Control valves for radiator thermostats RA are classified into two types: RA-N(for two-pipe pump heating systems) and RA-G(for one-pipe pumping and two-pipe gravitational systems) 1). The RA-N valve is a valve of increased hydraulic resistance with preliminary installation setting of its maximum flow capacity. The valves are produced with a nominal diameter of 10 to 25 mm, straight and angle, nickel-plated. The Danfoss range includes a modification of the DN = 15 mm RA-NCX valve with a chrome body, which is usually used in conjunction with RAX thermocouples in chrome or color. RA-NCX valves are used in rare cases, and RA-N valves DN = 10 and 25 mm do not find any practical application in Russia, therefore they are not presented in this manual. Angle horizontal and three-axis valves are used when it is necessary to use a thermostatic element with a built-in sensor and the pipelines supplying the heat carrier to the heating device are laid from below. The Danfoss product range also includes a RA-N DN = 15 mm valve with a pressure connection for a copper pipe ø15x1 mm, which is used in horizontal apartment heating systems. Technical information for RA-N valves DN = 10 and 25 mm , RA-NCX and RA-N DN = 15 mm for press connections are presented in catalog VD.53.P17.50 "Radiator thermo-regulators and pipe fittings for hot water heating systems". RA-N valves are supplied with a red protective cap.

The main advantage of valves Danfoss type RA-N - convenience and accuracy of adjustment to the required hydraulic resistance (throughput). In valves from other manufacturers, the setting is the number of revolutions of the special tool from the closed position. In this case, it is impossible to determine the value of the setting visually without disturbing the existing position of the device. It will not be accurate either, since it is not clear how many revolutions, for example, 3 or 3 ¼. The presence of a special tool complicates the setup work. Externally, the same valves from different companies have different fixed settings. During installation, builders often confuse them and in the future cannot establish the heating system. Some companies offer to make the setting not on the thermostat-regulator, but on the shut-off valve, changing the number of revolutions of its stem. This is inconvenient, as it leads to a rise in the cost of work and a decrease in the accuracy of adjustment.

The presetting device is a throttling cylinder associated with a rotary crown. The different positions of the crown and cylinder correspond to the specific flow rates of the thermostat valve. Numeric indices of the adjusting element positions are indicated on the crown. The setting indices must be determined during the hydraulic calculation of the heating system and set against drilling on the valve body during installation and commissioning work. Tuning is done without the use of any tool. The adjusting device is hidden under the thermostatic element and, when it is blocked, becomes inaccessible for accidental readjustment. In case of possible clogging of the valve at low presetting values, it is enough to turn the adjusting crown to the "N" position (fully open), and the valve is flushed with water. After that, the setting returns to its original position. The presetting values ​​are clearly visible on the crown (it is easy to set up or check the correctness of the setting). Each valve has 14 fixed setpoints (settings 1 to 7, N and six intermediate positions).

RA-G - a valve of low hydraulic resistance without a device to limit its capacity. The valves are manufactured with a nominal diameter of 15 to 25 mm with a nickel-plated body. They can also be straight and angled. The manual does not include the RA-G valves DN = 25 mm, since they are not practically used in Russia. Technical information on them is presented in the catalog VD.53.P17.50 “ Radiator thermostats and pipe and wire fittings for hot water heating systems ”. The RA-G valves are supplied with a gray protective cap. The RA-N and RA-G dampers are connected to the heating devices using threaded shanks with a union nut, and with the pipeline through a coupling socket. If necessary, in heating systems, a special version of RA-N valves can be used - with an external connecting thread or with a fitting for a press connection with a copper pipe ø15x1 mm. Many Russian factories produce heating devices with built-in Danfoss thermostat valves. Among them are the Moscow plant Santekhprom, which produces a bimetallic radiator Santekhprom-BMN Auto and convectors with a cover of the Santekhprom Auto series; JSC "Mechanical Plant" (St. Petersburg) - steel panel radiator of the "Konrad-Thermo" type; plant "Radiator" (Kimry) - steel tubular radiator of the "RS" type, etc. Convectors and steel radiators are equipped with thermostat valves for both two-pipe and one-pipe systems heating. Other devices with built-in thermostats are intended for two-pipe systems only. Danfoss thermostat valves built into a heater are generally similar in design and hydraulic performance to the RA-N and RA-G stand-alone thermostat valves. Specifications Russian heating devices with thermostats are given in the passports of manufacturers heating equipment, in the relevant materials of Danfoss LLC, and also included in the database of the Danfoss S.O. program for calculating heating systems on personal computers.

