Top Tankless Water Heater Service Companies in St Louis, Missouri Ranked

A tankless water heater provides hot water on demand, offering energy savings and endless supply compared to traditional tank models. For St. Louis homeowners, choosing the right on-demand system and ensuring proper installation and maintenance are crucial for long-term performance and efficiency. This guide helps you understand the key considerations for tankless water heaters and how to find qualified local professionals for your project.

Roto-Rooter Plumbing & Water Cleanup

300 Biltmore Dr Ste 348, Fenton, MO 63026

Roto-Rooter Plumbing & Water Cleanup provides a wide range of plumbing services in St Louis, MO, including sewer camera inspections, water heater repairs and installations, drain cleaning, hydro jetting, and sewer line repairs using both conventional excavation and trenchless methods. They also install water softeners and filtration systems to address hard water issues common in the area. The company offers 24/7 emergency plumbing services to address urgent problems promptly. Their technicians use video camera inspections to accurately diagnose sewer line issues and provide effective solutions.

5.0

504 Reviews

Anton's Plumbing, Heating/Cooling & Energy Experts

950 Bolger Ct, Fenton, MO 63026

Anton's Plumbing, Heating/Cooling & Energy Experts has been serving St. Louis, MO, since 1979, providing comprehensive plumbing, heating, and cooling services. They specialize in water heater repair and installation, including tankless water heaters, alongside HVAC system maintenance and upgrades. Their team offers energy-efficient solutions and whole-home comfort services tailored to customer needs, supported by NATE-certified technicians. Anton's is a family-owned company focused on delivering reliable plumbing and HVAC services with a commitment to long-term performance and indoor air quality.

4.9

4.2k Reviews

Tony LaMartina Plumbing Co. Inc

5705 Dale Ave, St. Louis, MO 63110

Tony LaMartina Plumbing Co. Inc is a family-owned plumbing company serving St Louis, MO. They offer a wide range of plumbing services including water heater repair and installation, tankless water heater services, drain cleaning, hydro jetting, sewer line repair, trenchless sewer repair, leak detection, and repiping. The company has over 40 years of experience and a legacy of plumbing expertise in the St. Louis area dating back over 100 years. They emphasize thorough preparation and clean work practices to ensure quality results.

4.9

1.4k Reviews

Roto-Rooter Plumbing & Water Cleanup

2671 Washington Ave, St. Louis, MO 63103

Roto-Rooter Plumbing & Water Cleanup provides a wide range of plumbing services in St. Louis, MO, including commercial plumbing, water heater repair and installation, sewer line repair, and water softener installation. They offer specialized services such as hydro jetting, video camera sewer inspections, and trenchless sewer repair methods to minimize disruption. The company serves various commercial clients and residential customers, addressing issues like hard water and sewer line problems with durable solutions. Their expertise includes servicing all types of water heaters, from conventional to tankless and solar models, and installing multiple water filtration systems to improve water quality.

4.8

5.3k Reviews

Roto-Rooter Plumbing & Water Cleanup

4806 Trade Access Blvd Ste 900, Hazelwood, MO 63042

Roto-Rooter Plumbing & Water Cleanup provides a wide range of plumbing services in St Louis, MO, including sewer camera inspections, water heater repairs and installations, drain cleaning, hydro jetting, sewer line repair, trenchless sewer repair, leak detection, and toilet repair. They serve the Hazelwood metro area and surrounding communities, addressing issues such as clogged drains, sewer backups, and water heater problems. Their capabilities include video camera inspections for sewer lines and trenchless sewer repair methods that minimize disruption. Roto-Rooter offers 24/7 emergency service to handle urgent plumbing and water-related problems at any time.

4.8

5.0k Reviews

See more providers in St Louis, MO

Understanding Tankless Water Heaters

Often called on-demand or instantaneous water heaters, these systems heat water directly without the use of a storage tank. When a hot water tap is turned on, cold water travels through a pipe into the unit, where it is heated by either a gas burner or an electric element. This process delivers a constant supply of hot water, eliminating the standby energy losses associated with storage water heaters ¹. For busy St. Louis households, this means no more waiting for the tank to refill and reheat between showers or laundry loads.

Key Benefits for St. Louis Homes

• Energy Efficiency: By heating water only when needed, tankless units can be 24%-34% more energy efficient for homes that use 41 gallons or less of hot water daily ².
• Space Savings: Wall-mounted units are compact, freeing up valuable floor space in basements, utility closets, or garages.
• Longer Lifespan: With proper maintenance, a tankless system can last more than 20 years, often outlasting traditional tank models.
• Endless Hot Water: Ideal for larger families or homes with high simultaneous demand, like multiple showers running at once.

Critical Considerations Before Installation

Installing an on-demand water heater is more complex than a simple swap for a tank model. Several site-specific factors must be evaluated by a professional to ensure optimal performance and safety.

Sizing Your System Correctly

The most important step is proper sizing, which involves matching the unit's flow rate (measured in gallons per minute, or GPM) to your home's peak hot water demand. A professional will calculate the total GPM needed if all hot water appliances (showers, dishwasher, washing machine) were to run simultaneously ^{1 3}. An undersized unit will struggle to meet demand, leading to lukewarm water and frustration.

