Telling if your Boiler Has Low Pressure

What You'll Need
Pressure test kit for boiler

Maintaining a boiler is the key to keeping the hot water system functioning properly, and if you are experiencing problems with the pressure in your boiler, you may need to perform a check to decide whether your boiler has significantly low pressure. Testing for low pressure is often done by experts, but if you are keen on DIY, then you can perform the test yourself without having to call out a boiler engineer. Checking the pressure on your boiler can be done quickly and easily, so long as you understand what you are looking for, and take care to perform a thorough check.

Step 1 - Perform a Blowdown

Before you begin testing the pressure in your boiler, perform a quick blowdown. This will help to remove sediment from the bottom of the boiler, which can cause low pressure in some boilers. You will have a release nozzle on the side of the boiler, which can be located using your manual. Place a bucket below the nozzle, and turn on. You will see water rush into the bucket, as well as possible gas escape, depending upon the location of the nozzle. Don't allow too much liquid to flow from the boiler, and turn the nozzle off when you have released between 1 and 5% of the boiler's contents.

Step 2 - Using the Pressure Test Kit

Remove the contents of the pressure test kit, which can be bought from local suppliers or online, and lay them out on the floor. Connect the pieces together as instructed in the kits, and ensure that all the connections are tight. Locate the air valve on your boiler, as in the boiler manual, and then apply the pressure test kit to this. Some kits will require that you pump the kit, much like an old-fashioned blood pressure test, but others can be turned on and left to complete the test by themselves. Some pressure test kits can be fitted to the boiler as a permanent feature, which may be useful if you are experiencing regular drops in pressure.

Step 3 - Checking the Connections

While your pressure test kit is still operating, this is a good time to check that all of the pipes and vents in your system are properly connected, as low pressure can be caused by loose-fitting joints, poor caulking, or not enough water in the system. Ensure that your water level is sufficient for the requirements of the boiler (checking the sight glass), and that air is not escaping from holes in connections between the pipes. You may need to tighten the joints using a wrench, screw plates and nozzles more firmly into their fittings, and caulk around the edges of anything which is entering the boiler. Try checking the pressure and connections when the boiler is cold, and then when it is warm, as changes in humidity can cause imperfections to appear. Your boiler may also be experiencing problems during the heating process, which may require the services of a boiler engineer or plumber to correct your low pressure.