Installing a pump in a heating system: how to choose, characteristics, installation rules

The task of the circulation pump is to drive the coolant along the entire line of pipes through the boiler with the most efficiently configured operating parameters. An incorrectly selected device will reduce the efficiency of the system, the water circulation will be less efficient, and the heating will be weak and slow. If the device is too powerful, excessive consumption of electricity is possible. It is necessary to pay attention to noise level, acceptable level of complexity of maintenance and repair. The pump must be installed and adjusted correctly. Let's look at how circulation pumps are selected, characteristics, stages and installation requirements, and how to install them.

Heating system pump

Circulation pumps (CP) are hydraulic equipment that provides forced circulation of coolant through the boiler through a closed pipe line with radiators. The device can be adjusted to different pressure modes.

The heating pump is a mandatory, default part of the circuit. Only an expansion tank (hydraulic accumulator) will not be able to ensure the full functioning of the equipment. The exception is systems with natural circulation, but pumps are often recommended for them as well to ensure safety and improve performance if necessary.

Pump value

The quality of heating depends on the circulation parameters provided by the pump. If the circuit is longer, with rises to the upper floors, then increased technical capabilities of the product will be required; more intense heating requires an increased flow rate.

The pump is installed in the heating system to ensure:

circulation;
uniform distribution of the resource with a given intensity, for the most efficient, effective heating.

The pump increases the intensity of the flow, heat flows faster to the radiators, and accordingly, heating occurs more quickly, its level is higher, and the room is heated in less time. At the same time, the load on the boiler is reduced, since the water is processed more quickly. With circulation pumps, there was no need for bulky, inconvenient pipes of significant diameter, and it became easier to disguise contours under finishing and place them inside walls.

When installing pumps in heating

Installation of a pump in the heating system will be required in the following cases:

to increase the efficiency of boiler systems. In our case - for heating systems (autonomous individual) for an apartment or private house. Schemes with natural circulation are used less often, but they often require a supercharger for backup;
when the natural movement of the coolant is impossible or too weak. And also to overcome the inertia of the scheme;
if the heat generator does not have a pump unit;
for circuits with two-pipe wiring, making it possible to adjust the heating of each individual battery.

The heat-releasing liquid must flow through a closed line (circuit), with certain adjustable speed parameters for effective heating for different conditions.

Requirements for installation of a circulation pump

There are a number of standards that regulate at the legislative level the installation of a circulation pump in a heating system. Some of the rules are set out in SNiP 2.04.05 “Heating...”. For example, it talks about the priority of schemes with forced circulation in heating networks.

Almost all requirements are justified by the operating efficiency of the system as a whole and the circulation device in particular. For example, the shaft of a device with a wet rotor must be installed on the pipe strictly horizontally in level so that there are no air pockets inside and the pump parts do not wear out prematurely.

A mandatory element of the system is an expansion tank that compensates for changes in the volume of coolant during heating/cooling. Its place in a closed system is on the return line, in front of the circulation pump

A filter for dirt and abrasive particles is needed in any case, even when installing monolithic models. Filtered coolant will cause much less damage to pump parts than liquid with sand and suspended matter.

The mudguard is installed with the plug down in the direction of water movement to reduce resistance and facilitate system maintenance.

Some rules are dictated by manufacturers. For example, it was customary to install old models of certain brands exclusively on the return line, since they could not withstand high temperatures.

Now pumps have become more versatile and can be installed in any suitable location, but subject to power parameters.

Types of circulation pumps, design

The devices in question are similar to the same products for pumping water for other purposes, the operating principle is similar, but in this case the device is created taking into account the nuances of heating: for high temperatures, their differences, as well as for the characteristics of the system, the need to regulate pressure, speed in a wide range range. The product is manufactured for insertion specifically into pipes and bypass (a whole unit with it and taps is often sold), taking into account their specifics.

Wet pump:

Dry type:

There are 2 types used: with a wet and dry rotor. The latter are more productive, but are less often used for home and domestic use, since they are noisy, with noticeable vibration, and more expensive.

The main disadvantage of all pumps is their dependence on electricity. If the facility has frequent power outages, then backup batteries are installed; a stabilizer is recommended to level out voltage surges.

As standard for a heating pump, for all types, manufacturers provide stepwise speed settings: you can select the optimal mode and control energy consumption.

A brief description of the disadvantages and advantages of the varieties is as follows. Dry type products are noisier, create vibration, are expensive, but more productive, the purity of the pumped resource is not significant. Wet - quiet, cheaper, more compact, but limited in pressure, the transported substance must be free of impurities.

There are dual models on the market used for backup in emergency situations.

Work order

To install and connect the pump yourself, you need to follow the following procedure:

if the boiler is running, then you need to stop it and give the coolant time to cool;
empty the system or boiler circuit, if possible. When the piping of the heat generator is done correctly, there is no need to drain the water from it; it is enough to cut it off from the system using the appropriate fittings;
if the system is gravity-fed, then the bypass unit with a pump and taps can be assembled in advance;
insert the unit or just the pump into the supply or return pipeline, adhering to the rules set out above;
make an electrical connection to the circulation pump.

Advice. We will not reinvent the wheel and offer a wiring diagram here. This is available in the operating instructions for any unit, even those made in China.

Further actions consist of filling the system with water and bleeding air from it using Mayevsky taps and valves. Next, it wouldn’t hurt to inspect the installation site to detect leaks. If they are not there, then you can safely put the circulation pump into operation. Do not forget to open the valves that shut off the unit and shut off the direct line if it is installed on a bypass.

