Sizing The New Boiler Based On The Old Boiler Is Dumb

Published: January 18, 2011 - by Dan Holohan

Categories: The Business of Heating, Darn-Good Stories, Troubled Heating Systems

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Back when our business was new, and before I had written any books, I was making my living doing seminars and consulting with homeowners who were, for the most part, rich, cold and miserable. I figured those three qualities made for the perfect client. They had lots of money but couldn't find anyone who could tell them why their pipes and radiators were banging and their fuel bills were so high. I would go their homes, spot the failed steam traps or missing main vents, the circulator that was in the wrong place, the boiler that was bigger than it ought to be, and I would write a report and hand them a bill that was large enough to make them wince. If they didn't wince, I hadn't done a good enough job of pricing my services.

This brings me to a story about this house in a very wealthy section of New Jersey. The new owner was frustrated because every 10 days or so, a fuel-oil truck that had 18 wheels grumbled up his street. The driver would stop, pull a long hose that was as thick as my thigh up to the oil tank's fill pipe, plug in, and whistle as the oil gushed from the truck to the tank. The new homeowner hated this man.

So he hired me to see what I had to say about him saving some fuel dollars. He was open to any suggestion. Should he stick with oil, or should he switch to gas? Should he keep the boilers he had, or get new ones? Should he have the whole system repiped? Should he burn down the house? Hmm, what to do?

I met him at his house, which was smaller than Versailles, but not by much. The oil truck was there. He asked me what I wanted to do first and I suggested we take a tour of the place, mostly because I'm nosey, and never pass on an opportunity to poke around in the stuff that rich folks like to accumulate.

We went from room to room and I ogled and gawked. The place had gravity hot-water heat and any of the cast-iron radiators could have held down the Graf Zeppelin. Yum.

"Can we go to the basement?" I asked.

"Sure," he said. "Wait 'til you see these boilers?"

"You have more than one?"

"There are two," he said. "And they're big."

"And they're connected to the truck," I said.

"Yes," he said, "there's that."

We got to the basement, where my legs suddenly stopped working because this place had horizontal mains made from eight-inch, screwed pipe. You ever see eight-inch screwed pipe? Trust me; it's bigger than eight inches. I stood there with my mouth open, thinking that there was once a day in America when someone lifted those bulky hunks of iron and caught a thread. Who was that guy? How big were his arms? What sort of wrenches did he own? Where the heck did he stand? I figured it was either Popeye or Bluto.

I was getting all sentimental and sloppy over my jaunt through time, when the homeowner gently reminded me about those boilers, so we walked a while through the basement and that's when I came upon the two Ideal Redflash boilers. Once again, my legs stopped working. These two had once burned coal, but were now connected to the 18-wheeler out in the street. Each had a rating of 500,000 Btuh, and both were firing.

But then, firing doesn't quite do what was going on justice. These beasts, each of which was the size of a minivan, now had tons of sand where the coal grates used to be. The burners, each bigger than the Fourth of July, hung from the doors (I could have crouch-walked through those doors) and vomited fire deeply into the bowels of those boilers. We could have toasted rye bread on the jackets.

I shut off the burners and carefully opened the door of one of the beasts. You could yodel in this boiler and get an echo. You could cremate your spouse in this boiler and no one would ever know. You'd probably get a No. 10 smoke for a few minutes, but other than that, you'd be fine. Seriously.

"Has anyone done a heat-loss calculation on the house?" I asked the homeowner.

"Yes," he said. "The salesman from the oil company did one."


"Yeah, it didn't take him long," the homeowner said.

"Did he go from room to room and measure the walls and windows and whatnot?" I asked. "Did he check the attic?"

"No," the homeowner said. "He just wrote down what was on the two labels and then gave me this quote." He took a sheet of paper from his folder. The quote was for a single boiler, rated at 1,300,000 Btuh.

"One boiler?" I said.

"Yeah, the salesman said that it's crazy to have two boilers. There's twice as much stuff to break down. He also said he knew that this would be the right size for the house because these two boilers have been here for all these years, and they're served the house well."

"But he's quoting 300,000 Btuhs over the total load of both boilers," I said.

"I know," the homeowner said. "The salesman mentioned that it's an old house, so it never hurts to have a little bit extra."

"Oh," I said.

So I did what the salesman should have done, which was a heat-loss calculation. That's the only way we were ever going to find out the actual heat loss of the house. Anything else is just guessing.

And here's what we learned: The total load for the house on the coldest day of the year was 375,000 Btuh. That other boiler was a stand-by. Why was it firing all the time? My guess is that a service tech turned them both on one day and they stayed turned on. The abnormal became the normal. Happens all the time.

The homeowner decided to fire the oil company, which didn't surprise me. "They're seeing my house as a vending machine," he said.

I made him a sketch of how I'd like to see all the main gravity lines tied together into a primary loop. "Stop by a local supply house and ask them if they have in stock four, eight-inch-screwed by two-inch-sweat reducers," I said. "And don't take no for an answer. They'll try to jerk you around because you're a homeowner. They've got them back there somewhere. They just won't want to look for you."

Just kidding.

So with the supply-and-return gravity mains connected (with flanges and copper tubing, not reducers), I sketched how to use two boilers, with a combined load of 375,000 Btuh, on secondary circuits. I included a couple of bypass lines so the flue gases wouldn't condense. This story goes back to before we had condensing boilers; otherwise, I would have suggested those. Condensing boilers love those old, high-volume systems.

He had this installed by a gas contractor and I followed up with him during the following winter. Most of the time, he ran just one of his new, relatively tiny, boilers, which is better than running a single 1,300,000 Btuh boiler. Right?

The homeowner was happy.

So what cost the oil company that account, and the contract for the new boilers? I think it was laziness. The salesman didn't want to take the time to do what a professional should always do when replacing a hot-water boiler, that being a proper heat-loss calculation. The salesman must have thought that if he went to the trouble to do the calculations, and then didn't get the job, he would have wasted his time.

But you can see where that got him.

Thing is, I've been telling this story at seminars for about 20 years now, and contractors still come to me during the breaks to argue with me. They can't afford to do heat-loss calculations on every job. It takes too much time. They'll go by the label on the old boiler. I was making them feel guilty. I have no idea what they're up against.

I'll mention that a proper heat-loss calculation will nearly always give you a smaller boiler than one you size by the Label Method, and that smaller boilers mean better prices, and more closed sales. They'll argue with me about this too. It takes too long to do. They don't have the time.

"So how's business?" I'll ask.

"It sucks," they'll say.

So I think I'll just keep telling about Redflash.