HEATING
SINGLE PIPE HEATING SYSTEM
The single-pipe heating system is the most economical way of installing and operating the classic central heating system combined with the advantages offered by independent heating per apartment.
In the single-pipe system there is a central column (pair of supply-return pipes) that starts from the boiler room and in the direction from the bottom up, feeds the supply collector with hot water from the boiler and receives lower temperature water (δt=20°C) from the return collector, which has made its “path” to the radiators of the house, and returns it to the boiler.
The single-pipe system is characterized by the cascade connection of the radiators in circuits up to 3-4 radiators each. A pipe starts from the inlet collector and goes to the first radiator There, the switch of the first body sends a quantity of water to the radiator (where passing through its folds, it is attributed to heat in the environment). The remaining amount of hot water, after being mixed with the return water of the first radiator, makes it bypass directly into the next radiator. That is, the 2 quantities of water, one with a temperature approximately equal to the central column and the other reduced due to the passage through the first radiator are directed to the second radiator, where exactly the same process takes place up to the last body of the particular circuit ,from which the water returns to the return collector. As we understand in the single pipe system, the bodies are connected in series. Characteristic of the system is that radiators that are second, third and last in a row in a loop, must be increased in size in order to have the desired performance, as the water that reaches them is of lower temperature.
Advantages
- It is possible to provide hot water by floors or apartments or groups of rooms (operation by zones), i.e. there is the possibility of their autonomy
- Fewer passages from plates
- No unsightly heating columns in the rooms
- Easy and low-cost provision for future expansion of the building
- High speed of water flow
- Easy and quick installation, without a lot of maintenance
- Low labour costs
- There is no dependence of the position of the radiator on the position of a column
- The installation of the single-pipe system is not governed by strict rules as in the twin-pipes system (inclination in horizontal paths, etc.) so that the possibility of errors during installation is reduced to a minimum.
Disadvantages
- The temperature of the water from radiator to radiator (in the same loop) decreases, so that the heating surface of the last radiators is increased in order to have the same thermal power.
- Special switches are required for the radiators, which can be adjusted so that a percentage of the hot water is sent to the radiator and the rest to the bypass. When they need to shut down the radiator, so that the other radiators in the loop are not affected. These switches are more expensive than the twin-pipes system.
- It is difficult to install in an already finished house.
The single-pipe heating system, apart from the above-mentioned advantages, allows even with a small additional cost and with the help of an electric valve, a room thermostat and a meter, indepedent heating of each apartment in every aspect (desired room temperature, operating time, consumption, etc.)
Pipes that are used for this system: RETIFLEX-NOXY, FLEXITHERM-NOXY, OCTATHERM-NOXY and AL-PERT-SOL.
TWO-PIPE RADIAL HEATING SYSTEM
In the technical terminology of heating systems, the term 'two-pipe system' refers to the connection architecture of the heat terminal units of the distribution network and corresponds to a system where all terminal units are directly connected to the central supply/return column (parallel connection).
There is a central column with water distribution collectors in every floor, like in the single pipe system. The only difference is that each circuit supplies only ne radiator. That means the entire water quantity, that leaves the collector inlet, enters the radiator, heats it and then goes back to the return collector and from there to the boiler room. The radiators in this system have theoretically the same temperature, so no increase on their surface is observed. The water inside the plastic pipes moves with double speed than in copper ones because the plastic pipes have smooth inner surface. At the horizontal routes, no slopes are required.
Advantages
- All radiators (terminal units) typically have the same average temperature, since they are directly connected to the supply/return branches
- High water speed and constant high temperature
- The network's manometers are relatively smaller, which means less flow energy consumption
- Radiator microdisplacements are easy, since there are several vertical columns for connection, and the connection pipes themselves can - usually - be relatively easily run on skirting boards or in other similar ways
- The network at most points is usually more easily accessible in case repairs, maintenance etc. are required. (however this is not always the case for the central distribution of vertical columns)
Disadvantages
- Heating autonomy is more difficult and more expensive to construct, since it requires the installation of a control and calorimeter system in each body separately
- Many pipe meters (60-70% more than the single pipe system) are required and therefore higher construction costs
The main advantage of this system is that it combines the high water velocity with the constant and high temperature of the radiators. (No increase in radiant surface area - savings on radiators surface area 10-15% compared to single pipe).
The basic disadvantage is that it requires many meters of pipe (60%-70% more than the quantity required for single pipe system). That means higher installation’s cost.
Pipes that are used for this system:
RETIFLEX-NOXY, FLEXITHERM-NOXY, OCTATHERM-NOXY and AL-PERT-SOL.
“UMBRELLA” HEATING SYSTEM
This system is applied in houses that are ready and no heating installation exists. The pipes are visible, installed along the vertical walls, just below the confluence with the ceiling.
They must be slightly inclined (around 1%), either upwards, or downwards, in order to release the air of the circuit using automatic air vent at the higher points of circuit. Through these pipes the hot water passes to all radiators of the apartment.
The pipes recommended for this type of system are composite pipes AL-PERT-SOL in linear sticks.
