FAQs

No,

You CANT cut the heating wires or cables at all as they are specially designed series resistive wires.

Shortening one of the heating cables means the rest of the load runs through a smaller circuit It will begin to get too hot and eventually fail

Each heating mat or cable is supplied with its own unique resistance rating, this specific resistance can also be found in the installation guide manual.

Each Fastwarm heating mat or cable comes supplied with a label attached on the power lead which will show the total power of the entire heating mat/cable.

Then if using more than 1 mat/cable you need to add the totals together

example… using a 200watt heating mat that is 5m2. The heating mat is 200watts pm2 , meaning the total power is 200 x 5 = 1000watts or 1 kilowatt. Divide mains voltage into this and you end up with your Amps or current.

1000 watts divided by 230volts = 4.38 Amps.

The installing electrician should use this information when working out what size supply to install for the heating system.

Or simply call our technical team for advice

No.

The heating cable or mat must control the underfloor heating system using a Fastwarm or heatmiser thermostat that is hard wired via a suitable isolation switch.

The thermostat prevents the heating system from overheating and also reduces running costs

We recommend the floor temperature is set around 23 to 28 degrees, we also recommend ensuring the floor sensor is installed per thermostat for each zone, most wooden floor manufacturers recommend that the surface temperature does not exceed 28 degrees

No.

You will need one thermostat per room or per heating zone.

Installing Fastwarm electric underfloor heating in small areas like ensuites and small kitchens can usually be supplied via a 13amp fused spur, the maximum load tends to be less than 13 amps

This is generally ok but always check with the Fastwarm technical team first

Yes Fastwarm heating mats and cables are easily repaired

Fastwarm repair kits are available to purchase on the main website,

When working out how much heating cable you need

You need to measure the room dimensions wall to wall, remove any fixed furniture from this area and deduct an additional 10% on top, then round down to the nearest suitable cable size.

Please call fastwarm technical if unsure ..

Any system over 12m2 will normally be 2 separate heating cables or mats

So when installing a 20m2 heating mat kit you will receive 2 x 10m2 heating mats.

Each heating mat/cable comes with a 2 metre power lead (cold tail) . These heating mats/cables will need to be connected in parallel near the thermostat.

Both power leads should be installed and connected to the thermostat or a suitable junction box before extending to the thermostat

Fastwarm underfloor heating can be installed under carpet providing the total tog value of both the carpet and underlay do not exceed 2.5 tog

Fastwarm offers multiple different systems that can be used depending on the installation type and subfloor, both electric and water underfloor heating are suitable to use providing the correct installation method is followed (please call us before buying a system when using carpets)

The majority of the work involved with installing underfloor heating does not need to be carried out by a qualified electrician, Fixing insulation boards and adhesive can be carried out by a competent persin providing they follow the installation guide

We recommend that you use an electrician to carry out the actual electrical installation, the system must be fully tested at intervals along the way of each part of the installation

They can…

however we strongly advise that a suitable Fastwarm insulation board is installed first.

Insulation boards greatly reduce warmup times and stop wasting energy being sucked down into the subfloor rather than up into the floor surface

Fastwarm offers multiple insulation boards to suit every different scenario (please check with our technical team for advice before purchasing a system)

Underfloor heating systems can be installed without an electrician, but any electrical work that has to be done, including wiring and mains, needs to be done by a part P or NICEIC certified and qualified electrician.

Assuming the room has good insulation levels and that you are covering 80% of the room's floor surface it can be used as a primary heat source.

Insulation is crucial to ensure that the area or room to be heated will be able to hit the desired temperatures

Fastwarm heating mats are 500mm wide and come in various different lengths to suit the size of the room

For instance, if you have an area to cover 5m2, you will be supplied with a roll 10 meters long by 500mm wide.

This will cover 5m2

The mesh can be cut and turned to suit the particular shape (DO NOT CUT THE CABLES)

We also recommend reducing the size ordered by 10%

So if you have an empty room 5m long x 2m wide = 10m2 - we would recommend a system 10% less, so this would be a 9m2 mat

When following our instruction guide Fastwarm underfloor heating systems can achieve floor temperatures ranging from 24-30 degrees. Please note that a 200 watts per square meter sticky mat will achieve a higher temperature than a 100 or 150 watts per square meter sticky mat but we recommend limiting the maximum floor temperature to 27 degrees Celsius for comfort.

Fastwarm heating cables are the thinnest in the UK market!

