Why Your Pool Heater Is Leaking and How to Prevent It for Good
Stop the frustration: Learn how to protect your heater and avoid costly damage
Introduction
Noticed your pool heater leaking from the bottom? Before you assume it’s a faulty unit, know this: most heater leaks, especially internal ones, are caused by poor water chemistry or improper system setup that damages the heat exchanger, the heart of your heater.
This guide will explain why your heater is leaking and how you can prevent further damage to protect your investment.
1. Find the Real Source of the Leak
Not all leaks are the same. Identify where the leak is coming from:
- Bottom of the heater: Likely a corroded heat exchanger.
- Pipe connections: Loose fittings or cracked unions.
- Only when running: Might be harmless condensation.
- Pressure relief valve area: Could indicate excess internal pressure.
2. How Bad Water Chemistry Destroys a Heater Fast
The heat exchanger, made of copper or cupro-nickel, is especially sensitive to corrosive water. Common issues include:
- Low pH (acidic water)
- High chlorine levels
- Low calcium hardness
- Poor water flow or trapped air
Damage can begin in just weeks.
Low pH and high chlorine can corrode a heat exchanger beyond repair in less than a month.
3. Balance Water Weekly And Get an In-Store Water Test
It's important to stay on top of your water chemistry. Here’s how:
- Test and balance your pool water 2-3 times per week. Test your water for pH, alkalinity, calcium hardness, and chlorine levels.
- Take your water to a local pool store for a test at least once a week. Many stores offer this service for free and provide a documented record of your water’s chemistry.
Why it helps: Having a record of your water tests can be crucial for warranty claims, showing that you've maintained proper water chemistry. This is especially important if you ever need to file a claim for a damaged heat exchanger.
| Water Parameter |
Ideal Range |
| pH |
7.4 – 7.6 |
| Alkalinity |
80 – 120 ppm |
| Calcium Hardness |
200 – 400 ppm |
| Free Chlorine |
1 – 3 ppm |
| Salt (if applicable) |
2500 – 3500 ppm |
Always adjust alkalinity first, then pH.
Use a reliable test kit or bring a sample to a pool store for verification.
4. Install a Check Valve to Block Chemical Backflow
If your chlorinator or acid feeder is installed after the heater, backflow can send chemical-rich water into the heat exchanger when the pump shuts off.
A check valve prevents this damage.
- Install it on the return line, between the heater and any downstream chemical feeders.
Conclusion
A leaking pool heater isn’t always a sign of a defective unit, it’s often the result of poor water chemistry or improper system setup. By maintaining balanced water, keeping a documented record, and using the right valves, you can avoid unnecessary repairs and ensure a longer, more efficient heater lifespan.
