technical guide : dual fuel

Dual fuel heated towel rails give you the choice of two different energy sources on one rail, electric or central heating. This is chosen by you, dependant on whether you want the whole central heating system running (typically in the winter), or whether you just want to have the heated towel rail alone running, when you would use the electric option (typically in the summer). You'll need both central heating pipes running into the rail and an element connected to a fused spur. Dual fuel is a great benefit in the summertime and is economically a good option and becoming ever more popular.

we present our dual fuel towel rails as complete sets where the price includes all components (seen in the images) : this includes the very best specialist dual fuel valves - often in a matching colour to the towel rail and provide a neat finish along with a matching or complementary colour heating element in the correct wattage. So you can simply add to cart and everything you need to the highest standard will be provided for you.

Unico

• This is the best valve to buy for installing a towel rail as dual fuel, as it allows the flow/return to be located on the same side of the radiator — leaving the opposing side free for the heating element (so no T-Piece is required, unlike a standard dual fuel set-up).
• The flow and return travel through the valve via the immersion tube: flow goes up the tube and the return comes back down the outside of the tube.
• Angled orientation, left sided (TRV head on the left hand side of the product, valve body on the right side). Chrome in colour.

Integra 3 Axis

• INTEGRA 3 Axis dual fuel valves with an integrated T-piece, allowing a heating element to be installed on either the left or right side of a heated towel rail.
• Supplied as valve sets including pipes and wall covers, finished to match the radiator for a clean, coordinated appearance, and removing the need for a separate T-piece in dual fuel installations.

Integra Duo

• INTEGA DUO are thermostatic, angled 50mm integrated valve set with a T-piece (for installing a towel rail as Dual Fuel).
• Specialist valves designed for heated towel rails with 50 mm pipe connections, allowing a heating element to be installed directly through the valve to enable dual fuel operation.

• The optimal and ideal combination for your dual fuel towel rail is the ONE element from Terma combined with the UNICO valve.
• You have two options with the ONE element - Internal ONE and external ONE.

`Internal ONE

• The internalised ONE heating element which is fully integrated within this dual fuel towel rail version for a minimalist design when compared to other electric towel rails on the market.
• Sleek, concealed design with no external components of the heating element visible at the bottom of the rail.
• Has the option to also fully conceal the cable from view (as seen in the lifestyle shots) - see installation section below for more notes on this.
• Usual lifespan of a heating element is 4 to 7 years dependent on use.
• At end of life, if you wish to replace an internalised heating element, the unit needs to go back to Terma UK for replacement due to how it is made. Alternatively, you can simply purchase a whole new unit.

External ONE

• The EXTERNAL ONE is a unique element from Terma which has been manufactured in matching profiles to Terma radiators.
• The shape of the element is 100% in line with the upright bar (collector) on the radiator or towel rail for a completely seamless look.
• Usual lifespan of a heating element is 4 to 7 years dependent on use.At end of life, if you wish to replace an external ONE heating element, you can simply purchase a new external ONE heating element and the unit can be swapped out.

• If you don't purchase specialist dual fuel valves as detailed above) the common way to install dual fuel is to use a T-Piece. This is the component which essentially turns one opening into two. This then allows both a heating element (fitted into the bottom) and a valve (connected into the side) to be installed into the same tapping on the radiator.
• If not carefully thought out in advance in terms of both the parts required and hot the final installation will look you run the risk of the installation looking very cumbersome.
• Therefore we have created these very useful dual fuel setup images showing the the optimal installations along with a shopping list of what you need to buy to achieve the look in the images.
• These cover both manual and thermostatic valves.
• Think about your personal preference in terms of

1. The Look
2. Accessibility
3. Your Room Setup

• to choose the best setup for you.

You will potentially need both a plumber and an electrician to install dual fuel (or a tradesman who can do both).

Our suggestion is to show images from this page to your tradesman to show them how you would like the setup to look.

This is important as we have seen some very odd looking installations over the years, which look very cumbersome. Remember with respect the tradesman sometimes will want to do what is easier for them and not for you as the homeowner and once they leave you are left to look at the installation in your home every day - so ensure your dual fuel towel rail is installed to you liking and not the tradesman's liking.

Using the Electric Option:

• For the optimal distribution of heat across the bars we suggest turning one of the valves to the fully closed position ideally the flow/element side), turn fully clockwise)  (tip: CLOCKWISE to CLOSE “CLO to CLO"). 
• However if you feel the distribution of heat across the bars, in the electric mode, is fine with both valves left open, for ease of
  use, you can simply just switch on the element going forward and leave valves open.
• If you have Thermostatic Valves with a TRV on one side and a smaller lockshield on the other, you don’t need to touch your valves at all, as the mechanics of the TRV already will close the flow side off.
• IMPORTANT: Never run in electric mode with BOTH of valves closed, as there is no room for thermal expansion of the water and the rail could potentially blow one of its plugs out.
• Now switch your heating element(s) on.

Using the Central Heating Option:

• If you have closed one of the valves for electric operation (see prev. section) open the valve and switch on your central
  heating.

When used in the electric mode it is best practice to switch off the element at the power (fused spur) to completely cut the power supply to it (not just switched off on the unit itself).

To Explain Why: The variable heat element normally heats up to a maximum of 70 degrees, but the temperature of the water coming through the rail from the central heating system might be higher, therefore if the element is only turned off on the unit itself (and not on the wall) it may switch itself on flash a warning to tell you that it is registering temperatures over its own limit. This is nothing to worry about. To stop the flashing, simply switch the element off at the fused spur when the dual fuel rail is used with the central heating option.

If you buy a complete dual fuel towel rail all the necessary components included the right wattage of element are already included.

On the "piped - heated towel rail" page, all towel rails tell you if that rail can be installed as dual fuel, the wattage of element you need (in the data attributes section) and the required accessories are shown on the product page in linked accessories. Use our dual fuel guide for further guidance.

If you are planning to convert your own towel rail to dual fuel the heat output of the heating element should be matched to the output of the rail as central heating. To convert BTUs output to Watts see our understanding heat output technical guide.

As a last resort.. you could also find an electric towel rail we sell, which is very similar in style and size to yours and see what wattage element we provide with that rail.