The cables are only 2mm thick, but you also need to add the height for any insulation boards and adhesives

Please call the Fastwarm technical team if in any doubt

We don't recommend installing more than 2 cables directly into one thermostat, if you are using more than 2 then we recommend using a suitable junction box to connect to first and then from there a suitable cable to the thermostat position

If you are installing a lot of underfloor heating mats or cables and would like to control this all from one thermostat then a contactor would be required, a contactor can switch a much higher load leaving the thermostat to operate as a switch only

We definitely recommend using an electrician if this is something you are looking to do, you can also call Fastwarm’s technical team for advice if you are unsure

Heating mats

Fastwarm Heating mats use the same heating cable as the loose cable system ( both the loose cable and the mat are rated @10/12 watts per linear)

The cable has already been spaced out for you on the mat and attached to a sticky adhesive mesh backing. Fastwarm Heating mats are much easier to install in larger areas and save a lot of time.

Fastwarm loose cables are ideally suited for smaller areas or awkward shaped rooms with fixed furniture like bathrooms/ensuites, they need to be stuck down at fixed set spaces to achieve the desired output, so these are time consuming over larger areas

Our heating mats come in 3 wattages 100w / 150w / 200w

200 watt mats

This is our most powerful heating mat, mainly used for under tile heating. Although It can be used for many different types of floor coverings, it is also recommended for high heat loss areas like a new conservatory or badly insulated areas.

If you are unable to fit in an insulation in with under tile heating then we recommend 200w mats

The largest area you can connect to using 1 thermostat is 18m2 of 200w matting - this would be supplied in 2 mats or cables

150 watt mats

Fastwarm’s 150w mat is our most popular and best selling heating system. These mats are suitable for most installations and they can be used as the primary heating source of heating beneath most floor types providing an insulation board has been installed prior.

Please note: Karndean or Amtico have a maximum rating of 150w pm2.

The largest area of Fastwarm 150w underfloor heating mats you can connect to 1 thermostat is 24m2

100 watt mats

These mats are not suitable for a primary heating source. They are only to be used as a secondary heat source in conjunction with either radiators or another type of heating source, 36m2 is the maximum that can used on 1 thermostat

Underwood heating mats

The Fastwarm underwood heating mat has been specifically designed for use directly underneath laminate and engineered wooden floor finishes, no need for any adhesives or levellers

This system must be used in conjunction with either Fastwarm XPS or classic insulation boards

The foil mat system can also be used under carpet and vinyl type floor coverings, if installing carpet or vinyl floors then HEAT PAK dual overlay boards must be installed on top of the foil mats prior to the carpet or vinyl being installed (DO NOT install vinyl or carpets directly onto the foil mats)

Loose Cables

Fastwarm loose cables are rated at 10/12 watts per linear meter

The cable is supplied on a plastic drum and the spacings are manually spaced out by the installer

Please refer to the cable spacing guide in the installation manual supplied in the box

We recommend covering 80-90% of the available floor space when installing underfloor heating in a room. Calculating less than 80% will create cold areas on your floors so measure the required area to be heated and remove fixed furniture and an extra 10% of the total to ensure there isn’t a surplus of electric heating mat or cable. The electric heating cable cannot be shortened so it's important that the sizing of the system is correct, if unsure please do not hesitate in contacting our experienced technical sales team and they will happily assist in providing your specific sized kit.

Most flooring manufacturers approve the use of their products with underfloor heating systems, providing the floor temperature does not exceed the recommended maximum of 27 degrees Celsius, this is easily achieved by using the function on any of our supplied thermostats. If ever in doubt, please contact the supplier or manufacturer of the wooden floor finish to clarify suitability.

When using a Fastwarm underwood system, it's highly recommended to use the greatest depth of XPS Insulation where possible but on the vast majority of installations the use of our Fastwarm 6mm EPS Classic Underlay or Fastwarm 6mm Premium XPS insulation boards are more than adequate to create a primary heat source.

Fastwarms electric underwood mats are compliant with the 18th edition wiring regulations when following our installation instructions. The cables are fully protected with an earth metallic covering. All electric systems are required to be protected by a 30 milliamp RCD, if unsure always consult with a qualified electrician.

The underwood mats have a rating of 140w’s per m2 e.g., 10m2 mat x 140w per m2 = 1400w’s.

All our wood mats come in predetermined lengths of 1m2 to 12m2 with a set 500mm width, for example a 7m2 mat would come in a length of 14 linear metres by 500mm width which equates to a coverage of 7m2. Underwood mats can be cut (Please make note that the heating cable cannot be cut) and turned to fit any given floor space which makes this system more versatile than the historic carbon film mats.

Any furniture that allows for air flow i.e., Situated on legs can be installed on top of the underwood heating system but we strongly advise against placing fitted wardrobes, appliances, rugs, pet beds over the heating system as this can cause heating issues.

