How to check the gas pressure in the boiler

Classification by method of operation

According to the method of operation, the devices can be water, electric or digital, in addition to these categories there are other varieties.


Water-based devices operate on the principle of balancing the gas substance with pressure, forming a column of liquid. They can be used to check vacuum, differential, overpressure, and atmospheric readings. This group consists of U-type regulators, which are designed like communicating vessels, in which the pressure is determined by the water level. Also include water compensation, cup, float, bell and ring gas gauges, the working fluid inside them is similar to the sensing element.

check, pressure, boiler


Strain gauge electrical pressure gauge

This instrument for measuring the domestic gas pressure converts it into electrical data. This category includes strain gauges and capacitance gauges. The first ones change the readings of conductive resistance after deformation and measure values up to 60-10 Pa with negligible errors. They are used in systems with fast processes. Capacitive gas gauges influence the moving electrode in the form of a diaphragm, the deflection of which can be determined electrically, they are suitable for systems with accelerated pressure drops.


Digital or electronic instruments belong to high accuracy devices and are most often used for installation in air or hydraulic medium. The advantages of such regulators are noted as convenience and compact size, the longest possible service life and the possibility to perform calibration at any time. They are mainly used to monitor the condition of vehicle components. Digital gas gauges are also used as part of fuel lines.


In addition to regulators with standard features and settings, other types of instruments are used to obtain accurate data. This list includes piston gas gauges, which are a kind of specimens for the verification of similar devices. Their main working part is a measuring column, which changes the error value depending on the condition and accuracy of readings. During operation, the cylinder is held inside the piston at the correct level, while at the same time it is affected by the calibration weights on one side and only by the pressure on the other.

How to choose a pressure gauge to regulate a gas boiler

When selecting devices must take into account: type, measuring range, accuracy class, size, functional load, operating conditions.

Device types

According to the structure and principle of operation there are 5 main types of sensors:

Spring and liquid instruments. the most popular. They are quite accurate and reliable at their low price. These two types are well suited for private homes and small businesses. In most boiler rooms spring pressure gauges are used.

Gas pressure measuring range

This is the most important parameter when choosing measuring equipment for the boiler room.

The main thing is that the working pressure in the boiler pipe fell into the range of 1/3-2/3 of the measuring scale of the device. If the pressure is less, the measurement error is too high, and if more. the device will be overloaded and will fail before the warranty period.

Accuracy class

The lower the value, the more accurate the instrument. Accuracy class. is a percentage of error of measurements from the measurement scale.

It is not difficult to calculate the error, for example, if the device is for 10 atm. has an accuracy class of 1.5., its permissible error is 1.5%. If the value is higher, it must be replaced.

Determine the fault can only be with the help of a reference pressure gauge, this is a special organization that performs verification of equipment. A precision instrument is connected to the system and then the readings are compared.


The diameter of the device is chosen according to the purpose.

  • 50, 63 mm. for installation on portable equipment or for pressure control of oxygen cylinders, welding machines.
  • 100 mm. the most common size, the most convenient in most cases.
  • 160 mm, 250 mm. for control of devices that are visually far away, for example, under the ceiling of the boiler room.

Functional load

According to the type of functional load devices can be:

How To: Check The Gas Pressure

check, pressure, boiler
  • Indicating. these are devices of technical direction. Measures pressure.
  • Alarming. control an external electrical circuit.
  • For accurate measurement have an accuracy grade of 0.6-1.0 units.
  • Reference ones are used to check the accuracy of other instruments.
  • Self-recording. they record the pressure in the form of a diagram on paper.
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Sample pressure gauge for gas boiler. The device has a high accuracy, it is used to calibrate other devices.

Operating conditions

The device is selected for the environment in which it will be used. The medium can be different, including aggressive. Various housings are available and it is important to consider whether it will be used in a humid, dusty, vibrating environment or not, to prevent corrosion and damage to the housing.

Classification of pressure gauges for adjusting gas boilers

The principle of operation of all pressure gauges is based on the fact that the measured pressure is balanced by the force of a tubular spring or two-plate diaphragm.

One end of the instrument is soldered onto the carrier, and the other end is connected to the pointer through a special mechanism. This mechanism converts the linear movement of the sensing element into the movement of the dial hand.


Sample gauges are gauges that are used to calibrate other. This type of devices are used for examination of equipment and precise measurement of fluid and gas pressure, they have higher accuracy class. 0,015-0,6 units. The high accuracy of these devices is due to the peculiarities of their design: gear organ in the transmission mechanism is executed very precisely.


These devices monitor the pressure limit and alert the system when it is reached. This kind of measuring equipment is usually used for gases, vapours, still liquids which are not prone to crystallization. Instruments can control external circuits when critical pressure is reached with a contact group or an optical pair.

