Is Low Boiler Pressure Dangerous

To have a boiler that is heating your home to the right temperature, you need to have enough pressure. If there isn’t enough pressure in the boiler, it won’t be able to reach the temperature required to properly heat your home.

Many homeowners are unaware that problems they have with their heating system might be linked to low boiler pressure.

Low boiler pressure is not dangerous but can be inconvenient. In most cases, your boiler pressure will slowly drop over time due to slow leaks in your heating system.

If not monitored and dealt with, it can eventually lead to freezing pipes, water damage, and burst pipes which can result in property damage.

It also means that the temperature of the water won’t be warm enough for taking a shower or washing dishes.

What should boiler pressure be when heating is off

The ideal boiler pressure when your heating is off should be in between 1 – 1.5 bars and up to 2 bars at a max. This range is often shown on your boiler gauge with a red and green indicator.

The red zone shows the low and high boiler pressure zones, while the green zone shows the ideal boiler pressure zone.

If the red zone is showing on your boiler gauge, you will likely have low boiler pressure

The green zone shows where your heating system should be operating, once it switches over to heating mode.

Low pressure boiler fix

If you find that your boiler pressure is too low, there are a number of steps you can take in order to solve the problem.

This applies if you have a low system pressure boiler or low pressure on a combi boiler.

Going through the following steps should help you identify the cause of the problem and help you fix it.

Step One

First, check for any leaks in your heating system. Walk around your home checking each radiator. Listen for sounds of dripping water and inspect the area where each radiator and pipe meets for any signs of moisture. Also, check the floor in front of the radiator to make sure there is no water pooled up near it or any wet patches on your flooring or carpeting.

Step Two

Check your external stop cock if you have one. This might be located just outside the boundary of your home.

Step Three

Leave your heating system off and make sure it is completely cold. Then walk round to bleed each radiator from upper-level rooms down to lower level rooms.

Bleed each radiator in turn by turning off the radiator valve and then opening up the vent screw slightly to allow any air inside to escape.

This will release any trapped air that is stopping your boiler from pumping water around your system efficiently, resulting in low pressure.

This will further reduce the pressure in your heating system but it will also remove all the air trapped in each radiator.

Step Four

  • Return to the location of your boiler.
  • Look for an external filling loop directly under the boiler.
  • If you can’t find it, check further instructions in your boiler manual.
  • Turn both valves to face the direction of the external filling loop.
  • Watch the boiler pressure gauge closely and listen for water running.
  • Shut off both valves at just under 1.5 bar (1.2 bar if you own a combi boiler).
  • Monitor the pressure guage for a few minutes to ensure the pressure does nto drop straight away.
  • Switch your boiler thermostat back on.

Does boiler pressure drop in summer

In old homes with old heating systems, the boiler pressure will probably need topping up once or twice a year. This is mainly because of the age of the heating system.

Your boiler pressure should not significantly drop in the summer as your heating system is not being used. That said, it still might drop if there are any slow leaks in your heating system.

If you have an old heating system or have recently done a power flush on a house with old pipework, then there’s a higher chance of leaks occurring, so low pressure can be a problem.

In new homes with newer boiler systems, this is less common as modern boilers are more efficient and newly connected pipes will have fewer leaks.

However, it can still be a problem in instances where it’s a completely new installation that hasn’t been tested much.

What if your Boiler pressure keeps dropping to 0

What if your boiler pressure keeps dropping to 0 after following the steps listed above? If your boiler pressure is dropping down to 0, this means that there are leaks in your heating system.

It’s likely there is a leak beneath your floorboards somewhere that is not visible around your home. So the only thing to do is call a plumber or heating engineer out to find them and fix them.

Depending on how fast your boiler loses pressure, it might be an idea to top the pressure up at least once a day to ensure your boiler doesn’t stop working.

If you have an older boiler then it might not be able to cope with the extra demand of repeatedly trying to get back to 1 bar.

Alternatively, just switch off your boiler and get a standalone electric heater to keep your home warm.