We strongly advise against the use of an underlay between the underwood foil mate and wood floor finish as this will lead to heating issues. Fastwarm supply XPS and EPS insulation boards which when fitted under the foil heating mate create a cushioned layer as well as insulating against a cold substrate.

Fastwarm supplies aluminium tape with the kits so when the mat is cut for a desired layout, we stipulate that the Aluminium tape is bridged over the heating cable from one piece of mat to the other.

Any system over 12m2 will consist of two mats which each come with a double insulated protected power cable, both of these will require wiring in parallel to the same terminals in the back of the thermostat (two mats will not exceed the rating of the 16amp thermostat).

Yes, this is possible but for customer protection we do not list kits of more than 24m2, we would advise speaking to our technical sales team who will assist in clarifying the system make up and what’s needed in terms of wiring from your qualified electrician. A system larger than 24m2’s is not uncommon as homeowners do regularly create larger living/kitchen areas etc.

A depth of 7mm to 18mm wood flooring is suggested to ensure the heating works as efficiently and effectively as possible.

Fastwarms underwood heating mats are manufactured to a 2mm thickness and when added in conjunction with our lowest depth of insulation, an 8mm total thickness is achieved (Please note that if adjoining room floor finishes are to be matched up level with the underwood heating system a deeper depth of XPS Insulation can be used to assist with height discrepancies).

The concept of water underfloor heating has been around for over 2000 years but its only recently that the use of modern pipes with modern insulation that underfloor heating has become widely available to the homeowner, with the added invention of various installation methods it has helped adapt most dwellings to this form of heating.

The use of water underfloor heating will help provide a more evenly spread form of ambient heating whilst also saving costs on your ever-increasing fuel bills. It achieves this by mimicking a radiator under your floor but with a lower running temperature whilst providing an even level of heating throughout a room.

Any type of boiler can be used for underfloor heating if the boiler is suitably sized for any additional demand such as existing radiators upstairs and an underfloor heating system downstairs.

Fastwarm Warm water underfloor heating will run 20% more economically than radiators when installed within a screed and covered in a low resistive floor finish such as tiles.

Underfloor heating provides many advantages over a conventional radiator system:

By running at a lower water temperature, it allows for cheaper running costs.

Saves on available floor space by allowing for furniture to be positioned in areas usually obstructed by radiators.

Underfloor heating works by gradually heating the floor and providing a constant even heat throughout the room whereas radiators primarily heat around the fixed unit location and then throwing heat into the ceiling void which can produce dust allergies from air circulation which harms people with allergies.

Like radiators, Water underfloor heating is fed from a heat source such as a boiler or an air source heat pump by calling for warm water when a thermostat requests heat. The warm water from the heat source travels to the underfloor heating manifold and is distributed to whatever room requires heat (when heating more than one room its highly recommended to incorporate a thermostat for each zone so the user can control areas independently).

When a room thermostat calls for heat it sends a signal to the manifold to provide a lower blended temperature of flowing warm water through the network of pipe specifically zoned for that room.

Yes, Fastwarm provide 16mm pipe diameter single loop kits with a coverage up to 24m2 which can be attached to an existing radiator system via a single circuit pump & mixing valve unit.

To comply with the Part L of the new building regulations you must install controls that allow the switching off the underfloor heating when it is not required.

Yes, we have a comprehensive range of underfloor heating systems that can be installed in any type of room and on any floor level e.g., Basement, ground, first and lofts levels etc

Water underfloor heating can be installed in a screed, between floor joists and our various types of retro fit panels which can provide a water system on to an existing subfloor with only a 16mm height build up prior to a floor finish going over the top.

Water underfloor heating can be fed via any water heat source such as boilers, Air source or Ground source heat pumps, biomass boilers, log burners with back boilers and thermal stores.

Heating zones are individual rooms controlled via their own designated thermostat and pipe network. Each circuit of 16mm pipe can be up to 110m’s and cover an area between 17m2 and 30m2 dependent on the spacing between laid pipes.

When using more than one circuit/loop of pipe a manifold is required which should be preferably positioned centrally to minimize length of pipe and number of ports on a manifold, a manifold will generally be located under a staircase or cupboard but can also be housed in a kitchen/utility unit or in a garage if needed.

Our experienced technical sales team are happy to calculate and provide a full layout design plus material breakdown when your floor plans and relevant information is sent over in an email or posted format, you can expect to receive this within 24 hrs.

Yes, this is possible, by installing a zone valve for each floor this will enable either both systems to work together or to run independently.

