Boiler Conversion To Liquefied Gas: Conversion And Reconfiguration Of The Boiler To Cylinder Fuel

The gas boilers offered for sale are oriented and configured to process mains gas. But in this case, what about the owners of private homes, which are not connected to the system of natural gas supply? After all, you need to live in normal civilized conditions with a functioning heating system now.

It is very simple - the transfer of the boiler to liquefied gas will allow you to heat your home and warm sanitary water, using a group of cylinders or a gas holder. To achieve this goal, your unit will have to slightly modify and reconfigure for other fuel pressure parameters. We will explain in detail how this work is done.

Content of the article:

  • Causes and principles of boiler modification
  • Steps for modifying a Baxi boiler
    • Nozzle replacement procedure
    • The process of pressure adjustment by \"folk means\"
  • Steps for modification with the change of burner
  • Safety instructions
  • Conclusions and useful video on the topic

Causes and principles of the boiler modification

We would like to warn you from the first lines that the work of converting the boiler to another type of fuel must be done by the foreman of the organization with which the contract for gas supply and maintenance of the equipment is concluded.

But any owner should know the essence and the steps of the process for the elementary control of the invited executors. And doubts about their competence sometimes justifiably creep in. Therefore, it is better to follow the implementation of the procedure, on which, incidentally, depends on the safety of the house and households.

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Boiler connection for liquefied gas bottles

Installation of gas bottle group

Powerless gas equipment

Autonomous system with floor standing boiler

It happens also that there is no way a gas service representative can get to a remote location. In this situation, the home handyman, of course, will try to do everything with his own hands. But the inexperienced person in the gas field would be responsible for the result and the producer's warranty would be invalid.

When you buy a gas boiler for domestic use you get a device adjusted for processing the mains fuel. The centralized pipeline supplies us with a mixture of combustible gases, dominated by methane. Trunk gas goes to appliances with a natural density and pressure of 21 mbar.

Liquefied gas is an exaggerated name for a propane-butane mixture in which either the first or second component may predominate. It may be predominantly butane with a small admixture of propane, or conversely, it may be 99% propane.

The density of a liquefied mixture increases by a factor of 600. The pressure is not increased by that much, but it is still higher than that of natural fuel, 30-31 mbar.

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

The pressure of propane and butane is increased by about 600 times to obtain liquefied gas. This procedure makes it possible to reduce the volume of the fuel and store it before use in a liquefied state

The types of gases on which boilers operate are standardized. They are assigned codes, which the manufacturer indicates in the technical documentation. Thus, the consumption of mains gas by the boiler is marked with the code G20. The boiler can run on liquefied gas with a predominance of butane is coded G30, with a propane predominance G31.

In order that the blue fuel fulfils its primary function, the gas flows through nozzles into the combustion chamber. There the gas is mixed with the air by means of a burner in the optimal proportions for the particular fuel. This means that the burner must be fed with the volume necessary for normal combustion.

Normal mixing is possible if the diameter of the nozzles is suitable for its execution. The size of the nozzles determines how much gas at a certain pressure gets into the combustion chamber for a given volume of air. That's why the nozzles for LPG and the main gas are of different sizes.

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

To switch to LPG consumption there is no need for a complete change of equipment, let alone for a new machine. It is only necessary to change either only the nozzles or the manifold (ramp) with the nozzles

We note that the nozzle cross section is determined not only by the type of gas, but also by the capacity of the boiler itself. For example, a 10 kW unit operating at maximum capacity requires 1.2 m³/h of mains gas and 0.86 kg/h of liquefied mix of any kind.

The more powerful the equipment, the more fuel it requires to operate. The larger must be the size of the nozzles that let the blue fuel into the combustion chamber. Their cross-section is clearly calculated and strictly regulated by the manufacturer producing burners with nozzles of a given diameter for a given boiler capacity.

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

When gas flows from the nozzle, the gas mixes with the portion of air it requires for normal combustion process. Both components must be fed into the combustion chamber in precise proportions

So how do you still switch to liquefied gas if you didn't initially think to buy a liquefied gas boiler? That's right, either replace the entire manifold with the entire set of nozzles, or just the nozzles, leaving the manifold in place. The second option is not possible in all boilers.