The main advantage of Danfoss RA-G valves- high throughput (RA-G DN = 20 mm has Kv = 2.06 m3 / h at Xp = 2 ° C). This is important in one-pipe heating systems to achieve optimal values ​​of the coefficient of flow of the coolant from the riser to the heater. High flow capacity is obtained due to the large valve seat area and increased stroke (more than 30% when using a thermostatic element with gas condensate filling compared to liquid-filled thermostats). These valves are the only ones with such a capacity that have the European quality certificate EN215. This is due to their ability to hermetically shut off the coolant flow through the heater when the room temperature is 2 ° C higher than the calculated one. In addition, the valve presents a unique service capability: its seat and plug can be completely replaced on site if required (without dismantling the valve).

RA-N valve for two-pipe pump heating system; PN = 10 bar, Tmax. = 120 ° С, with internal thread

Valves for two-pipe heating system RA

RA-N valve intended for use in two-pipe pumping systems for hot water heating with copper or stainless steel pipelines. Special crimping tools are required to connect the valve fitting to the pipeline.

RA-N valve for two-pipe pump heating system; PN = 10 bar, Tmax. = 120 ° С, for press connection with the pipeline. It is possible to use tools from Geberit Mapress, REMS, Rothenberger, SANHA, Viega

RA-G valve for one-pipe pumping and two-pipe gravitational heating systems; PN = 10 bar, Tmax. = 120 ° С, with internal thread

Control valve RA-G has an increased throughput and is intended for use in pumping one-pipe water heating systems with closing sections (bypasses).

The remote control thermostat is used when the heating devices and the thermostat valves installed on them are inaccessible to the user, for example, covered with non-removable decorative panels. In this case, the sensor and the adjusting unit are combined. Remote control thermostats should be located at a height of 1.2-1.6 meters from the floor or in another accessible place so that room air can freely circulate around the sensor.

Device and principle of operation

The main device of the thermostatic element is a bellows, which provides proportional control. The thermocouple sensor senses changes in the ambient temperature. The bellows and the sensor are filled with a highly volatile liquid and its vapors. The calibrated pressure in the bellows corresponds to its charging temperature. This pressure is balanced by the compression force of the tuning spring. As the air temperature around the sensor rises, some of the liquid evaporates, and the vapor pressure in the bellows increases. In this case, the bellows increases in volume, moving the valve spool towards closing the hole for the coolant flow into the heater until an equilibrium is achieved between the spring force and the vapor pressure. When the air temperature drops, the vapors condense, and the pressure in the bellows drops, which leads to a decrease in its volume and movement of the valve spool towards the opening until the position at which the system equilibrium is established again.

The vapor fill will always condense in the coldest part of the transmitter, usually the furthest from the valve body.

Therefore, the radiator thermostat will always react to changes room temperature without feeling the temperature of the coolant in the supply pipeline. Nevertheless, when the air around the valve is nevertheless heated by the heat given off by the pipeline, the sensor can register more high fever than indoors. Therefore, to exclude such influence, it is recommended to install thermostatic elements, as a rule, in a horizontal position. Otherwise, it is necessary to use thermoelements with a remote sensor.

The main task of any heating system is to provide a comfortable air temperature in the room. This temperature can be different depending on the purpose of the room, but if a prerequisite is its invariability during the day, then the thermostat becomes irreplaceable. structural element heater.
The Danfoss radiator thermostat consists of two parts: a valve and a thermostatic element (thermal head). Inside the thermostatic element there is a thin sealed cylinder - a bellows filled with a liquid or gaseous thermosensitive working substance. As the temperature rises, the bellows stretches and moves the associated rod, which presses on the rod in the valve, and the valve reduces the flow of coolant into the radiator. When the temperature drops, the process is reversed. Thus, the thermal head is a control mechanism, and the valve is an executive one.

