Warm floors can improve the energy efficiency of modern housing, make it more comfortable, and also significantly save money on heating. Of all the varieties of underfloor heating, water is the most difficult in terms of adjustment. But it is more popular because of its cost-effective operation, durability and reliability. The underfloor heating mixing unit is an important element of the control system. It maintains the required temperature inside the circuits and ensures the circulation of the coolant. Correct collector operation affects the functionality and efficiency of the hot water heating system.
Purpose of using the device
The use of a pumping and mixing unit for the construction of a warm floor is mandatory, since the water in the circuits must have a completely different, lower temperature than in conventional heating systems. Such a temperature regime is not acceptable for a floor heating system for several reasons:
- Coolant circuits are located throughout the entire area of the room. In addition, they are enclosed in a screed, which also has a high heat capacity. It follows that to maintain a comfortable room temperature, the heating level of the water system must be lower than in classic radiators.
- In order for a person to feel comfort when walking barefoot on a warm floor, the surface temperature of the coating should not exceed 30 degrees. Otherwise, uncomfortable sensations will appear.
- The materials used for flooring in residential premises do not involve strong heating. When the threshold of permissible heating is crossed, the material begins to lose its performance and deform. Inlaid coverings - parquet, laminate, parquet board, lose their solidity, cracks form between the lamellas, lock joints are damaged, waves and other defects are formed.
- The concrete screed, inside of which the heating circuits are located, can also lose its qualities if excessive overheating.
- Excessively high temperatures negatively affect the pipes themselves, which are deprived of the ability to expand when heated due to rigid fixation inside the screed. This leads to significant internal stresses that provoke rapid wear and damage to the integrity of products. Eliminating leaks in a water heating system is associated with serious financial costs.
The purpose of the pump-mixing unit is also associated with maintaining sufficient hydraulic pressure in circuits with a large length or complex curvilinear shape.
Principle of operation
The goal set for this type of equipment is to reduce the water temperature in the circuit to a comfortable value without affecting the main heating system. The role of the mixer is to mix cold water into a hot stream. The mixing unit consists of the following elements:
- Circulation pump installed at the inlet of the heating medium. Thanks to the pump, the system establishes and maintains the optimal pressure of the water flowing through the circuits, as well as the speed of its circulation.
- Mixing unit in the form of a control valve that feeds the water circuit with hot pressure. The valve opens after the signal from the temperature sensor.Hot water stops flowing into the circuit after it reaches the set temperature and the temperature sensor gives a corresponding signal.
- Distribution manifold with flow meters, allowing several circuits to be connected at the same time.
- A separator that automatically removes air from the system. Usually installed on ready-made mixing units from renowned manufacturers.
The main feature of the mixing unit for underfloor heating is its autonomy. It works in automatic mode without human intervention, independently controlling and regulating the pressure and temperature of the coolant in the circuit.
System elements
All schemes are united by ease of operation, the possibility of self-assembly, as well as the location of the main elements. The supply and return are located on the left side, and the manifold with combs - on the right. The differences between the schemes are in the addition of some details. Most often, the collector is located near the mixing unit, less often - at a distance, which may be due to a lack of free space or planning features of the room.
The composition of the components depends on the material of the pipes used - from cross-linked polypropylene, metal-plastic, corrugated stainless steel or copper.
The following elements are used in the scheme:
- Shut-off valves in the form of ball valves. They do not participate in adjusting the main indicators of the coolant - its temperature and pressure, but are necessary when carrying out repair work when it is required to turn off individual components of the system.
- An oblique filter designed for mechanical water purification. It is used in the system if there is no certainty about the purity of the water used. This filter will keep solids out of the tuner, thus ensuring correct system operation and extending valve life.
- Thermometers that provide visual control over the temperature of the water inside the circuit. Some models are equipped with a probe that comes into direct contact with the coolant. Thermometers are available in liquid, mechanical and digital.