Wet rotor pumps

In wet modifications, the shaft and impeller are in contact with the pumped resource, and it also serves as lubrication and cooling.

The stator is separated by a special flask that seals parts of the electric motor, otherwise voltage would be transmitted through water to all metal elements of the system.

Components and how they work

Wet central pump design:

housing that can withstand high pressures is made of cast iron, steel, aluminum. For standard home conditions, this is a small block that is attached directly to the pipe, bypass;
a shaft (moving segment), also known as a rotor made of steel, ceramics with a bearing unit, a working disk with blades. The latter is fixed motionless, it consists of 2 wheels with holes connected by blades: on one - for moving the resource, on the adjacent one - for securing to the electric motor shaft;
a stator (fixed unit) on the rotor with an excitation winding (inductor) to stabilize the rotation speed and flow, for which it has small blades at a certain angle. This part prevents flow stalling. This part consists of a core and a frame. In the grooves of the first there is a winding. The stator is also a magnetic circuit and a supporting structure;
control chip, power terminals. On models without the first element there is a capacitor, and on the contact block there is a speed selector.

When starting, the blade disk rotates, a vacuum is created inside the pipe, the coolant is drawn in and moved by the rotor further along the equipment (from inlet to outlet). Fence and ejection are carried out. Centrifugal force helps move the resource throughout the circuit. The resulting pressure creates the required force on different segments of the pipe line and creates circulation on its rises.

Nuances, pros and cons

Wet circulation pumps, however, like everything else, are usually modular. The devices are selected according to the parameters of the circuit (pressure, required maximum amount of pumped volume). An important plus is that the device is prefabricated, which simplifies its repair; broken parts are replaceable.

Wet central heating systems are installed on the vast majority of home systems, this is the standard, and here’s why:

the device is almost silent, which is suitable for living, for better comfort;
compactness, light weight - the device is a small box that does not require special fastening, partitions, or space on the floor. The product simply crashes into the pipe and “hangs” on it;
there is no need for additional cooling (unlike dry models), this function is performed by the water flowing inside;
There are fewer spare parts, the ability to replace them, easy repairs, dismantling, minimal maintenance frequency;
wide range of settings;
long-term performance if there is a filter and working fluid without fine particles;
cheaper if the device is for low standard productivity.

Disadvantages for home heating with a wet pump:

if the water contains fine abrasive particles (lime, iron, etc.), then the impeller and other parts (hydraulics) in contact with the liquid will wear out relatively soon and fail. For such products, a closed system with a purified resource is recommended; a dirt filter is mandatory;
low efficiency - about 55%;
the performance range is more limited than dry options. But it is enough to service the average private home, therefore, and also because of the low price, it is often used for housing.

From theory to practice

So. Let's start by defining what home heating is. Without going into terminology, this is heating the air in rooms to a given temperature and maintaining the set temperature for a certain time.

Air can be heated in three ways:

by convection (the convection method is classic and ancient, that is, air flows in the rooms constantly circulate, cold air heats up below and rises up), convection systems can be floor- and wall-mounted;
by radiant heating (this is an innovative method, the essence is that the energy from the heating device falls directly on the surface of objects and enclosing surfaces, one part is absorbed, the second is reflected, radiant heat exchange is formed, which makes it possible to ensure the desired temperature in the room), radiant systems are floor-mounted , wall and ceiling;
combined.

The second point is the type of heating:

the direct, classic principle by which fireplaces, stoves, and convectors operate is that the heating device directly heats the air in the room;
using intermediate coolants, in this case it is not the air itself that is heated, but the coolant circulating in the system, transferring thermal energy and allowing the air to be heated in a certain room for residential or domestic purposes.

Heating systems for a private home involve the use of two types of intermediate coolants:

classic option - water, pros - cost, cons - likelihood of the system defrosting;
antifreeze (solutions of propylene glycol and ethylene glycol with various modifying additives), plus – resistance to low temperatures (does not freeze), ensuring the safety of thermal registers, minus – higher cost;
steam, pros - high heat transfer, efficiency, cons - deformation of heating system elements, inability to accurately regulate the temperature, likelihood of burns (registers heat up to a very high temperature);
air, there are also systems where the air is heated, transfers thermal energy to a heating device, which heats either the air in the room, or objects and fences, and in some cases the heating device is a wall with channels for air circulation and a chimney.

The next point, all heating systems are:

local, necessary to maintain a given temperature in one or more rooms;
centralized common ones, designed to maintain temperature conditions in several rooms.

Local systems, as a rule, are direct, that is, they heat the air directly, while general systems use an intermediate coolant. By form factor, like

noted above, system elements can be installed on:
walls, a classic option for complex engineering systems;
ceiling, this is more related to radiant, local heating, although there are convection options, for example, thermal curtains;
floor (including island) and under the floor (in particular, “warm floor”), can be both local and general.

Everything is described and presented in more detail in the article “Types of heating”.

System components

What does the heating system of a private house consist of?

If we talk about local systems, then this is a source of heat that allows you to heat the air in a single room, the classic version is a stove and fireplace, modern ones are convectors, heat generators, thermal curtains, guns, infrared radiant heating panels, oil radiators, fan heaters and a number of others.

That is, a heater is installed in a separate room, which heats the air in this and adjacent rooms.