Manufacturer: Danfoss (Denmark).

Danfoss radiator thermostat valves

Radiator thermostat valves are divided into:
- valves for a two-pipe pump heating system (type RA-N) of increased resistance with a device for mounting adjustment of their throughput to perform hydraulic balancing of the pipeline system;
- valves of increased throughput type RA-G for pumping one-pipe or two-pipe gravitational heating system.

Danfoss valve bodies are made of brass. The connection allows easy and precise attachment of the thermostatic element to the control valve. To identify the RA-N valves, their protective caps are colored red and the RA-G valves are gray.

Danfoss RA-G thermostat valves

Danfoss RA-N thermostat valves

The RA series can be combined with the RA-G and RA-N valves.

Danfoss temperature control equipment set consists of radiator valve RA-G (for one-pipe or two-pipe heating system) or RA-N (for two-pipe heating system) and RA thermostatic element.
The set is designed for automatic regulation of the room temperature.
Easily installed on various types of heating devices in apartments with centralized one-pipe and two-pipe heating systems.

Danfoss thermostatic elements

Danfoss thermostatic elements (thermal heads) are automatic temperature control devices designed for completing radiator thermostats.
The thermostat, equipped with a thermostatic element, maintains a constant temperature in the room at the desired level within the range from + 5 ° C to + 26 ° C with an accuracy of ± 1 ° C.
It should be remembered that thermostats are for the most part regulatory fittings, but not shut-off(except for the RA2940 and RAW 5110 thermostats), therefore, if it is necessary to dismantle the radiator, the thermal head should be replaced with a bronze shut-off handle, which will completely shut off the coolant flow.

Danfoss thermostatic elements

	RA 2994	Thermostatic element with gas-filled temperature sensor. Temperature adjustment range: from + 5 ° С to + 26 ° С.	RUB 1,440
	RA 2992	Thermostatic element with gas-filled remote temperature sensor. Temperature adjustment range: from + 5 ° С to + 26 ° С. Capillary tube length: 2 m.	RUB 2 200
	RA 2920	Thermostatic element with gas-filled temperature sensor and tamper-proof. Temperature adjustment range: from + 5 ° С to + 26 ° С.	RUB 2 190
	RA 2940	Thermostatic element with gas-filled temperature sensor. Temperature adjustment range: from + 0 ° С to + 26 ° С. The ability to shut off the coolant supply.	RUB 1,600
	RAW 5010	Thermostatic element with liquid temperature sensor. Temperature adjustment range: from + 8 ° С to + 28 ° С.	RUB 1,390
	RAW-K	Thermostatic element with liquid temperature sensor. Temperature adjustment range: from + 8 ° С to + 28 ° С. For installation on built-in valves (M30x1.5) of radiators with a lower connection - Rifar, Copa, Kermi, Demrad, Stelrad, Purmo, Korado.	RUB 1,390
		Thermostatic remote control element with liquid temperature sensor. Temperature adjustment range: from + 8 ° С to + 28 ° С. Capillary tube length: 2 m (RA 5062), 5 m (RA 5065).	RUB 4,590 RUB 4,960

When installing thermostats, it should be remembered that the effect of their use will be noticeable if they control radiators with low thermal inertia. Practically, these are all known types of modern radiators except cast iron. The latter, due to the large mass of cast iron and water, will heat up and cool down very slowly, negating the effect of regulation.

Shut-off and connecting valves RLV are designed for lateral connection to the radiator of pipelines of a two-pipe heating system. Available in straight and angled versions.
P y = 10 bar *; T max = 120 ° C; ΔP max = 0.6 bar.

* Conditional pressure. See GOST 356-80 Fittings and pipeline parts. Nominal, test and working pressures.

Firm Danfoss has developed thermostatic elements of the RTR 7000 series - automatic temperature control devices intended for completing RTR-type radiator thermostats. The radiator thermostat is a direct-acting proportional air temperature controller with a small proportional band, which is currently used in heating systems for buildings for various purposes.

Two types of control valves can be installed on the radiators of your apartment, RTR-G or RTR-N, depending on specific conditions: a two-pipe or one-pipe heating system (Assistance in choosing and installing RA thermostats on radiators in your home >>>).