We recommend that manifolds are preferably mounted in a horizontal position for ease of installation but if restricted for space the manifold can be mounted vertically.

What is the lowest depth underfloor heating system I can install?

You can install a water underfloor heating system with pre-grooved panel (using our Fastwarm 12mm Pex Al Pex Pipe) for as little as a 16mm total build up height.

How do I calculate the amount of Fastwarm Pert-Al-Pert pipe needed for my room?

To work out the length of pipe needed for an area you’ll need to know several factors, room size, the pipe spacing and the distance going to and from the manifold location.

For example, if you have a room that is 12m2 and is 5 linear metres from the manifold and the pipe spacing is at 200mm centres, the calculator will be as follows:

1200mm/200mm = 5 (6 metres of pipe per m2 required)

12m2 x 5 = 60metres.

Distance from room to manifold is 5 metres, multiply

this by 2 for the flow and return and add this onto the pipe used in the room.

60 metres + (2x5) = 70 metres of pipe required.

How do I work out my flow rates and set these on the Fastwarm manifold?

The purpose of setting the flow rates is to ensure you have enough water flowing through each circuit and to balance the manifold, as its important to balance the manifold to ensure that some circuits do not receive all the flow whilst others struggle to get any at all.

The same applies to all heating systems including radiators.

Flow rates for 16mm pipe are calculated by dividing the length of pipe by 40, so for an 80m coil, you will have a flow rate of 2 Litres per min. To calculate flow rates for 12mm pipe a denominator of 50 will be used so an 80m coil will calculate at a flow rate of 1.6L/min.

Yes, with Fastwarm Warm Water Underfloor Heating this is possible, we do recommend that a low tog plus breathable underlay is used, this provides cushioning for foot traffic and comfort yet does not block the heat output. Tog value should be below 0.75 and thickness between 2mm – 5mm.

Generally, we recommend mounting a Fastwarm manifold as near as to the level its supplying, usually above the floor being heated. This helps take pressure of the pump and allowing any air that may build up in the system to be bled from the manifold.

However, with a sealed heating system it is possible to mount the manifold slightly lower than the heated floor area i.e., high up in the basement which will ease head loss/pressure on the pump but do not hesitate to contact us if you or your builder/plumber is unsure.

This will be dependent on whether you have other sources of heating in the house and what type of heating source you have. If the property has a combi boiler and your only using underfloor heating, then a motorised valve is not required BUT if you have a mixture of underfloor heating and radiators then the use of 2 x separate motorised valves will be needed to control the heating systems independently via their own thermostats.

If you have a system boiler and already have radiators and a hot water cylinder with their own 2 port motorised valves, then you’ll need to add a further one for the underfloor heating. Whether you or your installer needs further clarification on the separation of the systems please do not hesitate in contacting us and we’ll happily assist in supplying a schematic diagram to help.

Its preferable to always remove an existing floor covering before installing a new system as its better to affix to the subfloor, however the Fastwarm Duo boards have been designed with the added benefit of installing over an existing floor covering but please note that if you’re proposing to lay a solid floor i.e., Tiles over the Duo boards instead of a floating wood floor finish then the substrate will need to be suitably prepared as the panels will be fixed down with suitable tile adhesive.

The existing floor finish will need to keyed/scratched, cleaned and primed prior to the panels being applied with adhesive over the top, if you discover loose tiles then remove these and apply a levelling compound to finish level with the rest of the tiled floor.

Yes, this is fine, as mentioned in the previous question/answer you must ensure that the installation method is adhered to eradicate any future issues. These instructions can be found on our installation and manual guides.

A water tank is not required in most underfloor heating systems. Boilers or heat pumps are used to heat the water in underfloor heating systems.

While a water tank isn't specifically needed for a water underfloor heating system, if you use a boiler, you will need a water tank as part of the boiler system.

Installing water underfloor heating can be a complex task; however, if you're competent at DIY, a plumber is not always required.

If your underfloor heating system is being connected to a boiler, a certified Gas Safe engineer will be required to make the final connection.

Depending on the depth required a bag (20kg) will cover between 1m2 - 5m2.

For example - at 10mm thick, a bag will cover approx 10m2. at 5mm thick, a bag will cover approx 5m2

All of the levelling compounds we sell online have a coverage calculator to help with this calculation.

Almost all floor adhesives are required to be installed using a notched trowel. Depending on what the tile adhesive is being used for will dictate the depth required. If fixing Fastwarm tile backer or XP insulation boards, we would recommend a 3-5mm bed of adhesive. This can be achieved using a 6-1-mm notch.

