In the process of heating the boiler, the water expands, the excess coolant fills a special tank located at a certain point in the heating network. Hence our task is to explain how to install an expansion tank in the heating system of a private house. We also specify the connection point, the method of emptying and adjusting the expansion tank.
Where is the expansion tank installed for heating
So, the installation of the tank depends on the type of heating system and the purpose of the tank itself. The question is not why an expansion tank is needed, but in what place it should compensate for the expansion of water. That is, in the heating network of a private house there can be not one such vessel, but several. Here is a list of the functions assigned to the various expansion vessels:
- compensation of thermal expansion of water in closed heating systems;
- in open networks, the tank performs 2 functions - it perceives excess coolant and removes air from the system to the atmosphere;
- under certain conditions, a membrane tank serves as an addition to the standard expansion tank of a gas boiler;
- absorb excess hot water in the hot water network.
In open heating networks, the water in the tank is in contact with atmospheric air. Therefore, the installation of an expansion tank is provided at the highest point - on a riser going from the boiler. Often these systems are made gravity, with increased diameters of pipelines and a large amount of coolant. The capacity of the tank should be appropriate and make up about 10% of the total volume of water. Where, if not in the attic, to put such a dimensional tank.
Reference. In one-story houses of the old construction there are small expansion tanks for an open heating system installed in the kitchen next to the floor gas boiler. So it’s also right, the tank located under the ceiling is easier to control. True, this does not look too good in the interior. To put it mildly.
Closed heating systems are characterized in that the membrane expansion tank for water is completely tight. The best installation option is in the boiler room, next to the rest of the equipment. Another place where you sometimes have to install a closed expansion tank for heating is the kitchen in a small house, because the boiler is located there.
In closed-type systems operating on a non-freezing coolant, the tank volume should be increased to 15% of the total amount of liquid. The reason is the increased coefficient of thermal expansion of glycol antifreezes.
About additional capacities
Manufacturers complete wall-mounted heat generators with built-in tanks that perceive the excess of heated coolant. The dimensions of the tank do not always correspond to the home heating wiring, sometimes the capacity is not enough. To ensure that the coolant pressure during heating is within normal limits, the displacement calculation is performed and an additional expansion tank for the wall-mounted boiler is installed.
For example, you have converted an open gravity system into a closed one without replacing highways. The new heating unit was selected according to the heat load. The built-in boiler capacity is not enough to expand this amount of water.
Another example: heating with underfloor heating of all rooms of a two- or three-story building plus a radiator network. Here, the coolant volume will also be impressive, a small tank will not cope with its increase, the pressure inside the system will increase. Need a second expansion tank for the boiler.
Note.The second tank to help the boiler is also a closed membrane tank, located in the furnace room.
When the hot water supply at home provides an indirect heating boiler, a similar problem arises - where to put the excess of sanitary water from the drive? A simple solution is to install a relief valve, as is done on electric water heaters. But an indirect heating boiler with a volume of 200 ... 300 l will lose too much hot water through the valve. The correct solution is to select and install an expansion tank for the boiler.
How to put a tank
When installing an open tank in the attic, a number of rules should be observed:
- The tank must stand directly above the boiler and connect to it with a vertical riser of the supply line.
- The body of the vessel must be carefully insulated so as not to waste wasted heat for heating a cold attic.
- It is imperative to organize an emergency overflow, so that in an emergency, hot water does not flood the ceiling.
- In order to simplify level control and make-up, it is recommended to bring 2 additional pipelines to the boiler room, as shown in the tank connection diagram:
Note. The emergency overflow pipe is usually routed to the sewer network. But some homeowners, in order to simplify the task, take it out under the roof straight to the street.
Installation of the expansion tank of the membrane type is carried out vertically or horizontally in any position. It is customary to attach small containers to the wall with a clamp or hang them on a special bracket, large ones - simply put on the floor. There is one point: the performance of the membrane tank does not depend on its orientation in space, which cannot be said about the service life.
A vessel with a closed type will last longer if it is mounted vertically with the air chamber up. Sooner or later, the membrane will exhaust its life, cracks will appear. With a horizontal arrangement of the tank, air from the chamber will quickly penetrate into the coolant, and that one will take its place. To put a new expansion tank for heating will have to urgently. If the container hangs “upside down” on the bracket, the effect will manifest itself faster.
In a normal vertical position, air from the upper chamber will slowly penetrate through the cracks into the lower one, as the coolant will be reluctant to go up. Until the size and number of cracks increase to a critical level, the heating will work properly. The process takes a long time, the problem you will not notice immediately.
A sure sign of critical wear and cracking of the membrane in the expansion tank is the pressure drop in the home heating network. Periodically monitor the pressure gauge on the safety group.
But no matter how you place the vessel, you should adhere to the following recommendations:
- The product must be placed in the boiler room in such a way that it is convenient to maintain. Do not install floor units against a wall.
- When wall mounting the expansion tank of the heating system, do not put it too high so that during maintenance you do not have to reach the shut-off valve or air valve.
- The load from the supply pipelines and shutoff valves should not fall on the tank nozzle. Fix the pipes together with the taps separately, this will facilitate the replacement of the tank in case of breakage.
- It is not allowed to lay the supply pipe on the floor through the passage or to hang it at the height of the head.
Connection Methods
Hydraulically correctly connect the tank at the point located on the return line in front of the boiler and the circulation pump (if you look in the direction of the water flow). The tank can be inserted at the feed, but under 1 condition: the pump must be located on the supply line and still stand in front of the compensation tank.
The second moment: when the solid fuel boiler overheats, the tank connected to the supply will begin to fill with steam.Air and steam are compressible media, in this case the rubber "pear" will no longer compensate for the expansion of water.
The correct connection of the expansion tank to the heating system is always carried out through the shut-off ball valve with an American. Then the tank can be taken out of service at any time and quickly changed, without waiting for the coolant to cool. If you install a tee and a second tap on the eyeliner, as shown in the connection diagram, then the tank can be emptied beforehand:
How to check and pump up the expansion tank
Before connecting and filling the tank with coolant, it is necessary to check the pressure in the air chamber of the tank for compliance with the pressure in the heating network. To do this, a plastic plug is unscrewed or removed from the side of the air compartment, and under it there is an ordinary spool, familiar to you from car cameras. With a manometer, measure the pressure and adjust it to fit your system, pumping it up with a pump or lowering it by pressing the spool rod.
For example, the design pressure in the network after filling should be 1.3 Bar. Then it is necessary to make 1.1 Bar in the air compartment of the expansion tank, that is, 0.2 Bar less. The trick is that the rubber "pear" of the tank is pressed from the side of the water. Otherwise, when cooling, the compressed coolant will draw air through the automatic air vents, which is unacceptable. After setting, open the tap, fill the entire system with coolant and calmly start the boiler.
Note. Some manufacturers indicate on the packaging of their products the factory pressure in the air compartment. On it you can choose a suitable tank and not mess with pumping.
Conclusion
All works associated with the installation, connection and adjustment of the expansion tank are not highly qualified and can be done by yourself. Moreover, you better know how to check and adjust the pressure in the tank during operation. Its decrease or jumps is one of the reasons why the automation of a gas boiler shuts off the burner. If there are no serious coolant leaks, then the first thing to do is to measure the air pressure in the tank chamber with a manometer.