Last year you installed a new whole-house humidifier for a homeowner who was bothered by excessive static electricity. The installation required a sheet metal elbow and a few other design modifications but the job is done — all shiny, neat, and paid for. Good job, good profits.

This heating season, though, you get a call from the same customer, who says the home’s humidity is still too low, will you please send a tech to check out the humidifier.

A tech goes out and finds that the evaporative element is completely clogged with calcium and lime deposits. The bypass damper is open, but the tech rightly suspects that it was never closed in the summer.

These problems are relatively simple to fix — but what happened to your profits?

Spending as little as 10 minutes discussing proper operation and troubleshooting tips with the homeowner at the time of installation can help eliminate future callbacks, according to Bruce Darkow, Aprilaire Automatic Humidifier product manager, Research Products Corp.

If you leave them with some simple instructions on the unit’s operation and maintenance, you can cut down on related callbacks, he said.

However, not all contractors and installation technicians are gabby, especially with customers. Many like to work with their hands, not their mouths. For installers who are not particularly comfortable talking with customers, make sure to leave printed instructions and point out the importance of reading and following them. Even for those who are comfortable giving detailed instructions, it’s worthwhile leaving instructions behind.



Optimum Humidity

One of the first things you need to explain is that a humidistat, used with a manually controlled humidifier, needs time to react to an increase or decrease in the call for humidity. “Make sure your customers clearly understand the reaction time difference between a thermostat and a humidistat,” Darkow said.

A call for a change in humidity takes much longer to fulfill than a call for a change in temperature. “Therefore, it’s best to make a humidistat adjustment in the morning for what the anticipated evening low temperature will be.” So, if the low temp is expected to be 20°F, the relative humidity should be set for 35%.

“The humidifier should be adjusted for every major change in outdoor temperature,” Darkow commented. (See Table 1 for recommended settings.)

To avoid making constant manual adjustments, the homeowner can opt for an automatic humidifier, which constantly monitors indoor humidity and outdoor temperature to respond immediately to a humidity call.



Furnace Blower and the Basics

Darkow also recommended that homeowners run the furnace blower constantly. “Whole-house humidifiers work in conjunction with the furnace blower motor,” he said. “If the blower operates constantly, every time a humidity call is made, the call will be fulfilled immediately.”

Moreover, if there is excess humidity in the home, the furnace blower can dissipate it over time.

He added that for newer, tighter homes, an energy recovery ventilator can help remove excess moisture by circulating indoor air effectively and efficiently.

But most importantly, explain the basics of humidification, Darkow said. “Common sense might lead the average customer to assume that as temperature decreases, the humidifier adjustment would need to increase. However, the exact opposite holds true.” (Again, refer to Table 1.)

“As air becomes cooler, its capacity to hold moisture decreases. Therefore, when the temperature dips to below freezing, the recommended relative humidity will decrease.” In short, the homeowner will need to set the humidistat lower.

Darkow also recommended that contractors or installing technicians explain relative humidity to the customer. (See accompanying sidebar for a brief explanation of relative humidity.)



You installed the humidifier, but who will maintain it?

The Evap Element

Most homeowners don’t realize how critical the evaporative element is to humidification. In fact, most forget shortly after your installation.

It is, however, the heart of the unit, and needs to be in good condition for high-capacity, trouble-free performance, said Darkow.

Make sure homeowners know that it is the means by which moisture is added to the air. Its many small surfaces allow water to be dispersed and then evaporated for distribution as moisture.

The evaporative element also traps minerals left behind from the water passing through it, Darkow explained. As these mineral deposits build up, the humidifier’s evaporation rate could be affected.

Even if they don’t remember why they do it, it’s important for homeowners at least to remember that this element needs to be changed once a year. This service could be included in a contractor’s service contract offerings.

What happens when the homeowner is following all of the tips for achieving optimum humidity, but they’ve got condensation on their windows?

Often, the fault lies not with the humidifier but with other household conditions, Darkow said. “People, just through talking and perspiring, add humidity to a home’s air. And during the holidays, at a household event with numerous guests, condensation may sometimes appear on cold, outside windows.” Homeowners can control this by lowering the setting on the humidistat before family gatherings.

Also, let them know that moisture from internal sources — soup cooking for a long time on the stove, for example — will not dissipate once the temperature drops and condensation appears. Other humidity-causing events include taking showers and watering plants.

“While none of these events can bring enough moisture into the home for comfortable cold-weather living,” said Darkow, “any one, given the proper circumstances, can elevate the humidity level high enough to cause condensation on the windows. And this excess moisture can occur even when the humidifier is off, or in homes without a humidifier, so remind the homeowner that, on occasion, this is normal.” (See Table 2 for likely condensation points per window type.)

Whether the customer chooses a humidifier with manual or automatic operation, “Routine maintenance such as changing the evaporative element will still be required,” said Darkow.

And by educating customers on proper operation and maintenance of their comfort system, including accessories such as humidifiers, contractors can establish themselves as trusted comfort consultants.



Sidebar: Basics of Relative Humidity: What Customers Should Know

Relative humidity (rh) is the amount of water vapor, given as a percent, that is actually in the air compared to the maximum amount the air could hold at the same temperature.

For example, air in a home heated to 70°F can hold approximately 8 grains of moisture per cu ft; if it did, this would be 100% rh. At 100% rh, however, the water would condense from the air, and it would be raining in the house!

If there are 2 grains of moisture per cu ft in the home, then the air is holding one-fourth, or 25%, of its total capacity. The relative humidity is then 25% because it could hold four times as much moisture (not that you would want it to). The goal is never to reach 100% rh.

Optimum humidity varies depending on who you ask, but most people agree that a comfortable range is between 40% and 60% rh.



Sidebar: Checklist for DIY Customers

Some do-it-yourself customers prefer to do their own seasonal humidifier maintenance, or simply want to know what’s involved before they make the decision of whether or not to take advantage your company’s service contract, if you have one.

For those customers, here is a homeowner’s humidifier checklist:

  • Make sure the saddle valve is fully open.
  • Make sure the power cord is plugged in (if applicable).
  • Make sure the bypass damper is open during winter.
  • Make sure the bypass damper is closed during summer.
  • Make sure the drain is free of clogs.
  • Make sure water runs freely and the water line is open.
  • Change the evaporative element annually.

    • Publication date: 01/29/2001