All substrates must be adequately primed before any tile adhesive is applied.

All curing and drying times are based on good site conditions i.e. an air temperature of 20 degrees C, air humidity of 65% RH and good ventilation. Sites that are cold, humid or damp or in areas where the airflow is poor, will prolong drying and curing times, so allowances should be made accordingly. Applications to non-absorbent substrates and at thicker application depths will take longer to dry.

NOTE: Avoid strong drafts and direct sunlight during curing. UltraFloor Level IT Two is ready to receive light foot traffic normally after 2.5 hours based on a 3mm thick application.

When using self levelling compound just to cover the heating element and to provide a smooth levelled surface prior to tiling, you would require approx 6mm of self levelling compound. This would ensure the cable is fully encapsulated and provides a ready surface for a finished floor covering.

When using self levelling compound for LVT for example, would require a minimum of 10mm self levelling compound.

All levelling compounds on our site have a coverage calculator to help with this calculation.

To ensure a correct bond you must prime any surface prior to using tile adhesive or levelling compound

Primer will seal the floor, insulation board or levelling compound and ensure tile adhesive adheres correctly.

We would advise using the Ultra MSP (Multi surface primer).

The working time is the amount of time you have before the tile adhesive begins to set. We supply rapid setting tile adhesive or skilled tilers, or we can also provide extended setting tile adhesive if you need more time to work.

The humidity, temperature and subfloor porosity also plays a factor when it comes to the working time of a bag of tile adhesive.

When the floor heats up and cools down it will expand and contract slightly. This is why it is crucial to use a flexible tile adhesive and latex based self levelling compound to ensure to stop the floor from moving and cracking. We would also advise using a flexible grout to ensure grout lines do not crack.

Levelling compound is designed for making an existing floor flat and level, where it may be otherwise undulated, bumpy, uneven or unlevel. It is essential in flooring preparation and makes life a whole lot easier if fixing tiles or vinyl floor finishes.

Self levelling compound is also used over the top of underfloor heating to provide a level surface to tile on and to protect the heating elements whilst tiling.

It is also used to spread the head evenly across the floor and acts as a storage for heat.

For fixing Fastwarm insulation boards we would suggest one 20kg bag per 5m2. (assuming a levelled floor). A 6mm notched trowel with a 3mm bed.

All tile adhesives on our site have a coverage calculator to help with this calculation.

You can find all of our thermostat instructions and manuals in our installation guides and manuals area. Simply type the model of the thermostat into the search and you will be presented with any spec sheets or installation guides available.

You will need a 35mm deep single gang back box for all wall mounted thermostats. 35mm is deep enough to cater for the terminal back box, cold tail, floor sensor and live supply. Typically a metal back box would be required if chasing to brickwork walls or a plasterboard box if being installed into drywall or plasterboard. All Fastwarm thermostats are suitable for use with 35mm.

If the Fastwarm electric underfloor heating is installed within a bathroom or wet area, the thermostat would be situated outside of the bathroom with the floor sensor probe inside the bathroom. Typically the thermostat would be set to read the floor to ensure the temperature is accurate and not reading the ambient air temperature of the room where the thermostat is situated.

Floor mode may also be selected in certain scenarios where the flooring manufacturer advises that the floor temperature does not exceed 28 degrees.

Yes. ALL Fastwarm Electric Underfloor heating thermostats (16amp) come supplied with a floor sensor probe.

This is crucial for electric underfloor heating as this regulates the temperature of the floor. Some warm water underfloor heating thermostats (3amp) can be used with external sensor probes if in wet areas.

You need to access the menu and change the default floor temperature to Room Temp. When the unit is turned on in normal power mode, press the 'o' button once

Use the Up or Down keys to select SETUP

Press 'o' to enter setup menu

Press 'o' several times to change the menu number to 5

Press the UP or DOWN arrows to change the sensor to 00 Room Sensor

Press the Return arrow to go back to the main screen

You should now see Room temp on the display.

Alternatively you can find the manual here; https://ww2.fastwarm.com/document/download/07b07210-3733-4f8e-a65d-202dc73f6a3b

Heatmiser Neostats can be changed to Manual mode by accessing the setup menu. To do this you will need to enter setup and change feature 12 to 00. To do this follow pages 25 and 26 in the instruction manual found here: https://ww2.fastwarm.com/document/download/5d4746e8-0ed9-420d-87da-2afa60ae259b

No. Fastwarm Electric underfloor heating systems cannot be directly controlled via HIVE or NEST thermostats. These thermostats do have come equipped with the ability to read external floor sensors and thus can not regulate the floor temperature which is crucial for electric underfloor heating.