Fitting A Heated Towel Rail

Installing a new heated towel rails can seem daunting, but with a little common sense and technical know-how, it can often be done without the need to consult a plumber!


Selecting the right heated towel rail

To ensure you choose the a heated towel rails whose dimensions (or at least the relative positions of the water pipes) match as closely as possible with your existing pipework, as this reduces the likelihood of additional plumbing work being needed, and the ensuing re-tiling.

A lot of manufacturers (such as Aquaheat and Heatwise) have “standard” sized towel rails, whose piping arrangements are roughly analogous. So, the best way is to select a towel rail whose dimensions match your current one as closely as possible.

Another factor to consider is the heat output. The last thing anyone wants is a heated towel rails which either lacks the output to keep your bathroom warm, or is so hot that your bathroom may feel unpleasantly tropical! The output of heated towel railss is measured in BTU’s, or British Thermal Units. Many DIY websites include a BTU calculator, and the only technical information you’ll need are the dimensions of the room.


Replacing your heated towel rail

The first thing you need to do is drain your central heating system completely to prevent serious leaks.

Unscrew the pipes attached to the towel rail, bearing in mind that you should have a bucket nearby in case the central heating system still has residual water left.

Once your old rail is removed, remove any dirt and debris from the pipe ends, as this will be forced through your new towel rail and will damage it. Install your new heated towel rails as per the specific instructions included in the box, being sure to use the recommended number of screws (heated towel railss can be heavy, especially when full of water).

When connecting the pipes together, be sure to check that they’re fully tightened. Applying PTFE tape (plumbers tape) to the screw-threads first will give a watertight seal – PTFE tape is commonly available from DIY shops or most supermarkets.

Once the towel rail has been installed & connected to the water supply, refill the central heating system with water, making sure you keep a careful eye on your new towel rail, as this is when any leaks will become apparent – it may be safer to have someone near the stopcock to disconnect the water if you detect a water leak!

Having fitted your heated towel rail and refilled the central heating system, you’ll need to bleed the towel rail like a radiator, as some air will have become trapped during installation.

How To Drain A Central Heating System

Periodically, homeowners may need to drain the plumbing system in their home. This can be for maintenance, such as fitting a new toilet, sink, bath or shower. It’s also needed if you’re installing, removing or replacing a shower, such as a heated towel rail or new bathroom radiator (or radiator valves). You might also be leaving your home vacant for a while (particularly over winter) and want to remove the risk of cracked pipes and leaks.

Essentially all plumbing systems work in the same fashion, so these steps will almost certainly work. However, if you’re not confident, always consult an experienced plumber.


Disconnect the water supply to your boiler


A typical domestic thermal expansion tank.

This is easy to forget, but completely defeats the objective of draining the system! Turn the water off at the stopcock – this is often beneath the kitchen sink (but the location will vary between houses depending on the exact design).

When draining the heating system to carry out any work on your radiators, remember to switch off the gas & electricity supplies to the boiler (consult the boiler instruction manuals).

To prevent the system from automatically refilling, you’ll need to secure the ballcock in the “expansion tank”. This will be in your loft space. Gently lift the ballcock and carefully jam a length of timber underneath the rod it is attached to. If you don’t have a piece of timber, fashion a hook using some string & a wire coat hanger. Hook the coat hanger over one of the roof joists.


Draining the radiators

Radiator systems are designed with a “draincock” or drain valve on one of the downstairs radiators, which is intended to allow the water out via the lowest point (so gravity does the draining). Securely attach a garden hose to this, and put the other end of the hose down a drain in your garden. Don’t allow the water to drain onto paving slabs or over flowers beds/vegetable patches, as the water will probably be filthy.

radiator drain valve

A typical radiator drain valve, with angled drain. This will be found on a ground floor radiator.

Using an adjustable wrench, loosen the draincock until you hear water begin to flow through the hose. Once this is done, use a radiator key to loosen the bleed valves on the upstairs radiators, as this will allow air into the system and help drain the system more quickly.


