Polypropylene boiler tying: schemes and device rules

Engineering systems from affordable polypropylene pipes can last up to half a century. Polymer pipe products are extremely easy to install; only one soldering iron is needed to connect them. But is this material suitable for heating systems? Will the boiler strapping polypropylene durable and reliable?

If everything is done according to the technology, then the plastic pipelines quite safely deliver the coolant to the batteries.

What is a boiler harness and what is it made of?

Binding is a combination of heat engineering equipment that provides transportation of heated water to radiators and trouble-free operation of the heater itself.

On the one hand, it helps to evenly distribute heat throughout the rooms of the house, and on the other, it increases the reliability of the entire heating system, protecting the boiler from overheating and excessive fuel consumption.

There are certain nuances in the boiler equipment piping device:

Also under the strapping of the heating apparatus is meant the calculation of the parameters of all elements of the house heating system and their installation. Heating system should work not only reliably, but also correctly. A large number of additional devices and complex wiring can seriously reduce its effectiveness. Everything must be done correctly.

Optimal and ready for all buildings of heating systems without exception simply do not exist. In order to achieve maximum efficiency from a specific boiler, it is necessary for each house to prepare an internal heating network project individually. But there is a certain set of standard rules and a list of standard equipment.

Depending on the type of fuel used, the quadrature of the house, the model of the heater and its location, the strapping with polypropylene is done according to different schemes.

But in all of them are present:

1. Boiler (single or double).
2. Expansion tank. Hydraulic with diaphragm or conventional capacity depending on the type of heating system.
3. Polypropylene pipes and fittings.
4. Batteries (cast iron, steel, aluminum, bimetallic).
5. Bypasses (sections of the pipeline that allow disconnecting individual devices from the circuit). Recommended for all types of networks, but not always used in simple flow schemes.

According to the principle of the coolant movement, the heating circuits are divided into systems with natural (gravitational) and artificial (pumping or forced) circulation.

In the heating network of forced type, the above-mentioned set is complemented:

• Crane Mayevsky.
• Circulation pump.

In the scheme with the supply of coolant to each device along the supply and return lines designed specifically for it, the collector — the distribution device — is necessarily included.

In heating circuits requiring mandatory adjustment of the qualitative and quantitative characteristics of the circulating fluid or steam, monitoring devices are built in:

• Pressure gauge.
• Thermostat.
• Hydraulic arrow, if there is a need to equalize the pressure.

In the system with forced circulation of the coolant to maintain the specified pressure in it is put expansion tank with a membrane. And in its gravitational counterpart, the usual open tank without any inserts inside will suffice.

The expansion tank of the simplest heating system with the natural principle of movement is a conventional container with a pair of pipes screwed in or welded into it. One of them is a supply pipe, the second is a signal pipe, which tells about filling the tank with water that has expanded during heating. In a more complicated version of the tank, four pipes are screwed in already.

With an increase in the volume of the coolant above the prescribed rate, the excess is simply drained through the signal pipe. In the future, the coolant will expand in the same way and receive the same volume, but there will be no overflow into the signal pipe. By analogy, air is spontaneously discharged, therefore installation of Mayevsky cranes is not necessary.

Circulation pumps in the circuits based on the natural principle of the coolant movement, do not apply. In such a system, water moves under the influence of gravity.

She doesn’t need additional pressure blowers. On the one hand, this increases the reliability of heating (there is simply nothing to break), and on the other hand, it reduces the quality of heating of the far rooms in the house (the extreme coolant reaches the already cooled).

The subtleties of installation of a polypropylene pipe heating system are described in detail in one of popular articlesposted on our website.

Polypropylene pipes in heating systems

Polypropylene fittings and pipes (PPR) are popular for their low cost and ease of installation. They are not subject to corrosion, have smooth internal walls and serve no less than 50 years declared by the manufacturer.

There are several types of these pipe products, which differ in technical characteristics and purpose.

