The Radiator Detail Everyone Forgets: Why Your Valves Matter More Than You Think
You have picked out the radiator. A slim column in anthracite, perhaps, or something more traditional in cast iron, or even wall-mounted to disguise a long, awkward expanse. You have got the paint, the floorboards, the console table just right. And yet, you feel like one of those people who somehow bought matching curtains and blinds and nothing else in the room.
Two nondescript chrome valves, left over from installation or the previous owner, stick out like sore thumbs at the base of your radiator. It is the interior equivalent of getting all the kitchen cabinetry right but leaving the electrical fittings in white.
The good news is this is an easy fix. The better news is the same fittings control the warmth of every room in your house. It is hard to think of another improvement that has such immediate impact and is so inexpensive to implement.
Angled, straight or corner: which radiator valves do I need?
For all intents and purposes, it depends on your pipework. If the pipe reaches the radiator at an angle and needs to turn 90 degrees to enter the valve, you need an angled radiator valve. If it runs straight into the radiator, you need a straight valve. A corner valve is used when the pipe reaches the radiator at a ninety-degree angle, but has to turn another ninety degrees to meet the valve – they are similar to angled ones, but have a more compact design and face the room less intrusively.
It is the last detail that makes the most difference. It may not seem like it, but the positioning of the valve actually dictates the distance between the radiator and the wall, as well as how much pipework is visible. Corner valves in particular make a radiator look more integrated and less like an eyesore in the room.
Two quick notes to take with you:
- Pipe shrouds and collars are cheap, available in a range of finishes, and are a great way to disguise pipework and radiators that disappear into the floorboards.
- Valves come in pairs – and the pairs are not matched. One controls the flow of hot water into the radiator, while the other, the lockshield valve, is used to balance the system and is permanently capped. You will most likely see them sold as a pair, which is the right way to buy them.
Do radiator valves have to match the taps?
They should not have to match, but they should be chosen with the same care as the rest of the room’s hardware. The good news is, there is a wide variety of radiator valve finishes. They can be painted to match or come in brushed brass, antique brass, nickel, chrome, or white.
The same principles apply as with the rest of the hardware – a mixture of metals in one room is fine, as long as it is not more than two, and it all ties together. This could mean black window handles with black-framed furnishings and a dark radiator, or brushed brass door handles with light wood paneling and brass taps
Some good combinations to have in mind:
- Matte black valves: work well with black-framed mirrors and furniture in a contemporary room. They are also the safest option in a family home, as they are easy to clean and resistant to fingerprints.
- Brushed or antique brass valves: great with wood paneling and brass door handles in a traditional room. Also nice against a column radiator.
- Chrome: if the rest of the room’s hardware is chrome, it is best to stick to chrome valves.
- White valves: white radiators on a white wall, in a room that is otherwise white. If you only want to change one thing this month, changing your valves is the single improvement that will give you the most reward for the least effort.
What is a thermostatic radiator valve, and why should I care?
A thermostatic radiator valve, or TRV for short, is a special type of radiator valve that regulates room temperature. The head of the valve contains a temperature sensor that reacts to the temperature of the room: as the temperature rises, the valve lets less and less hot water through until it is fully closed, and the opposite happens as the room cools down. In effect, it lets you thermostat each individual radiator.
In short, it lets you cool your bedroom and heat your bathroom from the same boiler. It makes a world of a difference to your day-to-day comfort and is one of the easiest ways to improve the energy efficiency of your home.
The Energy Saving Trust recommends that most people should set their thermostat to around 18C – 21C, and reducing that by just one degree could save you up to £120 in Great Britain per year. Having a single thermostat in the hallway is not ideal for a house with multiple rooms with different heating requirements.
TRVs are also a great way to ensure that your entire household is comfortable and that nobody has to lower their personal comfort for everybody else. If your teenage children want it colder in their rooms and you want it warmer in the living room, nobody has to give up anything: just install a TRV on each radiator and set the thermostat to the most comfortable temperature in your bedroom. The hallway and bathroom will still be toasty, and your bedroom will not be freezing.
What do the numbers on a radiator valve mean?
The numbers are not temperatures – they are suggestions for the temperature of the room the radiator is in. Different companies tend to use different scales, but they all more or less follow the same pattern as seen in the table below.
| Setting | Approximate room temperature | Where it suits |
| ✻ / 0 | Frost protection only | Unused rooms, garage |
| 1 | ~10°C | Spare room that is rarely used |
| 2 | ~15°C | Landing, hallway |
| 3 | ~20°C | Living room, dining room, child’s bedroom |
| 4 | ~25°C | Bathroom |
| 5 | ~30°C | Almost never needed |
As you can probably tell, most people tend to leave their radiators on 5 – and not because they want it to be hotter or the house to heat up faster. The number 5 means the radiator will not be turned off automatically by the valve, which in turn means it will run constantly and heat up the room to a higher temperature than the recommended 20C for most living rooms.
