To make the heated water flow more fun through the pipes, a heating pump is provided in the heating systems of private houses. This solution provides tangible benefits. But the main question that worries homeowners and is highlighted in this material is where to put the pump and how to properly install it. After all, the main part of the disputes and doubts is caused precisely by the place of insertion of the unit. And at the same time we’ll figure out how to do it yourself with a home electrical network.
What are good pump heating systems
30 years ago, so-called steam heating was common in private homes, where the coolant circulated through pipes and batteries by gravity, and the gas boiler or wood-burning stove served as the heat source. Pumps for pumping water were used in district heating networks. When compact circulation pumps for heating appeared, they migrated to private housebuilding, as they gave the following advantages:
- The speed of the coolant has increased. The heat generated by the boiler began to be delivered faster to radiators and transferred to rooms.
- Accordingly, the process of heating the house has accelerated significantly.
- The higher the flow rate, the greater the throughput of the pipe. This means that the same amount of heat can be delivered to rooms on smaller mains. Simply put, pipelines have become half as much thanks to forced circulation of water from the pump, which is cheaper and more practical.
- Highways can now be laid with a minimum slope and make arbitrarily complex and extended water heating schemes. The main thing is the correct selection of the pumping unit in terms of power and generated pressure.
- A household circulation pump for heating made it possible to organize underfloor heating and more efficient indoor pressure systems.
- It was possible to remove from the eyes the ubiquitous pipes running through the rooms and not always in harmony with the interior. Increasingly, heating communications are laid in the walls, under the floor covering and behind suspended (suspended) ceilings.
Note. The minimum slope of 2-3 mm per 1 m of the pipeline is needed to empty the network in case of repair or maintenance. Previously, it was made at least 5 mm / 1 m.
Pumping systems also have disadvantages, where without them. This is a dependence on electricity and its consumption by the pumping unit during the heating season. Therefore, with frequent blackouts, the circulation pump must be installed together with an uninterruptible power supply unit or connected to an electric generator. The second drawback is not critical, if you choose the power of the device correctly, then the electricity consumption will be acceptable.
Leading manufacturers of heating equipment such as Grundfos (Grundfos) or Wilo (Vilo) have developed new models of units that can save energy. For example, if you buy and supply an Alpfa2 circulation pump from the Grundfos brand, it will automatically change the capacity depending on the needs of the heating system. True, its price starts at 120 y. e.
Where to put the pump - on the feed or in return
Despite the abundance of information on the Internet, it is quite difficult for the user to understand how to correctly install the pump for heating in order to ensure forced circulation of water in the system of his own house. The reason is the inconsistency of this information, causing constant debate on thematic forums.Most of the so-called specialists say that the unit is placed only on the return pipe, citing the following conclusions:
- the coolant temperature at 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 pipe is higher, which facilitates the operation of the pump.
Interesting fact. Sometimes a person accidentally enters the boiler room, providing central heating for apartments, and sees the local units cut into the return line. After that, he considers such a solution to be the only right one, although he does not know that in other boiler rooms centrifugal pumps can also stand on the supply pipe.
We answer the following statements on the points:
- 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 does not heat 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 an aggregate that develops a pressure of 4–6 m water column and capable of pumping about a ton of coolant in 1 hour, the difference in the density of the transported medium of 10 kg / m³ (volume of a ten-liter canister) is simply negligible.
- In practice, the difference between the static pressures of the coolant in the supply and return lines is just as insignificant.
Hence the simple conclusion: Circulating pumps for heating are allowed to be inserted into both the return and the supply piping of the heating system of a private house. This factor will not affect the performance of the unit or the heating efficiency of the building.
An exception is cheap solid fuel direct combustion boilers that are not equipped with automation. When overheated, the coolant boils in them, since burning firewood can not be extinguished at one time. If the circulation pump is installed on the feed, the steam formed, mixed with water, enters the housing with the impeller. The further process looks like this:
- The impeller of the transfer device is not designed to move gases. Therefore, the performance of the apparatus decreases sharply, and the flow rate of the coolant decreases.
- Less boiler water enters the boiler tank, which causes overheating to increase and steam to form even more.
