockwell
6 months ago
Sunny did an amazing job installing my solar heating. Buying from him was the best decision I could have made. He was super helpful, reliable and punctual, and he went above and beyond throughout the whole process. The installation was smooth with no issues at all. I am extremely happy with the result and highly recommend him.
Silke Dietzel
7 months ago
We recently had Sunny from Thermopools install our solar pool heating, and from start to finish, the experience was fantastic. Sunny came out personally to explain the entire process and what was involved, taking the time to make sure we understood everything. He was extremely knowledgeable and approachable, assuring us that we could contact him anytime with follow-up questions or if we ever had any issues. It's now been over two months since the installation, and we've really noticed a significant difference. We used to think our pool was too cold and only swam on the really hot summer days, but thanks to Sunny and the Thermorush technology, we've already been in the pool half a dozen times and it's only early in the season! It has absolutely been money well spent. I can't say enough kind words about how professional, personable, and reliable Sunny has been throughout the whole process. We highly recommend him and Thermopools to anyone considering solar pool heating. Kind Regards Andrew and Shamila Beattie
Andrew Beattie
7 months ago
Sunny from Thermo Pools was absolutely amazing! From start to finish, the whole process was seamless. Sunny first came out to inspect the pool size, existing piping, and the installation location. He clearly explained what electrical work was required — I arranged this through my own electrician, though he also kindly recommended one. Ordering online was quick and easy, and the installation was efficiently scheduled via email. On the day of the install, Sunny did an outstanding job — he installed and wall-mounted the system about a metre off the ground, removed all the old solar tubing, and even took care of the disposal. The site was left spotless, and the entire job was completed within 4 to 5 hours. The end result looks fantastic and is incredibly easy to use and maintain. I couldn’t be happier and would highly recommend Thermo Pools to anyone looking for professional, high-quality service.
Daniel Cheong
7 months ago
We highly recommend Sunny from Thermopools. He made the whole experience from quotation to install very smooth for our pool heating. We look forward to engaging Sunny for possible future pool reno in the off season. Thank you for a great experience after a few no-shows from other businesses ⭐️⭐️⭐️⭐️⭐️
Melissa Sayer
7 months ago
From my initial telephone call to the end product, we could not fault the service we received from Sunny and his team. Every aspect of dealing with Thermo Pools ran so smoothly. Could not recommend highly enough. We are grateful for the service and product we received.
Lisa Bolger
8 months ago
Sunny and the Team from Thermo Pools did an amazing job repairing and maintaining my pool solar system. Plus recently installed some pool railings. All the jobs were competitively priced and completed with the highest quality. I would highly recommend the Thermo Pools Team for any project you are planning associated with your pool.
Steven Sherry
8 months ago
Thermo Pools is nothing but professional! Responded quickly, came on time, explained everything, repaired the current old system and increased the systems capacity. I have, and will continue to recommend Thermo Pools.
Mike B
10 months ago
Highly recommend Thermo pools solar. Sunny was great, understands his products and was easy to work with. His workmanship was very professional.
Rocco Ursino
10 months ago