PHAM NEWS | OCTOBER 2026 18 Product Spotlight FAQs on TRVs


Thermostatic radiator valves (TRVs) are one of the simplest ways to improve comfort and energy efficiency within a heating system, yet they’re often misunderstood when it comes to installation, balancing and troubleshooting. Ed Morris, technical manager at Altecnic, answers some common questions.


What is a Thermostatic Radiator Valve and why is it needed? A TRV is a self-regulating valve fitted to a radiator that automatically controls the flow of hot water based on the room temperature. By allowing each room to be heated independently, TRVs improve comfort and reduce unnecessary energy consumption.


How does a TRV work? The TRV head contains a temperature- sensitive element, commonly liquid, wax or gas filled. As the surrounding air temperature rises, the element expands and progressively closes the valve as the room cools, helping to maintain a comfortable, consistent room temperature without electrical controls.


Where should TRVs be installed? TRVs should be fitted to radiators where individual room temperature control is required, but generally not in the same room as the main wall thermostat, as the two controls can conflict and reduce system efficiency. During installation, ensure the system is isolated and depressurised, and position the TRV head away from direct heat sources such as sunlight or electrical appliances, which can affect temperature sensing. Avoid fitting TRVs behind curtains,


furniture or radiator covers, as trapped heat around the sensor can cause the valve to close prematurely, preventing the room from reaching the desired temperature.


Can TRVs be fitted to any heating system? TRVs are suitable for most wet central heating systems, including traditional boilers and modern low-temperature heating systems. TRVs can also be used on some one-pipe systems, but the system layout, valve type and bypass arrangement must be suitable for one-pipe operation.


Are TRVs suitable for heat pump systems? Yes, provided they are set up correctly. Heat pumps operate most efficiently with low, consistent flow temperatures, so TRVs should maintain steady room temperatures rather than constantly opening and closing. Closing multiple TRVs at once can reduce system flow below the heat pump’s required minimum and may lead to poor performance, flow faults or increased cycling and reducing efficiency.


How should the heating system be balanced after installing TRVs? Balancing ensures each radiator receives the flow required to deliver its design heat output. The method depends on the valve and system design. With conventional TRVs, balancing is normally carried out


using the lockshield valves while the TRVs are fully open, checking radiator flow or the design temperature differential. Where pre-settable or dynamic TRVs are installed, flow may instead be set at the valve in accordance with the manufacturer’s commissioning data.


Can the TRV head be replaced without draining the system? In most cases, yes. The thermostatic head can usually be removed and replaced without draining the heating system because it operates the valve pin externally rather than containing system water.


What are the most common TRV faults? The radiator won’t heat up – the valve pin may have become stuck after a long period without use. Remove the TRV head and gently work the pin up and down to free it. The radiator is only partially warm –


sludge, debris or air within the radiator or system may be restricting flow. Flush the system, add inhibitor if required and check the TRV is allowing full water flow. The TRV is noisy - clicking or whistling


can indicate excessive flow rates or incorrect installation. Check the system pressure and ensure the valve has been installed in the correct flow direction. Installing a non-bi-directional valve incorrectly can also cause noise. The TRV is leaking – inspect valve


connections, seals and washers. If the valve body is damaged, replacement may be necessary.


What does the frost setting do? Most TRVs include a frost protection setting, usually identified by a snowflake symbol. This automatically opens the valve


if the room temperature falls to around 5–7°C, helping protect radiators and pipework during cold weather.


How can installers help prevent future TRV problems? Routine servicing is key to long-term performance. Keep valves clean, check system water quality, and ensure inhibitor levels are maintained to minimise sludge and corrosion, both of which can restrict valve movement over time.


