Something like that happened to us on the Jones job.

Our plan was straightforward in the beginning. Our heat core would be a high efficiency, condensing water heater installed in a storage space over the garage. We dislike remote manifolds so our idea was to bring 3/4-inch tails from each of the 11 zones back to a central manifold next to the water heater. This of course made for a lot of tubes and a large manifold, but it was manageable.

The project manager, Fred Biddle, approached me one day with a suggested change. The owner wanted to free up that storage space over the garage and wanted to know whether I could combine the heating with the domestic hot water and put it in the closet below.

Well, I didn't want to do that: I like the simplicity of a dedicated system. I like space to work in. The closet would be crowded.

Still, the man didn't ask what I wanted to do. The man asked me "Could I?" Under compulsion from the hydronic hive mind that tolerates no imperfection, I affirmed that I most certainly could. I mean, did the man think I was a novice?

The condensing water heater had to be changed to a version with a built-in heat exchanger -- but that was simple. The built-in heat exchanger required that a little circulator be attached to prevent thermal stratification -- but that wasn't hard. Of course, the plumber wanted to install a domestic hot water re-circ pump, so we had to work out a piping scheme that didn't interfere with the first circulator -- but that was doable, too.

Also, to get the heat-exchanger output we needed, the unit would have to operate at 180 degrees F; sort of unnatural for a condensing water heater since it can't condense at that temperature. But what had to be had to be. This meant, of course, we had to put a tempering valve on the domestic side and re-work the piping for the re-circ pump, but we quickly mastered that.

In the course of this, we realized the first slug of water out of the heat-exchange coil would be at 180 degrees F, which we didn't really want going through our PEX tube. That very hot water would be hitting the floor when only one of the 11 zones was operating, so we put a three-way valve on the heating side, too. Of course, tempering valves aren't all that useful if you don't know what their output is, so we added a couple of thermometers.

With all this going on, the closet was getting tight for space. Fortunately, the water heater was only 4 feet tall, so we had some room above it to hang our equipment. True, the manifold would be on the back wall, kind of high and awkward to service. Nonetheless, could I do it? Yes, I could!

Now, Fred came around again and, assiduous as ever in looking after his client's interests, expressed concern that the storage tank contained only 45 gallons of water.

"The owner sometimes has guests," he said. "It would be a big disappointment if they didn't have enough hot water."

Once again, I felt Borg probes burrowing into my brain.

Hastily, I reassured him that because we stored at 180 degrees F, we could supply as much as any conventional 80-gallon unit. Add to that the fact we had an input of 130,000 Btu and over 85 percent efficiency, and it was my opinion the hot water supply was more than adequate.

Sensing Fred wasn't buying it, and hoping to forestall further complications, I went for broke, "Also, we're going to install a reverse-acting aquastat to provide hot-water priority."

"Reverse acting aquastat? What's a reverse-acting aquastat?" Fred queried.

"It's a temperature-sensing device that will temporarily shut off the radiant heating system should the tank temperature drop below, say 125 degrees F," I responded. "For the short period of time demand is high, all the output of this fabulous heater will be directed to keeping the showers hot."

Fred rubbed his chin. "Hmmm, a reverse-acting aquastat," he murmured.

Later that afternoon, Mr. Jones, the owner, came by. "I want an 80-gallon tank," he asserted. "I saw them in the manufacturer's literature, and I want one."

He must have seen a shadow cross my face as he added: "Can you do that?"

Resistance was futile. Could I do it? Yes, I could! The manifold was going to be well nigh impossible to get to, but we could do it and we would do it. I talked over the new plan with Fred. Evidently my earlier ploy had made an impression as he asked, "You're still going to install the reverse-acting aquastat, aren't you?"

"Of course!" I rejoined.

The installation was getting complicated. An attempt to order the 80-gallon model brought the response it was available only in the 199,000 Btu input size. From recent experience, I knew the blower on this model would be too noisy to install in a closet that shared one wall with our clients' future office.

What to do? Admit I couldn't do what I had said I could? Beg to go back to the original attic location? Grovel? The reputation of Wet Heads the world over was in my hands and I wasn't going to come up short on this one.

"Here's what we do," I told Fred, "We get a 50-gallon storage tank from the same manufacturer. It's the same diameter and has the same beige vinyl cover. We stack the two units; storage tank on the bottom. Then we just pipe it together and we effectively have a 95-gallon storage tank."

"And will you install a reverse-acting aquastat?" asked Fred, unstoppable in his due diligence.

"You betcha!" I enthused.

Bruce, the foreman of the carpenters, loved to needle my installer, Steven de Nueve, as Steven struggled with every ball and check valve: "Do we know what we're doing?" Bruce would chortle.

The water heater and storage tank now towered nearly 8 feet tall. The manifold could no longer be placed above. We turned it sideways on the wall. True, the built in flow meters wouldn't work properly in this position, but you can't have everything. The 22 tubes it fed were no longer tidy; there are limits to the flexibility of PEX, after all. All connections had to be made before the heater and tank were installed. God help us if there was a leak.

"Interesting," opined Bruce.

"Goway don' boddame," responded a thoroughly nettled Steven.

The same applied to our control box. Vertical it had to be.

"Just how long is this little job going to take?" cooed Bruce.

"Gedoudahere!" growled Steven, brandishing his torch in Bruce's direction.

Wiring the system was a challenge: A bundle of cables the size of a plasma conduit snaked down the wall. As Steven was wrapping it up, Fred popped in to have a look. He started to speak, but his lips froze as his eyes took in our creation. Looming there in the closet; mechanical ventilator whirring, hot aqueous fluid whooshing through its polymer veins, glowering red LEDs threatening doom was this ¿this ¿THING.

Fred's lower lip trembled slightly. His face paled. A thread of spittle wet his chin.

Slowly, Fred gathered together the shreds of his dignity and, with only a slight stammer, asked: "Wh--wh--where's the reverse-acting aquastat?"

Too late. Realizing he had forgotten to install the reverse-acting aquastat and knowing the inevitable question was coming, Steven took advantage of Fred's momentary inattention to escape out the door. He was already halfway to his shuttle craft, sprinting for all he was worth.

Bruce stood in the background grinning.