HEATWAVE Electric Floor Heating System for Tile 40 sqft 120V 4Amps 480Watts-Heated Flooring System for Bathroom Floor Heating Kit Underfloor Comfort Heat 7Day/4Event Programmable GFCI Thermostat by Heatwave

I installed Heatwave’s 40‑sq‑ft underfloor heating kit in a small bathroom remodel to add some much‑needed morning comfort. It’s a straightforward package—adhesive mesh mat, 15‑ft cold lead, floor sensor, and a 7‑day/4‑event programmable thermostat with built‑in GFCI—all designed to run at 120 V and about 480 W (roughly 4 A). After living with it through a winter, here’s how it actually performs, what’s easy, what can trip you up, and who I think will be happiest with it.

What you get and the basics

• Coverage: 40 sq ft of heating area
• Power density: about 12 W/sq ft (480 W total)
• Voltage/current: 120 V, ~4 A
• Thermostat: 7‑day/4‑event programmable, supports 120/240 V up to 15 A, built‑in GFCI
• Mat: mesh with adhesive backing; reversible layout; 15‑ft cold lead

At 12 W/sq ft, it’s tuned as a floor warmer rather than a primary heat source, especially on a slab or in colder climates. Under tile and stone, it delivers a very even, pleasant warmth that takes the edge off cold floors without creating hot spots.

Planning and layout

The mat’s reversible mesh and the ability to cut the mesh (never the heating wire) make it adaptable to typical bathroom footprints. The key is careful planning. I started by mapping the room and marking no‑heat zones: under the vanity and toilet, within a few inches of the toilet flange, and away from floor penetrations. I dry‑fitted the mat and cut the mesh to snake the cable where I wanted coverage while maintaining the manufacturer’s wire spacing.

A few planning tips that paid off:
- Keep the floor sensor centered between two adjacent heating runs and away from exterior walls or direct sunlight.
- Plan a thermal break if possible. On a cold slab or over an uninsulated space, use an insulating backer board or an uncoupling/insulation membrane rated for heat. It noticeably improves warm‑up time and reduces energy loss.
- Confirm your circuit: 4 A isn’t much, but dedicate a GFCI‑protected circuit per local code. The thermostat includes GFCI, which simplifies compliance in wet areas.

Installation experience

The adhesive backing helps, but I still consider mechanical and spot‑adhesive fastening essential. Mesh can lift when you trowel thinset or pour self‑leveling underlayment. I secured every turn and any raised sections of mesh with hot‑glue dabs and a few staples outside of any heated wire path (staples through mesh only, never through the wire). That kept the cable flat during embedment.

Two approaches work:
- Directly embedding in thinset under tile (what I did): lighter build‑up, fast workflow, excellent heat transfer. Use a flat trowel to pre‑fill over the wires, then comb your notches and set tile.
- Encasing in a primered self‑leveling underlayment: creates a perfectly flat surface for tiling or LVP/laminate installs. The caveat is buoyancy—the mesh wants to float. Aggressive pre‑bonding/gluing is mandatory.

Throughout the process, I tested the mat’s resistance against the nameplate values, and I used a simple continuity alarm while working. It’s an extra box on the floor, but it immediately alerts you if you nick a wire so you can stop and avoid burying a problem. The kit’s cold lead is long enough to reach the wall box without splices, and the jacket handled troweling abuse well.

Overall, the install is within reach for a confident DIYer comfortable with tile and basic electrical work. If you’re newer to either, budget time for layout and protection of the cable, or consider professional install. The manual is clear and methodical; follow it to the letter.

Thermostat and controls

The thermostat is utilitarian but capable. Scheduling is 7‑day with up to four events per day, and it supports both room‑ and floor‑sensing modes. For tile, I prefer floor‑sensor mode to hold a specific floor temperature regardless of room swings. It pairs cleanly with the included sensor and has built‑in GFCI, which is handy in a bathroom.