In addition to replacing the devices for liquefied gas, you will also need to reconfigure the burner of a gas boiler with an electronic type of control. This is necessary to ensure that the amount of air required for uninterrupted combustion is fully delivered. The new settings will also ensure that the gas supply is interrupted in the event of a risky situation.

It will also be necessary to install a pressure reducer designed to regulate the pressure of the gaseous fuel. One or a group of cylinders may be connected to the gas pressure reducer. It may be necessary to change the gas valve if necessary.

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

To connect the boiler to cylinders or a gas tank it is necessary to adjust the pressure reducer to the operating gas pressure. Sometimes it is also necessary to change the gas valve in the boiler if it is not suitable for gas supply at the required pressure

In any situation, before ordering a contractor to convert a wall or floor gas boiler to liquefied fuel, it is worth consulting the gas service that oversees your equipment and gas supply to your facility.

They will tell you what devices should be purchased for conversion. They will calculate how much it will cost you to upgrade together with the master fee.

Stages of converting a Baxi boiler

In order to get a full and complete picture of how to convert a boiler to run on bottled gas, let's consider an example of the conversion of a wall mounted two-circuit unit of Baxi brand.

Jet replacement procedure

In most boilers with the Baxi logo it is not necessary to change the entire burner, it is sufficient to rearrange the nozzles. To do this, you need to purchase them in advance, focusing on the capacity of the appliance and the type of gas. In the example under consideration to switch to G31 fuel the nozzles with the diameter of 0,77 mm would be needed.

The price of a set of nozzles for these boilers is approximately 2,5 thousand rubles. In the set, produced for several similar models of boilers, there are 17 pcs. and also a spring. It is necessary to change 15 nozzles and 2 spare nozzles are useful in case of failure.

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Step 1: Removing the combustion cover

Step 2: Removing the gas burner

Step 3: Unscrewing the main gas nozzles

Step 4: Installing the new nozzles by screwing

And we will proceed as follows:

  • Turn off the power dependent devices of the boiler. Turn off the unit and shut off the taps on the pipes directly feeding the unit with gas and water.
  • Remove the front panel from the boiler, then remove the closed combustion chamber screen behind it.
  • Loosen the screws that hold the closed combustion chamber cover. It is just behind the screen.
  • Disconnect the wires of the two electrodes: one for the flame control and one for the ignition system.
  • Remove the burner. To remove it, unscrew the two Phillips head screws that hold it in place. They are on the right and left side, fixing the burner to the ramp.
  • Unscrew the nozzles with a screwdriver without dismantling and removing the ramp. Do not use pliers. They can deform nozzles without much effort. Nozzles nozzles are thin and extremely precise in execution, there is no sense to spoil - can be useful yet.
  • In place of the unscrewed nozzles, install new devices designed for liquefied gas and connect the electrodes for the lighter and flame control system.
  • Return the burner to its original position. Its position will be \"prompted\" by the rails.

With the burner in place, all conversion procedures are finished. It remains to reassemble the previously separated parts of the unit and to fix the cover, the screen with the outer panel in the reverse order of the disassembly.

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

After the remodeling, all disconnected devices and dismantled parts of the gas boiler are installed in their original places in the reverse order

But that is not all, the most serious and delicate work is ahead - adjustment.

The pressure adjustment process by \"folk means\"

This stage is often only available to representatives of gas service. After all, not every home handyman has a pressure gauge that recognizes pressure readings between 3 and 40 millibars. Buy a meter for the sake of a single operation is not too reasonable, it is easier to use the services of a master, whose arsenal is this device.

But domestic inventors still found a way to measure data on the pressure of gas in the system. They also managed to pick up a device capable of correctly displaying atmospheric pressure. Do not believe me, this is an ordinary tonometer, which probably had the older generation in your family.

Whether you will be in your possession pointer or electronic blood pressure meter. Both are fine. Most are fine for 3mbar (i.e. millibar) readings.