Electrocontact pressure gauge for the heating gas boiler. The device has a dial with divisions.

Conclusion and helpful video

Characteristics and applications of the pressure gauge:

Pressure gauges are produced for different tasks. The most popular are the general technical types, used in small industries, by various firms when working with gas equipment and systems. Electro-contact pressure gauges are devices that signal when a critical value is reached.

Reference pressure gauges are used for calibration and alignment of pressure gauges. Special pressure gauges are made to measure the pressure of a particular gaseous medium. Among them enjoy great popularity propane pressure gauges, which are often installed in conjunction with a reducer on gas cylinders.

Air pressure in the expansion tank

Air or nitrogen pressure in the expansion tank for different gas boilers will not be the same, it all depends on the type of equipment and design features. The standards are specified by the manufacturer in the product passport.

Usually the pressure in a new reservoir is 1.5 bar. But this setting may not be suitable for your particular heating system. The factory parameters are easy to reset. For these purposes in the body of the expansion tank there is a special fitting (in some manufacturers it is a slide valve for pumping), by which the air pressure is regulated.

For the normal operation of the gas boiler, the pressure in the membrane tank must be 0.2 bar less than in the system. Otherwise, the heated water that has increased in volume will not be able to enter the tank.

In small houses and apartments for closed heating systems, the pressure in the expansion tank is usually acceptable in the range of 0.8-1.0 bar (atm). But not less than 0.7 bar, since many gas boilers are protected and the device simply will not turn on.

Check the tank pressure level every year. If you notice pressure spikes in the heating system, it means that air has come out of the damping tank and needs to be pumped up.

Pressure gauge to adjust the gas boilers with their own hands

Yes, not the site, I know. But nowhere else is there (there is a video on YouTube, but about a different boiler, albeit similar). And the expert on call is not available to everyone, both in price and geographical location of the boiler. Very much I ask specialists just Baxi one favor: well, do not tell me about how difficult and tedious to translate the boiler and how many years to teach it to call a wizard is worth the money. I have already encountered this attitude (to be fair I say sincere thanks to the consultants from the forum Baxi for assistance and practical advice, given in substance and understandable language). And, yes, I do not give a damn about the warranty: it is easier for me to repair myself than to wait until a specialist arrives and replace my part, bought, again, at my expense, no “proper commissioning for the mad thousands” will not save my budget in case of a breakdown, I’ve been there, I know. Nothing phenomenally complicated in this boiler: automation, sensors, control panel and a banal gas boiler. Oh, and a fan, pump and tank.So one can only hope that search engines will index it and someone will find it, unlike me. I have not found it, all the following is the fruit of several days of thinking and smoking all kinds of literature, coupled with the memories of the school-institute knowledge of physics.

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Everything started prosaically: built a house, buried the gas holder, mounted the heating system and hung a boiler. And then have fun: the boiler is originally set to natural gas (methane), as stated on the label on the side of the boiler: G20. That’s it. Run it can not: different gases, different dynamics of combustion, we will not risk (although, I did start it, had to play with the settings of the gas valve and the system worked without overheating and failures, but still) Baxi requires that the transfer to LPG trained specialist. Not that I can’t afford it, but, pardon me, I can replace the nozzles and adjust the pressure myself. There is a nuance here though: the measured pressure is within 4.9. 37 mbar (you have to find such a manometer, yeah). But even on this, we will find an engineering solution. But more about this later.

First we need to replace the nozzles. For LPG we need nozzles with a nozzle diameter of 0.74mm. Purchased a set with the number JJJ000601520, its price was about 2500r (to order sometimes cheaper, but the question was urgent and did not have to choose). It has 17 nozzles and a spring, it is a universal set for several models. We need 15 nozzles.

We turn the boiler off, remove the front (white) lid and the heat shield of the combustion chamber. Under the cover is found CS: GO (my boiler Fi with a closed chamber) and remove it too. Mounting screws are marked with yellow circles, there are 4.

Now we remove the burner. It’s got two screws. I will show you one (right), on the left is the same. First remove the 2 wires from the ignition and flame control electrodes, they are put on tightly, but there are trivial terminals, no fixation, just pull down.

A pressure gauge exists to measure the pressure in the system. It connects to a safety relief valve and an air vent, thus guaranteeing safety.

If the pressure readings are out of acceptable limits, it means that the system is not working properly. Excessive pressure can cause burst piping and even explosion of equipment.

Increased pressure in the heating circuit

What to do if the pressure in the heating system increases too much?

The first thing to do is to establish the cause, and there can be several:

  • Improper filling of the circuit, it is blocked. Due to the rapid filling of the heating circuit air s can form in it. To avoid this phenomenon, when starting the heating, fill it slowly.
  • Temperature in the circuit is too high. Any increase in temperature and coolant leads to its expansion and increase the pressure in the system. It is necessary not to allow too high an increase in order to protect the heating equipment from critical loads.
  • Stopping the flow of the coolant. Can be caused by blocked valves, clogged strainer, airlocks.

