Best baseboard heater: the circuit and the thermostat are the real purchase, so the maker spec sheets sort Cadet, King and Fahrenheat 240 V and 120 V units by watts, amps, BTU, length and listing mark
Maker sheets compared: Cadet 6F1500 72 in 1,500 W 6.3 A 5,120 BTU UL; 3F750W 750 W 3.1 A; King 3K2407 cULus; plug-in Fahrenheat FBE15002 120 V 12.5 A.
- Verified
- Updated
- 11 min read
- 15 sources
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OwnerSpec compares published manufacturer specifications, certification listings and sourced technical documents. Unless a page explicitly states otherwise, OwnerSpec has not laboratory-tested or used the products it compares. Editorial policy
Short answer
The best electric baseboard heater for a normal US room is the Cadet 6F1500 (part 09956): Cadet’s F Series sheet prints 72 in, 1,500 W at 240 V (1,125 W at 208 V), 6.3 A, 5,120 BTU, a UL listing and a lifetime warranty. For a small room the 36 in Cadet 3F750W prints 750 W, 3.1 A and 2,560 BTU. The King 3K2407 is the step up: King’s submittal prints the same 750 W and 3.1 A, King’s page prints a cULus listing, and the submittal prints a 7-year limited warranty. Every one of these is hardwired and sold without a thermostat: Cadet’s sheet says all models require hard-wire installation and a thermostat, and its manual puts a 240 V unit on a double-pole breaker and a circuit dedicated to electric heat. If you rent or cannot touch the panel, the plug-in Fahrenheat FBE15002 prints 1,000 or 1,500 W at 120 V, 8.3 or 12.5 A, with its own thermostat.
The picks
The standard bedroom or living room run on a 240 V circuit
Cadet 6F1500 (part 09956) 72 in 1,500 W 240 V baseboard
Cadet F Series sheet: 72 in, 1,500 W at 240 V (1,125 W at 208 V), 6.3/5.4 A, 5,120/3,840 BTU, hardwired, thermostat required and sold separately, high-temperature shutoff, UL listed, lifetime warranty
Small bedroom or office, the short hardwired run
Cadet 3F750W (part 09952) 36 in 750 W 240 V baseboard
Cadet F Series sheet: 36 in, 750 W at 240 V (563 W at 208 V), 3.1/2.7 A, 2,560/1,925 BTU, hardwired, thermostat sold separately, UL listed, lifetime warranty
Hallway, entry or window nook where 500 W is enough
Cadet 2F500W (part 09950) 30 in 500 W 240 V baseboard
Cadet F Series sheet: 30 in, 500 W at 240 V (375 W at 208 V), 2.1/1.8 A, 1,710/1,280 BTU, hardwired, thermostat sold separately, UL listed, lifetime warranty
Wants a cULus mark and the longer warranty printed on a submittal sheet
King 3K2407-BK-BW K Series 3 ft 750 W 240 V baseboard with back-wire junction box
King K Series submittal, row 3K2407: 3 ft, 750 W at 240 V (563 W at 208 V), 3.1/2.7 A, aluminum ribbon fin element, full-length cutout, thermostat kit BKT1 or BKT2 sold separately, cULus listed on King's page; 7-year limited warranty on the submittal, 1-year on the web page
Renter, or no free breaker slot: the only plug-in unit here
Fahrenheat FBE15002 portable 120 V plug-in baseboard
Marley FBE Series page: 1,000/1,500 W, 120 V, 8.3/12.5 A, 3,413/5,120 BTU/h, built-in thermostat, thermal cutoff, 2-year limited warranty, 11 lb; the page prints no listing mark
If you need heat for a few cold evenings a year, or the panel is off limits, this is the wrong page: the best space heater comparison covers plug-in units, and only one heater below has a cord.
How was this shortlist built?
This is a comparison of published specifications, not a test. OwnerSpec read the Cadet F Series sheet and manual, the King K Series submittal and pages, the Marley flyers and manual for the Fahrenheat F2500, PLF and FBE lines, and the Stelpro Brava B catalogue on 2026-10-10, and confirmed every listing in stock that day.
