Review · 240 V unit heater
A 7,500 W hardwired ceiling unit for less than the 5,000 W units cost. The heat is real, the manual is unusually good, and the 40 amps of two-pole capacity is the catch.
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The Comfort Zone CZ230ER is a 7,500 W / 6,250 W hardwired 240 V ceiling-mount garage heater publishing 25,590 BTU/h, a 31.3 A draw, a 40 A breaker and 8 AWG copper wire — the three figures an installer needs, stated separately and correctly. It is the cheapest genuine garage heat on this site per kilowatt of output, and the right buy for a 400-600 sq ft garage if you have 40 A of two-pole capacity. It names no safety listing anywhere.
Top pick · A cold two-car garage
7,500 W with a digital thermostat, a remote and a 12-hour timer for less than the 5,000 W units cost — and its manual specifies the 40 A breaker and 8 AWG wire the load actually needs.
| Published specification | |
|---|---|
| Rated power | 7,500 W high (default) / 6,250 W low at 208–240 V |
| Current draw (maker's figures) | 31.3 A high / 26 A low — matches 7,500 ÷ 240 = 31.3 A |
| Recommended circuit breaker | 40 A or larger, per the manual — the draw grossed up by the NEC continuous-load rule is 39.1 A |
| Recommended wire | 8 AWG copper only, rated 167°F/75°C or larger, per the manual |
| Published output | 25,590 BTU/h high / 21,240 BTU/h low |
| Horizontal air throw | 18 ft (approximate), per the manual |
| Controls | Digital thermostat with an LED ambient-temperature display, remote, 12-hour timer with auto shut-off, fan-only mode. No set-point scale published |
| Weight | 25–30 lb (approximate), per the manual |
| Warranty | One year against defects in quality or workmanship (World and Main) |
| Installation | Hardwired, ceiling- or wall-mounted. No plug, and extension cords are prohibited |
| Heat type | Fan-forced |
| Maker’s coverage claim | None published — the coverage figure above is ours |
| Safety listing | Neither the listing nor the CZ230ER Series manual names a certification mark. On a hardwired 240 V unit the rating plate is what the installer works from. |
Who it is for
A two-car garage, a shop or an outbuilding of roughly 400–600 sq ft where you want it genuinely warm, and you have 40 A of two-pole space in the panel.
What it is not for
A single-car garage or a panel that is already full — 7,500 W is more heat than a small space needs and more current than a tight panel can give.
Sources for this entry
The reason this review exists is the second column below. Most garage-heater listings publish one electrical number and leave you to work out which number it is — the Fahrenheat FUH54's 26.1 A is printed as its draw almost everywhere and is actually its minimum circuit ampacity. Comfort Zone publishes the draw, the breaker and the wire separately, and all three check out.
| Specification | Comfort Zone publishes | Our arithmetic | Agree? |
|---|---|---|---|
| Rated power | 7,500 W high / 6,250 W low at 208-240 V | — | — |
| Current draw, high | 31.3 A | 7,500 ÷ 240 = 31.25 A | Yes |
| Current draw, low | 26 A | 6,250 ÷ 240 = 26.04 A | Yes |
| Output, high | 25,590 BTU/h | 7,500 × 3.412142 = 25,591 BTU/h | Yes |
| Output, low | 21,240 BTU/h | 6,250 × 3.412142 = 21,326 BTU/h | Within 0.4% — the maker's figure is the conservative one |
| Minimum circuit ampacity | “40 A or larger” breaker | 31.25 × 1.25 = 39.1 A, next standard size 40 A | Yes |
| Conductor | 8 AWG copper, rated 167°F/75°C or larger | Not ours to compute | — |
Maker's figures from the CZ230ER Series manual. Our column is watts ÷ volts for current, watts × 3.412142 for BTU/h, and the NEC continuous-load rule (125%, NFPA 70 210.19(A)(1) and 210.20(A)) for the minimum circuit ampacity.
That is four independent agreements and one conservative rounding, which is the best result any unit on this site has returned against its own paperwork. It does not make the heater better than its competitors — 7,500 W is 7,500 W whoever sells it — but it does mean the specification you hand the electrician is the specification the appliance has.
