Are On-Demand Water Heaters Worth It?

If you're thinking about upgrading your home’s water heating system, you've likely come across on-demand (or tankless) water heaters. Marketed as energy-efficient, space-saving, and capable of providing endless hot water, they seem like a no-brainer. But are they always the best choice?

We sat down with Matt Laack, owner of Pro Plumbing and Heating, to separate fact from fiction—especially when it comes to whether on-demand water heaters work better in new construction or retrofits.

What is an On-Demand Water Heater?

Unlike traditional tank-style water heaters that store and constantly heat a large volume of water, tankless water heaters heat water only when you need it. When you turn on the hot tap, cold water runs through a high-powered heat exchanger that quickly warms it before it reaches your faucet.

✔ Pros of On-Demand Water Heaters:
✅ Energy efficiency – No standby heat loss; only heats water as needed.
✅ Smaller footprint – Wall-mounted, freeing up storage space.
✅ Endless hot water – No running out mid-shower (if properly sized).
✅ Longer lifespan – Typically lasts 20+ years, compared to 10–15 years for tank models.

❌ Cons of On-Demand Water Heaters:
⚠️ Higher upfront cost – Equipment and installation are more expensive than standard tanks.
⚠️ Limited simultaneous use – If undersized, hot water output may struggle to meet demand for multiple fixtures at once.
⚠️ Gas line or electrical upgrades may be required – Particularly in retrofit situations, which is where Matt Laack sees potential issues.

Why On-Demand Water Heaters Work Better in New Construction

While many homeowners want to upgrade to a tankless system, Matt says they often don’t realize the infrastructure challenges that come with retrofitting.

🔧 Line Capacity Issues – Traditional homes have plumbing systems designed for tank-style heaters, which operate differently. A tankless system demands higher flow rates, meaning gas lines, water lines, and venting may need upgrades—adding unexpected costs.

💰 Retrofit Costs Add Up – In a new home build, a tankless water heater is designed into the system from the start, ensuring proper water flow, gas line sizing, and venting. But in an existing home, upgrading often means rerouting pipes, increasing gas line size, or adding electrical capacity—all of which drive up installation costs.

🏡 The Retrofit Exception? – If you’re already making major plumbing updates (like a full remodel) or your existing home has the right infrastructure, a tankless unit may still be a solid upgrade.

Final Verdict: Is an On-Demand Water Heater Right for You?

💡 Best for New Construction: If you're building a home, a tankless system can be an efficient and space-saving choice—just be sure to size it correctly for household demand.

💡 Retrofits Require Extra Planning: While possible, a tankless water heater isn’t always the best retrofit option due to gas line, venting, and plumbing constraints. Homeowners should weigh the extra installation costs before making the switch.

💬 Still unsure? Matt Laack and the team at Pro Plumbing and Heating can help assess whether an on-demand system makes sense for your home. Reach out for expert advice tailored to your specific setup!

📞 Contact Pro Plumbing and Heating today to explore your options! (507) 437-2557