What it’s not: connected. There’s no Wi‑Fi, app, or voice control. If you value those, you’ll need a third‑party smart stat that supports floor sensors and GFCI requirements, or you can live with simple but reliable scheduling here.

One practical note: test the GFCI and sensor before closing up the wall box. It’s a 30‑second check that can save a trip back later.

Performance and comfort

Under porcelain tile on a wood subfloor with an insulating backer board, warm‑up from cold takes around 45–60 minutes to feel warm underfoot and a couple of hours to reach a steady target around the low‑80s F. On a slab or under thicker toppings, expect slower response. That’s inherent to radiant mass heating, not a flaw of the kit.

Once at temperature, heat is even and consistent with no zebra stripes. It’s quiet, invisible, and very satisfying on cold mornings. The 12 W/sq ft density keeps surface temps comfortable and safe for most floor coverings. If you’re installing under LVP or laminate, respect the flooring manufacturer’s maximum temperature (commonly 80–85°F) and use floor‑sensor control mode with a cap.

Could it heat the entire room by itself? In a tight, well‑insulated bathroom, it might; but I treat it as a comfort layer. It reduces the temptation to crank central heating just to warm tile, which is where the real day‑to‑day benefit shows.

Energy use and operating strategy

At 480 W, leaving it on continuously would be modestly costly over a month. I had good results scheduling:
- Pre‑heat 60–90 minutes before the morning routine
- Hold a lower “background” floor setpoint during the day
- Nudge back up for evening showers

Cycle time is long, so pre‑heat matters. If your space loses heat quickly (slab, exterior exposure), consider a constant low setpoint to avoid repeated long warm‑ups.

Safety and durability considerations

The thermostat’s integral GFCI adds a layer of protection that’s appropriate for wet areas. Wiring and terminations are robust, and the cold‑lead transition is well made. Still, radiant mats are unforgiving of voids: air pockets around a cable can cause localized overheating. The cure is prevention:
- Fully embed the cable; don’t leave ridges or gaps under turns
- Bond the mesh so it cannot float during pour or troweling
- Keep proper coverage and spacing; never cross or bunch the wire
- Protect the cable during other trades’ work

If you ever suspect damage, it’s far easier to fix before tile goes down. Once buried, any repair is invasive.

Where it shines, and where it doesn’t

What I liked
- Predictable, even warmth with a sensible 12 W/sq ft output
- Clear instructions and a generous 15‑ft cold lead
- Built‑in GFCI thermostat with flexible 7‑day scheduling
- Reversible mat layout makes odd rooms workable
- Good value for a basic, reliable comfort upgrade

What gave me pause
- Mesh can lift in self‑leveling compounds without thorough anchoring
- Warm‑up is deliberate, especially on slabs or over thick toppings
- No smart features; the thermostat is basic
- As with all mats, install quality is make‑or‑break for longevity

Who it’s for

• Bathroom remodelers who want a warm tile experience without overhauling HVAC
• DIYers comfortable with tile work who can follow careful layout and testing procedures
• Owners on wood subfloors or insulated assemblies; it works on slab, but plan for slower response or add insulation
• People who prefer simple schedules over app‑based controls

If you’re looking to heat a large, drafty space or expect rapid, on‑demand heat, a higher‑density system, additional insulation, or a different heating approach may suit better.

Recommendation

I recommend the Heatwave underfloor heating kit for anyone seeking a dependable floor‑warming solution under tile or stone, especially in small to medium bathrooms. It’s thoughtfully packaged, the thermostat is straightforward and safe for wet areas, and the mat delivers even, comfortable heat once properly embedded. Installation demands care—anchoring the mesh, testing resistance during each step, and planning the layout—but if you take that seriously, the result is a low‑profile luxury that makes cold mornings far more pleasant. For slab installs or non‑tile surfaces, add the right insulation and respect flooring temperature limits, and you’ll get the best from this system.