Closed heating networks of private houses are isolated from contact with the atmosphere, therefore, they need protection against emergency pressure surges. This function is performed by the boiler safety group, which protects the heat unit and pipelines of the pressure heating system from destruction. From our material you will learn what this important element of the circuit consists of, how to properly install and connect it with your own hands.
Group structure and principle of operation
Typically, a prefabricated item is sold assembled and includes 4 parts:
- horizontal collector made of brass (less often - made of stainless steel or painted “black” metal) with four internal threads ½ ”(DN 15) and ¾” in size (DN 20);
- pressure gauge for pressure up to 6 bar;
- automatic air vent;
- relief valve.
The pressure gauge, air vent and valve are screwed into the small threads of the manifold (½ ”), large (¾”) is designed to connect the safety group to the heating system.
An important nuance. An automatic air valve always stands in front of or close to the inlet. The purpose of such an installation is to facilitate the release of air from the heating network, providing it with the shortest direct path.
The principle of operation of the group is extremely simple: each part performs a separate safety function:
- The pressure gauge helps the homeowner to control the pressure during the injection of the coolant and during the operation of the boiler.
- The safety valve ensures the safe operation of the heating system, and most importantly, protects the heat generator from explosion due to increased pressure above normal.
- The purpose of the air vent is clear from the name. It automatically removes air entering the heat main during filling or during operation.
- The collector combines parts into one element.
Regardless of the type of boiler used - solid fuel, gas or diesel - the safety group for heating is always placed in a closed system that operates with overpressure. If an open type expansion tank is used in the circuit, the installation of our element loses its meaning: air goes out through the tank, and the pressure in the pipes is equal to atmospheric pressure.
Installation Rules
Boiler equipment is the most expensive part of the heating network and its weak point. Judge for yourself: most units are designed to operate at a pressure of no higher than 3 Bar, while the maximum threshold of plastic pipes is 10 Bar, cast-iron radiators - 7 Bar. This is the first reason why the safety device is always located next to the heater on the supply pipe, protecting the latter from destruction in the event of an emergency pressure surge.
For reference. There are cheap models of solid fuel heat generators made of thin metal. To prevent their walls from bursting at the seams, the valve must operate at 1.5-2 Bar in the system.
Since the boiler generates heat, the temperature of the water in its shirt is the highest. It is here that steam is first formed during emergency overheating. To quickly divert the expanding steam-water mixture to the outside, both exhaust valves must be placed next to the heat generator, as shown above in the wiring diagram.
We will give some recommendations on how to properly install and connect a security group to the boiler:
- The installation location is the supply pipe at the outlet of the heating unit.
- The maximum distance from the heat source to the safety device is 50 cm.
- On the pipe section connecting the heat generator to the element, it is not allowed to install taps or tees with a branch to the membrane expansion tank. There should not be anything on this section of the highway.
- The specified section of the pipeline is made of metal. Polypropylene, metal-plastic and cross-linked polyethylene may be deformed from exposure to steam.
- The position of the air vent is strictly vertical.
- Connect a flexible hose to the safety valve, whose end is directed into a transparent plastic bottle or directly onto the floor.
Installing a crane in front of the GB is justified in the only case: you bought a cheap low-quality product, the valves leak, do not work, and so on. In order not to empty all pipelines with radiators for replacement, temporarily place the valve, but remove the butterfly handle from the stem.
Tip. Do not lower the tube from the valve of the solid fuel boiler into the sewer. If the fuse blows in your absence and returns to normal mode, there will be no trace. Another thing is spots on the floor or water in the bottle, indicating an emergency (overheating).
Installation of homemade automation
Quality products from well-known manufacturers are quite expensive. For example, the cost of a safety group for boilers of the Italian brand Icma is 40-43. e. If you buy components of the same manufacturer and assemble safety automation yourself, then the price will come out significantly lower:
- safety valve - 6 at. e .;
- manometer - 10 at. e .;
- automatic air vent - 5 o. e .;
- cross brass DN 15 as a collector - 2.2 at. e.
Total amount for a self-assembled security group is 23.2 c. e., the benefits are obvious.
When choosing components, be sure to consider the advice of our expert, based on many years of practice:
- Do not chase absolute cheapness when buying safety valves. Chinese products begin to leak after the first actuation or do not release pressure at all.
- Manometers from the Celestial Empire often lie. If the device underestimates the readings when the system is filled with coolant, then after heating the pressure in the network will jump to critical and an accident will occur.
- Select the safety valve according to the operating pressure of the boiler indicated in the technical data sheet.
- Do not buy an angled type air vent, only a straight one. The first creates increased resistance to the outgoing air.
- The cross must be made of high-quality thick-walled brass. When choosing, compare the weight of the cheap and expensive parts in the palm of your hand and feel the difference.
For reference. The vast majority of gas and wood heat generators operate with a maximum water pressure of 3 Bar. The exception is Stropuva long-life cylindrical heaters (max - 2 Bar) and completely cheap boilers with thin walls (max - 1.5 Bar).
Mounting a makeshift security group is pretty simple. Screw the air vent into the upper terminal of the cross, and install the pressure gauge and safety valve in the lateral in any order. Cut the finished element into the line next to the boiler according to the scheme (see in the previous section).
If you want to maximize the safety of a solid fuel heating unit, pay attention to the thermal relief valves. They work in tandem with the main group and, in case of overheating, discharge the coolant from the boiler’s water jacket, letting in cold water from the water supply. Product variations and wiring diagrams are described in our earlier publication.
Water heater protection
Indirect heating boilers and electric storage devices that prepare water for household needs also require protection. In this case, the danger is pressure surges in the water supply and the expansion of the liquid in the tank from heating.To prevent the tank from leaking, a boiler safety group consisting of the following parts is installed on the water supply:
- brass body;
- check valve, not allowing water to flow back from the tank back into the pipe;
- safety valve, relieving excess pressure;
- ball valve to close the dhw line.
In addition, indirect heating boilers are equipped with an automatic air vent mounted in the upper part of the tank and a pointer temperature meter. The pressure gauge is put on the unit optionally.
Conclusion
It is not always necessary to buy and put a security group for a closed heating circuit. The vast majority of wall-mounted gas boilers are equipped with this automation from the factory, which is reflected in the product instruction manual. At the same time, some manufacturers of wood heat generators supply these parts complete with their products, although they will have to be installed separately.