How to Increase or Reduce Boiler Pressure

San Rafael

(415) 942-6565

Santa Rosa

(707) 452-3464

We cannot emphasize enough the importance of maintaining the right boiler pressure. If you operate your boiler at lower pressure, it might fail to produce enough steam or fail to heat the water properly. Your boiler may turn off and display an alert code (this signifies that the pressure in your boiler has dropped drastically).

If, on the other hand, your boiler pressure is too high, your boiler can develop cracks, or the seal might break down.

The ideal boiler pressure is between 1 and 1.5 bar on the pressure gauge when the heating is turned off. Your boiler pressure should be between 1.5 and 2 bar when the heating is turned on.

To know if your boiler pressure is too low, check the pressure gauge (usually a circular dial with green and red zones marked on it). If the needle has fallen below the green zone, your boiler pressure is too low.

Some boilers tend to lose pressure over time. Leaks, faulty parts or a bleeding radiator can cause a boiler to lose pressure. Low boiler pressure is one of the most common and also the most frustrating boiler problems. Though it is usually nothing to worry about, low boiler pressure can affect your boiler’s efficiency. Fortunately, the problem is, more often than not, fairly simple to fix.

Follow these steps to increase boiler pressure:

  • Switch off your boiler. Allow your boiler to cool down
  • Locate the filling loop. Most combi boilers manufactured these days have external filling loops. An external filling loop looks like a braided hose. It’s usually located below the boiler casing
  • Check to see if the filling loop hoses are securely attached
  • Find the filling valves (they are where the hoses connect to your boiler). Using a screwdriver, open the filling valves. Once you open the valves, you will hear the water flowing
  • The gauge’s arm should start moving. Close the valves when the gauge reads 1.5 bar. Check to see if the filling loop is completely closed
  • Turn on your boiler. If the pressure does not remain steady, call a plumber to discuss the problem

Some common causes of high boiler pressure are – faulty parts, high water levels, and age-related deterioration.

Follow these steps to reduce boiler pressure:

  • Switch off your boiler. Allow it to cool down
  • Make sure the filling loop valves are fully closed
  • To release pressure, bleed the radiators. After you bleed your radiators, check the pressure. If it’s still high, repeat the process. Keep bleeding your radiators until the pressure gauge reads 1.5 bar

John Owens Services is a reputable plumbing contractor in San Rafael. We specialize in boiler replacement near you in Novato. We will help you choose the right boiler for your home and install it. To request a quote, call 415-322-7542.

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Serving Marin & Sonoma Counties

Good plumbing, heating, and air conditioning systems are vital in every North California home. John Owens Services, Inc. is proud to be the expert plumbing company you can count on

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Our philosophy is simple, we always want to maintain equipment to give it the longest life possible. Next, we want to focus on repairing when something goes wrong. Then only as the last choice, we replace equipment when needed. That’s the John Owens Way.

San Rafael
(415) 942-6565
Santa Rosa
(707) 452-3464



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San Rafael
(415) 942-6565
Santa Rosa
(707) 452-3464