Is there anything installers should consider when selecting a TRV? Not all TRVs are the same. Consider factors such as valve orientation, bi-directional operation, compatibility with low- temperature heating systems and overall build quality. Choosing the correct TRV for the application helps simplify installation, improve long-term reliability and deliver accurate room temperature control. ◼ phamnews.co.uk/1026/30


Industry viewpoint Avoiding fake parts


Counterfeit heating components can put consumers, installers and manufacturers at risk. Stewart Clements, director of the Heating and Hotwater Industry Council (HHIC), explains why heating engineers need to be vigilant when sourcing parts.


looks right and fits correctly. But when it comes to safety-critical equipment, appearance and compatibility are not enough. When a heating appliance is placed on


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the market, it must meet the relevant safety and regulatory requirements. Manufacturers test appliances and their components to ensure they operate safely and reliably under the conditions they are designed for. Genuine replacement parts are tested


and approved for use with specific appliances. They will normally carry the manufacturer’s branding and part number on the packaging and, where appropriate, on the component itself. Counterfeit parts may look almost


identical to genuine components, and may even carry misleading conformity markings, but they may be made from inferior materials or have never undergone the testing required to demonstrate that they are safe and suitable for the appliance. A typical example is where a manufacturer has introduced a software update to improve product performance; a copied part is unlikely to include the same feature or to have been validated for use with the updated appliance. For installers, this presents a significant risk. A counterfeit component may fail


prematurely, affect the performance of an appliance or cause repeated breakdowns and costly callouts. It can also damage the reputation of the heating engineer who fitted it. The fact that a part fits an appliance does not mean it is suitable for it.


Safety-critical components The risks are particularly serious when counterfeit components are used in gas appliances. Gas boilers and other gas appliances


are designed to operate safely under demanding conditions, including repeated heating and cooling cycles, variations in gas pressure and mains voltage, and exposure to corrosive condensate. Components such as seals and flues must be capable of withstanding these conditions. Gas appliances are subject to


certification and ongoing conformity requirements under the Gas Appliances Regulation (GAR). Using a non- genuine or unapproved component can undermine the safety and performance of the appliance as tested and approved by the manufacturer. A counterfeit component may use


inappropriate materials or have different performance characteristics from the genuine part. A failed seal, for example, could result in leakage or unsafe emissions, while a defective component could create a serious safety risk, including exposure to carbon monoxide.


hen replacing a component in a heating appliance, it can be tempting to focus on finding a part that


What it means for installers Heating engineers have an important role to play in protecting consumers from counterfeit parts. Under the Gas Safety (Installation and Use) Regulations, registered gas engineers are responsible for the work they undertake. This includes the replacement components they install. If a counterfeit component fails and


contributes to an incident, the installer could face significant consequences, including potential prosecution, as well as damage to their professional reputation. There is also the issue of warranties.


Manufacturers’ warranties will typically require genuine or approved replacement components to be used. Fitting a counterfeit or unsuitable part could therefore invalidate the appliance warranty, potentially leaving the consumer responsible for the cost of repairs. This is why sourcing replacement parts from a reputable supplier is so important.


What to look for Counterfeit components are not always easy to identify, but installers should be cautious if a part or its packaging looks different from what they would normally expect. Check the part number against the appliance manufacturer’s information and look for the appropriate manufacturer branding. Be particularly wary of unusually low prices, poor-quality packaging, spelling mistakes, missing information or markings that appear inconsistent with genuine products. If there is any doubt, contact the


appliance manufacturer to confirm the part number and its suitability before fitting it. Most importantly, use reputable suppliers and do not assume that a component is genuine simply because it is advertised as being compatible with a particular appliance.


Reducing risk Using genuine, approved replacement parts helps to protect both installers and consumers. It supports the safe and reliable operation of the appliance, reduces the risk of premature component failure and helps to protect manufacturers’ warranties. For gas appliances, it is also an important part of ensuring that the appliance continues to operate in accordance with its safety requirements. At HHIC, we are urging heating


engineers to remain vigilant and to report suspected counterfeit heating components to Trading Standards. The heating industry has a collective responsibility to tackle the fake spares market. We all have a part to play in ensuring that safety is not compromised by components that have not been properly tested and approved. A counterfeit part may look the same,


cost less and fit the appliance – but that does not mean it will perform safely when it matters. For installers, choosing genuine replacement parts is a simple but important step towards protecting their customers, their businesses and the reputation of the heating industry. ◼ www.benchmark.org.uk


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