FAQ How to Install SunTouch Radiant Floor Heat
By SunTouch A division of Watts Water Technologies, Inc.
Installing radiant (wood, tile, etc.) floor heating systems is not difficult; however, we have the answers to any questions you may have. SunTouch radiant UnderFloor heating mats are UL Listed for use with any type of finished floor. Radiant wood floor heating provides the comfort and warmth you’ve been looking for if you embed it in at least a quarter inch of masonry.
Get all your questions answered here on how to install radiant floor heat successfully.
Can i get quick quote and how?
Try our new improved Flooring / Heating Estimator
SunTouch is EASY to quote! it covers about 90% of the exposed area. So figure the total area of the room, then subtract out any cabinet. Tubs, toilets. Etc., and multiply by 90%. This is the sq. ft. of SunTouch you will need.
Or simply get your information and call us Toll Free 877 880 8453 (TILE), or send us Email at firstname.lastname@example.org
We will get you the best options available with the lowest price available, usually it’s all done while you are on the phone, or a few minutes after receiving your Email. (Some large projects require a few hours).
What makes the floor warm?
The blue heating elements in the orange weave of a SunTouch mat get warm and transfer heat to the floor. The floor, in turn, transfers heat to the rest of the room. WarmWire® does this with stainless steel covered heating elements attached to straps. SunTouch UnderFloor™ does this with a warm blue aluminum surface suspended between floor joists.
Where do most people put their SunTouch floors?
Bathrooms are the most common place, followed by kitchens and entryways. Mudrooms are a great place for a warm floor. WarmWire® works great in larger areas, like basements or great rooms.
Does SunTouch mat weaken or strengthen my floor?
SunTouch mats have been tested by the Tile Council of North America (TCNA) to ASTM C 627, officially known as “A Standard Test Method for Evaluating Ceramic Floor Tile Installation Systems Using the Robinson-Type Floor Tester”. It tests for deflection under increasing weight loads on a wooden framed floor or with a concrete slab floor. SunTouch mats passed these tests for HEAVY classifications, such as shopping malls, commercial areas and etc. SunTouch mats apparently add tensile strength to the tile and mortar sandwich. When in doubt, follow TCNA and ANSI (American National Standards Institute) specifications.
Is SunTouch electric floor warming efficient?
Radiant floors warm people and objects directly without overheating the air. Electric radiant converts nearly all its energy into a usable form. Set the home thermostat lower and still be comfortable. Use a programmable SunStat and the system automatically sets back to a lower temperature when the rooms are not in use. Insulate below the floor or below the heating system and on top of the concrete slab to allow the system to respond faster and use less energy.
My bathroom is heated, so do I need floor warming?
Even when bathrooms are heated with forced air or baseboard, the tile floors are cold. Imagine starting the day by stepping out of the shower and onto a warm, comfortable tile floor!
Is there any advantage to a “low voltage” electric radiant heating system?
No. SunTouch and competitors deliver about the same amount of energy to the floor. They may use fewer volts, but require higher amperage to be able to generate the same wattage (heat delivery). SunTouch, however, uses line voltage, and lower amperage to deliver the necessary wattage. This allows a larger SunTouch system to be installed with a smaller breaker. Low voltage systems use transformers that are noisy, hot and hard to hide, both visually and acoustically. All North American bathrooms have access to 120 Volt (VAC) power and by code, must install SunTouch systems with GFCI protection. A GFCI detects ground faults and will disconnect the energy to the heating system within milliseconds if necssary. Low voltage systems are not necessarily low EMF systems. Before buying any product, ask them if the EMF level of the product has been tested by an independent lab, and if they have comparative test data from their products and our independently verified low EMF products.
What does it mean that SunTouch is a very low EMF product?
EMF is the abbreviation for Electromagnetic Field, also commonly referred to as Electromagnetic radiation, or EMR. SunTouch twists two heating elements together to minimize EMF. We test our products to a protocol known as REET (Radiant Electric Emissions Test) which is conducted by an independent third party test lab known as ETL/Semko. Scientists don’t know exactly what EMF does to a human body, but recommendations suggest to reduce EMF exposure.