The specs that sort baseboards are few: length, watts at 240 and 208 V, amps, BTU, built-in or separate thermostat, and the listing mark as printed. Every sheet derates its dual-rated models at 208 V; King’s footnote puts it at 25 percent less wattage and 13 percent fewer amps.
Two gaps: Stelpro’s US AB-series has no readable US sheet, so Stelpro appears only through its Canadian B-series catalogue, and Cadet’s SoftHeat page prints no wattage table, so the only hydronic row is Fahrenheat’s PLF.
How do the units compare on paper?
Watts, amps and BTU are the makers’ printed figures at 240 V, with the 208 V rating after the slash where the sheet prints one.
| Model (maker document) | Length | Watts 240/208 V | Amps | BTU | Thermostat | Listing mark as printed |
|---|---|---|---|---|---|---|
| Cadet 2F500W, part 09950 (F Series sheet) | 30 in | 500/375 | 2.1/1.8 | 1,710/1,280 | separate, BTF1 or BTF2 kit | UL listed |
| Cadet 3F750W, part 09952 (F Series sheet) | 36 in | 750/563 | 3.1/2.7 | 2,560/1,925 | separate | UL listed |
| Cadet 4F1000, part 09954 (F Series sheet) | 48 in | 1,000/750 | 4.2/3.6 | 3,415/2,560 | separate | UL listed |
| Cadet 6F1500, part 09956 (F Series sheet) | 72 in | 1,500/1,125 | 6.3/5.4 | 5,120/3,840 | separate | UL listed |
| Cadet 8F2500, part 03360 (F Series sheet) | 96 in | 2,500/1,875 | 10.4/9.0 | 8,530/6,400 | separate | UL listed |
| King 3K2407 (K Series submittal) | 3 ft | 750/563 | 3.1/2.7 | not in the row read | separate, BKT1 or BKT2 kit | cULus (product page) |
| King 6K2415 (K Series submittal) | 6 ft | 1,500/1,125 | 6.3/5.5 | not in the row read | separate | cULus (product page) |
| King 8K2424 (K Series submittal) | 8 ft | 2,400/1,800 | 10.0/8.7 | not in the row read | separate | cULus (product page) |
| Fahrenheat F2546W (F2500 flyer) | 6 ft | 1,500/1,128 | 6.3/5.4 | 5,120/3,850 | separate, TA2AW kit | UL listed |
| Fahrenheat F25408W (F2500 flyer) | 8 ft | 2,500/1,880 | 10.4/9.0 | 8,533/6,416 | separate | UL listed |
| Fahrenheat PLF1504 hydronic (PLF flyer) | 70 in | 1,500/1,125 | 6.3/5.8 | 5,120/3,839 | separate, PT2DS kit | UL listed (product page) |
| Stelpro Brava B1502W (B catalogue) | 66 1/4 in | 1,500/1,125 | not printed in the row read | not printed | optional built-in SIBT1W or SIBT2W | CSA/UL mentioned in the manual |
| Cadet 6F1500-1, 120 V (F Series sheet) | 72 in | 1,500 at 120 V | 12.5 | 5,120 | separate | UL listed |
| King 4K1210, 120 V (K Series submittal) | 4 ft | 1,000 at 120 V | 8.3 | not in the row read | separate | cULus (product page) |
| Fahrenheat FBE15002, 120 V plug-in (FBE page) | 46 in listing | 1,000/1,500 at 120 V | 8.3/12.5 | 3,413/5,120 | built in | none printed |
Two patterns fall out of the table. At 240 V the same wattage draws half the amps of the 120 V version (Cadet’s 6F1500 at 6.3 A against its 6F1500-1 at 12.5 A), which is why Marley’s 15 A row fits a whole room of 240 V baseboard and barely one 120 V unit. And the length tracks the watts almost one to one across makers: Stelpro prints the rule as 250 W per linear foot.
What circuit does a baseboard need?