The general, centralized system, based on the use of an intermediate coolant, is more complex, it consists of:

heat source, the classic and most widespread option - a boiler, designed to convert various types of energy into heat with subsequent heating of the coolant;
pipelines, necessary for transferring coolant to heating devices, this includes pipes and a number of other elements;
heating appliances, six groups in total - convectors, radiators, smooth-tube appliances, panels, finned tubes and air heaters.

Dry rotor pumps

The entire internal working unit of dry devices does not come into contact with water and is completely isolated. These products are slightly larger and heavier. There is noise and vibration. Here, more often there is a need for a separate place, a fence, installation on the floor with larger piping and wiring. But the devices can also crash in the standard way, like wet ones - directly into a pipe, bypass on the line.

“Dry” pumps are installed to transport significant masses of coolant along long-distance circuits, for example, for a large number of apartments in a high-rise building, for objects with several floors, entertainment centers, administrative and industrial buildings.

The design features are as follows. Between the electric motor and the hydraulic working segment there are sealing insulating gaskets (2 rings). There are 2 discs with a close fit. One is movable on the shaft, the other is static, firmly fixed inside the housing. A thin film of the pumped resource is created between the wheels, pressing on the elements, increasing the tightness.

The efficiency of dry pumps is 85%, according to this parameter they are the best, but they are used less often for home systems due to the noise and vibration created by the cooling fan.

Dry circulation pumps can be of the following sizes:

monoblock - motor, all parts of the pump in a single body. Advantages: ease of maintenance and installation. But such devices, like console ones, are more often installed for MKD, on large objects, and these products are usually with a stand-foundation;
console option. Assembled on a single base, the axes of the elements are on 1 line, but the shaft and pipes are remote from the drive;
in-line. Compact, placed directly on the pipe. The pipes are on the same line (there are no snails, as in the previous version). There is automatic compensation for seal production. These are the popular options; they are usually used for not particularly demanding standard home heating.

In-line pump:

Advantages and disadvantages of dry circulation pumps Advantages of dry circulation pumps:

productivity, higher power, efficiency 85%;
more energy efficient;
does not require horizontal positioning;
low requirements for cleanliness of the coolant; abrasive particles will not damage the working parts of the mechanism, since they do not come into contact with it. Can be used on all systems - open, closed. The filter does not have to be mounted, although it is desirable;

Minuses:

Dimensions and weight are slightly greater. For high performance, a typical installation option is on the floor (not directly on the pipe, as with most dry pumps). Accordingly, installation becomes more complicated and costs increase. But such a need does not arise often, since for home systems a compact, not particularly powerful model is sufficient; in most cases, the device is mounted directly on the pipe;
Large devices require lubrication. For compact sizes, such a procedure may not be required or may be required extremely rarely, but this should be prescribed in the instructions;
if the cooler breaks down, the device will overheat, with a high probability of failure;
The cooling impeller is noisy and vibration occurs. A very significant drawback, since extraneous sounds, unnerving users, will nullify all the advantages. Sound insulation will be required, at least a box/fence with it or installation in a remote segment;
repairs and replacement of spare parts are somewhat more labor-intensive: the design is complicated by the cooling impeller, there are features associated with the insulation of internal parts;
expensive.

This type of equipment is productive, unpretentious to the coolant, works with high pressures, and does not require horizontal placement. But the device is noisy, with vibration, and is often made in overall sizes; this sometimes entails the need for installation on a foundation or a metal frame.

Choosing a boiler

So, first we decide whether there will be one boiler or two boilers operating on different types of fuel. One will be the main one, and the second will be auxiliary, duplicating, it all depends on the financial capabilities of the owner of the house.

Boilers differ in a number of parameters:

design features (single-circuit only for heating or additionally double-circuit for hot water supply);
type of fuel used (gas, solid, liquid fuel, electric and combined);
by placement method (wall-mounted, floor-mounted);
functional purpose, power and a number of other parameters.

For more information about choosing boilers, read the article “Selecting a heating boiler.”

Selection, calculation

Let's look briefly and clearly at how to choose a circulation pump for a heating system in specific situations.

What characteristics to pay attention to:

pressure Must cover hydraulic losses on the line;
productivity - max. pumped mass of resource per unit. time;
working t°. Most modern models are designed for a range of +2...+110° C, which is enough for most circuits;
power. Mechanical power, taking into account hydraulic losses, should prevail over useful power;
The diameter of the pipes should be selected to match the existing pipes (25, 32 mm), however, adapters can also be used.

Circuit type

For open systems, wet devices are not desirable, since the coolant in them usually contains abrasive particles (sand, oxidized iron, lime, etc.): if they get between the rotor and stator, impeller, they will quickly damage the device. But in closed systems where the water is filtered, distilled, or another clean special coolant (propylene glycol) is used, such products will last for years without special maintenance. For units with a dry rotor, the quality of the working resource and the type of circuit do not matter.

Open circuit bypass pump:

Examples of schemes for one- and two-pipe circuits:

Another typical example:

Power calculation

There is a standard formula for calculating pump performance based on equipment characteristics: for every 10 meters of line there is 0.6 m of device pressure. For a small house with a contour of 80 m, we take a pump with a head of 4.8 m. It is advisable to add 15–20% of the reserve to the obtained result, especially if there are rises to the upper floors.

More complex equation:

R is taken as standard for the European region 100 W/m² for properties with 1 or 2 apartments and 70 W/m² for multi-apartment buildings.