What voltage do I need for my SunTouch floor?
SunTouch is built for 120 VAC or 240 VAC for warming larger areas.
Does 120 VAC work better than 240 VAC?
Both systems have the same efficiency. The best option is to see what power is available for your installation. 240 VAC is more common outside the United States and in commercial applications. A SunStat can control up to 150 square feet of heated floor on 120 VAC or 300 square feet on 240 VAC.
What’s the warranty on SunTouch products?
SunTouch heating elements are covered by a limited twenty-five (25) year product replacement warranty. SunStat controls have a two year limited warranty. The SunTouch warranty is transferable to a new homeowner, unlike most other radiant companies. SunTouch warranties the product, not just the original homeowner.
What makes your heating elements special?
Heating elements must resist jobsite abuse and long term aging. SunTouch uses an expensive wire insulation called ETFE (Ethylene tetrafluoroethylene). The physical properties of this polymer are unmatched for the application, notably its water resistance, dielectric properties and long-term temperature aging. We also use oxygen-free alloys in our heating elements to give them greater longevity. The dual heating elements are braided with a durable ground shield and then jacketed cables are coated with either a highly visible water resistant PEX polymer jacket, or a very resilient TPU jacket with outstanding properties to avoid damage from minor job site abuses. No one builds a better heating element wire than SunTouch.
Can you just install part of the room?
Yes, you can install as little as 10sq, ft. Our 2′ & 3′ – wide are perfect for heating in front of vanities, toilets, kitchen sinks, etc. They come in 10. 15 20 & 25 sq. ft areas
How can I make my power leads longer?
You can extend your Power Leads by routing them to an electrical junction box in the wall where you can connect them to standard 14-gauge electrical wire. Then you can run 14 gage AWG electrical wire through the wall to your control. Most local codes require you to make these connections in the junction box and to provide a panel door that gives you access to the box when the wall is finished. Check your local code for details.
If you need to extend the Power Leads in the floor, simply “pull” the blue heating wire from the mat to get the end of the Power Lead closer to the wall. Hold down the loose wire with plastic tie downs or hot glue. There is approximately 4.3′ of blue wire per square foot of mat.
What gauge wire is appropriate if I decide to extend my Power Leads?
14 gauge AWG electrical wire is appropriate for a load of 15 amps in most city electrical codes, but in all cases, follow your local code.
Can I put the sensor wire and the power leads in the same electrical conduit?
You should not run the power leads and the sensor wire in the same conduit. Instead, run the sensor wire from the control box to the floor using a “wire fish” or nail on a string and then bring it out through a hole near the bottom of the wall. Or, put the sensor wire in its own separate conduit.
Will residual dried glue from a previous floor covering interfere with my SunTouch installation?
Your SunTouch will be embedded in latex modified thin set mortar. The SunTouch will not be affected by the residual glue.
Can I install vinyl flooring and adhesive over SunTouch?
We don’t recommend the use of flooring adhesives with SunTouch. They are not designed to withstand the operating temperatures of a radiant floor. Self leveling mortars or latex modified mortars are the preferred bonding coat. Check with the manufacturer of your vinyl floor to see if the product is temperature rated for use with a radiant floor before you begin installing.
Can SunTouch be installed over an isolation membrane or sound control membrane?
Yes. We recommend using our double-sided tape to hold the SunTouch mat to the membrane, then thin-set as you normally would.
If I’m using Schluter “Ditra” as an underlayment, does the SunTouch go over or underneath?
Schluter recommends SunTouch (or any other heating products) to be installed below the Ditra. SunTouch mats are approved for this product/installation. The warm-up time is ever-so-slightly longer due to the air pockets that result when you install the Ditra mat.
Can SunTouch be installed directly over old linoleum and then covered with a ceramic tile floor?
Yes, but we’d recommend installing a “crack isolation membrane” over the linoleum first.
After installing this membrane, lay out the SunTouch, then apply thinset mortar and new tile.
Can I install SunTouch UnderFloor heating mats on top of an old ceramic tile floor?
