Recommendation points
- What radiators are designed for bottom connection
- In which heating systems is the bottom inlet practiced
- Radiator piping
- Fittings and consumables
- Installation rules
The supply of pipes to the radiator from below is one of the best solutions in plumbing, providing a high level of aesthetics of heating devices. There are, however, a number of rules, the observance of which will ensure the correct operation of the entire hydraulic system and facilitate the connection process.
What radiators are designed for bottom connection
It is not without reason that the diagonal scheme for connecting radiators is considered the most effective. This is how the maximum heat removal, uniform distribution of the coolant and an optimal temperature gradient are ensured, contributing to intense convection. Even with the lower supply of pipes to the radiator, one of the mandatory requirements is to ensure the flow of water diagonally from the upper edge to the lower opposite. But not all radiators have a device that allows you to achieve such a distribution of the coolant..
Panel radiator design with bottom connection
The most common type of heating devices in which the required conditions are provided for by the design are steel panel radiators. Another type can be called sectional radiators with bottom connection, although only the first two sections have fundamental differences in their design, all the rest are the most common ones. Both of these types of heaters have a pair of nozzles located at the bottom, that is, oriented towards the floor. In both cases, the specificity of the device is such that the supply pipe is connected directly to the channel through which the coolant is directed to the upper part of the labyrinth.
Sectional radiator with bottom connection
It is also possible to retrofit conventional sectional radiators in order to connect them with a bottom side connection. For this, special fittings are used, due to which the configuration of the circulation channels is changed. The bottom connection can be two-way, in this case, instead of the foot, a valve is screwed in from the supply side, which rests on the end of the nipple of the first section and muffles it, while the outlet is directed straight up.
Valve for lower radiator connection
A one-way connection is also possible, for which it is necessary to install a valve with a tubular probe designed for the outflow of the cooled heat carrier.
Thermostatic unit for bottom radiator connection
The described range of fittings can be used for most models of sectional bimetallic and aluminum radiators. In the category of exceptions, there are perhaps such exotic representatives of the world of heating devices as Rifar Monolit, which do not have nipples, although there are modifications in their model range for the lower supply of pipes. In plumbing practice, there are also examples of lower connection of cast iron radiators, although the possibility of such installation is always determined individually, depending on the model.
In which heating systems is the bottom inlet practiced
It is obvious that the supply of the coolant from the bottom up is unnatural, because it is directed against the action of gravity. For this reason, the bottom connection of radiators cannot be carried out in open natural circulation heating systems. But this is far from the only limitation..
Even with a two-way bottom connection, where the connection of the return pipe is carried out according to the standard scheme, a special valve is installed on the supply. Its throughput is lower than that of a conventional case with a screwed-in fitting, therefore, the coefficient of local resistance of the radiator in this case will be at least twice the nominal value. This forces the use of circulation pumps with a more intense pressure and radically revise the procedure for hydraulic calculation..
With a one-way bottom connection, even more difficulties arise. Firstly, the local hydrodynamic resistance of the radiator increases even more, because now two opposite channels with a fairly small nominal bore pass through one outlet. In addition, there are difficulties with the installation of shutoff and control valves. High-quality lower connection nodes for radiators with built-in thermostatic head are a rarity in the domestic market. Most of the range is represented by Chinese-made products that do not provide sufficient flexibility and adjustment accuracy. Another nuance lies in the method of regulating the flow rate of the coolant: instead of a rod limiting the throughput, most injection units have a built-in bypass, which radically changes the balancing method. At the same time, the installation of an injection unit with a free-standing choke and a thermostatic head is often unacceptable due to lack of free space, and if such a configuration is still possible, it will be extremely cumbersome and inconvenient to operate..
Two-pipe heating system with a passing movement of the coolant
We can say that two-pipe systems with a passing movement of the coolant or radial junctions are best suited for lower connection of radiators. Due to the significant reduction in radiator throughput, there is no obvious reason to reject thin PEX tubing with compression fittings, which look much sleeker than other power systems. It is not a good idea to use the bottom connection for one-pipe circuits, in this case it is quite difficult to balance the system and ensure its stable operation.
