Why I Didn't Recommend Stiebel-Eltron Tempra Plus (And What We Chose Instead)

I'll never forget the day I sat down with our operations director to review the 2025 facilities budget. We'd been using traditional tank water heaters for the past eight years—six units across our main building and two remote warehouses. The numbers were ugly: over $12,000 in annual repair costs, $4,800 in emergency call-outs (one involved a flooded storage room), and the inevitable replacement cycle every five to seven years. Something had to change.

The Conventional Wisdom Trap

Everything I'd read online screamed tankless is the future. Lower standby losses, endless hot water, longer lifespan. So when I started researching replacements, the Stiebel-Eltron Tempra Plus tankless water heater kept popping up. German engineering, compact design, solid reviews from contractors. I downloaded the Stiebel Eltron heater manual and spent an evening going through electrical requirements, flow rates, and temperature rise charts. On paper, it looked perfect.

But here's the thing—I've been tracking procurement costs for six years. I've analyzed $180,000 in cumulative spending across 10+ vendors. I've learned that paper specs hide half the story. So I built a TCO spreadsheet, factored in installation, maintenance, and energy costs over a 10-year horizon. That's when the cracks started showing.

The Hidden Cost of 'Simple'

The Tempra Plus 36 kW model (the one we'd need for our medium-flow applications) requires three separate 40-amp breakers and 6 AWG copper wire. Our building's electrical panel is from 2007, and it has room for exactly one additional breaker. The upgrade quote came in at $4,200—just to get the panel up to code. Plus, the unit itself was $2,800 (as of January 2025). Total upfront: $7,000 per unit. For six units? That's $42,000 before we even touched labor.

Then I looked at our actual hot water demand patterns. We have two peaks: morning (7-9 AM) and lunch (11-1 PM). During those windows, multiple showers and sinks run simultaneously. The Tempra Plus can handle about 3.5 gallons per minute at a 70°F rise—enough for maybe two showers and a sink. Our peak draw hits 6 GPM. We'd need two units in parallel for each location. Double the cost, double the install complexity. Suddenly the tankless dream started looking like a luxury we couldn't justify.

The Experience That Changed My Mind

I almost pulled the trigger on the Tempra Plus anyway. I mean, the marketing is compelling: 99% energy efficiency, compact footprint, no standby losses. But then I visited a fellow procurement manager's facility (we share data in a small industry group). He'd installed three Stiebel-Eltron units in his commercial laundry last year. His advice: They're fantastic for steady, low-flow draws. But if you have spikes—like our lunch rush—you'll either be disappointed or paying for a massive oversize.

That was the moment of truth. I realized the Tempra Plus is a brilliant product—for the right scenario. For us? Not so much. And being honest about that limitation actually helped me recommend it to a colleague who runs a small office with only two sinks and one shower. She's thrilled with hers.

The Solution We Actually Implemented

After running the numbers, we went in a completely different direction. For our main building, we installed a heat pump water heater (different brand) paired with a small 30-gallon buffer tank. It cost about $3,000 per unit installed, but the energy savings from the heat pump—combined with our local utility rebate—gave us a payback period of 2.3 years. For our remote warehouses, we used space heaters for supplemental comfort and small point-of-use electric heaters for handwashing stations. It's not sexy, but TCO-wise, it's a slam dunk.

And yes—we also had to deal with an air compressor upgrade in one warehouse. The old one was wasting electricity constantly. We replaced it with a variable-speed model that cut our compressed air energy costs by 37%. Funny how one decision leads to another.

What About Double Boilers?

This might sound like a tangent, but I get asked what is a double boiler more often than you'd think. In commercial facilities, a double boiler setup typically refers to a system with two separate heating circuits—one for space heating, one for domestic hot water. It's common in larger installations where you need redundancy or high simultaneous demand. We briefly considered it, but the complexity and cost (two separate boilers, piping, controls) made it overkill for our use case. Sometimes simpler is smarter.

The Lesson: Honest Limitations Build Trust

Looking back, I'm glad we didn't force the Stiebel-Eltron Tempra Plus into our situation. If I'd gone with it, we'd be stuck with an expensive system that couldn't handle our peak loads—and I'd be the person explaining the budget overrun. Instead, we got a solution that fits 80% of our needs, and I can confidently tell others when the Tempra Plus is the right choice (low flow, stable demand, good electrical infrastructure) and when it's not.

That's the thing about procurement. The best product isn't the one with the highest efficiency rating or the strongest brand name. It's the one that matches your specific constraints—upfront budget, infrastructure, usage patterns, and risk tolerance. Stiebel-Eltron makes excellent equipment. But 'excellent' doesn't mean 'right for everyone.'

So if you're evaluating tankless water heaters, download the manual, run the TCO, and check your electrical panel. Don't trust the hype. Trust the numbers. And if your situation doesn't align, don't be afraid to say this isn't for me. That honesty will save you a lot more than any rebate ever will.