BoilersBoiler Pressure Drop, and Other Faults – What Could Be The Causes, and How To Deal With It?

10/13/2019by Mack Galus0

Autumn is the time of increased work of service technicians caring for gas or oil boilers. This is the time at which most users are commissioned to perform a review. Service graphics are full during this period, sometimes even overcrowded, especially during the first wave of frost, when most people run boilers for heating purposes. Suddenly it turns out that our boiler has the following problems: boiler power drop, boiler pressure drop, gas pressure too low

In many cases, it appears that the boiler is not working properly. The service technicians have their hands full of robots. Continuous customer calls, haste sometimes, that instead of smoothly perform the steps and accept the payment of the visit of the service is prolonged, and sometimes even a further approach is necessary. Half-poverty If the reason for repeated visits is the emergency shutdown of the boiler.

Worse if the service technician forgot about the action and caused the threat, e.g. and leaving the gas pressure measuring port open. This type of “Mishka” can, unfortunately, happen even the most experienced service technician. Independently, from the acquis, every service technician should take care of the proper organization of the work at this time.

You cannot afford to ignore clients as well as unreliable work. One of the other must in the long term result in fewer customers.

Boiler pressure drop and others – Before you start work.

  • Determine

Starting a service visit, it is worth to start by finding all the facts that can be helpful at work and make the visit effective. To this end, it is always worth listening to the customer information about the symptoms of possible improper operation of the boiler, and if we do a routine review of it and so it is worth to ask the user whether or not noticed anything disturbing in the installation work.

All information obtained can help us on the one hand and shorten the time of the visit, and on the other hand, it may be an opportunity to offer additional services, e.g. Replacing the old expansion vessel or other.

  • Adopting the device for review/repair

It is one of the most important moments, which can finally err on the effects of the visit. Before we proceed to the possible disassembly of the individual components, let’s check that the boiler actually behaves as described by the user.

It happens that the customer’s observations are not justified in the actual state of the boiler. Checking the boiler will allow us to save time in this case and in some cases quickly dispose of the user’s doubts.

Effective control of the boiler condition also avoids any confusion. If we do not, then there is a risk that after the service visit the client reports another fault and considers that it is the cause of our actions taken, e.g. During the review.

Even if the user reports that the boiler is not working only for hot water preparation, it is worth checking how the boiler works for heating the building.

This will allow us to avoid a situation in which the user calls us a few days after the visit and the alleges that “it was true that the Lord repaired, but the second broke, the boiler does not warm the house.”

Careful inspection of the boiler before the repair or review avoids such unpleasant situations, dissatisfied customers and repeated visits.

Boiler pressure drop and others – Common symptoms reported by users.

  • A sudden drop in boiler power

Especially during the frost, many customers notice that the boiler is working continuously and cannot heat the building. Of course, if the outdoor temperature is extremely low, e.g. – 30 ⁰ C As of 2006 years is the continuous operation of the boiler is not unnatural. However, if we are outdoors, for example, -5 ⁰ C and the boiler is unable to reach the specified temperature then it is necessary to check what is the cause. It is always worth to start the control from basic operations that do not immediately require dismantling parts of the boiler.

  • Gas pressure too low.

The basis, in this case, is always the measurement of gas pressure at the entrance to the boiler.

The permissible pressure range for natural gas from group E and Lw (former GZ 50 and GZ 41.5) is 16-25 bar, for liquefied petroleum gas It is 29-44 bar, but always check the required pressure as given in the device documentation.

If the pressure is lower than the recommended value, the boiler will not reach the required power, and sometimes the flame or the impure ignition may be lost.

Cases of too low gas pressure occur especially in winter in the medium pressure gas networks when the pressure regulator is blocked. The fault must be reported immediately to the gas ambulance.

Another reason for the pressure drop occurring especially during the first months of operation of the boiler used in the old installation is contamination of the gas filter with swarf’s, sealing materials or contaminants that have detached from the surface of the pipes.

In heavily loaded low-pressure networks, pressure drops occur especially on cold days when gas intake is highest.

It is trivial, but contrary to appearances, it is also a common cause of accidental stopping of the gas valve.

  • Abnormal, too low flow through the heat exchanger

Many boilers, especially those equipped with a small-capacity heat exchanger, have a flow control system through the exchanger. It can be based on direct flow measurement or measurement of the difference in supply and return temperature. This system is designed to prevent the boiler from working with high efficiency when the flowing heating agent is unable to take over the required power.

