trolleyShop online as usualarrow rightcashbackEarn cashbackarrow rightgiftGet paid in days, not months

Fast Cashback & Exciting Wins Await!

Experience the thrill of shopping like never before with Not only do you earn fast cashback on your purchases (paid in days, not months), but every buy also gives you a shot at winning amazing prizes. It's shopping, redefined. Dive in now and make every purchase count double!


Cooling And Heating

Greenstar 28i Junior Pressure Low

Written by Dale Richardson - Updated: June 23, 2023

Stay Updated with Expert Tips!

Love our DIY guides and solutions for common household problems? Get expert advice, tips, and exclusive offers in our newsletter. From garden hacks to home maintenance and special deals, we've got it all. Join our growing community now!

We care about your data in our privacy policy.

If your Greenstar 28i Junior pressure is low, you've come to the right place. There are a lot of things that can go wrong with a boiler, so it's good to pay attention to things like boiler pressure. While this may seem like a massive issue, it's actually something that you can fix at home, yourself. No fuss, no engineers, and just a bit of elbow grease will solve this in an hour or so.

If your Greenstar 28i Junior's pressure gauge has dropped or it's become less efficient, you'll need to up the pressure. You'll need to identify the filling system you have and then just follow our instructions, easy as that!

Now without further ado, let's get right into it, shall we?

Read Next: Ideal Logic pump overrun; here's why.

Greenstar 28i Junior Pressure: Troubleshooting & Fix



Your boiler will need to be repressurised differently depending on its filling loop. These come in one of three forms:

  1. An external filling loop
  2. An internal (keyed) filling loop
  3. An internal (keyless) filling loop

Before we get started, if you're a visual learner like myself, click here for a video guide on how to repressurise a boiler.

External Filling Loop

If you have an external filling loop, you'll notice two valves near the boiler. One will be running from the main's cold water, while the second will be connected to the heating system. To repressurize an external filling loop boiler:

  1. Take a silver braided hose similar to this and attach it to each side of the valve. Lay down a towel to collect any water that may fall out.
  2. Open your main's cold water tap.
  3. Open the second tap attached to the heating system.
  4. Watch your water pressure gauge rise and turn stop once it reaches around 1. Turn off both taps.
  5. Remove the taps from the hose.

Keyed Internal Filling Loop



To repressurize a keyed internal loop, you'll first need to locate the key. This will generally appear as a plastic "key" or tab on the bottom of the boiler. You may have also been given one upon installation if you owned the home when it was installed.

To repressurize your boiler:

  1. Locate the key and/or its slot. It should be a black port into which the key can fit. Lay down a towel to catch any drips.
  2. There should be a picture of an open and closed padlock, with an arrow on the key. Align the arrow with the open padlock, pushing it up into the port.
  3. Turn the key until the pressure reaches where you need it (right around 1).
  4. Turn the key back to the open padlock and remove it. Clean up any spilled water.

Read Next: This is why your Triton shower has low pressure.

Keyless Interal Filling Loop

This is by far the easiest type of filling loop to repressurise. You'll see a blue lever at the bottom of your boiler attached to a valve. Simply pull the lever down until it reaches where you need the pressure (1 bar) and release the lever. Simple as that!

Final Thoughts

Finally, something that you can fix yourself! While this is an easy fix, hopefully, it got you feeling like a big, strong fixer-upper for your home. Low pressure on a boiler is never fun, but it's luckily a super quick fix that takes very little technical know-how. As long as you can identify whether you have an internal or external filling loop (and whether or not it's keyed), you'll be able to get your boiler back up to proper pressure in a matter of minutes.

One More Thing Before You Go!

Craving more DIY insights? Don't miss our expert guides and exclusive deals. Subscribe now and get the best of home and garden tips straight to your inbox. Join our community and stay in the know!

We care about your data in our privacy policy.

Get Cashback Faster & Earn Free Fraffle Tickets

Shop at your favourite stores and enjoy cashback in days, not months. Plus, sign up today to get 5x Free Fraffle tickets!

ALDI logo
B&Q logo
Adidas logo
Argos logo
North face logo
Currys logo
Pets-at-home logo
AA logo
AO logo
BT logo