Speed, noise

Modern average units are equipped with three speeds as standard. The selected unit must have adjustment; the wider its range, the better. The setting will allow you to quickly heat your home when it gets cold, and when it warms up, you can reduce heating and electricity consumption.

A dry pump cooler makes noise; if it is not possible to provide sound insulation and extraneous sounds are undesirable, then choose a wet version of the product.

Example of a circulation pump, manufacturers

Examples of popular brands with a good reputation:

As an example for a heating circuit for a house of 100 m², you can take the Grundfos UPS model, its characteristics are as follows:

for pipe connection Ø32 mm;
for productivity - 62 l/sec.;
weight 3.65 kg;
cast iron;
The power is enough to raise the resource to the 2nd floor.

Central heating unit Wilo STAR-RS 25/6 180 (wet) can be considered as an average sample of a product for a not too demanding system:

There are electronically controlled devices that allow you to quickly, automatically switch the equipment to the desired mode depending on changes in pressure and temperature. Such devices are equipped with digital displays that display data on temperature, pressure, and resistance.

Dry or wet rotor

Wet pumps have the following features:

if the pressure (meaning provided by the device, the calculation we described above) is more than 15–17 m, then for this parameter the products in question are rare on the market, they are expensive;
used only for closed systems, where there is less need for high pressure, clean coolant;
in terms of price, if the pressure is more than 10–14 m, it is often more expensive than a dry pump, and in addition, they have increased motor sizes;
It is not recommended to place it on an open system where there may be dirt, sand and other abrasive particles. The pump will fail in a year or two, since water here acts as a lubricant, washes the internal parts, there is a constant circulation and friction of the abrasive, the gap between the rotor and stator quickly becomes clogged, and the graphite bearings wear out.

Up to 7–10 m of head for a productivity of 25–30 m³/hour, wet products are cheaper than dry ones. But the noise of the latter is much greater.

Tips on what to choose:

at working requirements 1–10 m of water. Art., flow rate 1–25 m³/h, it is advisable to take wet products;
at 12 m water. Art. and we select dry pumps for any performance. They are for particularly high consumption;
in any case, if it is possible to make noise insulation, then a dry pump is a good choice;
if less noise is required, then only wet types. You can use 2-3 such devices: they will cope with the increased requirements of the system, and at the same time there will be no noise, although the price of such a scheme may be somewhat more expensive. You can also install one powerful wet blower for heating, but such models, as we have already noted, are rare on the market and expensive.

Basic rules for heating a private home

Heating in a private home is a very complex and capacious concept. Therefore, the first rule is that the development of the system and its installation should be carried out only by professionals. You need to remember this and not engage in amateur performances.

Only a heating engineer with the necessary knowledge and practical experience is able to correctly and competently create a heating project, taking into account the architectural features of the building, the functional purpose of the premises, the requirements and wishes of the customer, and his financial capabilities.

Therefore, it is necessary to perform a thermal engineering calculation, calculate heat losses, select the equipment correctly, know the specifics and features of its use, select the installation location, and carry out the installation.

Only in this case will the heating system in a private house be as efficient and economical as possible, and the costs of its installation and maintenance will be minimal. The purpose of this article is to outline the basic parameters based on which a contractor can develop the optimal heating plan for a home. Rule two is “cheaper in bulk.” To save on heating installation, you need to contact companies that provide comprehensive services.

That is:

draw up design documentation based on the requirements and wishes of the customer, architectural features of the building, functionality of individual rooms, operating mode, climatic and many other factors, performing thermal, hydraulic, thermal calculations, calculation of heat losses, establish the thermal load and determine many other parameters;
select the optimal equipment configuration, install it, start up the heating system, check its performance with further warranty and post-warranty service;
are engaged in the sale of everything necessary, and even better, they are dealers of manufacturers, this allows you to avoid additional trade markups, and the installation technicians thoroughly know the features of all models, even those that are not listed in the manufacturer’s technical documentation and identified during installation and operation.

Only with this approach will a heating system in a private house be installed quickly, at the lowest possible cost, without headaches for the person and work as efficiently as possible.

Installation Basics

The inclusion of autonomous heating in the circuit and the presence of central heating there is regulated by SP 60.13330. According to this act, a heating system with forced circulation is considered priority (not with natural circulation, although this is also possible).

The installation process briefly consists of securing the assembled pump unit (with filters, taps) with union nuts to a pre-cut pipe in a certain place.

Peculiarities

For wet pumps:

placed so that the position of the shaft is clearly horizontal (not necessary for dry options) - this will eliminate airing, spare parts will not break because of it;
the filter is a standard mud trap; it is mounted with its branch downwards along the flow of water to reduce resistance and facilitate maintenance.

For older products, the factory can indicate the installation location; once upon a time only the return line was considered such, but modern pumps can be installed anywhere (on the supply side too).

Autonomous heating pump installation diagrams

Let's look at the basic diagrams of how to install a pump and embed it onto a pipe.

They put it on return/feed, there is no difference. You can cut it directly onto the main pipe or make a bypass (outlet) and place it on it. The last method is the best, it makes it possible to more conveniently dismantle/install the device for maintenance; when replacing, it is usually so familiar that it is assumed by default.

There are several options for the installation location; there is also a diagram for several pumps (manifold connection).

Let's consider the traditional option with installation on a bypass.

For modern models, the location - return or supply - is not significant. They choose at their own discretion, as is more convenient for the user.