- The thermostatic valve is the main control element of the mixing unit. A thermostatic head is put on top of it. When the temperature of the coolant changes, the head mechanically acts on the thermal valve. If the degree is exceeded, the valve closes, and when the temperature drops, it opens.
- A bypass for cold water withdrawal is a jumper, which is formed between the supply and return pipes with the help of sanitary tees. To accurately adjust the pressure of the coolant, a balancing valve is installed on the bypass, which will ensure the optimal operation of the system and its noiselessness.
- The optimal speed of movement of water through the pipes is ensured by means of a circulation pump.
Supply choke
Thus, water from the "return" is supplied unlimited, and hot only when necessary under the control of the valve. Due to this, overheating of the warm floor is excluded and its service life is extended. The low flow capacity of the two-way valve ensures smooth regulation of the water temperature, eliminating sudden changes.
Reliable and efficient valves are recommended by most professionals. But in their opinion, the supply valves will not be useful if the area of the premises is too large (over 200 m2).
Three-way choke
Unlike a two-way valve, a three-way valve mixes water of different temperatures inside itself.This element combines a supply bypass valve and a bypass. The peculiarity lies in the possibility of adjusting the amount of hot and cold heat carrier for mixing, thanks to a damper located between the hot water pipe and the "return".
Such valves have disadvantages. There is a possibility of very hot water being supplied by a signal from a temperature sensor, which, due to a sharp drop, can provoke an increase in pressure in the pipes and a violation of the integrity of the circuits. The large flow capacity of the three-way valve can cause a sharp drop in the temperature of the water in the circuit, even with a minimal displacement of the device control.
Features of setting up the mixing unit
The adjustment mechanism provides precise control of the temperature of the water moving through the pipes of the heating system. This is primarily necessary to create a comfortable floor surface and conditions that extend the life of the system. Water leaves the boiler with a temperature of 60-80 degrees, and the temperature is acceptable for the floor surface not higher than 30 degrees. The mixing unit introduces cold water into the heated coolant, bringing it to optimal performance.
Adjustment is performed in manual or automated mode - the servo drive will need to be purchased additionally, since it is not included in the basic kit. Each circuit is equipped with shut-off valves, with which each circuit has its own settings. In this way, you can set different temperatures for the floor surface for individual rooms or for individual areas in the same room.
Self assembly
You can assemble the collector yourself. In the kit, as a rule, the manufacturer encloses a detailed wiring diagram. The following types of work will be required:
- The equipment is fixed horizontally on a wall or in a niche. The main requirement is to provide access to service and control the elements of the node. If the collector is not installed in a separate room, but in a bathroom or hallway, it must be masked for aesthetic purposes by installing it inside a collector cabinet.
- Heated water from the boiler is supplied from below, and a "return" is mounted on top. To install shut-off valves, a section is selected in front of the frame, after which a pump is mounted. It will help to mix the "return" and hot water, as well as maintain the optimal pressure in the pipes.
- Install a bypass valve and a manifold.
- After that, it is necessary to carry out the piping. Those that go to the floor are fixed at the top, and the pipes from the heating system are fixed at the bottom.
- When connecting the manifold, components are used in the form of compression fittings, which include a support sleeve, a clamping ring and an intermediate brass nut.
- When the installation work is completed, they begin to check the tightness of the connections - pressure testing. To do this, using a special pump, the pressure in the system is increased and left for 24 hours. The manifold unit is completely ready for operation if the initially set pressure value has not changed within 24 hours.
With a lack of experience in self-assembly of the collector, the following mistakes can be made:
- Incorrect bypass setting due to incorrect calculations of the allowable circuit load. Such calculations must be performed before starting installation work.
- The absence of a separator leads to the formation of air locks in the water circuits, which reduces the efficiency of the heating system.
- Wrong selection of hot water dispensing point. The heating medium must come from the top, not from the bottom.
- The lack of a check valve, which is needed to prevent leakage.
If the collector is initially assembled incorrectly, then it will be problematic to eliminate errors and redo the system. Therefore, it is better to entrust the work to a specialist who will make the correct assembly and adjustment of the equipment.