In the construction of heating systems, as well as in the device close to them according to the operational parameters of the DHW circuits are used:

• Pipes with markings PN 25. Products with reinforcement made of aluminum foil. Used in systems with a nominal pressure of up to 2.5 MPa. Limit of working temperatures + 95º C.
• Pipes marked PN 20. Reinforced version used in DHW branches of double-circuit heating boilers. They will work out the period declared by the manufacturer, if the coolant temperature is not higher than + 80º С, and the pressure is up to 2 MPa.
• Pipes with markings PN 10. Thin-walled polymer products. They are used if the boiler supplies coolant to the underfloor heating system. Working temperature is not higher than + 45º С, nominal pressure is up to 1 MPa.

Polymer pipes are suitable for all known methods of laying: open and hidden. But this material has a large coefficient of thermal expansion. When heated, such products begin to slightly increase in length. This effect is called thermal linear expansion, it must be considered when constructing pipelines.

In order to prevent the destruction of polypropylene heating pipes, compensation loops can be installed. But it is easier to take multi-layer pipes, reinforcement in which is specifically designed to compensate for this stretching. The foil layer inside the PN 25 polypropylene pipes reduces their thermal elongation by half, and the glass fibers all five times.

Features of mounting PPR pipelines

When performing the boiler strapping polypropylene pipes and fittings they are joined mainly by cold or hot welding; in the case of connection to metal pipelines, threaded connections are used. Screwing is much more convenient, but because of them, the assembly of the system will be much more expensive.

However, if you wish, you can attach a polypropylene pipe to a metal counterpart without threaded fittings.

“Hot” is welded with a special apparatus (soldering iron, “iron”). The pipes are heated with a suitable nozzle to a melting point of 260 degrees, and then the parts with softened edges are pressed against each other. The result is a solid and solid connection.

Before welding, the foil of reinforced pipes should be cleaned without fail. Otherwise, it will prevent the connection of polymer products, making the seam fragile. With fiberglass these extra actions will not be required. It melts quietly with plastic.

Cold welding involves the use of a specialized adhesive composition. In recent years, this method is rarely used, because The result is not reliable enough.

In heating systems, threaded joints should be sealed with paronite or high-temperature sealant. Do not forget about the relatively high operating temperature of the coolant.

There is one more nuance of the use of polypropylene for tying the heating boiler. Antifreeze with plastic - quite a bad combination. Water is recommended as a coolant for a system of plastic pipes.

Selecting the layout of the heating system

There are several options for tying the boiler with polypropylene. For each house, this scheme is selected individually. What is optimal in one building may be ineffective in another.

In addition, heating systems according to the principle of water movement are divided into: forced with a hydraulic pump and gravity (self-flowing, natural), there is also a classification according to the arrangement of pipelines. According to their structure, they are one- and two-pipe, collector beam or analogs with closed rings.

Which is better: gravity or pump?

AT gravity circuit heated water to the radiators from the boiler enters by gravity. A hot heat carrier having a high temperature always seeks to replace the colder liquid. It is easiest to assemble this heating system for the boiler. In addition to the heater, it contains polypropylene pipes, radiators and an expansion tank.

In the variant with the upper distribution, water after heating rises to the highest point - to the expander, and from there it goes down to the batteries. After returning heat, it returns to the boiler, where it is reheated, then starting a new cycle.

According to this scheme, heating is arranged in many houses in local villages. Only there is a solid fuel stove. This is the easiest and cheapest way to organize heating a small cottage. However, it has limitations both in the number of connected radiators and in the distance of the outermost one from the water heater.

More complex and expensive enforcement system. However, it greatly simplifies the creation of comfortable temperatures in individual rooms. In it, the coolant moves already due to the stimulation of its movement by the pump.

The choice of pipework layout of polypropylene and the boiler itself is closely related. The system with natural circulation is non-volatile. If the water heater in it does not require power from the mains, then even in the event of a power outage, the house will be heated.

In the forced circuit, the pump needs constant power supply for operation. Therefore, the boiler for it is best to choose dependent on electricity, which has additional features. But in order to hedge against problems with voltage, you will have to buy a backup generator or a standalone generator for them.

Which heating scheme is better to choose?

There are many ways to separate pipelines made of polypropylene from the boiler to the radiators.

But all these schemes are divided into:

• single tube;
• two-pipe.

AT single pipe systems heated water supplied as a coolant is supplied and discharged in one pipe. In the two-pipe coolant supply and return flow, i.e. diverting cooled water back to the boiler for heating, separate lines are constructed.