Normally, we recommend you consider a “crack isolation membrane” when installing SunTouch over an old floor, especially if the old tile is broken, cracked, or has other symptoms of slab or tile failure. If the old floor looks good (and has been there for several years), then make sure the mortar you use is recommended by the manufacturer for bonding to tile.
Can we install SunTouch over my existing vinyl flooring and cover it with a new tile floor?
Yes you can, but you should install a “crack isolation membrane” over the vinyl first. For more information, contact us
Can I install SunTouch under vinyl flooring?
SunTouch radiant heat mats are UL listed for use with any type of finished floor if you embed it in at least a quarter inch of masonry. But, first make sure the vinyl flooring manufacturer rates their product for use with a radiant floor. Some types of floor coverings are not built for the temperatures of a radiant floor (80-85 degrees F) and they may discolor or deform over time.
Can I install SunTouch UnderFloor heating mat directly over masonry?
Yes. Simply tape the UnderFloor heating mat to the mortar with double-sided tape that we supply and lay your tile or stone as you normally would. When in doubt, apply more tape. Thinset spreads easier when the mat is thoroughly attached. However, concrete slabs especially will “drain” some of the heat from your floor. So, a good idea is to attach a layer of cork or other insulating material to the concrete first. Then attach the mat. Talk to your tile distributor for recommended underpayments.
What do you recommend to level my concrete floor before installing SunTouch?
Several major companies make self leveling mortar products. These are mixed with water to a pancake batter consistency and are designed to be poured over uneven spaces to level a floor. SunTouch has been tested with these products and is compatible. You can apply SunTouch to the existing floor and pour self leveling on top and then apply your finished floor, but the deeper the mat is below the surface, the longer it takes to respond from a cold start. You might consider pouring the masonry first, allow it harden and then use double sided tape to secure the SunTouch mat on top. Then you could apply a thinset and tile/stone finish to the floor.
Should I install aluminized radiant barriers under my SunTouch floor? Will that direct the radiant energy upwards?
We don’t think so. To reflect radiant energy back to its source, you need an air gap. If you install that barrier below the floor (like in the joist bay) and allow for an air gap between it and the subfloor above, then the radiant barrier will help insulate your warm floor. When you install thinset over the SunTouch mat, that masonry bonds to the layer below through the gaps in the orange weave. If you put in a barrier below the mat, you can compromise that bond and actually make your finished floor more subject to cracking.
Can you put the UnderFloor heating mats right on to the plywood subfloor without backer board?
Yes you can. We have the UL listing for direct application on plywood, but have you considered using a cement based backer board on top of the plywood? It costs a little more money, but the Tile Council of America likes it because the thinset bonds better to a cement surface than to a wooden surface. It also stiffens the floor and reduces flexing. Backer board means less chance of cracked tile over the lifetime of your floor.
Can WarmWire or Mat system be installed in Thinset under durock backer or Hardi Backer (over a plywood subfloor), instead of in Thinset with the tile?
According to our Installation Applications and TCA applications this is not recommended. The SunTouch product should always be installed on top of the Backer Board to reach maximum capacity.
What is the overall thickness of a SunTouch installation over an existing plywood floor?
Here are some common rules of thumb:
- 1/8 inch to 1/4 inch of thinset over the plywood.
- Then, 1/4 inch or 1/2 inch backer board.
- Then, SunTouch mat.
- Then 1/4 inch to 3/8 inch thinset over the SunTouch.
- Finally, 1/4 inch tile.
So, the overall thickness of your completed SunTouch tile floor will be about 7/8″ – 1″ thick.
Why do you recommend a 4-6 inch space between walls and the edge of the SunTouch mat?
This space next to walls reduces the chance of damage to the underfloor heating mat by new construction or future remodeling. If these issues aren’t relevant in your case, we recommend putting your radiant floor mats no closer than 3 inches to the wall. Definitely stay at least 3-4″ from the toilet ring. Another good reason for the space is to save you money. In most cases, you don’t stand that close to the wall so you can use less mat by leaving a space.
