What’s a thermostatic radiator valve?

In this blog post, you’ll read:A thermostatic radiator valve is a mechanical device that controls the flow at ambient room temperature. As the room heats up, the TRV starts decreasing the flow. When the room cools down, the TRV allows the flow to rise
Table of Contents

Introduction of Thermostatic Radiator Valve

A thermostatic radiator valve is a mechanical device that controls the flow at ambient room temperature. As the room heats up, the TRV starts decreasing the flow. When the room cools down, the TRV allows the flow to rise. A thermostatic radiator valve can control single & multiple heat emitters in a zone.

Thermostatic radiator valves are devaluated hydronic components. Yet they are so ordinary, cheap, and valuable. We are all concerned about electronic controls for system zoning. There are valves or pumps in the majority of the systems. Place a low-voltage thermostat in a location that best denotes that zone’s temperature.

Historically it is said that TRVs were invented by Danfoss back in 1943. TRVs can control the heat output from the radiators. It helps to stable the system and provide room-by-room zoning. Most of the TRVs were mounted on a radiator. It was one of the most common configurations. Today TRVs are suitable for most applications.

From plumberparts


We can set a thermostatic radiator valve within a hot-water or steam heating system on a radiator. It can provide greater control of the temperature and comfort of that room or space.

The replacement of a manual heating control with a TRV is much more consuming. Estimation says that it saves at least 620 lb of carbon-di-oxide per year. They are also budget worthy & efficient. By TRV, you will use heat only when you need it. It can decrease heating bills by up to 17 percent a year.

Since 2012, electronic thermostatic radiator valves have become popular, and use electronic temperature sensing. Radiators are programmed for different temperatures at different times of the day. The magnificence of a thermostatic radiator valve is that it doesn’t need any adjusting when the outside temperature fluctuates. There is a thermo-sensitive element in the TRV. It automatically adapts to the changing temperature and keeps the radiator heating longer.

leak test
leak test

Installation of Thermostatic Radiator Valve

TRVs are fitted on radiators and convectors to control room temperature. The valves work automatically. These are comprised of two parts: a sensor and a valve casing. The valve casing is set directly onto the radiator or the supply pipe. The sensor is fixed to the valve casing. 

The sensor is either built-in or remote. A remote sensor is convenient if the radiator is behind a screen/cover. Otherwise, it can cause inaccurate room temperature readings. The sensor works by way of gas-filled bellows. The gas temperature heats up as the room temperature rises, which expands. This causes a movement of a pin in the valve casing. It reduces the water flow rate through the radiator. Turning the sensing element can change the distance between the pin/plug and bellows.

The valve casing comes with a valve limiter. It can limit the maximum flow rate of water through the radiator.

From dereton33

Thermostatic radiator valves can develop the heating system’s efficiency. Suppose you have a radiator in your kitchen. You may want to comprise a TRV on it. If your thermostat is set to 72 Fahrenheit in your living room and there is an oven in the kitchen, chances are you don’t need your kitchen radiator to pump out more heat. You can use your thermostatic radiator valve to decrease the heat for the kitchen radiator at the time of cooking. Programmable thermostatic radiator valves are a good option for this.

These TRVs are made up of two parts: the thermostatic head & valve body. The thermostatic head holds an actuator that increases and contracts with temperature rise and fall. There is a sprung plunger inside the valve body. It can open & close the supply of water into the radiator. When these two are put together, the heat flow into the radiator is spontaneously controlled to the room’s temperature. The valve closes after achieving the preferred temperature, and the radiator stops heating. After that, the area becomes calm, and the valve opens. The radiator initiates to heat again. 

The handle of the thermostatic head can adjust the distance that the actuator must expand. It helps to close the valve. Most of the TRVs have a 1 to 5 scale distance. Here 1 represents the smallest distance and five the largest. If the gap is high, the room will be warmer. It must have happened before the valve was closed. Thermostatic valves are designed to protect against frost. They let a small portion of water pass through when the room is cold. 

air leak test
air leak test

Types of Radiator Valve

Thermostatic Radiator Valves: TRVs measure the temperature in the room. These can adapt the radiator’s output based on how hot or cold the space is.

Manual Radiator Valves – these are simple. We can turn the radiator on & off by this. 

H-block Radiator Valves – these work with central connection radiators and towel rails. They are friendly to install. These valves will make the radiator’s pipework hidden & create a stylish finish.

Corner Radiator Valves – these valves are known as flat-fronted radiator valves. These will help you to save space. A stylishly designed touch can be expressed by using these.

Depending on where our pipework comes from, like up from the floor, out of the wall, etc. There are various valves to suit our demands.

Angled Radiator Valves: These are the most popular type of valves. These valves are connected with the radiator to central heating pipes at an ‘angle,’ generally around 90 degrees. If the pipework is out of the wall or from below the floorboards, these valves are best to use. We need an angle to place the pipes properly into the radiator’s inlet connection. These valves leave you with less noticeable pipework than the straight valve alternatives. It makes them perfect for more simple installations.

radiators
Angle type radiators

Straight Radiator Valves: The water flows’ straight’ inside these valves. The flow is not directed, distracted, or circulated at an angle. These valves have no bends or curvatures. Usually, these are connected from the floor horizontally. You can use these valves if your pipework runs along the wall and directly into the radiator. You can use these also if the pipework runs straight up and out of the flooring. Whatever the situation is, you need to ensure the heating works efficiently.

testing of radiator valve
testing of straight radiator valve

H-Block Valves: These valves are appropriate to use with central or middle connection radiators. H-Block valves are much more relaxed to install & remove. These are easier to replace than standard straight and angled valves. It makes this more stylish and convenient for your home heating.