Refilling the system

Make sure the draincock and bleed valves on the radiators are securely closed. If you’ve replaced a radiator, or radiator valve, be sure to check the pipes are sealed.

Once done, release the ballcock in the tank upstairs, making sure someone is keeping an eye on any work you’ve done to ensure there aren’t any leaks. Be ready to secure the ballcock & quickly drain the system if a leak is detected.

Some water pipes may creak or groan as the air is forced out, so don’t be alarmed!


Testing the system

Once the system is refilled, switch the gas & electricity supplies to the boiler back on. Switch the boiler on to allow it to heat up the radiators and drive any airlocks to the top of the radiators, from where you can bleed the radiators.

How To Bleed A Radiator

Bleeding your radiators and heated towel rails is a routine yet simple task which is often overlooked by many homeowners & tenants. As many new homeowners aren’t sure how to bleed a radiator correctly & safely, carrying out DIY like this is often left until a Gas Safe engineer carries out a routine inspection and/or service, which can be a problem if an airlock stops radiators working long before an inspection is due. In addition, an airlock can be interpreted as a serious problem and result in a call-out, when a few minutes of simple maintenance can prevent an expensive (and embarrassing) visit by a plumber. Clearing airlocks also improves the efficiency of your radiator and towel rail system.


Equipment needed:

  • Radiator keys (available cheaply from supermarkets or DIY stores)
  • Old hand towel or cloth


Checking for airlocks in radiators and heated towel rails

This is best done at the start of a cold season (generally around September or October in the UK), but checking every few months isn’t a bad idea.

To check for airlocks in radiators, switch the system on, making sure the radiator thermostats are all switched on to allow water to flow through the radiators. Once the system is warmed up, check the temperature of both the top & bottom of each radiator in your house with your hand (be careful). If any radiator is significantly cooler at the top than the bottom, then there’s probably an airlock in that radiator, as any air will float to the top. Remember that bathroom radiators and heated towel rails (which generally don’t have a thermostat) are more likely to contain air, as are any upstairs radiators.


Radiators on vs. radiators off

There’s probably a 50/50 split between those who think you should have the heating system ON and those who think it’s safer to have the heating system OFF.

Although having the system ON will make bleeding the radiators quicker and more effective (the pressure of the water will force the air out quicker), you’ve got the increased risk of scalding due to hot water leaking out of bleed valves.


Bleeding a radiator

The bleed valve will be at the top of the radiator. Most standard radiators will have one, but may have two, much like a heated towel rail (bleed valves on towel rails will be right at the top or the rail, facing upwards). Fit the radiator key into the bleed valve (modern radiator bleed valves are a standard shape & size).


Bleed valves will look similar to this, and will be at the TOP of a radiator or heated towel rail.

Whilst holding the cloth immediately under the valve to catch any water drops, turn the radiator key anti-clockwise – be careful to avoid fully opening the valve, as you could make it difficult to close it again!

If you hear a hissing, then you’re releasing the airlock. As soon as the airlock is removed, water will begin to drip from the valve. Once water drips out, close the valve by turning it clockwise.


Sludge or residue build-up

Some heating systems, particularly older ones, are prone to a build-up of sludge, dirt or rust in some radiators. This is sometimes due to corrosion on the inside of pipes, or due to the fact that the water in heating systems doesn’t need to be “potable” (ie. “safe for drinking”).

If radiators are significantly cooler at the bottom after prolonged use, then something is displacing the water. Although some modern systems can be drained by the homeowner (commercial cleaning solutions are available), older systems will need the attentions of a qualified engineer, particularly as come cleaning products may cause damage, or could reveal more serious corrosion levels which may indicate serious repairs are required urgently.


The UK “Gas Safe” Register

If you’re carrying out any boiler maintenance, or are unsure (or lack experience or confidence), First Bathrooms always recommend that you consult a suitably qualified professional.

The Gas Safe Register is a list of qualified and legally authorised gas installation & maintenance professionals. Click on the logo to search for your local Gas Safe engineers.

To search for a Gas Safe engineer in your area, click the logo.

To search for a Gas Safe engineer in your area, click the logo.