By the method of connecting the working components of the heating circuits are divided into:

• tee;
• collector.

Tee types can be used both with gravity and forced circulation. The collector circuit can work only with the circulation pump.

The one-pipe method involves laying one loop-back line and connecting batteries to it in series. In the two-pipe scheme from the boiler there are two independent pipelines with hot water and return pipe. And already connected to them radiators.

With collector harness One or two collectors are built into the system, from which individual pipes are pushed to each battery. Also such a distributor allows you to connect to the boiler "warm floor", made all of the same PPR.

The use of collectors and separate risers for each battery leads to a significant increase in the cost of both design and installation. At the stage of preparation of the project it is necessary to do more complex calculations. And at assembly the much bigger volume of polypropylene is spent. But it turns out the system, each part of which can be adjusted to specific conditions and requirements.

Polypropylene contour for different boilers

Most manufacturers of water heaters are recommended to make the first meter of the pipeline from metal. This is especially true of solid fuel devices with a higher water temperature at the outlet. During piping, polypropylene should be connected to this branch already; otherwise, in case of failures in the boiler, it will receive thermal shock and may burst.

Option # 1: Gas water heater

Polypropylene gas boiler tie is recommended to be performed using a hydraulic needle and collector. Often, models on gas are already equipped with built-in pumps for pumping water. Almost all of them were originally designed for enforcement systems.

The most reliable in terms of safety will be a circuit with circulating equipment for each circuit behind the collector.

In this case built-in pump will pressurize a small section of the pipeline from the boiler to the distributor, and further pumps will be used. The main load on transferring the heat carrier will fall on them.

If the gas boiler has a cast iron heat exchanger, then when it is strapped into the system, an additional heat accumulator should be installed. It will smooth out sharp drops in water temperature, which have a negative effect on cast iron. It can even burst when the heating fluid is abruptly heated or cooled.

When piping a double-circuit apparatus with parallel heating of water for hot water supply, it will be necessary to install fine and coarse filters on this tap as well. They should also be mounted at the entrance to the water heater, where cold water is fed.

Option # 2: Solid fuel model

The main feature of a solid fuel boiler is its inertness when stopping the supply of fuel. As long as everything in the furnace does not burn completely, it will continue to heat the coolant. And this can adversely affect polypropylene.

When tying a solid fuel boiler, metal pipes should be connected to it immediately, and only after a meter and a half, polypropylene pipes can be embedded. In addition to this, it is necessary to provide a backup supply of cold water for emergency cooling of the heat exchanger, as well as its drainage to the sewage system.

If the system is built on forced circulation, then it will definitely need to install an uninterruptible power supply for the pump. Water must constantly remove heat from the firebox, where solid fuel burns, even during power outages.

In addition to it, you can make a small gravity circuit or equip all batteries. bypasses to disconnect individual sections system. In case of accidents, this will allow repairing the damaged section while the heating is running.

Solid fuel boiler should be covered with a protective casing, which limits the spread of heat from the walls of the furnace to the boiler room. But even with it, the collector and plastic pipes should be removed away from the stove.

Option # 3: Heaters on liquid fuel and electricity

A boiler for working off or a diesel engine is tied with polypropylene according to an identical circuit with a solid fuel analogue. The polymer must be removed from it at the maximum possible distance.

Heat coolant in the water heater on electricity up to temperatures critical for polypropylene is practically excluded. When the power fails, it simply stops working. In this case, the pipes are protected from water hammering by means of a hydroaccumulator and valves to relieve excess pressure.

Conclusions and useful video on the topic

Video # 1. How to choose PPR pipes:

Video # 2. Technology binding solid fuel boiler:

Video # 3. How to tie a heater in a two-story cottage:

When choosing a scheme for tying the boiler with polypropylene pipes, it is necessary to take into account all the features of a particular building. The process of installation of pipelines and connection of equipment is simple, even a novice master can handle it.

With a soldering iron for polypropylene fittings and pipes, working is easier than ever. But it’s better to entrust the preparation of the heating system project to a specialist, mistakes are unacceptable here.

There is a desire to share personal experience gained during the hand-assembled assembly of polypropylene strapping, found shortcomings or want to get answers to your questions? Please write comments in the block located under the article's test.