The only drawback is that not all have a proper mbar scale. But there is a scale in mm of mercury column and a sufficient number of programs on the Internet, which convert all comparable physical units.

We make a table with the units conversion for our convenience and then proceed with the adjustment of the boiler automatics for the LPG gas mixture.

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

In order to set the boiler for LPG operation using a pressure gauge, the table with the pressure values in different units is useful

In the example given for consideration the pressure at the unit inlet must be 37 mbar. The pressure limits for burner operation are set to 4.9 mbar at the minimum, 29.4 mbar at the maximum.

We must first reconfigure the pressure before the inlet to the wall mounted gas boiler. In our case, everything was designed to use mains gas, coming in at 27-28 mbar. Now we adjust to 37 mbar the reducer of the gas holder or group of gas cylinders.

In this way:

  • Remove the lower connection of the gas valve, in fact releasing the gas inlet point for the dynamic pressure adjustment.
  • Connect the gas pressure gauge. Simply disconnect the electronic meter from the tonometer reading system, and then connect the narrow hose to the gas inlet point, and immediately connect the dial to the bulb hose.
  • Set the pressure to the parameters we require, given that the device will show us mmHg. This means that we need 27.7 mm.

We note that the dial version of the tonometer is much more convenient in this case. Superprecision, which is trying to demonstrate the electronic system, is not needed here. Besides, it is easier to catch tenths of a fraction with a dial device that works without excessive \"fuss\".

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

The maximum pressure of a Baksi gas boiler is adjusted with the help of this nut. By moving it clockwise it increases the value, in the opposite direction it decreases

Furthermore, we proceed to readjust the gas pressure going into the burner itself:

  • Withdraw the upper connector from the gas valve. To the freed opening, connect a pressure gauge.
  • Start the boiler so that it works with the maximum settings for hot water and heating water characteristics.
  • Set the upper and lower limits for heating water and sanitary water by turning their setting nut to the left and right.

Turn the setting nut carefully around its own axis. Turn it clockwise to increase, counterclockwise to decrease. Use a screwdriver and head. Proceed in this way until the values are the same as the translated values in mm Hg 22 mm for the upper limit, 3.7 mm for the lower limit.

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Step 1: Connecting Tonometer to the lower connection

Step 2: Connecting Tonometer to the upper valve connection

Step 3: Setting the temperature for water and coolant

Step 4: Setting the boiler to operate at minimum power

Tenths are determined on a scale literally \"by eye\". To set 3.7 mm, find approximately the middle between 3 and 4, then move the reading slightly towards 4. Well, we can say that we have set it.

Now we screw in the connector and assemble the boiler, then start it and check its operation. The error of the carried out adjustment in the example did not exceed 1%, which for home performance is really remarkable.

Similarly all works on re-equipment and reconfiguration are carried out on many two-circuit wall-mounted units. This includes products from Airfel, for example the Digifel and Digifel DUO models.

Burner changeover steps

Some boilers are designed so that there is no point in unscrewing the nozzles separately. For these, manufacturers make modules designed for liquefied gas. Easily change the burner module can be, for example, in a boiler Navien Deluxe.

The whole job is to replace the manifold with nozzles on exactly the same device, but with holes of a different size. The fact that it will be factory-made is a definite plus, guaranteeing the tightness of the gas ducts. There will be no doubt about its further safe operation.

Rebuild and readjustment operations in this case are as follows:

  • Disconnect the unit from the power supply and turn off the tap on the gas supply pipe.
  • Remove the front panel from the boiler body.
  • Disconnect the electrodes connected to the ignition system.
  • Disconnect the gas supply pipe inside the boiler by removing the 4 screws that hold it.
  • Remove the cover fitted to the closed combustion chamber. To do this remove the 11 screws.
  • Dismantle the overheating protection sensor with its bracket.
  • Remove the manifold with the nozzles mounted on it. To remove it, unscrew the two screws on the right and left side of the device.
  • Insert the O-ring sealing the gas pipe inlet on the new manifold to be mounted. Mount the new manifold in its original position and fix it with the screws.
  • Set the micro switch, fifth from the bottom, to the right. In this way we reconfigure the appliance for liquid gas operation.