- An increase in the amount of steam and its ingress into the impeller leads to a complete stop of the movement of the coolant in the system. An emergency occurs and, as a result of the increase in pressure, a safety valve is activated, which releases steam directly into the boiler room.
- If fire extinguishing measures are not taken, then the valve does not cope with the release of pressure 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 provided at the level of 3 Bar.
Practice shows that from the start of the overheating process until the valve is activated, it takes no more than 5 minutes. If you install a circulation pump on the return pipe, then steam will not get into it and the period of time before the accident will increase to 20 minutes. That is, mounting the unit to the return will not prevent the explosion, but delay it, which will give more time to fix the problem. Hence the recommendation: pumps for boilers running on wood and coal should be installed on the return pipe.
For well-automated pellet heaters, the installation location does not matter. You will learn more information on the topic from the video of our expert:
Installation diagrams in various types of systems
To begin with, we will specify the place where to put the flow pump, which ensures the circulation of water through the boiler and forcibly directs it to the radiators of the heating system.According to our expert Vladimir Sukhorukov, whose experience is trustworthy, the installation site must be chosen so that the unit is convenient to maintain. At the feed, it should stand after the safety group and the shutoff valves, as shown in the installation diagram:
At the return, the pump must be installed directly in front of the heat generator, and in tandem with a filter - a dirt collector, so that you do not have to buy and install extra taps. The piping of the pumping unit looks like this:
Recommendation. It is possible to install the circulation pump in both a closed and an open heating system in this way, there is not much difference. The statement also applies to the collector system, where the coolant moves to the radiators through separate hoses connected to the distribution comb.
A separate issue is an open heating system with a circulation pump, capable of working in 2 modes - forced and gravity. The latter is useful for homes where power outages often occur, and incomes do not allow owners to buy an uninterruptible power supply unit or generator. Then the device with the shutoff valves must be installed on the bypass, and a crane should be inserted into a straight line, as shown in the diagram:
An important point. On sale there are ready-made bypass units with a pump, where instead of a tap on the duct there is a check valve. Such a solution cannot be called correct, since the spring-type check valve creates a resistance of the order of 0.08-0.1 Bar, which is too much for a gravity heating system. Instead, you can use a flap valve, but it must be installed only in a horizontal position.
Finally, we explain how to install and connect the circulation pump to a solid fuel boiler. As mentioned above, it is better to put the unit on the highway going from the heating system to the heat generator, as shown in the diagram:
As you can see, the piping used to connect the pump to the boiler circulation circuit with a bypass and a three-way mixing valve. The important role of these strapping elements is described in detail in the manual for connecting solid fuel boilers.
Installation Rules
The design of a household circulation pump from any manufacturer provides for its fastening to pipelines or valves using union nuts (American women). This allows you to quickly dismantle it if necessary, for example, for replacement or repair. When installing the pump unit, follow these recommendations:
- Place the device on any sections of pipelines - horizontal, vertical or inclined, but with one condition: the rotor axis must be in a horizontal position. That is, installation "head" up or down is unacceptable.
- Please note that the plastic box with electrical contacts is on top of the case, otherwise it will flood with water in the event of an accident. And servicing the product will not be easy. This is not difficult to achieve: unscrew the screws securing the casing and turn it to the desired angle.
- Remember the flow direction indicated by the arrow on the body.
- So that the product can be removed without emptying the system, put shut-off valves before and after it, as shown in the diagrams in the previous section.
Tip. It so happened that the load from the weight of the circulating unit will lie on 1 or 2 ball valves (depending on the orientation of the site in space). Hence the recommendation: do not save and buy high-quality shut-off valves, whose body will not crack over time due to mechanical stress.
About installing additional units
As a rule, in a closed or open radiator heating system, where the only boiler is the heat source, 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). They are put in such cases:
- when more than one boiler plant is involved in heating a private house;
- if a buffer capacity is involved in the strapping scheme;
- the heating system has several branches serving various consumers - batteries, underfloor heating and indirect heating boiler;
- the same with the use of a hydraulic separator (hydraulic arrows);
- to organize the circulation of water in the contours of underfloor heating.
Correct piping of several boilers operating on different types of fuel requires that each of them has its own pumping unit, as shown in the diagram for the joint connection of an electric and TT boiler. How it works is described in our other article.
