Tankless Water Heater Installation in St. George, UT
Endless hot water, 20–30% energy savings, 20+ year lifespan. Marlin installs and services tankless water heaters for Southern Utah homes.
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47+
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Serving Southern Utah
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Upgrade to Endless Hot Water — Done Right
Tankless water heaters are a genuine upgrade in comfort and efficiency — but only when they're properly sized and installed. An undersized unit for a large household, or one connected to a gas line that can't support its BTU demand, will underperform. Marlin Plumbing handles the complete evaluation and installation process so your system delivers on its promise from day one.
St. George's hard water requires serious attention when installing tankless systems. Mineral scale accumulates quickly inside the heat exchanger without proper water treatment or regular maintenance. We discuss descaling schedules and water softener options with every tankless installation — because a $3,000 unit that fails in 8 years due to neglected scale isn't actually saving you money over a standard water heater. With the right setup and annual maintenance, these systems genuinely deliver their 20+ year rated lifespan.
The conversion from a tank system to tankless involves more than swapping one box for another. Gas line sizing, venting requirements, condensate drainage, and electrical connections all need to be evaluated and potentially upgraded. We handle every aspect of the conversion so you don't need to coordinate multiple contractors. If you're also looking at whole-house water treatment, combining a tankless install with a reverse osmosis or water filtration system is the most cost-effective time to do both.
What's Included in Our Installation
Gas line sizing and upgrade if needed, venting design and installation, electrical requirements, cold water shut-off, pressure relief valve, and removal of the old unit. We install from all major manufacturers and can help you choose the right model for your household's demand.
- Endless hot water on demand
- 20–30% energy savings vs. tank heaters
- Compact wall-mounted design
- 20+ year lifespan
- Gas line sizing included
- Hard water maintenance guidance
Service Details
Quick Info
Typical Cost
$1,800–$4,500+
Timeline
1–2 days
Warranty
1-year labor + manufacturer
Know the Warning Signs
Signs You Need Tankless Water Heater Installation
Catching these early prevents a small issue from becoming a costly emergency.
If a standard 40–50 gallon tank can't keep up with your household's demand, a tankless system is worth serious consideration.
An existing tankless system that isn't meeting hot water demand may be undersized, have a failing component, or have scale buildup in the heat exchanger.
If water heating represents a significant portion of your utility bill, a high-efficiency tankless unit can meaningfully reduce that cost.
Local Expertise
How St. George's Desert Climate Affects Tankless Performance
Tankless water heaters are rated by temperature rise at a given flow rate. In practical terms, this means your incoming water temperature directly affects how much hot water the unit can produce simultaneously. St. George's incoming water temperature swings significantly — mid-70s°F in summer versus low-40s°F in January. A unit that handles three showers simultaneously in July may struggle with two in January because it needs to produce a much larger temperature rise to reach 120°F.
This is why proper sizing matters more in Southern Utah than in more temperate climates. We calculate your household's peak demand using winter conditions — the worst case — so the system performs reliably year-round. A common mistake by less experienced installers is sizing based on summer inlet temperatures, which leads to disappointing performance exactly when you need hot water most. If you already have a tankless unit that underperforms in winter, it may be undersized rather than malfunctioning.
The hard water factor can't be overstated either. Without annual descaling, a tankless unit in St. George will lose noticeable output within 2–3 years as scale narrows the passages in the heat exchanger. We've serviced units where the exchanger was so clogged it triggered the high-temperature safety limit — essentially shutting itself down to prevent damage. A water softener upstream of the tankless unit dramatically reduces descaling frequency and protects the investment.
Transparent from Start to Finish
How Our Service Works
Assessment & Sizing
We assess your household's hot water demand, gas line capacity, and venting options to recommend the right unit.
Equipment & Scheduling
We source the recommended unit and schedule installation at your convenience.
Full Installation
We complete gas line work, venting, water connections, and unit mounting — handling every aspect of the installation.
