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Boilers are key components of many central heating and water heating systems. Everything from the most modern radiant floor heating systems to older heaters may use boilers. As they create and move very hot water, the pressure of your boiler is very important. They need enough pressure to do their job efficiently, but not so much that they are damaged, risk leaks or damage the other parts of the heating system.   

Ideal Boiler Pressure Settings 

So, you’ve noticed the pressure scale on the side of your boiler. Where should it be? That depends on a few factors, such as whether the boiler is currently hot, how many stories the boiler services, and its own manufacturer’s guidelines. The best place to get your boiler pressure settings is in the owner’s manual or from the manufacturer. However, if you can’t find that information, you can use the following as a basic guideline. 

When cool, a boiler should read 12 psi (pounds per square inch) or so. When heated, the pressure will increase to 20 psi or so. This should be within your boiler’s “green” range if it has one. Any pressure reading outside of the green range is a cause for concern. 

Boilers that service larger buildings may need more than 12 psi. Those that service two or three-floor homes may need 15 or 18 psi when cold. They may go up to 30 psi when warm. A reading over 30 psi on a boiler is a cause for concern. 

Interested in more information about boilers? Get in touch with Advantage Airtech ClimateCare today!

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Boiler Pressure Safety Mechanisms 

Modern boilers have fail-safes that prevent high pressure from causing serious accidents. Boilers have relief valves that trigger at about 30 psi, releasing some pressure to get the boiler back down to safe levels. It may also turn off the boiler in order to prevent more pressure from being created and causing the same issue. If your boiler keeps switching off, this may be what’s going on. You will likely need professional assistance to remedy the problem. 

There is no safety mechanism for low boiler pressure because technically it isn’t a safety concern. There is a mechanism to refill the boiler and get it back to 12 psi if it has dropped below this minimum amount. However, you will still likely need a professional to fix the underlying cause of the boiler’s low pressure. 

Should I Adjust My Boiler Pressure Control Valve? 

It is typically a bad idea to try to adjust the boiler pressure control valve without professional guidance. The boiler can be damaged by both high and low pressure, and an HVAC technician is better equipped to adjust your pressure and ensure that your boiler is working properly and set to the right pressure. 

As always, talking with a professional about your specific concern is the best way to get the HVAC information you’re looking for. Are you looking for more information on boilers? Our team at Advantage Airtech ClimateCare would be happy to answer any of your questions. Give us a call today. 


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