Your Body Is A Radiator


Ever been to Ocean City, Maryland? It’s a summertime wonderland, and I was lucky enough years ago to get hired to do a seminar on hydronic radiant heating for a group of contractors who were having a conference there. I brought The Lovely Marianne and our four daughters along because they all told me there was no way I was going there without them.

I went out to run a few miles on the boardwalk with Kelly, our eldest, before the seminar that morning and felt the heat pouring off me when I finished.

"I’m a radiator,” I said.

“Don’t start, Dad,” Kelly said.

“Well, I am,” I said.

“Save it.”

She’s crazy about me.

The conference was in a big hotel. So big that it had an NHL-size skating rink in its lobby. That’s not something you’d normally find in a hotel that’s just a few hundred feet from the Atlantic Ocean. You can sun yourself all morning, and skate all afternoon in Ocean City, Maryland. What season is it? Who cares; we’re on vacation.

Well, sort of — I had to work.

Our meeting room was right next to the ice rink, and as the contractors arrived in their t-shirts and shorts (it was a very casual seminar), most complained about how cold it was when they walked by the rink.

Now, that morning, I was tasked with having to explain to these folks that hydronic radiant heating is different from any other type of heating system because it controls the heat loss from your body more than it does the heat loss from the room.

With hydronic radiant heat, you’re trying to get the temperature of the surfaces of the room as close as possible to the skin temperature of most human beings, that being about 85° F. You do this because our bodies are radiators. We generate heat. Half the heat we lose leaves our bodies as radiant energy, moving toward things that are cooler than 86°. When you control the rate of heat loss from your body, you also control your degree of comfort. It’s that simple.

That’s the key to understanding hydronic radiant heat. It’s why we use a different sort of heat loss calculation when we size these systems. We’re really not concerned with heating the air in the rooms. In fact, in a room that’s heated with a hydronic radiant system, the air temperature at the ceiling will be about the same temperature as it is a foot or so above the floor.

Since the air temperature at the ceiling is relatively cool, the heat loss from the building is less. The greater the temperature difference from one side to the other, the greater the heat loss. That, too, is simple.

There’s also less heat loss from infiltration in a room heated with hydronic radiant heat because there’s little or no convective movement of air, and that’s what makes these systems so efficient. A well-designed hydronic radiant system can save quite a bit on fuel.

The key to understanding this, and to explaining it to others, is to think of our bodies as radiators and to forget about heating air. At my seminar, I decided to use the ice skating rink to make this point. It was a gift sitting right there and I couldn’t resist.

I waited for the last contractor to arrive and get a cup of coffee. He mentioned how chilly it was out there at the skating rink and the others agreed. Perfect!

When everyone was seated, I asked them what temperature they thought it was in the conference room. Their guesses ranged from 68° to 72°. I took out a digital thermometer and checked. The temperature was exactly 70°.

“Not bad!” I said. “You were all very close.”

“That’s because we’re in the business,” one guy offered. “We get calls from people all the time who complain that it’s too cold. But when we get there, we can feel that it’s 70°. And when we check, it’s usually within a degree of what we said it was. Some people have no sense for air temperature, but we do. We’re all in the business. We have a knack for it. You get so you can be as accurate as a thermometer when you’re in at this long enough.”

“I’m glad to hear that,” I said. “What temperature do you suppose it is out by the ice skating rink?”

They all started to laugh. “It can’t be more than 60° degrees out there,” one woman said. “I’d agree with her,” a man said. The others nodded.

“Okay,” I said. “Let’s go check it out.” I picked up the digital thermometer and we all walked out to the rink. I held the thermometer’s probe about a foot off the surface of the ice.

“It’s 77°,” I said.

“No way!” one guy shouted. “Let me see that.” I handed him the thermometer and let him check for himself. The others gathered around, and each had a turn to take a good look.

“Want to go back inside?” I asked.

“Yeah,” one of the women said. “It’s too cold here!”

“It’s 77° here,” I said.

“I don’t care what that thermometer says,” she laughed. “I’m cold!” She scurried back to get another cup of coffee in our relatively “warm” conference room where the temperature was only 70°.

Now that I had their attention, I told them about a phenomenon called “Cold-70.” It’s the feeling you get when there’s a big difference between the air temperature and the temperature of the surfaces around you. This is because your body is a radiator and it will radiate heat toward anything that’s colder than it is. When you stand next to cold objects, your body’s heat loss increases and you feel uncomfortable, even though the air might be 70°.

Engineers have talked about this since the 1930s. It’s what often makes a forced air system feel uncomfortable while a hydronic radiant floor feel so good.

“That’s the way you market hydronic radiant heat to your customers,” I told them.

“We have to take them to a skating rink?” One of the guys asked. “We don’t have one of those in our town.”

“No, not a skating rink,” I said. “A supermarket.”

“A supermarket?”

“Yes, grab your thermometer and walk them up and down the aisles. Most supermarkets have warm-air heating systems. When you get to the frozen food aisle, you and your customer will feel the same way you just felt when you stood next to the ice rink. Take the temperature of the air in the frozen food aisle and show them that it’s the same as it is in every other aisle in the store. That’s Cold-70, and that’s the best way to sell hydronic radiant heat.”

“But what if they don’t want to go with me to the supermarket?” A guy in the back asked.

“Then you use words to paint a word picture for them. Just as I’m doing now,” I replied.

People who are good at marketing do that. They paint beautiful word pictures that connect things people know intuitively with the technical aspects of what they have to sell. They focus on the benefits, the way the system makes you feel. They market what the thing does more than what it is.

If I can do that, so can you.

Be a radiator and go tell your story. Or make this story your own and tell them you were the person at the seminar. You can’t miss. You’re a radiator. You’re hot stuff!


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