But, undoubtedly, in all cases the best option is to tap into the bypass in these places.

Some specialists remain adherents of the old traditional rule, according to which the return is the best section for installation. Through this segment, the liquid that has given off heat returns to the boiler. A less warm, cooled resource does not have such an aggressive effect on the device. The described opinion has completely lost its relevance for modern models designed for high temperatures, however, we indicate it for a full disclosure of the topic. It is important to read the instructions, since for older products the manufacturer may recommend a return line.

If the device is cut into the supply segment, then not directly close to the boiler, but after the safety group.

Option for solid fuel boiler. NC is not installed on the supply section due to the risk of explosion, since with the specified type of unit the heating does not stop quickly. This is a boiler with great inertia. Even if you turn it off, the intensity of fuel combustion may increase for some time, there is a risk of water boiling, the liquid expands, the pressure increases, creating a steam bomb. Boiling water is mixed with steam, gets inside the device, reduces productivity, and the cooled resource in the circuit does not have time to refill the boiler in the required volume - the device becomes hot, and there is a high probability of an explosion.

When a cooled resource is launched into a heated TD boiler, condensation forms. To eliminate this phenomenon, the liquid is first heated on the small circuit to +55° C, and then the thermal valve slowly switches to the main circuit. Cool masses are mixed with already heated ones, the sharp difference in temperature is leveled out.

Pump in a natural circulation system

One of the options for autonomous heating is an open line, where the expansion tank is mounted at the highest point. The inclusion of a circulation pump in such a scheme will increase the performance and versatility of the equipment.

The natural circulation is always somewhat limited and unstable, so if you need an increased quality of heating, you can use a pump, and when weak heating is enough or in case of power outages, you can use gravity.

To switch from a forced circulation to a natural one, a particularly important installation is to install the heating pump on the bypass. When the pump is activated, the gravity pipe is closed with a tap. Let us add that installation on bypass is always recommended for all circuits.

Harness

First you need to decide how many superchargers there will be. For one simple line, one device is enough.

When two units are required:

for a system with complex or multiple circuits;
if “warm floor” is combined;
an indirect heating boiler is used;
two boilers are used, for example, TD and electric (a pump for each).

What is required for installation

What parts need to be prepared for strapping:

Ball Valves. Mounted together with the pump. They are needed to cut off the flow of water during emergencies and repairs. Placed at the entrance and exit;
thermostat for the pump (not mandatory, but a desirable element);
check valve - brass, cast iron - for movement in one given direction. Placed after the pump in the direction of flow;
a regular dirt filter (for the roughest cleaning). Devices for fine filtration are not installed on heating; if you need clean water, and this quality is always recommended, and especially for “wet” pumps, then it is cleaned before filling;
air bleed valve to remove air pockets. The unit can be activated automatically, there are also manual products, and it may already be integrated into the device;
American nuts (often included with pumps);
bends - sections of pipes with threads at both ends for fitting, connecting pipeline segments when they cannot be rotated;
tools: open-end wrenches, adjustable wrenches;
pliers;
tow, fum tape, sealant (Unipak).

If you need to install a heating pump with assembling the system and inserting it from scratch, then the procedure is not always accessible for you to do it yourself, since you will need to make a bypass, cut the pipe, prepare its ends, which will require welding, a grinder, dies for cutting threads for caps pump lead nuts, for American women.

American women are often included. Taps, adapters, bends (for connecting pipe sections) must be prepared. There should be no difficulties in selecting diameters: they are standard, usually 25, 32 mm.

About installing additional units

As a rule, in a closed or open radiator heating system, where the heat source is a single boiler, it is enough to install one circulation pump. In more complex schemes, additional units are used for pumping water (there may be 2 or more of them). They are placed in the following cases:

when more than one boiler installation is used to heat a private house;
if a buffer tank is involved in the piping scheme;
the heating system has several branches serving various consumers - radiators, heated floors and an indirect heating boiler;
the same, using a hydraulic separator (hydraulic arrow);
for organizing water circulation in underfloor heating circuits.

Correct wiring of several boilers operating on different types of fuel requires that each of them have its own pumping unit, as shown in the diagram for the joint connection of an electric and TT boiler. How it functions is described in our other article.

Connecting an electric and TT boiler with two pumping devices

In a circuit with a buffer tank, it is necessary to install an additional pump, because it involves at least 2 circulation circuits - boiler and heating.

The buffer tank divides the system into 2 circuits, although in practice there are more of them

A separate story is a complex heating scheme with several branches, implemented in large cottages with 2-4 floors. Here, from 3 to 8 pumping devices can be used (sometimes more), supplying coolant floor by floor and to different heating devices. An example of such a circuit is shown below.

Finally, a second circulation pump is installed when heating the house with water-heated floors. Together with the mixing unit, it performs the task of preparing coolant with a temperature of 35-45 ° C. The operating principle of the circuit presented below is clearly described in a separate material.

This pumping unit forces coolant to circulate through the heating circuits of underfloor heating.

Reminder. Sometimes pumping devices do not need to be installed for heating at all. The fact is that most electric and gas wall-mounted heat generators are equipped with their own pumping units built inside the housing.

Installation instructions

So, we will describe the installation stages when circulation pumps are installed on the bypass. This scheme is used most often and is recommended by experts due to the following advantages:

quick, convenient dismantling;
convenient temporary shutdown.

For wet options, a horizontal, level position is critical:

There are various modifications of already assembled bypass loops on the market: for welding, for flanges, with segments for shut-off elements.

