According to Aprilaire engineer Todd Hader (shown here), the HALT chamber is capable of a temperature range of -100° to 200°C, and vibration levels up to 60 g.

MADISON, Wis. - When Aprilaire introduced its 1700 and 1720 whole-home dehumidifier models a few years ago, the company already had a system in place to make improvements. Those are now available thanks to an accelerated review process and paying close attention to contractor and end user feedback.

“We came up with the product three years ago, and since it’s new, we are sensitive to customer needs and acceptance in the market,” said John Bloemer, director of product development. “Since the introduction, we’ve listened very closely to dealers and homeowners, gathering information on what they like and don’t like.” The company also looked at warranty returns, etc.

“What we were finding is that we needed to upgrade it,” he said.


“One of the things we are constantly doing is improving the quality of our product,” said Bloemer. “So we looked at warranty returns and talked to dealers about installation issues.

“One of the big things that popped up was ‘no fault found’ returns. As we analyzed the data, we learned that it was so quiet the people couldn’t tell that it was running. So, we put an LED light on the outside.” The light can also communicate whether the unit registered a fault. “It always had the diagnostics, but we put the LEDs on the outside instead of the inside.”

When it comes to noise levels, perception is the key to consumer happiness. “Sometimes it’s easier for a dealer to pull it out and put another one in, so the home- owner will believe it’s working,” Bloemer said. “So we get back some products that worked fine.”


The internal testing used by the manufacturer is called HALT - Highly Accelerated Life Testing. It puts the device in extreme conditions of vibration and temperature, which accelerates the aging process until the weakest aspect of the equipment fails.

“The HALT chamber will shake the product up to 50 g’s, take it from -40 to 300 degrees,” said Bloemer. “You’re forcing a weak spot in the design to show up. Then we work on removing the next weakest point.”

It’s almost like accelerated Darwinian evolution.

“We saw some small failures in the refrigeration system, where we’d have a leak,” he continued. “Through this and reliability testing, we made a change to the refrigeration system that led to a five-fold increase in reliability. The refrigeration system would vibrate close to its natural frequency; you put a lot of stress on the device that’s shaking, the tube and weld joints,” he said. “By changing the design, we changed the frequency.”

The company’s HALT chamber is capable of a temperature range of -100 to 200°C, and vibration levels up to 60 g (for comparison, astronauts experience 3-4 g’s when the space shuttle takes off). HALT testing “applies stresses that might cause failures to occur as soon as practicable,” Bloemer said. “There are no limits set to the types and levels of stresses that can be applied.

“Every product you buy has some failure mode. We put a high standard on ourselves. What most companies would consider an acceptable amount of failure, we’ve raised the bar for ourselves.”


Of course, the most important feedback comes from the contractors dealing with the products, and their failures, on a regular basis.

“Our field sales sources are in with the dealers daily,” Bloemer said. “From Madison, our marketers and engineers will go out and meet with dealers, either individually or as a group, for face-to-face contact and to gain an understanding of what’s going on.” Watching and monitoring calls at the service center (from both end user and dealer) adds the final piece of improvement data.

In the installation process, some of the system’s diagnostics can indicate miswiring. “If the installer inadvertently crosses the wires in the test mode, they can tell by the number of links where the problem is,” he said.

Other modifications have improved reliability in salt-air applications. “In seaside applications, the salt air destroys everything,” Bloemer said. “We were able to create a test to monitor and reduplicate that failure mode. With our design change, we’ve moved that failure mode to a factor of 10. When you go to these seaside applications, the control will go into the living area, where there is less salt air contact.”

The company also encourages dealers to give product feedback to their reps; if that doesn’t seem to be working, they encourage dealers to call the company’s 800 number to customer service. “If they don’t have the answers, they go to engineering,” Bloemer said. “You get your answer pretty quickly.”

The 1750 (90 pints per day) and 1770 (150) whole-house dehumidification systems are now available. “Now we’re mining for the next level of improvement,” he said.

“All of this geekiness is about making products stronger, better, and faster, keeping what the customers want in mind.”

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Publication date:08/04/2008