Systems can leave guests pushing buttons in vain. Now some have started resisting, scouring manuals to uncover overrides of the override

By SCOTT MCCARTNEY of The Wall Street Journal.

It’s not your imagination. Hotel thermostats often aren’t under your control.

Unknowing guests around the world are left to push thermostats up and down in vain. Fixing the problem requires a degree—or six or seven—as well as a bit of a mischievous streak.

“I can’t tell you how many times I have awakened sweating bullets at 3 a.m. and the a/c was off,” says Houston finance and accounting consultant Jay Callahan.

Clever, clammy travelers have started resisting, scouring thermostat manuals to uncover secret overrides of the override.

One Tumblr blog, thermostatbypass, collects bypass instructions. Travelers have posted YouTube videos on various thermostat models. A Disney hotel discussion board also has thermostat bypass instructions. On some Inncom thermostats, for example, hold down Display then tap Off then tap the Up arrow. That puts the unit in VIP mode, giving control back to the occupant.

A spokesman for Inncom’s parent company Honeywell International Inc. says even though the override capability has been made public, “we have not seen widespread use of it by guests.” Hotels continue to set bypasses for guests’ desired temperature on request, he said.

The humble hotel wall thermostat, once just a mechanical temperature sensor and fan-speed switch, has become an infrared heat and motion detector wirelessly networked into building controls that cut costs by reducing energy consumption. Many are tied to door switches, shutting off when people leave the room or even open a window or balcony door.

Sensors can be fooled by sound sleepers and erroneously shut off air in the middle of the night. Guests wake up and realize a quick wave of the arm will bring back A/C. Hotels acknowledge this happens. They also say lack of cleaning and maintenance can render many hotel thermostats inaccurate by as much as 20%.

Overall, hotels say new systems increase guest comfort and reduce costs. Some can measure and adjust humidity in a room. Limiting how far guests can push thermostats reduces maintenance expenses (sometimes making a room too cold can freeze up air-conditioning condensers). And new room control systems, which have become much more affordable for hotels, comply with tougher energy-conservation building codes around the country and sometimes qualify for tax rebates.

“When it comes to thermostats, the world has evolved,” says Randy Gaines, Hilton’s vice president operations and new project development for the Americas.

Hilton’s goal is for simple, passive control so guests will be comfortable without playing with the thermostat. “We’re getting far fewer complaints than we used to years ago,” he says.

The New York Hilton has a system that keeps unoccupied rooms at 78 degrees and then automatically sets the thermostat to 74 when a guest checks in. The system cools the room down in about 5 minutes. Companywide, new temperature control systems have helped Hilton reduce energy use by 14% since 2009.

Thermostat big-brothering is a sensitive subject for some hotel companies. InterContinental Hotels Group, which includes Kimpton, Holiday Inn and other brands, was lukewarm to discussing its energy policy. “This topic isn’t a fit right now,” a spokeswoman says.

Steve Torbett, a product manager from Charlotte who has spent 30 years on the road, keeps track of which hotels he stays in that use motion sensors on thermostats and refuses to book them in the future. His worst experience was in Miami a couple of years ago where a thermostat shut off air so frequently he woke up five times. “The timer was pretty short and it was just miserable waking up about every hour and having to wave your arms around,’’ he says.

Mr. Torbett says he has had to hunt down override codes less frequently because some hotels are getting better at programming the devices. On the flip side, some newer thermostats block unauthorized overrides.

Tim Fountain, who spends 150 nights a year in hotels managing sales for a technology company, thinks central limits imposed by hotels make it harder to get rooms to desired temperatures. He carries a travel alarm clock with a thermometer and says 30% of the rooms he has been in have thermostats that misreport room temperature. Worst case: a thermostat that said it was 65 when it was really 72. “It just gets to be silly,’’ he says.

Hotel consultants and owners say that more than half of all hotel and motel rooms have heating/air-conditioning units mounted on an exterior wall, called Package Terminal Air Conditioning or PTAC. They are notoriously noisy and nicknamed wall-bangers in the industry. If the units aren’t cleaned monthly and switches and controls well maintained, their temperature sensing can be inaccurate by 12% to 20%, says Greg Posmantur, chief executive of JYI Hospitality Management & Consultants, of Cypress, Texas.

“If it’s a limited-service hotel, you’re often dealing with tight budgets,” and units may not get cleaned frequently, he says.

Hotels are retrofitting wireless wall thermostats and door switches in some rooms now that devices are cheaper to buy. The advantage is that they can be centrally controlled. Guests may still fiddle with old knobs on the PTAC units, but it won’t get cooler or warmer. “We can read the room’s temperature and comfort, find out when you come, find out when you go and we can control it,” Mr. Gaines says.

Robert Rauch, a hotel owner and consultant from San Diego, says he has thermostat problems himself on the road. He sets thermostats to 66 to find the minimum temperature the hotel allows, usually 68 or 69.

“Our hotels allow guests to go down to 65, but lots of hotels are only 68 to 70,” says Mr. Rauch, chief executive of RAR Hospitality. His company manages 23 hotels, including in Phoenix and San Diego.

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