If it is not advisable to buy a ready-made assembly, for example, when all the parts are in stock or if there are specific features of the location, then the bypass piping is made from scratch. But you will need skills in working with pipes (welding, thread cutting).

A good, recommended location is between the membrane tank and the boiler. Below is a universal option: for open/closed circuits, for connecting using the collector method (several pumps).

Assembly order

Diagram showing the movement of water, please note: shut-off valves are mandatory - when removing the device for repair or maintenance, they are turned off:

They start by assembling a unit (module) with taps: one per inlet/outlet. pump, the third is part of the lower straight pipe. It is necessary to carefully measure the return segment in order to accurately weld the segment with the shut-off fittings.

The bypass section from the central station is assembled. The nuts are only screwed on, tightening is postponed until the final stage. The top is the pump part (in the photo below the GRUNDFOS UPS pump) with two already screwed in taps, a filter, at the ends of the module there are small sections of pipe with threads like squeegees, they serve as material for welding. Below is a shut-off valve for the supply pipe (main).

They try on a bypass loop, mark the welding points on the pipe, use a drill with special drills to make a hole for the diameter of the section being mounted, and weld the joint.

They cut in the entire assembly with the lower shut-off valve on the main pipe, in our case, on the supply from the gas boiler:

The last step is to connect the pump to power.

Connecting the pump to power

So, the system is completely assembled, the pump is selected, installed, and then the device is connected to the power supply. Before the procedure, the entire line is completely de-energized—the machine is turned off on the panel. The device may have a plug for a socket or without it - just wires of a certain length for connecting directly to the home network on the panel.

Procedure: The pump wires are connected, taking into account the polarity, to the line. The terminals are labeled and have standard colors. If the device does not have a cable with a plug for a socket and you decide to use just such a connection, then you can buy it in any store, you will need a three-core cable, usually a cross-section of 2.5 mm² is more than enough.

It is highly desirable to have grounding (three-wire wiring), since proximity to water creates a significant risk of current entering the equipment elements. It is recommended to connect the device via an uninterruptible power supply (UPS); you can also connect a boiler to it.

An excellent solution is to insert a thermostat into the system (see diagram below), it can also be immediately included in the unit, which will automatically switch off when the coolant temperature drops below the set limits.

It is also highly advisable to install the device with a connection to the network through a difavtomat (its analogue of an RCD + AB) or through the boiler automation system, on which all these measures should be taken by default. And also, if there is an automatic protective device on any line with an outlet and the pump is not too powerful, for example, 90 W, that is, it will withstand all the consumers hung on it, then separate individual wiring with RCBOs and RCDs under the pump may not be installed. The device can be connected to such an outlet and not bother.

Connections without grounding are allowed, for example, when the house is old with two-wire wiring, but then the presence of a difavtomat or RCD+AV in the diagram is vital.

Power connection

The circulation pumps operate from a 220 V network. The connection is standard; a separate power supply line with a circuit breaker is desirable. The connection requires three wires - phase, neutral and ground.

Circulation pump electrical connection diagram

The connection to the network itself can be organized using a three-pin socket and plug. This connection method is used if the pump comes with a connected power wire. It can also be connected via a terminal block or directly with a cable to the terminals.

The terminals are located under a plastic cover. We remove it by unscrewing several bolts and find three connectors. They are usually labeled (the pictograms are N - neutral wire, L - phase, and “ground” has an international designation), so it’s hard to make a mistake.

Where to connect the power cable

Since the entire system depends on the performance of the circulation pump, it makes sense to make a backup power supply - install a stabilizer with connected batteries. With such a power supply system, everything will work for several days, since the pump itself and the boiler automation “pulls” electricity to a maximum of 250-300 W. But when organizing, you need to calculate everything and select the battery capacity. The disadvantage of such a system is the need to ensure that the batteries do not discharge.

How to connect a circulator to electricity through a stabilizer

Bottom line

As you can see, the main difficulty of installation for a circulation pump is the need for welding, cutting pipes, and threading. The assembly itself is elementary: you need to carefully measure all the distances and screw in the elements. The connections are sealed with tow and sealant.

What to pay attention to during operation:

it is necessary to periodically clean the filter and check the pressure gauge readings;
The noise emitted by the device does not always indicate a breakdown; often the cause is air accumulating in the circuit. The problem can be solved simply - by bleeding with special valves;
Dry pumps may require periodic lubrication.

Shut-off valves and other elements

It should be remembered that the main enemy of any heating system is air. Therefore, it is necessary to fight it. For this purpose, valves are installed to remove air from the system (automatic vents, air vents, they also allow you to partially compensate for water hammer if necessary) and radiator needle air valves, popularly called “Mayevsky taps”. Installation locations are radiators, collectors, and in some cases other places, it all depends on the system configuration.

The main shut-off valves in the heating system are taps and balancers, which are placed on heating devices and boiler room piping and other elements of the heating system.

It is better to use proven high-quality shut-off valves. Installing cheap fittings can lead to a sudden accident - a leak, a breakthrough of the heating system, which can lead to the heating system stopping, which can lead to defrosting of the heating system in the winter season. High-quality shut-off valves: Giacomini

,
Grundfoss
,
Dunfos
,
Bugatti
.

Shut-off valves

Second point

. As noted above, the coolant tends to expand and an expansion tank is clearly not enough. Therefore, it is mandatory to install a safety group; it consists of an automatic air vent, a safety valve and a pressure gauge located on a common console.