To identify the problem area, it is necessary to examine the entire circuit step by step.

Leaks can be caused by breakage of the make-up valve. wear and tear of the valve gasket, mechanical damage of parts, scale between the seat and gasket. If the tap leaks, the extra water coming from the water system in the heating system, increases the pressure in it, because the pressure in the pipeline HTW is always higher. You need to tighten the faucet or replace it if it is out of order.

Air clogs are a common cause of problems with the heating system. They can be caused by malfunctions of the gas boiler itself, as well as problems in the circuit or improper heating start.

To eliminate the problems you can restart the system by slowly filling it with fluid, starting from the lowest point until the water flows from the top of the circuit. All bleeding and venting valves must be open. Aeration in the system can cause the pressure to rise or fall.

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To check the measuring equipment with the three-way valve, proceed as follows

  • In the operating position note the readings of the device.
  • Slowly turn the 3-way valve to the left a quarter turn. The pressure gauge is disconnected from the boiler and connected to the atmosphere, the arrow should return smoothly to the zero mark.
  • Slowly turn the cock back to the right about a quarter of a turn, the arrow should return to its previous position.

If the pointer is moving jerkily it means that the connection and the valve are clogged and must be blown out. to turn the tap so that water (gas) flows, then return it to the operating position.

Important! The accuracy of the pressure gauge is checked only with a reference device.

is carried out according to МРБ М МП document.No. 2136-2011 “Verification procedure. Gas pressure meter FD-09”, approved by RUE “BelGIM 8 April 2011.

1 Pressure calibrator DPI 705, measuring range. 0 to 20 kPa, uncertainty ±0,1 % API.

2 Pressure gauge, indicating MP2-UU2, measuring range 0 to 100 kPa, accuracy class 2.5.

4 PCV-3,5×0,8 hose connector.

It is allowed to use similar verification means ensuring determination of metrological characteristics of verifiable MI with the required accuracy.

Verification mark is marked on the FD-09 gas pressure meter according to the figure 2.

Adjustment of boiler automatics and pressure

A readjustment is performed if the automatism is triggered too often. This problem is called pounding, and it is caused by an excessive increase in the temperature of the coolant. Reduce the gas supply to the main burner, so you protect the boiler from wear and tear.

The method also has a fallback option. just twist the faucet in front of the boiler. Remember that incomplete combustion of fuel leads to an increase in the volume of flue gases and carbon monoxide.

To get rid of the knocking, move the room thermostat (if available) to a cooler location or reduce the air temperature in the place of installation. Increase the amount of coolant in the heating system. Replace the main burner, if the tacho appeared due to its increased capacity.

Problems with the automatics and frequent shutdowns are observed under the following circumstances:

  • Voltage dropped or jumped;
  • A strong wind has extinguished the burner;
  • The chimney’s permeability has decreased;
  • The gas pressure has decreased.

To improve the operation of the automatics, set the handle of the autoblock (gas valve) to the “spark” position. Light the igniter (pilot burner, ignition burner). Leave the knob in this position for 30 seconds, then turn it back to the “off” position with a white circle.

Boilers are produced with thermostats (thermoregulators) and with daily and weekly programs. The thermostat switches the boiler off when the set temperature is reached, then the device switches it on automatically. While the owners are away, they can rely on the regulator with a 7-day period. The daily appliance eliminates the need for constant monitoring of the boiler.

Set the pressure on the autoblock. Take the Eurosit 630, for example. The appliance maintains the temperature of the water in the heating circuit and stops the gas supply in an emergency situation. The Eurosit 630 has a rotary knob with 7 flame modes. point it at position “1”, remove the cover and tighten the screw on the left side under the knob. If you turn it clockwise, the gas flow is less and smoother, and the automatics work better.

Also set the maximum mode. Set the knob to “7” and tighten the screw on the bottom of the unit, now counterclockwise. Reducing the flame level will decrease the gas pressure and the efficiency of the boiler burner at the same output setting.

Determine the correct sides on the autoblock first. Consider the surface with the handle as a side. The unit is installed in different ways: sometimes this side is on the side, sometimes on the top. Do not confuse the correct screws (gold-plated) with the fasteners.

The pressure should be reduced in such cases:

  • The flame goes out soon after ignition;2
  • There is a popping noise on ignition;
  • the flame extends beyond its allotted limits;
  • Red or red-orange lights.

Pressure usually increases in winter: gas distribution companies raise the value from 200 to 280 mm water column. Install a pressure regulator or reduce the flow through the outlet.

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