Looking at the table, a well-adjusted set of radiators would have looked something like this:
- Bedrooms: set to 2 or 3 for around 16C – 20C – the recommended room temperature for sleeping.
- Living room: 3 for 20C – the standard room temperature for most people.
- Bathroom: 4 or 5 for 25C – a warm and comfortable temperature after a shower.
- Hallway and landing: 2 or possibly 1 for around 15C – cool but not uncomfortable. If you have a radiator in your hallway, it should be a degree or two cooler than the rooms it borders.
- Spare room: 0 or 1 – if the room is unheated, the valve should be on frost protection. If it is heated, 1 is the lowest temperature you can set it to.
Do radiator covers reduce the effectiveness of TRVs?
Unfortunately, yes – and the Energy Saving Trust explicitly warns against using radiator covers on radiators fitted with TRVs. Covers act as an insulator and prevent the valve from reaching the correct temperature, causing it to close prematurely and stop the radiator from heating up. This causes the room to stay cooler than desired while wasting hot water.
Radiator covers are useful and common, especially in families with small children, as they serve to hide an unsightly radiator and provide extra storage space without taking up much floor area. The same covers, however, interfere with the functionality of TRVs and reduce the amount of heat a room receives.
That being said, there are a few ways to reduce the effect. If you can, pick a cover with an open front and large gaps on the sides to allow warm air to escape the room. Another option is to have the sensor on the TRV replaced with a remote sensor, which is mounted elsewhere in the room and can read the temperature accurately.
The same principle applies to other common objects found in an interior room: long curtains that hang over a radiator traps warm air against the window and the valve; a sofa pushed tightly against a radiator does the same thing. This causes the temperature of the room to be inaccurately read by the valve and leads to the same problems as radiator covers.
Where should I not fit a TRV?
There are two places where a TRV should not be fitted, and both result in the same issue: an inconsistently heated house.
- The room with the thermostat: the thermostat and the TRV fight each other for control of the temperature in the house. Fitting a TRV in the same room as the thermostat causes the room to remain cooler than the rest of the house while the boiler works overtime to compensate. Just leave the radiator in the room with the thermostat on a manual valve.
- Every radiator: leave one radiator, ideally the one in the bathroom or the hallway, on a manual valve at all times.
TRVs should be fitted on all radiators that do not run on a continuous loop – in other words, all of them. If your system does not have a bypass, at least one radiator should always be on a manual valve so that the water has somewhere to go when the others are closed. Fitting valves requires bleeding the system, which is not a task for homeowners, so a local plumber can help you with that and most other tasks in this guide.
Buy the valves and matching pipe shrouds yourself from a supplier like MonsterPlumb and you get the finish you actually chose, rather than whatever happened to be in the van.
The short version
- Take a look at the valves you already have and determine whether they are angled, straight, or corner before you buy any new ones.
- Pick a finish that looks nice in the room in question and invest in some pipe shrouds while you are at it.
- Install TRVs on all radiators except the ones in the room with the thermostat and the one bypass radiator, if there is one.
- Adjust the valves to keep each room at a comfortable temperature.
- Make sure nothing hangs over your valves, and book a plumber to change them if the system needs to be bled.
FAQ
What number should radiator valves be on?
Setting 3 is a good average for most rooms, with bedrooms set to 2 or 3 and bathrooms set to 4. The numbers on a radiator valve do not correspond to degrees Celsius – they dictate the approximate temperature of the room the radiator is in, and that varies from manufacturer to manufacturer.
Do radiator valves have to match the taps?
No, but they should be selected in the same vein as the rest of the room’s hardware. Mixing metals is not a problem, as long as it is done within reason.
What is the difference between angled and straight radiator valves?
Angled radiator valves are used when the pipework reaches the radiator at an angle and has to turn before entering the valve. Straight valves are used when the piping runs straight into the valve. Corner valves are used in much the same way as angled ones, but have a tighter design and face the room less intrusively.
Do radiator covers stop TRVs working properly?
They reduce their effectiveness, which is why the Energy Saving Trust explicitly warns against using them on radiators fitted with TRVs. An open-fronted cover or a remote sensor can mitigate the issue.
Can I fit radiator valves myself?
You can, but it is not recommended. Fitting a radiator valve requires bleeding the system, which is a job for a professional. The valves themselves are inexpensive, which is why replacing them is one of the most inexpensive home improvements you can make.