Third point.

Whatever you do, there will always be foreign impurities in the coolant, and this can lead to failure of the circulation pump, automation and boiler. Therefore, a filter with a coarse mesh is installed on the return line in front of the pump. Don't forget to clean it periodically.

Fourth point.

When using an intermediate coolant, you cannot do without shut-off, shut-off and control, mixing and control valves. It allows you to regulate the intensity of the coolant flow and, as a result, the temperature in a certain room.

The classic option is a tap (shut-off valve). They are installed in various places. One, as a rule, is after the circulation pump in front of the boiler and serves to drain the coolant from the system, the others are at the radiators or on the collector, if such a system is used, in some cases, in front of the pump, which is very convenient. To replace the pump, you can simply shut off the return line and that’s it. Conventionally, reinforcement is divided into two groups:

mechanical (valves, ball valves, different types of valves, valves of various types (including shut-off and check valves, balancing and safety), sensors for determining coolant flow and pressure, air vents, pressure reducers, butterfly valves, pressure gauges), advantages - structural simplicity, low cost, disadvantages – manual adjustment;
thermostatic (allows automatic temperature changes in accordance with specified parameters), it includes thermostatic heads and valves with mechanical or electronic control, advantages - high accuracy of maintaining the temperature in the room without human intervention, disadvantages - higher cost and structural complexity.

Heat pipe elements

After you have decided on the heat source, expansion tank, circulation pump, shut-off and control valves, you need to select a heat pipe or, in simple terms, heating pipes. There are several options to choose from, the main one being the material. Main pipe options:

steel, a classic of the genre, advantages - durability, high resistance to troubles (water hammer, high pressure and pressure surges), reduced temperature coefficient of the resulting linear expansion, affordable cost, disadvantages - corrosion, stray currents, the occurrence of deposits inside, high cost of installation;
polypropylene, advantages - durability, resistance to corrosion, chemical resistance, low noise level, tightness and reliability of connections, oxygen impermeability, low cost, mechanical strength, resistance to high temperatures and possible defrosting, environmental safety, disadvantages - low temperature stability;
metal-plastic, advantages - small linear elongation when heated, possibility of use in rooms with complex configurations, long coil length (from 50 to 500 meters), corrosion resistance, durability, oxygen impermeability, resistance to deposits, disadvantages - low resistance to ultraviolet radiation, mechanical loads;
stainless steel, including corrugated, pluses - durability, flexibility, resistance to water hammer, linear expansion, defrosting, high heat transfer, biological stability, minus - high cost;
copper, annealed and unannealed, pros - high corrosion resistance, high heat transfer, excellent appearance, minus - prohibitive cost and difficulty in installation;
PEX (cross-linked polyethylene), pros - high strength and resistance to high temperatures, cons - difficult to install, high cost.

Second parameter

- connection type. They can be detachable or permanent, depending on the material from which the pipes are made. Main options:

one-piece, welding (with a welding machine for metal or a “soldering iron” for polymers) and soldering, socket and coupling;
detachable threaded and collet connections, using couplings, tees, angles, flanges;
conditionally detachable compression fittings;
one-piece press fittings (pressure testing);
split flaring.

Third important parameter

– pipe diameter, external (external), nominal and internal. It is better to leave his calculations to the masters. This is a complex engineering calculation associated with the need to take into account such factors as the thermal power of the system, the speed of movement of the coolant in the system, the temperature difference between the supply and return, and a number of others, taking into account the specified standard values.

An incorrectly selected diameter is bad: less than the specified diameter means noise in the system and increased load on the elements; more than the specified diameter means loss of system efficiency.

And, one more important point. If there are financial possibilities, then you can use a radial, collector circuit, and for this you need a collector, it is designed for a uniform or specified distribution of the coolant. That is, you can regulate the temperature in rooms, even to the point of turning off the heat supply to a certain place.

The manifold consists of a comb, with leads for connecting pipes and devices, the number of leads is different. Valves for draining coolant and air, a heat meter, and taps (inlet, shut-off and adjustment) are installed on the terminals. There are at least a pair of combs – feed and return. The collectors are hidden in cabinets, and the pipe routing is hidden.

System check

For normal water circulation, the heating system needs to warm up. It takes 2-3 hours. Wait the specified time and check each battery by touch, they should all be at the same temperature.

If you find a hotter or colder one, try deflating. For overheated batteries, you need to bleed them in a subsequent radiator, for cold ones - in the previous one. Most likely, the problem will be resolved.

Another possible reason is a leak. Carefully inspect the connection points between the batteries and the pipe. Even if there are no obvious puddles, water may appear at the joints. Recheck the connection and the problem will go away.

The last uncharacteristic point is extraneous noise in the pump. In new models, this problem only occurs if foreign objects, rust or other debris gets into the pump. To avoid this, it is recommended to install a filter on the supply pipe. Eliminated by disassembling and cleaning the pump.

One-pipe and two-pipe systems

Experts distinguish between two heating schemes with forced circulation of the thermal agent - one-pipe and two-pipe. The choice of one or another option determines not only the location of the circuits, but also the length of the pipelines, as well as the type and quantity of equipment for shutdown, regulation and control.

