Flammable Vapor Sensors

There are many things a flooring contractor has to worry about on the jobsite. Finishing wood floors, in particular, poses a unique set of concerns: adhesion, air flow, dry times, other trades on the jobsite, and even pets in the home. But a new issue recently has caught the attention of our industry: the flammable vapor sensor on some hot water heaters.

There have been numerous reports in recent months about flammable vapor sensors tripping when finish is being applied to wood floors. The sensors are intended to detect flammable vapors that could combust, causing a fire or catastrophic explosion. When these kinds of vapors are detected, the sensor trips and shuts off the hot water heater to prevent a potentially dangerous situation. It also results in the loss of hot water for the homeowner, which may not seem like a significant problem, but some contractors are reporting that the sensors cannot be reset. This means that the sensor will need to be replaced, or, more inconveniently, the entire water heater will need to be replaced.

“It has happened to me,” says Dave Snyder with D Snyder Hardwood Flooring in East Hanover, New Jersey. “In fact, it has happened three times.”

In Snyder’s case, he was working in another area of the house, on a different level than where the hot water heater was located, all three times he encountered this issue. “Each time it happened, we were on the first floor of the home, and the hot water heater was in the basement,” he said. “We were finishing about 50 percent of the flooring on that first level on each job when the sensor tripped. The problem is, the system won’t reset once the sensor trips, so it requires a service call.”

Snyder shared that one customer was an HVAC mechanic and was able to replace the sensor for about $35, but other customers without that expertise would have to pay for a service call as well. He also has heard of other situations where the homeowner has been told that the entire unit must be replaced. “The issue is that, in some cases, the plumbers who are called in to trouble shoot the job are taking advantage of the situation,” says Snyder, “so instead of a simple $35 repair, the homeowner is left with the cost to replace the entire unit. That can run about $1,200 or more with labor.”

A call to AO Smith, a leading manufacturer of hot water heaters, revealed that different units react differently to the sensor tripping. In some cases, it may be possible to turn off the hot water heater to avoid the system tripping. In other cases, that may not work, and the system may trip as soon as it is turned back on. In all cases, it is recommended to call the hot water heater manufacturer to evaluate the issue on a case-by-case basis to avoid an unnecessary service call with a plumber.

Steve Dana with Dana Floor Sanding in Erie, Pennsylvania, has run into the same problem in his market as well. “There has been no pattern to it,” he shares. “It has happened to us four times in the last year or so, and each time, the conditions were different. One job was during the spring with no humidity and the windows open; another time was during the early summer with mild humidity, the windows open and the ceiling fans running; and another time was during the winter with no humidity and the windows closed. The environmental conditions just didn’t seem to be a factor.”

Like Snyder, all the jobs on which Dana experienced the problem were when they were working on a different floor than the hot water heater. “On the first job,” he said, “we were putting down about 400 square feet of an oil-based poly that was about 450 VOCs, and we were doing about two quarts per coat. We had the windows open and we had fans running. The customer was sleeping in the basement during the refinish and said they couldn’t smell any fumes at all. But the next day, sure enough, no hot water.”

Dana called in a friend who also was an HVAC mechanic. The mechanic was able to reset the sensor, but told Dana that the code could only be reset once. After that, he said that the system locks out and will need to be replaced. The mechanic’s feeling was that some sensors may be more sensitive than others, but he had no real sense of which units, or manufacturers, were more affected than others.

“What’s weird,” said Dana, “is that none of the variables you’d think would possibly trip the sensor were an issue. The jobs were not huge, maybe 400 to 600 square feet, we weren’t using stain, we had good ventilation, we sealed off our work area, and the furnace wasn’t running to move fumes throughout the home. There was just no common denominator that we could say was causing the problem, except that the hot water heaters were all fairly new, maybe two or three years old or so.”

While it may seem intuitive to conclude that newer water heaters may be the problem, another major water heater manufacturer, Rheem, shared that the sensors have been in place on units since about 2006, so the problem likely is not limited to newer units only. Rheem’s service center indicated that the sensors are in place to detect dangerous hydrocarbons and cannot be bypassed, but that they can be reset when tripped in certain situations. A multimeter can be used to read the system’s resistance. If the system registers 9,000 to 45,000 ohms (Ω), the sensor can likely be reset. If the system registers outside this range, it will be need to be replaced.

For his part, Snyder recognizes the importance of sensors like these. “Years ago, we did a job and the plumber came in and turned on the pilot light while we were coating. As soon as we shut the front door and the air flow was shut down, the house exploded. A sensor like this would have prevented that from happening.”

Contractors should be aware of this issue and make it a regular practice to look at the hot water heater on each jobsite. Letting your customers know, up front, about any potential issues that may arise will go a long way to decreasing liability and improving customer expectations.

Anita Howard is Chief Operating Officer at the National Wood Flooring Association in St. Louis. She can be reached at anita.howard@nwfa.org.