System Walkthrough
We demonstrate operation, explain maintenance requirements, and answer all your questions before we leave.
Compare Your Options
Gas vs. Electric Tankless Water Heaters
Both types eliminate the storage tank, but they differ significantly in output, installation requirements, and operating cost.
Our recommendation: For whole-house water heating in St. George, gas tankless is the clear winner — natural gas is cost-effective in Utah, and the higher BTU output handles multi-fixture demand. Electric tankless units work well as point-of-use supplements for a detached casita, workshop bathroom, or distant fixture that's far from the main unit.
The Marlin Difference
Why Southern Utah Trusts Marlin
Proper Sizing Every Time
We calculate your household's peak demand before recommending a unit. An undersized system is a common mistake we prevent.
Complete Installation Service
Gas, venting, water connections — we handle the entire installation. No need to coordinate multiple contractors.
Hard Water Maintenance Guidance
We explain how St. George's water affects tankless systems and set you up with the right maintenance schedule.
All Major Brands
We install Rinnai, Navien, Rheem, Noritz, and others. We recommend based on your needs, not brand preference.
Real Customers, Real Results
What Our Customers Say
“Switched from a 50-gallon tank to a Navien tankless and the difference is night and day. Endless hot water, our gas bill dropped, and we gained a closet back. Marlin handled the whole conversion — gas line, venting, everything. Couldn't be happier.”
— Greg A.
St. George, UT
“We were skeptical about tankless — sounded like marketing hype. Marlin's tech sat down and actually calculated our hot water demand, showed us the gas line needed an upgrade, and walked us through the real costs vs. savings. No pressure, just math. We went with a Rinnai unit and haven't run out of hot water once in 14 months. The gas bill savings are real.”
— Jeff and Lisa M.
Bloomington, UT
“Had another company install a tankless unit two years ago that never worked right — lukewarm water when multiple fixtures were running. Marlin diagnosed it as undersized for our 4-bathroom house. They replaced it with a properly sized Navien unit and upgraded the gas line. Night and day difference. Wish I'd called Marlin first.”
— Carlos R.
Hurricane, UT
Real Work, Real Results
Tank-to-Tankless Conversion: 4-Bathroom Home in Bloomington
The Problem
A family of six in a 3,200 sq ft home was constantly running out of hot water. Their 50-gallon gas tank heater couldn't keep up with back-to-back showers, laundry, and the dishwasher running simultaneously. They'd been told by another company to install a second tank, which would have consumed significant garage space.
Our Solution
We evaluated their peak hot water demand — four simultaneous fixtures during morning routines — and specified a Navien NPE-240A unit rated for that flow at St. George's winter inlet temperature. The existing 1/2-inch gas line was undersized, so we ran a new 3/4-inch gas supply. We installed the unit wall-mounted in the garage, added proper B-vent, and connected a recirculation loop to eliminate cold water delays at distant fixtures.
The Result
The family went from rationing showers to running all four bathrooms simultaneously without any drop in temperature. Monthly gas costs decreased by approximately $25. The wall-mounted unit freed up the floor space previously occupied by the tank. No performance issues in 18 months, including through the winter season.
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Got Questions?
Tankless Water Heater Installation FAQ
Answers from our certified technicians — based on the questions St. George homeowners ask most.
For most households, yes — especially with 3+ people. The 20–30% energy savings, unlimited hot water, and 20+ year lifespan make the higher upfront cost pay off within 5–7 years. The key in St. George is pairing it with a water softener and committing to annual descaling.
Tankless Water Heater Installation Across Southern Utah
Serving St. George and the surrounding Washington County communities since 1978.
Need Tankless Water Heater Installation?
Call us 24/7 for same-day service. Free estimates on all projects. No hidden fees, no surprises — just honest work from a team that's served St. George since 1978.
IAPMO Certified • 47+ Years • Licensed & Insured • Certiflow-Certified Parts