Can the blue heating wire be passed through a gap in the bottom plate of a wall so one continuous mat can serve two rooms?
No. The mat may go through a doorway but never through a wall.
How do I shape the UnderFloor heating mat to fit my custom bathroom?
SunTouch makes 55 different mat sizes and there is one radiant floor mat or several that will fit your room exactly. Refer to the design library to see how the UnderFloor heating mat begins at the control location and then rolls out until it meets an obstruction or comes to the limit of the area you want to heat. Use ordinary household scissors and carefully cut the orange mat between the blue heating wires. Never cut the blue heating wire. The blue wire acts as a hinge so the mat can swivel to make a right turn, a left turn or a u-turn. Proceed in the new direction until you meet another obstruction or come to the limit of the area you want to heat. Repeat the process until you have used all the UnderFloor heating mat. At this point, you go back and secure the mat to what’s below.
Why do I need to use a LoudMouth and an ohm meter to check the blue wire during installation?
Although the wire is extremely tough, it can be damaged during installation. The culprit is usually the sharp edge of a trowel. When you open your SunTouch box, there is a label that shows the resistance of the wire in the UnderFloor heating mat. You need to confirm this value before you begin work and when you are finished. During the job, however, you should hook up the LoudMouth which doesn’t give you a resistance value, but does sound an alarm if that value changes suddenly. These two devices work very well together and give you peace of mind during the entire installation.
Why do you recommend I wait up to 28 days to use my new SunTouch system after the thinset and tile are installed?
This is the recommendation of thinset manufacturers. Their products require a curing period before the masonry reaches its fully rated strength. This process cannot be rushed by heating and apparently, the process can be adversely affected by the modest temperatures of the heating wires if they are turned on before 28 days.
If I end up with extra SunTouch mat during layout, can I cut the mat to a shorter size?
No. The orange mat can be cut and then rearranged to fit your room, but you must never cut the blue heating wire. If you find that you have a few feet of mat left over, you can pull out some of the blue heating wire from the mat and install it around the perimeter of the room or at the sides or behind your toilet. Normally this area isn’t heated, but it’s a good place to serve as a buffer for extra wire.
Can you recommend a thinset mortar?
Any of the popular water-based latex modified thin-sets will work fine, such as those by Custom Building Products, Mapei, or TEC. Buy dry thinset mortar in bags and mix it up like the pros, into a thick blend that holds to the stirring stick. If you have a big enough job, buy a paddle that chucks into a cordless drill to make mixing easy. The pros use light color thin-set for light color grout and dark-color thin-set for dark color grout Avoid any glue-type adhesives meant for vinyl tile or ceramic wall tile. Also, avoid the pre-mixed mortars, usually sold in buckets.
If I put SunTouch over an existing un insulated slab, will it perform well?
SunTouch mats give off 12 watts per square foot, which is quite a bit of heat. But sometimes this is not enough to bring your floor up to 80-85 degrees F. Slabs can be quite a drain on floor heating systems depending on the thickness, the sub grade below slab, moisture content, heat loss from the room or outside temperatures. If you live in a cold climate and there is a lot of heat loss from the room, we recommend installing 1/4″-1/2″ cork underlayment as insulation. Bond the cork to the slab with an adhesive that is rated for radiant floors and then install the heating mats and tile as normal. See this link to the national cork flooring association. If the edge of your new radiant slab is exposed to the outside, we recommend you insulate it with a layer of extruded polystyrene. You may also be able to reduce the heat loss from your room by installing higher R-value doors and windows, by reducing air infiltration and by adding ceiling insulation.
Can the LoudMouth monitor several mats at a time?
Yes. View this information to see how to connect up to three mats together in series to the LoudMouth.
I’ve covered SunTouch mats with masonry. What’s the best adhesive to hold down a cork finished floor?
Contact the cork manufacturer and ask for an adhesive appropriate for radiant floors. The surface temperature of your finished floor should not exceed 85 degrees F.
What is the recommended procedure to apply thinset over the SunTouch mat?