A single-pipe heating system is characterized by the sequential inclusion of heating radiators in the circuit. The coolant returns through a separate pipeline to the boiler only after it turns one by one through all the devices of the system. The disadvantage of this method is that radiators that are closer to the thermal block become warmer than those further away, and this reduces thermal efficiency and equipment life. Introducing a circulation pump into the circuit and equalizing the temperature is achieved at all points of the system.

A two-pipe arrangement has advantages over a single-pipe arrangement, since all heating devices are connected in parallel to the supply and return lines, which promotes uniform temperature distribution throughout all rooms. Forced circulation of the refrigerant leads to increased efficiency of the system and the ability to regulate its thermal power.

Where to install the pump - supply or return

Despite the abundance of information on the Internet, it is quite difficult for the user to understand how to correctly install a heating pump in order to ensure forced circulation of water in the system of their own home. The reason is the inconsistency of this information, which causes constant debate on thematic forums. Most of the so-called specialists claim that the unit is installed only on the return pipeline, citing the following conclusions:

the coolant temperature in the supply is much higher than in the return, so the pump will not last long;
The density of hot water in the supply line is less, so it is more difficult to pump;
The static pressure in the return line is higher, which makes the pump easier to operate.

Interesting fact. Sometimes a person accidentally ends up in a boiler room that provides central heating for apartments, and sees the units there embedded in the return line. After this, he considers this solution to be the only correct one, although he does not know that in other boiler houses centrifugal pumps can also be installed on the supply pipe.

We respond to the above statements point by point:

Household circulation pumps are designed for a maximum coolant temperature of 110 °C. In a home heating network it rarely rises above 70 degrees, and the boiler will not heat the water more than 90 °C.
The density of water at 50 degrees is 988 kg/m³, and at 70 °C – 977.8 kg/m³. For a unit that develops a pressure of 4-6 m of water column and is capable of pumping about a ton of coolant in 1 hour, the difference in the density of the transported medium is 10 kg/m³ (the volume of a ten-liter canister) is simply negligible.
In practice, the difference in static pressure of the coolant in the supply and return lines is equally insignificant.

Hence the simple conclusion: circulation pumps for heating can be installed both in the return and supply pipelines of the heating system of a private house. This factor will not in any way affect the performance of the unit or the heating efficiency of the building.

Boiler room made by our expert Vladimir Sukhorukov. There is convenient access to all equipment, including pumps.

The exception is cheap solid fuel direct combustion boilers that are not equipped with automation. When overheated, the coolant in them boils, since burning wood cannot be extinguished at once. If the circulation pump is installed on the supply side, then the resulting steam mixed with water enters the housing with the impeller. The further process looks like this:

The impeller of the pumping device is not designed to move gases. Therefore, the performance of the device decreases sharply, and the flow rate of the coolant drops.
Less cooling water enters the boiler tank, causing overheating to increase and even more steam to be produced.
An increase in the amount of steam and its entry into the impeller leads to a complete stop of the coolant movement in the system. An emergency situation occurs and, as a result of an increase in pressure, a safety valve is activated, releasing steam directly into the boiler room.
If no measures are taken to extinguish the firewood, the valve cannot cope with the pressure release and an explosion occurs with the destruction of the boiler shell.

For reference. In cheap heat generators made of thin metal, the response threshold of the safety valve is 2 Bar. In higher quality TT boilers, this threshold is set at 3 Bar.

Practice shows that no more than 5 minutes pass from the start of the overheating process to the valve activation. If you install a circulation pump on the return pipe, then steam will not enter it and the time period before an accident will increase to 20 minutes. That is, installing the unit on the return line will not prevent an explosion, but will delay it, which will give more time to fix the problem. Hence the recommendation: it is better to install pumps for boilers running on wood and coal on the return pipeline.

Selecting a pump installation location

A modern “wet” type circulation pump can be installed in both the return and direct heating branches. Traditionally, the circulation pump is placed in the “return” in front of the boiler in order to:

Reduce wear and increase the service life of the pump rotor;
Avoid boiler boiling due to air being drawn out of the boiler by the pump;
Damage to the pump due to possible boiling of the boiler, especially solid fuel.

Pump diagram in the forward pipeline and Pump diagram in the return pipeline

Circulation device and boiler operating on solid fuel

Here the pump is connected to the system on the return branch and connected with a mixing valve and bypass to the boiler circuit. The three-way valve can be equipped with a servo drive and a clamp-on temperature sensor. Since heating devices operate at full power only in the cold season, you can install a heat accumulator that can absorb excess heat and then, upon request, return it to the heating system. On the battery, on one side there are two pipes for connecting it and two on the other side for connecting to the radiator branch.

Why connect the pump?

Gravity heating is based on the principle of communicating vessels: water in the upper reservoir is heated by a gas burner and begins to flow through the pipes, passes through all the batteries and returns to the lower reservoir, from which it again enters the heating chamber. Using a natural circulation system, it is necessary to ensure a height difference sufficient for good coolant flow.

In practice, this is extremely difficult to do, so heating with natural circulation is characterized by a small heating area, a maximum of 60-80 m². For large, and even more so 2 or 3-story houses, you will definitely need to install a water circulation pump. This will ensure uniform distribution of the coolant along the entire length of the heating system.

In addition, due to the installation of the pump, fuel consumption is reduced. Water passes through the system faster, therefore, it does not have time to cool down too much and less thermal energy is required to reheat it.

An alternative option is to install larger diameter pipes. But in this case, the total cost of materials and work will be much higher, in addition, for houses with an area of more than 200 m², this still will not completely solve the problem.