Comfort Zone publishes no coverage figure for this unit, which is the honest choice on a hardwired heater whose job depends entirely on the building. So here is ours, at the 15 W per square foot an unheated envelope needs rather than the 10 W a room inside the house uses:
| Room size | Watts needed | BTU/h | Plug-in heaters |
|---|---|---|---|
| 400 sq ft | 6,000 W | 20,473 | 4 (different circuits) |
| 500 sq ft | 7,500 W | 25,591 | 5 (different circuits) |
| 600 sq ft | 9,000 W | 30,709 | 6 (different circuits) |
| 720 sq ft | 10,800 W | 36,851 | 8 (different circuits) |
Computed as square feet x 10 W x insulation factor x (ceiling / 8 ft), for an unheated space (garage, unfinished basement) — 15 W/sq ft, 8 ft ceiling. Heater count assumes the 1,500 W plug-in ceiling.
At 7,500 W this unit covers about 500 sq ft of garage — a standard two-car space with an uninsulated door, a concrete slab and no ceiling insulation. That is the first unit on this site that genuinely closes the gap for that building: a 1,500 W plug-in heater in the same garage supplies between a sixth and a quarter of the demand, which is not a quality problem but an arithmetic one.
The manual also publishes an 18-foot horizontal air throw, which is the specification that decides whether a ceiling-mounted fan-forced unit reaches the bench you actually stand at. In a 20-foot garage, mounted at the back wall and aimed down the length, that figure is the difference between a warm shop and a warm ceiling.
| Wattage | Per hour | 1 h | 4 h |
|---|---|---|---|
| 1,500 W | 27.5¢ | $0.28 | $1.10 |
| 6,250 W | 114.6¢ | $1.15 | $4.58 |
| 7,500 W | 137.6¢ | $1.38 | $5.50 |
Computed at 18.34¢/kWh — the U.S. residential average for June 2026 (EIA, Electric Power Monthly, Table 5.6.A, released August 26, 2026). Your rate is on your own bill; substitute it and the arithmetic still holds. Figures assume full output for the whole period.
$1.38 an hour at full output is the highest running cost of anything on this site, and it is not inefficiency — electric resistance heating is essentially 100% efficient at any wattage, so you are buying five times the heat of a plug-in heater and paying five times as much for it. The low setting is a genuine second operating point at $1.15 an hour, and the gap between them is smaller than people expect because 6,250 W is only a sixth less than 7,500 W.
Which makes the 12-hour timer with auto shut-off the feature that protects the bill rather than a convenience. On a 7,500 W load, forgetting the heater for a working day costs about $11. A garage heater is exactly the appliance people forget, and it is the only unit in its class here that ships with a timer.
The rate behind every figure on this site
18.34¢per kilowatt-hour
U.S. residential average for June 2026. EIA, Electric Power Monthly, Table 5.6.A, released August 26, 2026.
This is the most recent month EIA has published. Residential rates move seasonally and vary enormously by state — from roughly a dime per kilowatt-hour in parts of the South to more than 40¢ in Hawaii — so treat it as a national reference point, not as your rate.
There is no plug on this heater and the manual prohibits extension cords. It is hardwired to a dedicated two-pole circuit and bolted to a ceiling or wall bracket, which in most jurisdictions is licensed work with a permit attached. Get the quote before the heater, not after.
| Rated power | Draw at 240 V | Minimum circuit ampacity | Smallest standard breaker | Output |
|---|---|---|---|---|
| 5,000 W | 20.8 A | 26.0 A | 30 A | 17,061 BTU/h |
| 6,000 W | 25.0 A | 31.3 A | 35 A | 20,473 BTU/h |
| 7,500 W | 31.3 A | 39.1 A | 40 A | 25,591 BTU/h |
Draw computed as watts / 240 V. Minimum circuit ampacity is 125% of the draw, per the NEC continuous-load rule (NFPA 70, 210.19(A)(1) and 210.20(A)); the breaker column is the smallest standard rating at or above it (240.6(A)). Confirm against your own unit's rating plate and manual — the installer sizes the conductors.
