Dr. Infrared DR-975 Review: 7,500W With a Low Setting That Matters

Buy the Dr. Infrared Heater DR-975 7,500W 240V garage heater for a two-car garage or shop that needs real heat on cold days and only a little on mild ones. Its 4,700 W low setting is the reason to pick it over the cheaper Comfort Zone CZ230ER: on low it still makes about 16,000 BTU/h, but it isn't running at full blast every time the thermostat calls.

Three things to accept first. It's hardwired, and the manual says a certified or licensed electrician installs it on its own 40 amp circuit with 8 AWG copper, so the circuit can cost more than the heater. Its built-in remote thermostat bottoms out at 50°F, so on its own it can't hold a garage at 40°F. And the manual says it isn't a residential or household heater and can't run where gasoline, paint or flammable liquids are used or stored.

If the low setting doesn't matter to you, Comfort Zone's CZ230ER makes the same 7,500 W for noticeably less money. There isn't much owner history on the DR-975 itself, so our verdict leans on the manual, the arithmetic and owners of its smaller sibling.

Size it from the manual, not the box

Dr. Heater gives a sizing rule most makers skip: 1.25 watts per cubic foot. At 7,500 W that's 6,000 cubic feet of garage, so the floor area it covers depends on the ceiling:

That lines up with the common 10 watts per square foot rule for an 8 foot ceiling, which also lands at 750 square feet. Both are rules of thumb. Insulation, the door and how cold your winters get matter more, and an uninsulated garage at those sizes will struggle on the coldest mornings. The heat is resistance heat: 7,500 W makes 25,597 BTU/h at any outdoor temperature, the same as any other 7,500 W heater.

The low setting is the point

HIGH is 7,500 W and LOW is 4,700 W, about 63% of full power. By our arithmetic LOW still makes about 16,000 BTU/h. Comfort Zone's CZ230ER, its closest rival, has a LOW of 6,250 W, 83% of its HIGH, so in a smaller or better-insulated garage the Comfort Zone mostly cycles at near full power. The DR-975's low setting should give longer, steadier cycles once the space is warm.

One quirk: the manual says you can only switch between HIGH and LOW while the heater is heating. When the room is above the setpoint, the button does nothing. One owner who added a wall thermostat reports that the heater keeps whichever mode you last chose every time it turns on.

Thermostat, remote and timer

• Range: 50-85°F on the remote, per Dr. Heater's product page; the manual doesn't print a range. That rules out holding a garage just above freezing. The CZ230ER's digital thermostat goes down to 45°F, and the plug-in DR-988 to 37°F.
• Swing: the manual says it starts heating at 2°F below the setpoint and stops at 2°F above it, a 4°F band. Factory setting is 70°F.
• Timer: shuts the heater off after 1 to 12 hours, 3 by default. Useful if you forget it on a Saturday night.
• Wall thermostat: the manual lists a 240 V line-voltage double-pole wall thermostat (Dr. Heater's DR-001, sold separately) as compatible, installed by a licensed electrician. Pick it if you'd rather not hunt for a remote.

The install the manual requires

We won't walk you through wiring it, and neither should a forum. Here is what the manual requires, so you can price the job before you buy:

• Electrician: all wiring by a certified or licensed electrician, to local codes.
• Circuit: its own branch circuit on a 40 amp double-pole breaker, with 8 AWG copper supply wire. No cord, no plug.
• Off switch: the circuit breaker is the heater's power switch. The manual wants the breaker within sight of the heater or able to be locked open, which may mean a disconnect near the heater if your panel is in another room. Ask your electrician.
• Mounting: wall or ceiling, at least 6 feet off the floor, at least 1 foot from adjacent surfaces, and 4.5 inches from the back wall even with the wall bracket.
• Clearance: keep combustibles at least 3 feet from the front and away from the sides and rear.

Budget the electrician and any permit alongside the heater. If your panel has room and the garage is close, it's a modest job; a long run or a full panel is not. The DR-988 dodges the hardwiring with a plug, but it still needs a dedicated 30 amp circuit and a NEMA 6-30R receptacle, and its manual says floor use only.

What the manual rules out

The DR-975 manual carries the same limits as the DR-988's, and they decide whether it belongs in your space. It says DO NOT USE AS A RESIDENTIAL OR HOUSEHOLD HEATER, and we read that as ruling out a garage converted into living space, a bonus room or a basement apartment. It says a heater has hot and arcing or sparking parts inside and not to use it where gasoline, paint, or flammable vapors and liquids are used or stored. In most garages that means moving the gas cans, the mower fuel and the paint shelf out of the heated space, not picking a different heater; the CZ220, FUH54 and DR-988 manuals carry the same warning. It's also not for outdoor use.

If it overheats, an alarm light flashes. The manual says to turn it off at the breaker, wait for the thermal cutoff to reset, look for anything blocking the airflow, and call an electrician if it trips again. It also says not to open or repair the heater yourself.

Running cost

At full power the DR-975 uses 7.5 kWh for every hour the elements are on, and 4.7 kWh on LOW. At an example rate of 15 cents per kWh that's about $1.13 an hour on HIGH and $0.71 on LOW; multiply by your own rate. The thermostat cuts that once the garage is warm. For a few hours on weekends it's affordable heat. All winter, it isn't.

A heat pump moves heat instead of making it. ENERGY STAR's cold-climate criteria call for a coefficient of performance of at least 1.75 at 5°F, which would make the DR-975's 25,597 BTU/h on about 4.3 kW instead of 7.5, roughly 43% less electricity on the coldest night and more on mild ones. If you heat the garage most days or want it cooled in summer, a mini-split is the better buy.

Reliability and warranty

We'd call it unproven rather than weak. DR-975 owners rarely post about it, and when they do it's to add a wall thermostat, not to report a failure. Owners of the smaller DR-966, Dr. Infrared's 3,000 and 6,000 W hardwired heater, are more forthcoming: one has run theirs four winters in a partly insulated Michigan garage, another holds a 20 x 25 foot garage at 53°F on its 3,000 W low setting. That says something about the brand's hardwired line, not about the DR-975's own track record.

The warranty is a one-year limited component warranty, and the manual says nothing more about what it covers. Register it on Dr. Heater's site, keep the receipt, and use the service line in the manual (1-800-317-1688). The heater is UL and cUL listed, per its product page.

How it compares

• Comfort Zone CZ230ER: same top output, a lower thermostat floor and a lower price when we checked. Its LOW is only modestly lower than its HIGH. Pick it if you'll mostly run it flat out in a cold garage.
• Dr. Infrared DR-988: about 25% less heat (7,500 is 34% more than 5,600) on a plug instead of hardwiring, for about half the price. Floor use only per its manual.
• Mr. Heater Big Maxx MHU50: if you have natural gas or propane and heat a bigger space often. It needs venting and a qualified gas installer, and costs much more up front.

Who should buy it

Buy the DR-975 if your garage is in the 500-750 square foot range for its ceiling height, you'll pay an electrician for a 40 amp circuit, and you want a heater that throttles back to 4,700 W instead of slamming on at near full power. Skip it for living space, for holding a garage at 40°F while you're away, or if the CZ230ER's lower price matters more than the low setting. And move the gas cans, whichever heater you buy.