Marley’s 2500 Series manual, Table 1, is the only baseboard-specific wire table that was readable. King’s table is its generic heater table and agrees with it.
| Total heater amps on the circuit | Minimum copper wire (Marley Table 1) | Breaker (Marley Table 1) | King’s generic table, 240 V example |
|---|---|---|---|
| 0 to 12 A | #14 | 15 A | 500 W 2.1 A, 1,000 W 4.2 A, 2,250 W 9.4 A, 2,850 W 11.9 A: all #14/2, 15 A two-pole |
| 12.1 to 16 A | #12 | 20 A | 120 V 1,750 W 14.6 A: #14/2, 20 A |
| 16.1 to 24 A | #10 | 30 A | 120 V 2,250 W 18.8 A: #12/2, 25 A |
King’s rule behind the table: wire and protection are sized for at least 125 percent of the heater load, or equivalently the load should not exceed 80 percent of the branch circuit rating. On that rule a 15 A two-pole 240 V circuit carries up to about 2,850 W of baseboard, which is one 6F1500 plus one 4F1000 and change.
Cadet’s manual adds what the table does not: copper conductors only, a double-pole breaker for 240 V, a single-pole for 120 V, and a circuit dedicated to electric heaters, shared with no outlets, lights or appliances. The breaker-tripping guide covers what the 120 V side of the panel can take, and the running cost calculator turns the watts above into a monthly bill at your rate.
Cadet 6F1500: buy it or skip it?
Buy it if the room has a 240 V run and an outside wall under a window, Cadet’s recommended spot. The F Series sheet prints 72 in, 1,500 W at 240 V and 1,125 W at 208 V, 6.3/5.4 A, 5,120/3,840 BTU, a high-temperature shutoff, a UL listing, hard-wire only, and a lifetime warranty.
The flaw is the label. The sheet says all models require a thermostat, and the manual says to match the voltage on the old heater’s nameplate: Marley’s manual puts the other direction bluntly: never connect a heater to a voltage above its nameplate. Cadet’s own article claims baseboards usually last more than 20 years against 8 to 12 for its wall heaters.
Skip it if the wall is shorter than 6 ft plus Cadet’s 6 in side clearance each side: the Cadet 3F750W halves the length and the heat.
Cadet 3F750W and 2F500W: buy them or skip them?
Buy one for a small bedroom, office, hallway or entry. The F Series sheet prints the 3F750W (part 09952) at 36 in, 750/563 W, 3.1/2.7 A and 2,560/1,925 BTU, and the 2F500W (part 09950) at 30 in, 500/375 W, 2.1/1.8 A and 1,710/1,280 BTU, both hardwired, UL listed and under lifetime warranty.
The flaw is that the electrician costs the same for 500 W as for 1,500 W. A 2F500W at 2.1 A makes sense where the circuit exists already, or where several small units share one 15 A two-pole run, which Marley’s Table 1 allows up to 12 A.
Skip both for a bathroom: Cadet’s article calls a wall heater the logical choice for a small room like a bathroom, because such rooms rarely have long stretches of free wall near the floor, and Cadet’s sheet prints the 1,000 W 4F1000 at 48 in.
King 3K2407: buy it or skip it?
Buy it if you want the paperwork printed. King’s K Series submittal, row 3K2407, prints 3 ft, 750 W at 240 V and 563 W at 208 V, 3.1/2.7 A, an aluminum ribbon fin element, a full-length cutout, a back-wire design and an optional high-altitude limit for use above 7,000 ft; King’s product page prints a cULus listing. The linked listing is the -BK version with a back-wire junction box.
The flaw is that King’s two documents disagree: the submittal prints a 7-year limited warranty and the product page prints 1 year, and King’s own installation PDF was not readable this session, so its clearances are not quoted here.
Skip it if you only need the watts: the Cadet 3F750W prints the same watts and amps.
Fahrenheat FBE15002: buy it or skip it?
Buy it if you rent, the panel is full, or the heat is for one winter. Marley’s FBE Series page prints 1,000/1,500 W at 120 V, 8.3/12.5 A, 3,413/5,120 BTU/h, a built-in thermostat, a thermal cutoff, 11 lb and a 2-year limited warranty, and it is the only unit on this page with a plug.
The flaw is the circuit it shares: at 12.5 A it takes most of a 15 A outlet circuit, and Marley’s page prints no listing mark. King’s KP1210 is the smaller alternative at 1,000 W, 120 V, 8.3 A and 4 ft, with a built-in thermostat, a 6 ft grounded cord, a tip-over switch and a cULus listing on King’s page.
