What Is The Right Boiler Pressure? Mathematically Explained!

What Is The Right Boiler Pressure? Mathematically Explained!

The boiler pressure should be adjusted automatically as you turn on the boiler system. However, sometimes, the pressure can get to an abnormal range and makes you think if the pressure is correct. 

So, what is the right boiler pressure? 

The right boiler pressure for a one-story building is at least 10 psi. For a two-story and three-story building, the minimum pressure is 15 psi and 20 psi respectively when the system is cold. When hot, the normal boiler pressure should be up to 30 psi. If the pressure is lower or higher than these ranges, you need to adjust the pressure. 

Adjusting the pressure wouldn’t be enough if the system is faulty, you need to troubleshoot further and fix the problem, keep reading to discover it all. 

What Is The Right Boiler Pressure?

The right boiler pressure depends on the total height of the boiler system. In a 2.31 feet column, if you provide 1 psi pressure, it has the capability to raise water. So, for 1 foot of the column, you need 1 psi / 2.31 = 0.4329 psi of boiler pressure. 

You have to calculate the required pressure of the boiler for your home by multiplying this psi by the height of the house. 

Boiler Pressure Remarks
5 psi Pressure is too low
10 psi Enough for a one-story building when the system is off
15 psi Enough for a two-story building when the system is off
20 psi Enough for three-story building
30 psi Maximum pressure when the system is hot
40 psi Pressure is too high
50 psi Pressure is extremely high

Boiler Pressure At 5 Psi:

Boiler pressure at 5 psi is too low even for residential buildings. Suppose, the boiler is in a 1-story building and a one-story building is usually 14 feet tall. 

Now, to raise the water to a 14 feet building, the boiler pressure should be 14’ x 0.4329 = 6.06 or 6 psi. For residential-size circulators, extra 3 psi pressure is required. 

That means, 6 + 3 = 9 psi.

So, the boiler pressure should be at least 9 psi in a one-story building when the system is cold. 

If your boiler pressure gauge is showing 5 psi or less than 1 bar, you should take action to increase the boiler pressure. 

Boiler Pressure 10 Psi:

Boiler pressure at 10 psi should be enough for a one-storied building. However, for a 12 storied building, this pressure is not enough. 

Suppose, you are using the boiler pressure in a 2-storied building. The 2 story building is on average 18 feet to 20 feet tall. 

If the boiler is set in the basement, to raise the water to 18 feet from the radiator in the column, the boiler pressure should be 18′ x 0.4329 = 7.79 or 8.00 psi. For residential-size circulators, extra 3 psi pressure is required. 

So, the boiler pressure will be 8 + 3 = 11 psi

Sometimes, the radiator in a two-storied building can be taller. In that case, the recommended psi of a boiler for a two-storeyed building is at least 12 psi. This psi is accurate when the boiler is cold or the heating is off. 

Boiler Pressure 15 Psi: 

The 15 psi boiler pressure when the system is cold is enough for a two-storied building. However, for a three-story building, 15 psi is not enough. 

The average height for a three-storied building is around 30 feet tall. Let’s take the minimum number. 

So, the minimum boiler pressure when the system is cold is 30′ x 0.4329 = 12.98 or 13 psi. Add 3 more psi. So,13 + 3 = 16 psi. As the radiator size can vary, the recommended boiler pressure for a three-story building is at least 18 psi when cold. 

The minimum pressure rate will increase as per the height of the building. 

Boiler Pressure 20 psi:

A boiler pressure of 20 psi is considered to be within the normal range for the system. In a two-story house, you will notice the pressure meter going around 19 to 24 psi when the system is hot. 

Boiler Pressure At 30 Psi:

If your boiler pressure is at 30 psi, it indicates that it is at the highest limit of the boiler pressure range. In a three-storied building, it is normal for a boiler to reach up to 30 psi. A two-story building can also sometimes reach this limit when the system is hot. 

Boiler Pressure At 40 Psi:

If your boiler pressure gauge shows 40 psi, that means the pressure is too high. If the boiler pressure exceeds 30 psi or 2 bar in a residential boiler, it indicates a certain problem with the system. In that case, you have to take action to lower the pressure. 

If your boiler pressure goes outside the optimal range, you have to adjust the pressure. The boiler temperature should beat the optimal level as well.

Boiler Pressure At 40 Psi

Source: boilerspecialists.com

What To Do When The Boiler Pressure Is Too High?

If the boiler pressure is too high, you have to bleed water from the system. Due to excess water in the boiler system, the boiler pressure goes too high. Follow the process below to bleed the excess water from the radiator. 

Tools Required:

Process: 

Step 1: Identify the radiator valve or pressure relief valve. It is usually at the top corner of the radiator.

Step 2: Place a drain pan beneath the valve to catch water.  

Step 3: Set the radiator key on the valve and rotate the valve anti-clockwise. You will hear a hissing noise as the air escapes from the valve. Some water will also escape from the radiator. 

Step 4: Check the boiler pressure meter. If the pressure decreases to the optimal number, rotate the valve clockwise to tighten it. 

If the pressure doesn’t decrease after bleeding the radiator, you need to go for further troubleshooting. 

Here are some causes that can cause the boiler pressure to be high. 

Filling Valve Is Left Open:

If the filling valve is accidentally left open in the boiler, the system will be overfilled with water. As a result, the pressure will increase. 

Solution: Check the filling valve and tighten it if required. 

Faulty Boiler:

A malfunctioning boiler can cause the boiler pressure to get abnormally high. 

Solution: You need to replace the boiler in this case. Instead of a boiler, you also consider buying a wall heater and disguising it, as they are less expensive. 

Frequently Asked Questions (FAQs):

What Is The Difference Between Bar And Psi In Boiler?

Bar and psi are two different measurement scales. The Bar measures only pressure whereas the psi unit measures both pressure and stress. Some boilers have a pressure gauge in the bar unit, some have a psi unit and other boilers use both the unit in the pressure gauge. 1 bar is equal to around 14.5 psi. 

Is 2 Too High For Boiler Pressure?

No, it’s not. 2 bar means the boiler pressure is 2 x 14.5 = 29 psi, which is within the normal boiler pressure range. If the boiler pressure gauge shows more than 2 bar, it means the pressure is too high and you need to lower the boiler pressure. 

How To Maintain a Residential Boiler?

To maintain the boiler, keep the boiler pressure in check. Increase or decrease the pressure if required. Look for the warning signs and get it repaired as soon as possible. Don’t forget the annual boiler servicing. 

Conclusion

That’s all on what is the right boiler pressure. If the boiler pressure is out of the range you should correct it immediately before it can cause further damage to the boiler. Also, don’t forget the regular maintenance of the boiler.

Now it’s time for me to go. Stay safe. Goodbye.


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