Start with a good quality latex-modified thinset. Use the flat edge of a 3/8 inch x 1/4 inch notched trowel or the size recommended for your tile size, to push the thinset over and into the UnderFloor heating mat. Then reverse the trowel and use the “comb” side to rake the mortar over the mat in straight parallel lines. Work in small areas.
What is the best way to secure SunTouch to a cement backer board before applying thinset?
Our double sided tape is your best bet when working over a slab, but backer board can be penetrated by staples. Use a small finish staple gun and air compressor to staple a lot of mat in a very short time. On small projects, you can use a hand stapler. In both cases, use short leg staples. Remember not to staple the blue wire or you will damage it. If you find yourself making a lot of cuts to the orange mat to shape it to your room, go back and staple down loose mat so it doesn’t interfere with your trowel later on. When in doubt, apply more staples.
Can I apply a skim coat of thinset over my SunTouch radiant floor heating system, let it dry for a day and then apply another coat before setting the tile?
Yes. Some tile installers would rather work over very flat surfaces and they prefer this two part method. First they cover the SunTouch mat with a self leveling mortar or they apply a level skim coat of thinset over the mat. The following day or later, they secure the mat over the first layer and cover it with thinset before applying tile. Many installers secure the mat to the backer board and immediately apply thinset and tile. This is a one-step method. Both work fine, so it’s a matter of personal preference. In both cases, we recommend using the Loudmouth monitor during the entire installation.
What is the total height of the mat and thinset below a 1/2” thick stone floor?
We recommend using a 3/8 inch x 1/4 inch trowel to apply the thinset over the mat and by the time you’ve finished, you’ll be approximately 1/4 inch over the backer board which is usually 1/4 to 1/2 inch thick. For perimeter areas where there is no SunTouch radiant floor heating mat, you will apply a slightly thicker layer of thinset, so take that into account when you are planning your material list.
Can I put SunTouch under the tub in my bathroom?
We don’t recommend it because the heat transfer will be poor below the tub.
Can SunTouch be installed under wood floors, laminate flooring or under carpet?
SunTouch radiant heat mats are UL Listed for use with any type of finished floor if you embed it in at least a quarter inch of masonry. Start with a strong subfloor, secure the SunTouch radiant floor heating system, and cover with self leveling mortar which is manufactured by several different companies. Once this mortar is in place, follow the manufacturer’s instructions for cure time and then cover with laminate or carpet. Do not use nail-down coverings and be careful where you place carpet tack strips.
How close to a toilet can SunTouch be installed?
SunTouch can be installed within 4 to 6 inches of the wax ring and can slightly underlay the foot of the toilet if needed. (See illustration on right)
My SunTouch floor mat is 12 amps or less, it’s just a small mat. I should never exceed 15 amps on the thermostat… meaning what? I can’t run it on a 20 amp circuit, or not overload it with 15 amps worth of mats?
#1. A dedicated circuit is preferred, and likely the way you have yours run, with outlets sharing, will cause tripping problems.
There is a GFCI built in to the SunTouch Thermostat, so if there are any other GFCI’s on the circuit, they will conflict with each other. Electricians call this, “Cross-Talk”.
#2. Here is a simple formula for calculating breaker amperage: exceed the load by 25%.
So, if you have a load of 15 amps, use a 20 amp breaker. SunTouch products are made to be used (If you are using a SunTouch Thermostat) without a GFI breaker.
So, you have a 12 amp system, requiring a 20 amp breaker. It would probably work O.K. with a 15, but a 20 wont hurt and doesn’t cost much more and will not give any problems.
Can a damaged heating wire be repaired on the jobsite?
Yes, but you’ll need a licensed electrician to make the repair. Call us toll free 877-880-8453 and we’ll send your electrician a repair kit. A detailed instruction sheet is also available.
If the damaged wire has been buried below tile, a good tile setter can carefully remove the tile and expose the wire. Once you find the break, the electrician will separate the elements of the wire and splice the two sections back together again. The connections are tested and then covered with a section of shrink tube that provides waterproofing Then another test is performed. The repaired assembly is then re-embedded below the tile in fresh thinset. Call our toll free number with any questions you have at any part of the process: 877.880.TILE
Can I Install WarmWire and Mat on same controller?