After installing radiator thermostats, there is no need to open windows to regulate the room temperature. The thermostats will maintain a constant temperature in the range of 5-26 ° C, at the desired level, with an accuracy of ± 1 ° C.

Radiator thermostats guarantee the required distribution of water throughout the entire heating system. At the same time, even the most remote radiators will provide the required heat supply in the room.

You can read more about Danfoss thermostats and their settings here >>>

Thermostatic elements for installation on valves RTR-N, RTR-G (old RA series) and valves built into radiators:

Sketch	Arthkul			Description	Temperature setting range, ºC	Capillary tube length, m	Accession
				With gas-filled built-in temperature sensor
	013G7091	RTR 7000	RTR 7091 BIS, "0"	With gas-filled built-in temperature sensor, adjustable to 0ºC
				With gas-filled remote temperature sensor
			RTR 7094 BIS, Temperproof	With gas-filled built-in temperature sensor and tamper-proof cover
				With a gas-filled remote temperature sensor and a protective casing against unauthorized interference
				RTR 7095 BIS, RTD Service
				With built-in temperature sensor
			RTRW 7081 BIS, "0"	With built-in temperature sensor, adjustable to 0 ° C
	013G7082			With remote temperature sensor
				Remote control, with liquid built-in temperature sensor
				With gas-filled built-in temperature sensor. For mounting on RTD valves with connecting thread M30x1.5
				With a gas-filled remote temperature sensor. For mounting on RTD valves with connecting thread M30x1.5			Copa, Rifar Ventil, Diatherm, Kermi, Korado, Purmo, Rettig, Radson, Demrad, Stelrad
				With liquid built-in temperature sensor. For installation on valves with a snap connection			Axis VC (with bottom piping)

Among the many offers from foreign, domestic manufacturers, a special place is occupied by the products of the Danfoss concern - the world leader in the production of thermal automation. The company has been manufacturing thermostatic elements (valves), or, more simply, thermostats since 1943, constantly offering consumers products that meet European quality standards, characterized by high ergonomics, ease of installation and adjustment.

This series belongs to the category of liquid-filled thermocouples with bellows. These controls are used to equip type RA radiator thermostats with direct action with a small proportional band. They are used in conjunction with the RA-N and RA-G temperature controlled valves, which have a capacity presetting function.

It should be noted that thermoelements RAW series are very popular due to the versatile possibilities of equipping both one-pipe heating systems ("Leningradok") and two-pipe heating systems.

The model range of this series is represented by the following types of thermostatic elements:

RAW 5010 (with built-in temperature sensor)
RAW 5012 (with remote temperature sensor)
RAW 5110 (with built-in sensor, thermostat valve shut-off device).

The designs of the RAW series thermal heads have additional functional devices that provide ease of installation, protection against unauthorized access, negative consequences from temperature changes. All this provides favorable conditions for their safe operation, creating a comfortable temperature in the premises.

This line of automatic thermal heads with liquid filling, small proportional band is intended for use on valves of such companies as: "Heimeier", "Oventrop", "MNG".

They are optimal solution when installing various designs of steel panel radiators, and, in particular, of the following types: Biasi, Diatherm, DiaNorm, Henrad, Ferroli, Kaimann, Korado, Kermi, Purmo, Radson, Stelrad, Superia, Veha, Zehnder-Completto Fix.

Today the Danfoss company offers the following modifications of devices of this series:

RAW-K 5030 (with built-in temperature sensor)
RAW-K 5032 (with remote sensor)
RAW-K 5130 (with built-in temperature sensor, complete valve closing device).

In addition to standard structural elements, thermoelements are additionally equipped with accessories to protect against unauthorized dismantling, freezing, as well as special tools for installation, blocking, temperature setting limiters.

This series differs from the rest of the Danfoss brand products by being equipped with modern electronic devices for programming 3 heating modes on weekdays, weekends and holidays and time of day.

The RA Plus thermocouples are intended to be installed on all Danfoss RA valves, while the RA-K Plus models can be used on valves from other manufacturers (Heimeier, Oventrop, MNG).