Radiator Valve 1
H block Radiator Valve

Corner Radiator Valves: Corner radiator valves are known as flat front valves. A corner radiator valve will not overhang from the bottom of the radiator. You should be careful when choosing this type of valve, depending on your radiator’s position. It might be more awkward to adjust than just using an angled valve.

Manual Radiator Valves: A manual radiator valve is the most common type. It functions in a very related way to a water tap. We turn it on to allow the water to pass into the radiator. When it has touched the expected temperature, we can turn it off. It would be best to be very careful about the heating bill when using a manual radiator valve. We often start to forget to turn them off. 

These manual valves are available in both straight and angled designs. They tend to be slighter, do not have a dial, and offer a shipshape look. Manual radiator valves can control the temperature and the water flow running through them like TRVs. The exception is they don’t have a dial that controls the radiator to set temperatures. These valves work like an on-off switch. They allow us to turn off their radiator without turning off the central heating system.

jx 0932
Thermostatic valve

How can I Choose the best Radiator Valve?

Selecting a Radiator Valve will depend on personal style and preference. Size of fittings is not always necessary. The look of a finished radiator is essential for choosing a radiator valve. The width of the joints and the length of pipework in millimeters should be considered. Sizes of pipework are available, ranging from 8mm to 28mm. There are different adapters and connectors that you can use with this size of pipework. It is better to know the size of your pipework before you buy your radiator and valves.

Experts always suggest a radiator valve that is the user’s hands-on. So we should measure our pipework and choose our radiators. After that, we will decide whether we need a manual or a thermostatic.

Angled radiator valves are suitable for adding a sleek finishing touch to the radiator. This valve works with both modern and traditional styles. The h-Block valve is also very trendy. It has a beautiful way to hide away the pipework. It creates a seamless finish to your home heating

trv valve drawing
trv valve drawing

Choosing the best Thermostatic Radiator Valve

A great way to adjust the temperature in various rooms is that TRVs can become useless if they aren’t used correctly. For example, a TRV can be fitted to a radiator except for a wall-mounted thermostat. If there is a wall-mounted thermostat, TRVs shouldn’t be installed. This is because of the conflict between the two thermostats. These two thermostats will fight to increase or decrease the heat needed to warm the space. We should avoid this.

It is also not good to fit thermostatic radiator valves in the bathroom or showering space. The heat from showering can turn the TRV off.

Working Principle of Thermostatic Radiator Valve

The classic thermostatic radiator valve has a plug. It is made of wax which expands or contracts the surrounding temperature. This plug is coupled to a pin linked to a valve. When the temperature of the neighboring area increases, the valve slowly closes. It confines the amount of hot water entering the radiator. Any material shouldn’t cover the valve. It works by sensing the temperature of the air surrounding it. The radiator will always be hot if we remove the controller from the valve.

We should remember that the thermostatic radiator valve & boiler thermostat shouldn’t be fitted in the same area. The TRV will turn off the radiator if the TRV temperature is below the boiler thermostat temperature. If both TRV and thermostat temperatures are set equally, abnormal behavior may occur. Both of the devices will try to control the room temperature.

mix valve
mix valve

Problems & Troubleshoot

Thermostatic radiator valves have simplicity in design and function. It shouldn’t be so difficult to diagnose any problems. 

The most public and frequently occurring problem of the thermostatic radiator valve is with the head of the valve. The head of the valve starts to stick or catch. This happens to open or close the valve. This is because if the setting on the valve has not been appropriately adjusted. It may occur at the end of a long hot summer. It has a simple solution that will not cost any money. You need to turn the TRV to its top setting. This is usually shown as a number 5. You need to fully open the valve and then eliminate the top of the TRV. It should be done by undoing the large thumbwheel above the radiator tail. Once destroyed, you can see a little metal pin that would normally move up and down. If everything is okay, it could be that the liquid cartridge at the top of the TRV has failed. At this point, you need to buy a new thermostatic radiator valve head.

From Trade Radiators

If the pin in the valve will not move, you need to purchase a new set altogether. You also need to drain down the heating system.

Why Isn’t TRV Working Properly?

It can be happened because of a draught. Sometimes the TRV thinks that your room is colder than it is. It may occur when you have a door close to your radiator.

A piece of furniture or something else might be blocking the TRV. If this happens, the wax or the liquid won’t function properly. Therefore, ensuring that TRV is positioned correctly is very much important.

In many cases, the radiator cover possibly stops the TRV from functioning at its best. It may block any draught or airflow to the valve which could lead to the valve functioning incorrectly. As a result, the area will not heat up as well as your expectation. In this instance, you need to start a few tests to ensure hot and cozy radiators when the cover is in place.

Experts say that the most common cause for a thermostatic radiator valve not working is the wrong number set up. The valves are always set by turning the control knob to the wanted setting. It can provide a favorite room temperature. The process is anti-clockwise to increase and clockwise to decrease. It may take time to be exact & proper to ensure your TRV is at the correct temperature, which isn’t an overnight process. For this, you need to open the valve fully. Then start heating and let it run for a while to be sure it has stabilized. If the room becomes too hot, you should turn the TRV down by one mark. It would be best if you rechecked the temperature the following day. If the room becomes too cold, unscrew the valve by one spot. You should repeat this process until the temperature is exact and calm.

spare parts of trv
spare parts of trv

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