In a circuit with a buffer tank, an additional pump is necessary, because at least 2 circulation circuits are involved in it - boiler and heating.
Another story is a complex heating scheme with several branches, implemented in large cottages on 2-4 floors. Here, from 3 to 8 pumping devices (sometimes more) can be used, which supply the coolant floor by floor and to various heating devices. An example of such a circuit is shown below.
Finally, the second circulation pump is installed when the house is heated with water underfloor heating. Together with the mixing unit, he performs the task of preparing a coolant with a temperature of 35–45 ° С. The principle of operation of the diagram below is described in a separate material.
Reminder. Sometimes it is not necessary to install pumping devices for heating at all. The fact is that most wall-mounted electric and gas heat generators are equipped with their own pumping units built into the case.
Connecting the circulation pump to the mains
There are several ways to connect power to the unit:
- through a conventional differential automaton;
- with thermostat control;
- connection to a network together with the uninterruptible power supply unit (UPS);
- powering the unit from the boiler automation.
Warning. Often, homeowners simply plug the pump into a conventional power outlet by connecting the wires to the plug they’ve purchased. We cannot recommend this approach, because a connection without grounding and a safety circuit breaker is dangerous. In the event of a malfunction or flooding of the apparatus, you run the risk of electric shock.
The first connection scheme is quite simple and any user can assemble it with their own hands. An 8 A differential circuit breaker, wires and contacts are required. Connect to grounding as in this scheme, and in all others.
To automatically stop the movement of the coolant when cooling to a certain temperature, an electrical circuit for connecting a circulation pump with a thermostat is used. The latter is attached to the supply pipe and breaks the power supply circuit when the water temperature drops below a predetermined value.
Attention! In order for the thermostat not to lie and turn off the circulation in time, it must be fixed to the metal section of the highway. Polymers do not transfer heat well, so when installed on a plastic pipe, the device will not work correctly.
There is no difficulty in connecting power via the UPS, for which the latter has special connectors. The heat generator itself should also be connected to them if it needs electricity. But connecting the pump to the boiler control panel or to its automation is a more complicated procedure. It is advisable to have knowledge and skills in the field of electrical engineering.
At what speed should the pump in the heating system work
The purpose of forced circulation is the effective heating of the house due to reliable heat supply to all consumers of the system, up to the farthest radiator.For this, the pump unit must develop the necessary pressure (otherwise, pressure), which is ideally calculated by the design engineers for the hydraulic resistance of the pipeline network.
Most domestic pumps have from 3 to 7 rotor speeds, due to which the productivity and created pressure can be increased or decreased. In order not to torment you with hydraulic calculations, we offer the following methodology for selecting the optimal speed:
- Find a laser surface thermometer (pyrometer). Put the heating system into operation.
- Measure the surface temperature of the pipe at the inlet and outlet of the boiler.
- If the temperature difference is more than 20 ° C, increase the rotor speed. After 30 minutes, repeat the measurement.
- If the temperature difference is less than 10 ° C, the water flow rate must be reduced. The task is to achieve a delta between feed and return of about 15 ° C.
Tip. Switching the pump to a different circulation speed, do not do it on the fly. Disconnect it from the network, reposition the regulator to another position, and then restart operation.
You can do without a pyrometer when thermometers are installed on the supply and return lines. If the adjustment limits do not allow you to enter the temperature difference range of 10–20 ° С, your system is inefficient due to improperly selected circulation pump. Too cold water in the return gives an increased load on the boiler and fuel consumption. The arrival of too hot water means that it flows too quickly and does not have time to transfer heat to the heating appliances.
The leading European brand Grundfos (Grundfos) offers the latest generation Alpfa3 circulation pumps, which can independently choose the capacity depending on the load and in this way adapt the work to changing conditions. With their help, you can even balance the heating system, as our expert will tell you in the next video:
Conclusion
Now you know how to correctly install a circulation pump in a water heating system and connect it to the electricity network of a country house. This will save you from making all sorts of mistakes leading to minor and major troubles. Again, you can do the installation and tying the unit with your own hands. The only difficulty is to embed it in a section of a steel pipeline. But there is a way out: find a set of handles for manual cutting of pipe threads, cut a piece of pipe with a grinder and mount the pump assembly.