You just had a new boiler installed. Everything should be running perfectly, but the pressure gauge keeps dropping.
It’s frustrating, especially when you’re topping it up every few days. The good news is, this problem is common and fixable.
Let’s break down why your new boiler keeps losing pressure, what to check, and when to call a professional to keep your home warm and worry-free.
Key Takeaways
- A new boiler should hold steady pressure between 1 and 1.5 bar when cold.
- Pressure loss usually points to leaks, trapped air, or faulty components.
- Repeated top-ups can damage your system if the cause isn’t fixed.
- Rhode Island homeowners should call certified technicians for inspection.
- Acorn Oil offers reliable boiler repair, replacement, and installation services.
What is the correct pressure for a new boiler system?
For most sealed boiler systems, the ideal cold pressure sits between 1 and 1.5 bar (roughly 14–22 PSI). When the system heats up, the pressure can rise slightly. If it falls below 1 bar or spikes above 3 bar, your boiler may lock out or underperform.
Every new boiler includes a pressure gauge, usually on the front panel. If your system consistently drops below the recommended level, there’s an underlying issue that needs attention before it worsens.
Why your new boiler keeps losing pressure
Leaks in the heating system
One of the most common causes of pressure loss is a leak. Even a small drip can reduce pressure over time.
Look for damp patches on walls or floors near radiators and pipes. Corrosion around joints or valves is another giveaway.
If the leak isn’t visible, it might be hidden under flooring or behind walls. In that case, you’ll need a heating engineer to test for it.
Ignoring small leaks can lead to bigger problems, including damage to your boiler’s internal components.
Action step: Check visible pipework, radiators, and the area beneath the boiler. If you notice water stains or rust, call a professional right away.
Faulty expansion vessel or pressure relief valve
Your boiler’s expansion vessel helps absorb changes in water pressure as the system heats up.
If its internal diaphragm fails, it can no longer regulate pressure properly. This can cause your system to release water through the pressure relief valve and lead to a constant drop.
The relief valve itself can also malfunction. If it’s stuck slightly open or worn out, it will keep letting out small amounts of water.
These issues usually need a qualified engineer to inspect and fix. They might need to recharge or replace the expansion vessel or fit a new valve.
Action step: If your pressure drops even after topping up, ask a technician to check these internal components.
Air in the system or an incorrect filling process
After a new boiler installation, it’s normal for some air to remain trapped inside the system. As that air escapes, the water level and pressure can drop. That’s why installers often recommend bleeding the radiators after the first week or two.
Another possible cause is incorrect filling. If the system wasn’t filled or flushed properly during installation, corrosion or trapped gas may form over time. This can gradually push out water and lower pressure.
Action step: Bleed your radiators to release trapped air, then re-pressurize to the correct level. If pressure loss continues, have a professional inspect the installation.
What to do when your new boiler loses pressure
Here’s a quick checklist for homeowners in Rhode Island:
- Check your pressure gauge. Note the reading when the system is cold.
- Inspect for leaks. Look around radiators, joints, and beneath the boiler for any water.
- Bleed radiators. Trapped air can make the system inefficient and lower the pressure.
- Repressurize carefully. Use the filling loop to bring pressure back to 1–1.5 bar, following the manufacturer’s instructions.
- Monitor for a few days. If pressure drops again, don’t ignore it — call a licensed technician.
A new boiler should stay consistent once properly filled and bled. Frequent pressure drops suggest something deeper that requires professional repair.
When a pressure-loss issue signals it might be time for replacement instead of repair
If your “new” boiler keeps losing pressure despite multiple repairs, it could indicate a manufacturing fault or poor installation.
While this is rare, serious internal leaks or a defective heat exchanger can make replacement more cost-effective in the long run.
Fortunately, new units come with strong warranties. If your system is still under warranty, contact the installer or manufacturer right away.
In Rhode Island, always use certified HVAC contractors who can verify installation quality and maintain your warranty protection.
Book Boiler Repair, Replacement, and Installation Service
If your new boiler keeps losing pressure, don’t wait for winter to make things worse.
Acorn Oil provides trusted boiler repair, replacement, and installation services throughout Rhode Island. Their experienced technicians can quickly diagnose pressure issues, fix leaks, and ensure your system runs efficiently all season long.
Visit acornoil.com to schedule your service today.
Frequently Asked Questions
1. Why did my brand-new boiler lose pressure in the first week?
Trapped air or small leaks in the heating system are common early issues after installation.
2. Can I repressurize my boiler myself, or do I need a technician?
You can top it up if you follow the manual, but persistent drops need a professional inspection.
3. Is it dangerous to run a boiler with low pressure?
Yes. Low pressure can cause your boiler to shut down or overheat components.
4. How often should I check the pressure on my new boiler?
Check it monthly during heating season to ensure it stays between 1 and 1.5 bar.
5. Will topping up the pressure fix the root cause?
No. Frequent topping up hides the problem and can damage internal parts.
6. Does frequent pressure loss affect the boiler warranty?
Yes, if you ignore it. Report persistent pressure issues early to your installer.
Conclusion
A new boiler losing pressure can be frustrating, but it’s not a mystery once you know what to look for. Leaks, trapped air, or faulty parts are the main culprits, and early attention prevents costly repairs later.
For reliable help, contact Acorn Oil for expert boiler repair, replacement, and installation service in Rhode Island.
Keep your system efficient, safe, and ready for the cold months ahead.