Skip it if a 240 V run is possible: the best oil-filled radiator comparison is the other plug-in route at the same 1,500 W ceiling, and the hardwired Cadet needs the electrician and the thermostat on top.
Count the whole bill before the heater
Do not order a hardwired baseboard until you know three things: whether a two-pole breaker slot is free, what the run’s wire can carry on Marley’s Table 1, and which thermostat the room will use. The heater is the cheap part; the circuit and the thermostat are the purchase. If the room is a garage or a shop, the best garage heater comparison sorts the 240 V forced-air units instead.
Which thermostat does it need?
A line-voltage thermostat switches the heater’s own 240 V or 120 V supply; the 24 V thermostat wiring covered in the thermostat wire colors guide does not apply. Cadet’s sheet lists the BTF2 double-pole built-in kit and the BTF1 single-pole kit, both 22 A at 120, 208 or 240 V with a 40 to 85 F range; Marley lists the TA2AW at 22 A for the F2500 and the PT2DS at 25 A for the PLF, and King sells the BKT1 and BKT2.
Cadet’s manual explains the pole count: a double-pole thermostat has an OFF setting and a single-pole one does not. Honeywell’s and Mysa’s line-voltage pages were not readable this session, so their load ratings are not quoted.
Who should skip all of them?
Anyone who cannot open the panel. Cadet’s manual says to consult a licensed electrician if you are uncomfortable with wiring or installing a breaker, and Stelpro’s manual says its heaters are installed by a qualified person and connected by a certified electrician under the NEC.
Anyone with a short wall or a receptacle in the way. Cadet, Marley and Stelpro all say never to install a baseboard below an electrical receptacle, and Cadet wants 12 in clear above and in front.
Anyone heating a bathroom or a workshop. Cadet points bathroom buyers at a wall heater; the best garage heater page covers shops.
What goes wrong?
The drapes touch it. Marley’s manual keeps drapes and furniture at least 6 in from the heater, and allows carpet up to 3/4 in only where it does not block airflow.
The thermostat is single-pole. Cadet’s manual says it has no OFF, so the heater can run whenever the dial drops below room temperature in a shoulder season.
The circuit is shared. Cadet’s manual wants a circuit dedicated to electric heaters; a 12.5 A plug-in unit on a bedroom outlet circuit is how a 15 A breaker trips. The space heater deal check says when the plug-in prices on the cards above tend to move.
Frequently asked questions
What size breaker does a 1,500 W 240 V baseboard heater need?
Cadet prints 6.3 A for its 1,500 W 240 V 6F1500. Marley's 2500 Series manual Table 1 puts any load from 0 to 12 A on #14 copper with a 15 A breaker, and King's sizing table puts 1,000 W at 240 V on #14/2 with a 15 A two-pole breaker. Cadet's manual says a 240 V heater takes a double-pole breaker on a circuit dedicated to electric heat.
Can you plug a baseboard heater into a wall outlet?
Only a portable model. Cadet's F Series sheet says all models require hard-wire installation with no cord or plug. The Fahrenheat FBE15002 is the plug-in exception on this page: Marley prints 1,000 or 1,500 W at 120 V, 8.3 or 12.5 A and a built-in thermostat, and King's KP1210 prints 1,000 W, 120 V, 8.3 A and a 6 ft grounded cord.
Does a baseboard heater come with a thermostat?
Hardwired ones usually do not. Cadet's sheet says all models require a thermostat and sells the BTF1 single-pole and BTF2 double-pole built-in kits, both rated 22 A at 120, 208 or 240 V. King's K Series page says the thermostat is required and sold separately. Cadet's manual adds that a double-pole thermostat has an OFF setting and a single-pole one does not.
How much wall does a baseboard heater need?
Roughly the length in the table: Cadet prints 72 in for 1,500 W and 36 in for 750 W, and Stelpro's Brava catalogue prints a 250 W per linear foot density. Cadet's manual asks for 12 in clear above and in front and 6 in at each side, and both Cadet and Marley say never to mount a baseboard below an electrical receptacle.
Is a hydronic baseboard heater better than a standard one?