Four gaps, and the first is the one worth weighing hardest.
This heater is sold twice on the same marketplace: once as the CZ230ER and once as the CZ230ERBK. The titles are otherwise word-for-word identical, the suffix is the colorway, and one manual covers both. The two listings are priced and stocked independently, which means the cheaper one changes.
When we checked on 2026-10-17 the CZ230ER was the cheaper of the two and in stock, while the CZ230ERBK was a few dollars more and carried a two-to-four-week lead time — so our buy link points at the first one. Both listings show their own live price. Open both before you buy; on another day the answer is the other way round.
| Unit | Output | Cost per kilowatt of output | Certification published |
|---|---|---|---|
| Comfort Zone CZ230ER | 7,500 W | The lowest of the four | None published |
| Comfort Zone CZ220 | 5,000 W | Within a dollar per kW of the CZ230ER | “ETL Compliant” in the listing only |
| Dr. Infrared DR-966 | 6,000 W | About half again as much | UL and cUL Listed |
| Fahrenheat FUH54 | 5,000 W | About six times as much | None published |
Relative cost per kilowatt of output as checked on 2026-10-17 — deliberately relative rather than absolute, because prices move daily and every buy link on this site shows the live one. Full picks and the breaker each unit needs are on the 240 V roundup.
The CZ230ER and its 5,000 W sibling are the value end of this market, and the FUH54 is roughly six times the cost per kilowatt — which buys a Marley-published thermostat range, an automatic fan delay and a named manufacturer with a support line, and does not buy more heat. All four compared, with the breaker each one needs.
31.3 A at 240 V on its high setting and 26 A on low — the maker's published figures, and they match the arithmetic exactly (7,500 ÷ 240 = 31.25 A). The 40 A figure in the manual is the breaker size, not the draw.
A 40 A two-pole breaker. The heater draws 31.3 A, the NEC continuous-load rule requires the circuit to be sized at 125% of that — 39.1 A — and the next standard breaker size up is 40 A. The CZ230ER manual specifies 40 A or larger and 8 AWG copper, which agrees.
Yes, which is the point of it. A two-car garage of 400-600 sq ft with an uninsulated door needs roughly 6,000-9,000 W at the 15 W per square foot an unheated envelope wants, and 7,500 W sits inside that range. Comfort Zone publishes no coverage figure; our computed figure is about 500 sq ft of garage.
About $1.38 an hour at 7,500 W and $1.15 an hour on its 6,250 W setting, at the US average residential rate of 18.34 cents per kilowatt-hour. That is the highest hourly figure on this site, in proportion to the heat — resistance heating is essentially 100% efficient at any wattage.
Not that we can verify. Neither the Amazon listing nor the CZ230ER Series manual names a UL or ETL mark anywhere. On a hardwired unit the rating plate and the installation inspection carry more weight than on a portable, but the Dr. Infrared DR-966 in the same class does publish UL and cUL listing.
The colorway suffix, and nothing else we can find — the listing titles are otherwise identical and one manual covers both. They are priced and stocked independently, so check both; on 2026-10-17 the CZ230ER was the cheaper one and in stock, while the CZ230ERBK was a few dollars more on a two-to-four-week lead time.
No. It is a hardwired 240 V appliance with no plug, and the manual prohibits extension cords. If a plug-in solution is the requirement, nothing in the 120 V category will heat a two-car garage — the ceiling there is 1,500 W.
5,000 to 7,500 W, hardwired. The draw, the breaker each one needs, and four units whose manuals we read.
A two-car garage needs about 9,000 W. An outlet gives you 1,500. What to do instead.
5,000 W of real garage heat — and the 26.1 A figure in every listing is the circuit rating, not the draw.
12.5 A against a 12 A continuous limit — the arithmetic nobody publishes, and what to do about it.
5,000 W of demand against 1,500 W of supply — what actually works in a studio or open-plan space.
Size the room, decide room-or-person, then type, thermostat, cutoffs and shape — in that order, with a rule at each step.