Radiator piping
Of course, the use of cross-linked polyethylene in the heating junction is not at all necessary, although it is preferable for reasons of reliability and aesthetics. The use of steel pipes should definitely be abandoned. The reason for this is simple: traditionally, with the lower connection, the pipes go into the floor and run either under the cover or along the ceiling of the lower floor. If the heating pipe runs through a ceiling, a casing is required, which does not have the best effect on the appearance of the floor covering. Otherwise, the choice of material for decoupling the system is completely free, polypropylene, mentioned PEX, and even copper can be used .
Separately, it is worth touching on the topic of using pipe insulation. There are three positions on this issue:
- Without insulation, pipes can perform the function of floor heating, provided that they are located in the passage area.
- The insulating casing effectively reduces parasitic heat leaks, which is important when laying pipes in the technical cavity of the lower floor ceiling.
- When pipes are found in dense, incompressible media, such as floor screed, the insulation acts as a damper, compensating for the thermal expansion of the plastic and allowing it to expand in both directions.
At the time of wiring installation, the installation position of the radiators must be precisely known. Height may vary, but horizontal offset is generally unacceptable. This is due to the fact that the swivel fitting is not located on the surface, that is, only a straight section protrudes above the coating, which is connected to the radiator outlet. You can deviate from this rule only if the nodes of the lower side connection are used, in which case the pipe outlets are located at a distance of about 100-120 mm from the end of the radiator case.
Fittings and consumables
The installation of radiators with a bottom connection itself does not imply much difficulty, but this requires that all the necessary fittings, fittings and packaging means be prepared in advance. Depending on the type of radiators, the list may differ.
For radiators, the bottom connection of which is provided for by the design, a set of adapters is required that corresponds to the pipe material. As a rule, these are straight press fittings or sleeves for soldering; when using polypropylene, it is recommended to install threaded “American” fittings. In such cases, control valves are rarely installed directly under the radiator, their optimal location is on the distribution manifold. Exactly the same is the case with the installation of injection units..
With lateral bottom piping, it is possible to install thermostatic and control valves on the radiator. In this case, all fittings are installed on the “metal” part, that is, they are packed on threaded connections with fittings or threaded fittings for bottom connection valves. In any case, each radiator is equipped with two shut-off ball valves for the possibility of removing the radiator without stopping the system. You will also need one or two radiator plugs and a Mayevsky crane. Sealing of threaded connections is traditionally performed with tow and Unipak sealing paste..
Installation rules
Before connecting the radiator to the system, it is assembled in a lying state with the installation of all the fittings. Ultimately, there should be only two straight press fittings or swivel nut connections: on the supply and return pipe.
The bottom connection valve replaces the radiator sleeve. It is sealed in a standard way for this unit – using an O-ring. It is advisable to mark the position of the through hole on the shank on the valve nut, so that after screwing it is located strictly vertically. To correct the position, you can use seals of different thicknesses and adjust the degree of tightening.
The injector unit is connected in a similar way, but quite often it does not have a nut that replaces the sleeve. With a one-sided lower connection, the outlet on the reverse side is muffled with a plug, like one of the upper ones, a Mayevsky crane is installed in the remaining one. The further assembly scheme is simple: all the necessary shut-off and control equipment is packed onto the threaded fittings of the valve, injection unit or lower outlets on tow with a sealing paste. Ultimately, the radiator is installed in place as an assembly and fixed using a wall or floor mounting method, then it is connected to the system.
What are the advantages and disadvantages of having a bottom connection for heating radiators? Does it offer better heat distribution and efficiency compared to other connection types?
Bottom connection for heating radiators has several advantages and disadvantages. The main advantage is that it allows for more efficient heat distribution since the hot water enters from the bottom of the radiator and rises up, creating a natural convection cycle. This can result in quicker heating of the room and more even distribution of heat. Another advantage is that bottom connection radiators are often easier to install and maintain compared to other connection types.
However, there are also some disadvantages to bottom connection radiators. One downside is that they can be more prone to trapping air, which can reduce their efficiency and require bleeding to remove the air pockets. Additionally, bottom connection radiators may be more difficult to clean and paint due to their positioning close to the floor.
Overall, bottom connection radiators can offer better heat distribution and efficiency compared to other connection types due to the natural convection cycle they create. However, they may come with some drawbacks such as air trapping issues and difficulty in cleaning. Ultimately, the choice of radiator connection type will depend on the specific needs and preferences of the homeowner.