Security Seal Facebook Twitter GooglePlus Pinterest Newsletter Sign-up

How to be irresistible

Info

Author
Dan Holohan
Published
December 16, 2010
Subscribe to RSS feed

They built the house we’re living in 1950 and they gave it a copper-in-concrete radiant heating system.  In 1970, the previous owner of my house noticed wet spots on his kitchen floor and knew that the family budget was about to take a trip down Hershey Highway.  There's not much you can do when the copper in the concrete dissolves.

            So the guy called a heating contractor who came in and pronounced the radiant floor heating system dead.  The contractor gave the guy a price to convert to baseboard, and then he did what every heating contractor on Long Island does, which is to run the baseboard everywhere there was a wall.   He skipped only the front and back doors because they don't make baseboard with hinges.  Every foot of that loop was live element.  Why did he do this?  Because this is the way he was taught to do it. 

            When its time came, the upstairs portion of my house, not coincidentally, was sized using the same method, so I now am the proud owner of 200 linear feet of 3/4" baseboard.  If you ever need any, give me a call.

            You know what got me thinking about this?  A heating contractor I know let me in on the way he does his heat loss calculation. 

            "I go around and measure the radiators," he said.

            "You mean on a steam system?" I asked.

            "Not just steam," he said, shaking his head.  "I do it on every system.  You gotta support the radiation, you know."

            "I agree with you in the case of steam," I said.  "With steam, you have to match the firing rate to the connected load because steam is a gas that wants to condense.  If you have more metal than steam, the steam won't make it to the end of the run and you'll have a cold house.  But I think you're making a mistake if you size a hot water boiler that way."

            He shook his head.  "Nope, that's the way I do it.  Been doing it that way for years."

            "But you're probably going to oversize the boiler if you measure the radiation on a hot water job," I told him.

            He just shook his head.  "Works for me,” he said.  “Been doing it this way for years."

            "You have to do a heat loss calculation when it comes to hot water heat," I continued.  "That's all that matters."

            He kept shaking his head.  "Takes too long to do a heat loss calculation. Gotta get on to the next job.  It's much easier to measure the radiation." 

            So I invited him over for a beer.

            "What's the heat loss of my house?" I asked. 

            "You're gonna make me work?" he chuckled.

            "I'm just curious.  How would you size this house?  C'mon, show me."

            He got up from the couch, tugged up his pants and went out to his truck.  He came back with a tape measure, a pad and pencil and a calculator.  He laid the tape around the perimeter of the house - both upstairs and down - and he recorded the numbers.  Then he added it all up.

            "You got 200 feet of 3/4" baseboard," he said.

            "I know."

            "Each foot of three-quarter puts out 580 BTUH when the water's 180 degrees," he said.

            "I know."

            "So two-hundred times five-eighty is a hundred-sixteen-thousand.  That's the heat loss for your house."

            "That's what you'd quote me on?  If I called you for a price on a replacement boiler, I mean."

            "Yep," he said.  "Plus the domestic hot water load, of course.  You have an indirect water heater, so we'll have to add quite a bit for that."

            "Come here for a minute," I said as I walked him into my office.  He rolled his eyes and followed me, shaking his head all the way.

            "You're gonna show me I'm wrong now, right?” he said.  “You're gonna whip out some book or something and show me how what I've been doing for all these years is wrong, right?"  He laughed and shook his head again.

            I didn't say anything.  I just turned on my computer and called up the heat-loss calculation software program.   

            Ten minutes later, I'd sized the whole house for the heat loss on a 15-degree day. 

            "The heat loss is forty-thousand BTUH."

            "That can't be," he said, shaking his head.  "Not with all that radiation you have. Can't be.  You'd never support the radiation with that small a boiler."

            "So in other words, you'd put in a boiler four times bigger than what the house actually needs?"

            He waved his hand at the computer screen, dismissing it.  "I don't need any of that technical crap," he said.  "You just match the radiation, that's all.  You gotta support the radiation. It’s there in the room!"

            "But radiation isn't heat loss," I said, trying my best to convince him.  "Your price is going to be out of line if you base your boiler size on the radiation.  It’s not in the customer’s self-interest."

            He just kept shaking his head.  "Been doing it this way for years," he said.  "I'm not about to change now.  I’m not putting in something that's too small.  Not me.  I don't need those kind of problems."

            Whenever my friend loses a job he blames it on the price.  “Boilers are just too expensive,” he says.

            Smarter contractors regularly beat him up. They understand that radiation is not heat.  Heat is what they have to put into the house to overcome heat loss.  If they put in too much heat, they know they'll be wasting their customer's money and short-cycling the boiler.  Neither of those things is in the customer’s self-interest.

            When a smart contractor comes across an over-radiated house he’ll use it to his advantage by accurately sizing the boiler, and then running the boiler on outdoor-reset with continuous circulation.  That saves the customer money, and customers like that a lot. 

            Here's an example of what I'm talking about.  Let's say you have a room with a heat loss of 5,800 BTUH.  If the installer put in 10 feet of 3/4" baseboard and supplied it with 180-degree water, he'd match the heat loss on that cold day because 3/4" baseboard puts out 580 BTUH when there's 180-degree water flowing through it.

            But suppose the installer put in 15 feet of 3/4" baseboard instead of ten.  With 180-degree water flowing through it, 15 feet of 3/4" baseboard will put about 8,700 BTUH into the room.  That’s way too much - even on the coldest day of the year.  The burner will cycle too often, and combustion efficiency will suffer.  That’s not in the customer’s self-interest.

            But since this "extra" baseboard is already there, a smart contractor will make it work to his advantage.  Here, consider what happens if you run 150-degree water through that baseboard.  At 150 degrees, each foot of 3/4" baseboard will put out 380 BTUH.  Since you have 15 linear feet, you'll be emitting 5,700 BTUH into the room.  That's just about right for the coldest day of the year.  It costs less to operate at 150 degrees than it does to operate at 180, right?  That’s in the customer’s self-interest!  Oh, and condensing boilers love over-radiator houses and that low-temperature water.

            Smart contractors discuss these things right up front.  Their prices are better and so are their jobs. The fuel bills are lower and the level of comfort is higher.  The baseboard is quieter because it doesn't expand and contract as much. Everyone's happy.

            The more we think in terms of the what's in the customer’s self-interest the more irresistible we become.  And that's a mighty fine thing to be, especially these days.

            Pass it on.