Warm floors for many of us today have ceased to be something distant and unattainable. Thanks to the mass of information literature, practical use, it became possible to equip such heating systems with your own hands. Moreover, the scope of use of heating floors has expanded significantly. Not only private houses and cottages are equipped with heated floors. Even with all their design flaws, city apartments today can be equipped with heating floors. The main thing is how to carry out the installation and how to select the necessary equipment, consumables.
For underfloor heating, the availability of additional equipment is crucial, with the help of which the heating heating circuit functions as intended. A key element in the design of any autonomous heating is a circulation pump, for a warm floor it is the “heart of the heating system”. The importance of this device can hardly be overestimated, especially if you study in detail the operation of underfloor heating.
The principle of operation of the circulation pump in the heating system «warm floor»
The name of the device, circulation pump, speaks for itself. Due to the operation of the rotor with the impeller, the movable and rotating parts of the device, the circulation of the liquid heat carrier in the pipeline is ensured. It is appropriate to recall here that for a central heating system or a DHW main, the presence of a circulation unit is not necessary. Thanks to the centralized supply, the necessary working pressure is created in the system, which ensures a sufficiently intense flow of the coolant in the pipelines.
On a note: circulation pumps for centralized heating systems have not one, but several installations (pumping stations), with the help of which the hot coolant is first distributed to heated objects, and only then, it diverges directly to consumers.
Pumps used for heating systems can work both with boiler water and with other liquid media used as a heat carrier. However, the device, which is a pump designed for a water-heated floor, works only on water. It should be remembered.
The unit is installed immediately after the three-way valve, which mixes cool water into the system. Underfloor heating requires the selection of a pump that will meet the relevant parameters of all autonomous heating. The unit installed in the system must draw out the liquid obtained as a result of admixture for subsequent supply to the collector. Due to the fact that the impeller is equipped with blades, during the rotation of the rotor, a low pressure zone is created inside the working cavity. As a result of the rotation of the rotor with the impeller, the liquid entering the body of the device under the influence of the laws of physics continues further, only more intensively with increased speed.
Together with a safety valve, a bypass and an expansion unit, the pump makes up a single set of equipment — a pumping and mixing unit. As a result of the operation of the pumping group, an optimal working pressure is created in the loops of the water circuits, due to which water enters each heating water circuit at the desired speed and intensity.
Design features of the device
By its design, the pump looks like a snail. A small sealed housing has two nozzles — inlet and outlet. An electric motor is installed in a sealed housing that rotates a rotor with an impeller. The electric pump is powered by a 220V home electrical network.
Structurally, all units used when working with hydraulic systems are divided into two types:
- type of equipment with a dry rotor;
- wet equipment.
Before proceeding with the installation of heating floors and the selection of appropriate equipment, you should understand the nuances of both types of pumping equipment.
The first type “with a dry rotor” is a device, the main work of which is performed by a dry rotor without direct contact with the aqueous medium. In this type, the rotor is in a hermetic position and is protected from liquid penetration by an o-ring (gland). The main feature of this type of pumps is high efficiency. Some models have efficiency up to 85%. However, dry models are characterized by high noise during operation.
On a note: equipment with a dry rotor are of considerable size, in comparison with models of a wet type. Such devices are more often used to ensure the operation of heating systems in apartment buildings, or in production.
For wet type equipment, the location of the rotor is a distinguishing feature. The rotating part of the pump is in direct contact with the aqueous medium. Only the stator of the electric motor is insulated.
Here it must be said that upon contact with the liquid, natural lubrication of all parts of the rotating group occurs. Due to this, the noise of a running engine is minimized, and the service life of the devices is significantly increased.
The efficiency in wet pumps is inferior to analogues with a dry rotor. Some models have an efficiency of up to 65-70%, and the bulk of mechanisms for underfloor heating have an efficiency even lower. But in this case, the devices have their advantages. Small size, low noise threshold. Such a pump is convenient for underfloor heating, ideal for domestic use, especially since wet units do not require maintenance.
What to look for when choosing equipment
In order for underfloor heating to be effective, it is necessary to make certain thermal calculations before installation. Accurate data and operating parameters of almost all heating elements will be required. It is not necessary to reset the circulation pump with the bill. The choice of model and type of this unit must be taken seriously.
On a note: it is possible to equip a warm floor without a pump if you plan to heat a small room in this way. For example, a bathroom or a nursery, rooms where the heated area is small, it is customary to connect to the hot water system or to central heating batteries. One water circuit of small length will quite cope with this task, especially since the pressure in the system is sufficient for the coolant to diverge through the water loop.
In all other cases, a pump is indispensable. How to choose a pump if you have a large number of water heating pipes, a large length of water circuits. All this imposes an additional load on the heating system. Without forced circulation, without a mixing unit, such heating will not work.
- The circulation pump must comply with the technical parameters of the system;
- You must know exactly the area of the heated room;
- Probability of heat losses in the heating circuit.
Choosing a pump will help you correctly understand its performance — one of the most important characteristics. It is necessary to calculate the maximum capacity of the unit, which will be required to create sufficient pressure and constant circulation of water in the system. This parameter is defined in m3 per pump hour. According to the rules of thermodynamics, the pump must, on average, drive through itself a volume of water 3 times the volume of the coolant poured into the heating system.
Accordingly, the more heating circuits, the greater should be the performance of the unit. Therefore, when choosing a unit model, one should focus on equipment with a power reserve of 10-20%. Thanks to the existing power gap, you will save the equipment, providing it with long service life.
Important! In winter, for the normal operation of the «warm floor» heating system, a greater pressure of the coolant in the system will be required. A high power pump will solve this problem painlessly
The area of the heated room is also taken into account when choosing equipment. The larger the house, the more power it is necessary to install the circulation pump. As a rule, in houses where many rooms are heated, not one, but several pumping and mixing stations are installed.
The next parameter that is paid attention to when buying a pump is pressure. Each unit has its own capacity, and, consequently, a certain amount of pressure. In order for the coolant to normally overcome all the loops and bends of the water circuits, a fairly strong pressure is required. The intensity of the coolant supply to the system depends on the pressure value. A good and powerful pump will ensure the normal circulation of water in the heating circuit, reaching the most remote areas of the heated room, without losing its design characteristics.
Calculation of the performance of the circulation pump for underfloor heating
When making calculations, it is important to obtain the minimum power that will be enough to operate the heating system. We use the formula for calculations:
G \u003d Q X 0.86 / Δt, where
G is the system capacity in l/h;
Q is the thermal energy of the system (W).
0.86 is the conversion factor Kcal/h;
Δt is the difference between the water temperature parameters in the supply-return connection (°C).
Usually, for underfloor heating, pump models are taken that have a capacity of 2.5 m3/ h at a pressure of 6 m. This is for an average underfloor heating, in which there is a standard number of water circuits (2-4 circuits). However, if you plan to heat a residential building in full, such pump power for underfloor heating will not be enough, for the reason that the coolant flow rate will be significant and more pressure will be required. For this purpose, the real losses of working pressure in the pipeline of heating floors are determined, thermal and hydraulic calculations are made.
You can try to do such calculations yourself or turn to the services of specialists to perform such work. The latter option would be preferable, since mistakes made in these calculations can turn into trouble for you.
For use in everyday life to equip underfloor heating with a pumping and mixing station, it is better to focus on adjustable pump models. With such a device, you can easily control the pressure of the coolant in almost any heating system with a different number of heated water circuits.
Do not discount the dimensions of the device and the methods of installation. Compact in size, the pumps are easy to use and easy to install. The pumps are mounted together with other mixing devices, representing a single pump and mixing module.