You can combine WarmWire and Mat together the will both connect to the same controller
NOTE: you using same voltage for the WarmWire and the mat
Do I need an extra sensor?
Sometimes a customer will order an extra sensor for peace of mind. Although it’s extremely rare for a sensor to fail, we think it’s a reasonable precaution. Run both sensors from the control box to the floor below and then weave them into the mat 6 to 12 inches from the wall. You can put them side by side, but connect only one to the thermostatic control. If you ever need to replace a faulty sensor, you’ll have one at your fingertips.
I forgot to put the sensor in my floor- what can I do?
You have a couple of options. If your drywall is already in, and your grout lines are at least 1/4” wide, you may run your sensor wire from the control location behind the wall and fish it out through a hole near the floor by using a fish tape or a nail on a string. Use a hand grout cutting tool and gently remove the grout from between the tiles for a distance of 6-9 inches into the heated floor. Be careful not to cut too deep and damage a heating wire. Locate the sensor between the tiles, but make sure not to put it directly on top of a blue heating wire. Re-apply grout and then cover the sensor hole in the wall with trim. If your grout lines are not wide enough, or if you are uncomfortable with cutting the grout, you may be able to fish the sensor wire below the subfloor. Use a 1/4” drill bit to carefully drill a pocket under the heated floor in the subfloor up to the underlayment (stop before you get to the mat!). Secure the sensor in the pocket with adhesive and then insulate. Your SunStat will read the floor sensor and you can adjust the temperature to your liking.
How is the mat controlled?
SunTouch is controlled using a SunStat control. the mats(s) are wired directly to it and the floor sensor tells the controller when to turn on & off the electricity based on the set point temperature.
Can you heat areas using more than one mat on one SunTouch?
Multiple mats can be connected at the controller to heat larger areas.
The power leads connected to the mat are wired together in “parallel” inside a 4” x 4” electrical junction box located in a wall, above the ceiling or below the floor.
One thermostat & sensor can control all mats from a single location.
What sizes do the mats come in?
Mat widths are 1’, 2’, 2.5″ & 3’ wide with lengths of 5 feet to 80 feet long, with areas 10-160 sq, ft. Check our web site for size availability
What it is EMF?
Electromagnetic fields (EMF) come from all electrical appliances. Studies show daily average personal exposure is likely less than 1 unit (mG) of EMF1. When you sit on an unshielded electric radiant floor, however, you may be exposed to emissions at 22 times this background level. Or 46 times this background level.
How SunTouch ensure my Safety from ETF?
If we select five radiant floor products that cover 35-40 square feet of heated area that represents the most common size for residential bathroom installations.
The Watts Radiant mat in that size range emits a mG value that is 20 times lower than the average US exposure.
Watts Radiant (SunTouch) recently selecting four competing products in that size range, the REET test, as conducted by the prestigious ETL Semco Laboratory, produced these values:
Product A: 42.38 times the U.S. average exposure
Product B: 45.74 times the U.S. average exposure
Product C: 71.34 times the U.S. average exposure
Product D: 92.54 times the U.S. average exposure
A word from Flooring Supply Shop
As a Licensed General contractor and Flooring Contractor for many years, I used and tried all brands on the market.
I found SunTouch to be the best in:
2. Labor Time ( cost)
3. Simplicity of installation
4. When you calculate the product cost and labor cost, Suntouch is the best buy for the money.
5. A 130 years company I could trust when had an issue with installing, warranty and excellent customer support.
6. Safety: The most important is the safety of the product to both your loved ones and yourself. Electromagnetic Fields are a health issue CLICK HERE to read abut the Electromagnetic fields (EMF) None of the other companies like WarmlyYours (TempZone) or NuHeat was even close to the minimum I would recommend to any of my customers.
I chose to carry SunTouch because I care for my customers. I only carry products that I would use myself.
SunTouch Floor Heating Mat Links
SunTouch Floor Heating Spool Links
Heating Controls Links
Misc SunTouch Links