Stiebel Eltron Water Heater Emergency Guide: Tempra 29 Plus vs DHC-E & How to Reset Thermostat

Disclaimer: I’m not a licensed electrician or HVAC engineer. What I share here comes from 12 years of coordinating emergency equipment replacements for commercial and residential projects. Always consult the official Stiebel Eltron manual and a certified installer for your specific situation.

There’s no one-size-fits-all answer – it depends on your situation

If you’ve ever had a water heater fail on a Friday afternoon, you know the panic. The client is calling every hour, the plumber wants a decision, and the budget is already stretched. In my role handling rush orders for Stiebel Eltron units, I’ve seen three common scenarios – and the right choice changes completely depending on which one you’re in.

Here’s how I break it down:

• Scenario A – Emergency replacement (failed unit, must have hot water within 24–48 hours)
• Scenario B – New installation with time buffer (project still on schedule, but you want a reliable long-term solution)
• Scenario C – Thermostat or control issue (unit is still working but acting up; you need to reset or troubleshoot before calling a service tech)

Scenario A: Emergency replacement – when minutes matter

Last winter, a contractor called me at 3 PM on a Tuesday. A 10-year-old tank heater had burst in a 4-unit apartment building. Tenants had no hot water, tempers were rising. Normal lead time for a Stiebel Eltron Tempra 29 Plus is 3–5 business days. We scrambled, found one in a regional warehouse, paid $280 expedited freight (on top of the $1,150 unit cost), and had it installed by noon the next day. The alternative was a $600 hotel bill per night plus lost rent – that would have been far worse.

My advice for this scenario: Don’t overthink. Go with the model that’s available and matches your electrical capacity. The Stiebel Eltron Tempra 29 Plus (rated at 29 kW) is a workhorse – it delivers 5.7 GPM at a 45°F rise, enough for two showers simultaneously. If your panel can’t handle 29 kW (requires 4x 40A breakers), the Stiebel Eltron DHC-E series (e.g., DHC-E 12, DHC-E 18) is a compact, less power-hungry alternative. For emergency replacements, speed of installation matters more than perfect efficiency. You can always upgrade later (though honestly, most clients don’t).

“In March 2024, a church needed a replacement for their Sunday service. We used a DHC-E 12 because it fit the existing 240V, 30A circuit. Worked perfectly for their low-flow sinks – and saved them from cancelling the baptism.”

Scenario B: New installation with lead time – value over price

When you’re not racing a deadline, the temptation is to save money upfront. I get it – budgets are tight. But here’s the thing: in my experience managing over 200 water heater projects, the cheapest option has cost more in 60% of cases. A $200 savings on a DHC-E over a Tempra 29 Plus can turn into a $1,500 problem if the unit undersizes for the building’s peak demand – think callbacks, angry tenants, and plumber overtime.

For new construction or planned retrofits, I strongly recommend the Tempra 29 Plus. Here’s why:

• Its 29 kW rating handles higher simultaneous demand (three sinks + one shower) without flow rate drop
• Stiebel Eltron’s German engineering means the flow sensor and heating elements last longer – we’ve seen units go 10+ years without issue
• The digital output allows remote monitoring (handy for facility managers)

Yes, the Tempra 29 Plus costs about 25% more than a DHC-E 18. But total cost of ownership over 10 years (including installation, energy, and minimal maintenance) is typically lower because you avoid upsizing later. I’ve tested six different rush-delivery options over the years; the Tempra has been the most reliable under stress. (Note to self: I really should document that comparative test data for the team.)

Scenario C: How to reset thermostat – simple fix before you panic

Sometimes the water heater isn’t broken – it’s just confused. A power surge, a tripped safety limit, or a misbehaving thermostat can make a perfectly good Stiebel Eltron unit stop heating. Before you call an emergency service (and pay $500+ for a house call), try a reset.

For Tempra 29 Plus and DHC-E models:

1. Turn off power at the breaker. Wait 2 minutes – this drains residual voltage from the control board.
2. Locate the reset button (on the bottom of the unit, near the water connections). It’s usually a small red or black button recessed into a hole. Use a paper clip or screwdriver to press it firmly.
3. Flip the breaker back on. If the unit starts heating again (check the flow indicator LED), you’re good.
4. If it still doesn’t work, the high-limit thermostat might have tripped due to overheating. Let the unit cool for 30 minutes, then try again.

“I’m not an electrical engineer, so I can’t explain the internal logic. But in my experience, about 40% of ‘dead heater’ calls I’ve handled were fixed by a simple reset. It’s the first thing I tell contractors to try before I expedite a replacement.”

When NOT to reset: If you smell burning, see smoke, or the unit has visible water leaks – skip the reset and call a licensed technician immediately. Safety first.

How to figure out which scenario you’re in

Ask yourself these three questions:

• How much time do I have? Less than 48 hours → Scenario A. More than a week → Scenario B.
• Is the unit completely dead or just acting weird? Dead → A or B. Weird (intermittent heating, no hot water but power light on) → try Scenario C first.
• What’s the cost of being wrong? If a one-day delay means losing a $20,000 contract (or making tenants homeless), spend the extra for Scenario A’s sure thing. If you can afford a few days to evaluate, Scenario B’s value approach pays off.

The most frustrating part of this job? Seeing people overpay for rushed solutions when a simple reset would have saved the day – or, worse, seeing them penny-pinch on a new build and end up with an undersized system. Take it from someone who’s been on the phone at 11 PM trying to find a Tempra 29 Plus in stock: a little planning upfront saves a lot of headache. But if you’re already in the fire, I hope this guide helps you cut through the noise.

Prices mentioned are for reference as of January 2025; verify current pricing with your distributor.