Marley's Fahrenheat PLF flyer describes an element partially submerged in a heat-transfer fluid sealed in a 7/8 in copper tube, with a 10-year limited warranty on the element; its PLF1504 prints 1,500 W, 6.3 A and 70 in. Cadet says its SoftHeat line has lower surface temperatures than a standard baseboard but prints no wattage table, so this page has no hydronic pick.
Fact sheet and how to cite this page
- Answer
- The Cadet 6F1500 is the pick for a normal room: Cadet’s F Series sheet prints 72 in, 1,500 W at 240 V, 6.3 A, 5,120 BTU and a UL listing, hardwired with the thermostat sold separately. The 36 in Cadet 3F750W prints 750 W and 3.1 A for a small room. Without a 240 V circuit, the plug-in Fahrenheat FBE15002 prints 1,500 W, 120 V and 12.5 A with its own thermostat.
- Comparison basis
- Manufacturer specification sheets and manuals for the Cadet F Series (Glen Dimplex Americas), the King K Series submittal and product pages (King Electric), the Fahrenheat F2500, PLF and FBE Series (Marley Engineered Products) and the Stelpro Brava B catalogue, compared on length, watts at 240 and 208 V, amps, BTU, thermostat arrangement, listing mark and warranty; Marley’s 2500 Series Table 1 and King Electric’s circuit-sizing page for wire gauge and breaker by amps.
- Assumptions
- A US single-phase 240 V or 120 V supply; watts, amps and BTU are the figures each maker prints for the 240 V and 208 V ratings
- ‘Not printed’ means the maker document read on 2026-10-10 does not list the item; it is not proof the heater lacks it
- Wire gauge and breaker figures are Marley’s Table 1 (copper, by total amps) and King Electric’s generic heater table at 125 percent of load; the nameplate, the manual and local code govern
- Each Amazon listing was matched to the maker model by the listing title and part number; the King listing is the -BK back-wire junction box version of the 3K2407 row
- No maker or regulator sizing rule in watts per square foot was found, so this page states none; the makers print watts per unit and Stelpro prints 250 W per linear foot
- Method
- OwnerSpec compared manufacturer-published specifications read on 2026-10-10 and confirmed each linked listing in stock the same day. No heater was installed, run, measured or used, and the page reports only the figures the cited document states. Prices on the product cards are Amazon’s live figures and are never written into this page.
- Primary source
- Cadet F Series electric baseboard product sheet (Glen Dimplex Americas) (manufacturer or vendor document)
- Facts verified
- Last updated
- Cite as
- OwnerSpec, "Best baseboard heater: the circuit and the thermostat are the real purchase, so the maker spec sheets sort Cadet, King and Fahrenheat 240 V and 120 V units by watts, amps, BTU, length and listing mark", https://ownerspec.com/air/reviews/best-baseboard-heater/, facts verified 10 October 2026.
Every figure above also appears, with its source, in the article. All sources ยท How OwnerSpec verifies numbers
Sources
- Cadet F Series electric baseboard product sheet (Glen Dimplex Americas) (manufacturer or vendor document)
- Cadet F Series baseboard owner's manual (manufacturer or vendor document)
- King Electric K Series baseboard submittal sheet (manufacturer or vendor document)
- King Electric K Series product page (manufacturer or vendor document)
- King Electric, Pro tips: sizing the heater circuit (manufacturer or vendor document)
- King Electric KP1210 portable baseboard page (manufacturer or vendor document)
- Marley Engineered Products, Fahrenheat F2500 sales flyer (manufacturer or vendor document)
- Marley 2500 Series installation, operation and maintenance instructions (manufacturer or vendor document)
- Marley Engineered Products, Fahrenheat PLF hydronic sales flyer (manufacturer or vendor document)
- Marley Engineered Products, Fahrenheat PLF product page (manufacturer or vendor document)
- Marley Engineered Products, Fahrenheat FBE Series page (manufacturer or vendor document)
- Stelpro Brava B electric baseboard catalogue sheet (manufacturer or vendor document)
- Stelpro Brava B installation manual (manufacturer or vendor document)
- Cadet, Electric baseboard or wall heater (manufacturer or vendor document)
- Cadet, Advantages of SoftHeat hydronic baseboard (manufacturer or vendor document)