This would threaten a significant and rapid increase in temperature and the emergence of significant stresses in the heat exchanger material due to the large temperature difference between the power supply and the back. So when a user reports a sudden drop in boiler power, if the boiler has an extensive system of diagnostics, we check what is indicated by the boiler the state of operation or failure and what faults are in the fault history (if the boiler has Opportunities). 

Many boilers indicate too low water flow or excessive temperature difference. Some boilers have no such possibility. Only the fault lamp flashes or does not indicate abnormal operation in any way. In this case, you need to check the difference between the supply and return temperatures. 

Many boilers go into reduced power mode when the difference between the supply and return temperatures is higher than 25-30 K. If, so we restart the boiler and the flow of water is limited we will see that suddenly the difference in temperature rises after that The boiler reduces power and the temperature difference is set at 20-25 K. We already know that we need to take care of the proper flow of water in the boiler circuit.

Let’s start again with the basic and simplest steps. Let’s check if anyone accidentally set the pump in the lower gear, or did not get stuck one of the valves. 

Let us also check whether the presence of air in the heat exchanger or the walls of the exchanger (water cooking sounds) is not heard during the boiler operation. If you have excluded all these eventualities, let’s check the status of the water filter or other elements where contaminants can be collected, e.g. Air separator.

It must be remembered that part of the boilers is equipped with small filters installed inside the boiler, they also need to be checked. If we ruled out these causes then we can probably have to deal with damage to the circulating pump.

Reduced water flow can cause a number of inconveniences and sometimes even serious damage. Sometimes finding the cause of system obstruction or decreasing pump performance is difficult and takes a lot of time. In any case, observing the temperature difference in the first minutes of torch operation is necessary in such cases.

  • No gas flow due to chimney obstruction

Many condensing boilers are equipped with a gas unit with pneumatic air and gas flow coupling. The operation of the ventilator and the airflow through the venturi causes a vacuum, the movement of the diaphragm and the opening of the gas valve. But sometimes the fan is working and the gas… does not flow. 

This is because, for example, the Exhaust pipe has been clogged. By doing so, the air does not flow through the venturi. There is also no opening of the gas valve. If, therefore, we see that despite the fan operation, the gas pressure does not even vibrant, then let’s check the Fluor of the combustion line.

  • Water pressure spikes in the installation

The cause of sudden pressure spikes is a usually incorrect operation or damage to the expansion vessel. During installation and commissioning, the pressure of the gas cushion is not correctly adjusted to the installation height.

This is a very important activity, which is the basis for ensuring proper operation of the vessel. If the pressure of the gas cushion is significantly too low or too high in relation to the hydrostatic pressure in the installation, then after filling the installation the vessel does not fulfil its role at all, since it is immediately filled with water (when the pressure of the cushion is too low) or the membrane is even pressed against the water inlet into the vessel (when the cushion pressure is too high).

In order to verify the pressure of the gas cushion, we need to detach the vessel from the installation or drain the part of the installation to which it was connected. The pressure should be determined on par with the hydrostatic pressure in the installation. In simple terms, this pressure should be 0.1 x installation height, e.g. 0.1 x 10 m = > 1 bar.

Pressure spikes during warming up and cool down may also be a symptom of vessel damage. Another symptom of this is often the presence of water in the space where the gas should be. Sometimes, when you press the vessel valve instead of gas, water flows out.

The pipe connecting the vessel to the hydraulic system must also be inspected in pre-fitted boilers with an expansion vessel. Sometimes there are impurities that hinder the flow of water to and from the vessel after a while.

Boiler pressure drop and others – Recommendations

After performing a review or repair, especially if its reason was the improper operation of the boiler, it is certainly necessary to instruct users how they should proceed to avoid in the future hazards and ensure the highest efficiency Boiler.

For its part, the service technician should remember to leave the boiler in a state of safe use, in particular check that the gas pressure measuring points have been closed and the gas installation is sealed. 

In order to avoid confusion and to remember all activities, it is worth, the model of the car workshops to include in the repair or review protocol The most important activities and check whether they were made. This will ensure that we do not put anyone at risk, and a satisfied customer would recommend us another.

In the protocol or on the sticker, it is worth to enter the date of the next annual review, so that you know and remember when you should contact the service.


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