After these simple manipulations we reassemble the boiler, following the reverse sequence. In the same way is done remodeling and reconfiguration of most floor gas boilers, especially if they are of the condensing type. This variant of boilers is most often even designed to be convertible.

The following photo selection will help to visualize the procedure for replacing the manifold with gas nozzles and reconfiguring the boiler:

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Step 1: Buying a replacement manifold

Step 2: Removing the boiler faceplate

Step 3: Disconnecting the ignition system wires

Step 4: Removing the burner gas supply pipe

Step 5: Removing the overheat protection sensor

Step 6: Unscrewing the sensor bracket

Step 7: Removing the screws from the burner cover

Step 8: Removing the closed burner cover

Now all that's left is to change the manifold and set up the gas unit to run on cylinders or a gas tank:

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Step 9: Inspecting the inside of the combustion chamber

Step 10: Disconnecting the natural gas manifold

Step 11: Installing the LPG manifold

Step 12: Setting up the boiler for LPG

But be aware that both of the above conversion techniques are not implemented with all unit models at all. There are boilers that should not even be attempted to be converted to liquefied gas, especially long-standing units.

In any case, before planning a conversion and transfer, you should ask representatives of the company that performed the first run if such a project can be implemented. It is also worth studying the passport of the gas processing equipment and the manufacturer's recommendations. There is usually a possibility there.

Safety instructions

The conversion of a boiler and its adjustment to LPG consumption dictates the need to \"readjust\" your attitude towards the supply and storage of blue fuel.

It must be remembered that:

  • Cylinders or gas holders, which are gas storage tanks supplying fuel to household appliances as needed, must be periodically refilled.
  • Fill a group of cylinders or gas holders with certified organizations having equipment to record the weight of gas in the cylinder and its actual volume in the gas holder.
  • Fill closed gas tanks to 85% of the useful volume of the tank. This reserve is necessary in case the fuel expands thermally to avoid explosion.

A non-hazardous but demanding situation when refilling liquefied blue fuel is the filling of a liquid with a density different from that of the previous liquid. Because of this difference the residual liquefied gas may not mix with the newly filled portion.

In the tank from the difference in density a kind of semblance of two non-connecting sectors is formed, in each of which the liquefied gas circulates. However, convective heat exchange will occur at the boundary of the sectors after a short period. After the temperatures equalize, the densities will equalize and the liquids will be able to mix.

Boiler conversion to liquefied gas: conversion and reconfiguration of the boiler to cylinder fuel

Liquid gas, like mains gas, is a flammable, combustible liquid with a high flame propagation speed. In order to avoid a catastrophic situation, the operating rules must be strictly observed and the bottles must be filled to no more than 85%

This process, meaning the mixing itself, is usually accompanied by an intense evaporation of the liquefied gas. To avoid losses associated with it, mixing devices should be used in the filling process. But it is better to choose a method that allows to exclude the above phenomenon.

Filling of cylinders and gas holders with blue fuel in general - a process requiring increased attention, otherwise the problems can be very serious and even catastrophic. A significant problem is recognized the rapid spread and evaporation of liquefied gas mixture.

If the rules of safe operation of gas-consuming equipment are not violated, the main methane rarely explodes. It only happens when there are significant leaks, if the technical condition of the gas in the surrounding area changes dramatically. For example, in a kitchen with obvious signs of a leak, lights are turned on instead of mandatory ventilation.

Liquefied gas, when expanding in a closed vessel from external heat, is bound to explode if not enough space is left in the tank for it to expand. The blue fuel burns extremely intensely. Since the gas is quickly absorbed by the atmosphere, the combustion zone expands at a high rate.

Conclusions and useful video on the subject

The following video will introduce the organization of heating on liquefied gas and the procedure of transferring the boiler to its consumption:

The technical and technological essence of the boiler transfer to consumption of gas mixture in liquefied state should be known both by independent home makers and customers of gas service workers.

It should be remembered that the second option is preferable, as gas is explosive, toxic and flammable. In addition, the warranty is invalidated if the equipment is tampered with.


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