When Wet Heat Dries Out<br>Carol Fey

Home humidification is a multimillion-dollar business — and it should be ours.

Every year at about this time the humidity inside the house drops. We blame it on the cooler weather and get ready to suffer the consequences. The consequences are cracked lips, dried-out skin, perhaps bloody noses, maybe cracked wood floors or furniture.

As winter sets in and clamps down, we might even experience a little electrical shock (oooh) as we reach for a light switch, or a little electrical snap (aaah) when we start to smooch our sweetie.

None of this is very comfortable to live with (What business are we in? The comfort business!). None of it is necessary. And with America’s ever-growing appetite for comfort, it’s a business opportunity! Home humidification is a multimillion-dollar business and a big chunk of that ought to be ours.

I can just hear you saying, “Yeah, but I’m not in the humidification business, so there.”

Well, you’re in the water business, and what’s humidification but water. If you’re not in the humidification business, maybe you ought to be. Let’s take a look at some reasons you may not be in the humidification business if you’re in the hydronic heating business:

Hydronic heat is wet heat — it doesn’t dry out the air.
There’s no way to humidify with hydronic heating.
Humidification doesn’t work.
Humidification wastes water.
You can’t humidify with hard water.
Humidification means water running down the windows.
Humidification is too expensive.

Now, let’s talk about why you might want to reconsider your beliefs.

Belief No. 1 — Hydronic heat is wet heat.

I’m going to challenge a hydronics industry sacred cow. We’ve all said it until we believe it, “Hydronic heat is wet heat.” But it isn’t when we’re talking about room humidity. The water in the pipes certainly is wet, but there should be no connection between water in the pipes and the air.

We’re not heating with an open vat of water steaming on the stove. If we’re humidifying the air with the water in the pipes, there’s not going to be water in the pipes for long.

We like to put wet heat up against “scorched air” from a furnace and conclude that, of course, wet heat has more humidity. That’s faulty, nonscientific thinking! Here’s why.

Heating — no matter how you do it — is what dries the air in a house.

As the temperature of the air rises, the air gets drier. The same amount of temperature increase, whether by boiler or furnace or wood stove, is going to cause the same amount of dryness. It’s all about relative humidity.

Recall plaid-suited weather reporters on TV. They talk about the “relative” humidity. So, what does relative mean? Relative to what? Humidity is measured relative to the air temperature. One way to think about it is that air gets bigger as it becomes warmer. Warmer air wants to hold much more water than cooler air does. In fact, warm air is a water hog. It’ll gobble up water from anywhere. But first, how did the air get dry?

Let’s go outside first thing in the morning when it’s cold out there. That dew or frost on your windshield — where does it come from? When the air is cooled at night, it has to give up water. It gets wrung out, kind of like a sponge. The water has to go somewhere, so it collects on the nearest surface, the most bothersome of which is your windshield. It’s also on the lawn and almost any other surface outside.

In the course of the morning, some of that cool air comes into the house. Even if you aren’t actively heating, it’s still warmed by the surroundings in the house. As the air gets warmer, its capacity to hold water increases. It becomes mighty thirsty. The warmer it gets, the thirstier it gets. That’s the relative part. Humidity measurement is the percentage of water in the air to the amount it wants to hold.

Back to the TV weather report. Let’s say they tell us that the relative humidity is 40 percent. Hey, that’s nothing to worry about because the heating industry standard for the “comfort zone” is in the neighborhood of 40-50 percent.

But whoa, back up. What about that word relative? If the temperature outside is 30 degrees F and the humidity is 40 percent, that same air when heated to 70 degrees has a relative humidity of 10 percent. That’s right, 10.

Of course if you had a completely open hot water heating system, such as an open pot of boiling water, that would add water to the air. But our hydronic systems don’t expose the water to the air. The water is carrying heat to a convector, which in turn gives up its heat to the air that comes in contact with it. The water goes back to the boiler without ever touching the air. And the air, when heated, gets mighty thirsty.

Thirsty air is a desperate hombre. Like a dirty-handed, low-down horse thief in an old western movie, it will steal any and every chance it gets.

Belief No. 2 — There’s no way to humidify with hydronic heat anyway.

True, you need to have a way to distribute the humidity, and air ducts are the best way.

In the old days there weren’t any air ducts in a hydronic house. But now air conditioning or second-stage heating is often installed in addition to hydronic heating. There’s nothing practical or inexpensive about this at all. It’s all about comfort. Somebody’s going to get that work to add humidification — it might as well be you.

Belief No. 3 — Humidification doesn’t work.

Of course humidification works. But most of us have some experience that says it doesn’t. What makes it look like it doesn’t work is that we usually don’t add enough humidity to make a difference.

You buy a portable plug-in humidifier and place it next to your lounge chair in front of the TV. But you still wake up every morning with cracked lips and a nosebleed. Darn thing don’t work!

Here’s an analogy for you — if you plopped one little electric heater next to your TV room lounge chair, would you expect the bedroom to get warm?

Belief No. 4 — Humidification wastes water.

So when did we decide that saving water was more important than convenience, comfort or popular practice? Have you really heard much about folks not using their shower, dishwasher or toilet in order to save a few gallons a day?

Belief No. 5 — You can’t humidify with hard water (and everyone’s got some amount of hard water).

The term “hard water” means that there are dissolved minerals in the water. Harder water means that there will be more mineral deposits left in the humidifier. Always with humidification, someone needs to clean out the humidifier or change the pad once or twice a year. It’s normal maintenance.

Belief No. 6 — Humidification means water running down the windows.

Remember the explanation of what happens to the water in air when the air is cooled? The water comes out, just like wringing a sponge. The water collects on cold windows and metal window frames because that’s where the air gets cold.

But, with today’s multipane windows and nonmetal frames, windows aren’t so cold anymore. There are also humidifiers that “temperature compensate.” As the temperature drops outside, they deliver less humidity so there’s less humidity to collect on cold single-pane windows.