Accounting for St. Louis Water Quality

St. Louis has notably hard water, which contains high levels of minerals like calcium and magnesium ^{1 4}. These minerals can accumulate and scale inside the heat exchanger of a tankless unit, reducing efficiency, restricting flow, and potentially causing damage over time. Many local professionals strongly recommend installing or maintaining a water softener or treatment system to protect your investment ^{1 4}.

Choosing the Right Fuel Type: Gas vs. Electric

• Gas Tankless Heaters: These are popular for their high flow rates, suitable for whole-home heating. They require a sufficient gas line (often needing an upgrade to a ¾-inch line), proper venting, and access to combustion air ¹.
• Electric Tankless Heaters: These are easier to vent but require significant electrical power. They often need dedicated, high-amperage circuits (like 120-amp breakers) and may necessitate an upgrade to your home's electrical panel ¹.

Installation Location and Venting Requirements

The unit must be mounted on a wall within 50 feet of a power source. Venting is a critical and code-specific component:

• High-Efficiency Gas Models: Use PVC piping for direct venting, which also requires a condensate drain to handle acidic condensation ¹.
• Standard Gas Models: Typically require expensive stainless steel venting for power vent or atmospheric vent setups ¹.
• Combustion Air: Modern, tightly-sealed St. Louis homes may need a dedicated combustion air intake pipe to ensure the burner operates safely and efficiently ¹.

The Professional Installation Process

A proper tankless water heater installation by a licensed plumber involves several key steps to ensure safety, compliance with local codes, and peak efficiency.

1. Site Evaluation & Load Calculation: A technician assesses your home's hot water usage, inspects existing gas/electrical lines, and determines the best location.
2. System Preparation: This may involve upgrading gas lines to ¾-inch diameter, installing new electrical circuits, or adding a condensate drain line.
3. Mounting & Connection: The unit is securely mounted, and all water, gas, electrical, and vent connections are made.
4. Venting Installation: The correct venting system (PVC or stainless steel) is installed according to manufacturer and code specifications.
5. Startup & Testing: The system is powered on, purged of air, and tested for proper ignition, temperature rise, and flow rate.

Understanding Costs and Incentives

The initial investment for a tankless system is higher than for a conventional tank heater. In the St. Louis area, total installation costs typically range from $2,400 to $5,400 or more, depending on the unit's complexity, fuel type, and necessary upgrades to your home's infrastructure ^{3 5 2}.

However, utility rebates can help offset this cost. For example, Spire offers rebates of approximately $300 for qualifying high-efficiency gas tankless water heaters, and Liberty Utilities offers around $200 ⁵. Some local service companies also offer financing options to make the upgrade more manageable ³.

Essential Maintenance for Longevity

Annual professional maintenance is not just recommended; it's essential for protecting your tankless water heater investment, especially given St. Louis's hard water ^{6 7}. A typical maintenance visit includes:

• Flushing the System: A chemical descaling solution is circulated through the heat exchanger to dissolve and remove mineral buildup, the primary cause of reduced efficiency and failure ^{8 7}.
• Comprehensive Inspection: The technician will check and test gas connections, vent integrity, water flow, ignition sequences, and safety devices.
• Filter Cleaning: Inlet water screens and air filters are cleaned to ensure unrestricted flow.

Neglecting this maintenance can void warranties and lead to costly repairs or premature replacement. A professional maintenance checklist helps ensure your system operates safely and efficiently for years to come ^{6 8}.

Common Repairs and Troubleshooting

Even with diligent maintenance, components can wear out. Common issues with on-demand water heaters include:

• Mineral Buildup (Scaling): The most frequent repair need in hard water areas, causing error codes, reduced hot water output, or complete shutdown.
• Ignition Failure: Problems with the gas valve, igniter, or flame sensor can prevent the burner from lighting.
• Vent Blockage: Debris or improper installation can cause venting issues, triggering safety shut-offs.
• Flow Sensor Issues: A faulty sensor may not detect water flow, preventing the unit from activating.

It's crucial to contact a qualified professional for diagnosis and repair. Attempting DIY fixes on gas or complex electrical components can be dangerous and may violate local codes.

Finding a Qualified Professional in St. Louis

When selecting a provider for your tankless water heater installation, repair, or maintenance, look for:

• Proper Licensing & Insurance: Ensure the company holds current Missouri plumbing and HVAC licenses and carries liability insurance.
• Specific Experience: Ask how many tankless systems they install and service annually. Experience with local water conditions is a plus.
• Detailed Estimates: A reputable company will provide a written, detailed quote that includes all labor, materials, permits, and potential upgrade costs.
• Warranty Offerings: Understand the warranties on both the equipment and the labor provided by the installer.

Local companies like Academy Air, Unique Heating & Cooling, Classic Aire Care, Hosack Plumbing, Anton's Plumbing, and Precision Plumbing Solutions have experience with tankless systems in the St. Louis metro area ^{1 3 5 9 10 11}.

Frequently asked questions

Sources