A How to Guide on How to Repressurise a Navien Boiler

If your Navien boiler is currently displaying an E302 code, its water level is too low, and it must be repressurised.

Usually, you’ll first notice that the Navien boiler has switched itself to prevent it damaging itself.

Before you panic, repressurising a home boiler is a common maintenance task almost all homeowners will have to do once in their lifetime, as general use will cause it to lose water.

For those who have an annual boiler service done by a Gas Safe registered engineer, you might not need to do it at all. This is due to the fact that the Gas Safe registered engineer will top up the pressure level to ensure it is running as efficiently as possible.

But what are the steps to repressurising a Navien boiler?

Step-By-Step Guide For Repressurising a Navien Boiler

Navien recommends that their boilers’ pressure should be maintained between 1 to 1.2 bars. With Navien boilers, there is a small pressure gauge under the unit to the left hand-corner.

To start the repressurising process you need to follow these steps:

Step 1: Turn Off The Heating System

To turn off your boiler you will need to locate its fuse spur (or, for the layman, a big switch). If you can’t find this switch, boilers can also be wired into a standard home socket.

This variation is simply down to whoever installed the boiler. But if you can’t find the on/off switch, turn off all the power in your home from the switchboard.

It is recommended to allow the system to cool down for a number of hours. A cool heating system means you can take an accurate reading of the system’s pressure level.

When you’re confident the power is off, that it has cooled down, it is time locate your system’s filling loop system.

Step 2: Identify and Find The Filling Loop System

A filling loop system is used to top up the water levels in your boiler’s heating system or to connect your boiler to your home’s cold water mains.

There are two main types of filling loop systems:

• External filling loop: A detachable, braided silver hose.
• Internal filling loop: Built into the boiler, typically operated with a key or lever.

In most cases, the filling loop system is underneath the boiler. With Navien boilers, some are equipped with their NaviFill system, which makes repressurising even simpler.

However, selected Navien boilers still use an external filling loop.

Step 3: Attaching the Filling Loop

When attaching the filling loop, ensure the valves are closed.

When shut off, the valve handles should be at a 90-degree angle from the water pipe’s direction.

Remove the plug and cap from the filling loop connection and set them aside for later. Attach the filling loop securely by hand to the domestic hot water inlet. Avoid over-tightening, as this may cause leaks.

With the NaviFill system, no prep work is necessary. All you need to do is locate the plastic and brass link with a green plastic leaver under the boiler and open it.

Now that your filling loop systems are attached, it is time to open the valves.

Step 4: Open the Filling Loop Valves

Once the loop is attached, align the first valve with the pipe opening the cold water mains. Then, slowly open the second valve to allow water to enter the boiler’s heating system.

Monitor the pressure gauge, and when it reaches 1 to 1.2 bars, close both valves.

With the NaviFill system, you only need to open and close the valve when the water reaches the desired pressure.

Step 5: Clean Up and Check

If you’ve attached a filling loop to your boiler, you will need to disconnect it. Prepare a bucket and towels to catch any water that spills during this process.

Once completed, your repressurised Navien boiler should be ready for use.

However, if you notice that you must repeat this process frequently, whether after a few hours, days, or every week, this could indicate a more serious pressure issue.

Common Causes For Boilers To Lose Pressure

If your Navien boiler is still losing pressure, a few common causes:

Bad DIY: Bleeding Radiators

Bleeding your heating system‘s radiators removes trapped air from the heating system, improving its efficiency.

However, releasing too much water and air during the process can lower the system’s pressure.

If you’ve recently tried to bleed your radiators, this could be the cause.

Leaks in the System

Leaks are a common cause for a boiler to lose its pressure. A small leak in your pipes, radiators, or boiler can cause the pressure to drop gradually, while a bigger one might make it plummet suddenly.

It must be mentioned that finding leaks can be tricky. If they’re hidden behind walls or under floors, you might not notice them immediately. If you suspect a leak, it’s best to call a pro to track it down.

Faulty Pressure Relief Valve

Your boiler’s pressure relief valve is one of its key safety features. It is designed to release excess pressure and keep your system running safely.

But if something goes wrong with it, here’s what might happen:

• It could open when it’s not supposed to, causing a pressure drop.
• It might not seal properly, leading to a slow leak.
• In rare cases, it could stop working entirely, which might create a safety risk.

Don’t try to fix this yourself if you think the pressure relief valve is the problem. Only a Gas Safe registered engineer is qualified to do so safely.

Expansion Vessel Problems

The expansion vessel plays a significant role in keeping your boiler’s pressure steady.

If it’s damaged or not working correctly, the pressure will drop, which you can’t ignore.

This is another issue that needs expert attention. A Gas Safe registered engineer can check the vessel and get things back to normal.

If you suspect that your Navien boiler is losing pressure due to an issue requiring a Gas Safe registered engineer, what should you do?

Contact WarmZilla!

If your Navien boiler is losing pressure due to a leak, faulty components, or anything else that needs professional attention, you’ll need a Gas Safe registered engineer to handle the repairs safely.

At WarmZilla, we’ve got you covered with nationwide service and can provide a Gas Safe registered engineer within 48 hours.

But maybe you want to talk through the problem? Well, feel free to reach out to one of our professional consultants today, and they’ll be able to make an educated suggestion that will get your Navien heating system back on track!