5 Star Plumbing | Tankless Water Heater Installation: Step-by-Step Guide for Homeowners
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Tankless Water Heater Installation: Step-by-Step Guide for Homeowners

5 Star Plumbing > Blog > Tankless Water Heater Installation: Step-by-Step Guide for Homeowners
Tankless water heaters, also known as on-demand or instantaneous water heaters, have become an increasingly popular option for domestic hot water over traditional tank-style units. As the names suggest, tankless heaters do not rely on a storage tank, but rather employ heating coils to quickly warm water as it flows through the unit. This allows for a nearly endless supply of hot water on demand instead of running out when a tank’s capacity maxes out. Tankless units were originally pioneered in Europe and Asia where higher energy costs and smaller spaces made their efficiency and compact size more appealing. While pricier upfront, electrical or gas-fueled tankless models available today typically last twice as long as tank heaters and save owners 20-50% on their utility bills in the long run. As demand for energy conservation and smart home accessories grow, tankless water heaters are now mainstream options for American homes.

How do Tankless Units Work?

Rather than constantly maintaining a full tank of water hot 24/7 as energy intensive storage tank models do, tankless systems utilize heat exchangers to rapidly increase cold water temperatures only on demand when a hot water tap is activated. This maximizes energy efficiency as no residual heat is lost to the air when the unit sits idle. Cold incoming water passes through precision engineered copper or stainless steel tubes warmed externally by natural gas burners or internal electrical coils up to 199°F if desired. An electronic control module swiftly gauges flow volumes and temperature needs to modulate gas input or electric wattage to efficiently achieve the target temp. Tankless heat exchangers transfer heat so rapidly they can supply 2-5 gallons per minute endlessly, though flow depends on unit size and incoming cold water temps. How do Tankless Units Work

Benefits of Tankless Water Heaters Installation

Homeowners choosing tankless water heater installation instead of a traditional model enjoy numerous advantages:
  • Cost Savings: Consuming gas or electricity only when activated rather than 24/7 translates to 30-60% savings on monthly utility bills, recovering install costs over 3-5 years.
  • Environmentally-Friendly: Less fossil fuel consumption and superior insulation cut carbon emissions over 30%.
  • Endless Hot Water: Tankless systems supply unlimited hot water for long showers, filling baths or the hot tub without discomfort or unexpected cold shocks.
  • Space Saving Design: Compact modular construction mounts on walls with no bulky tank needing closet space and complex venting like older models.
  • Durability: Tankless units last over 20 years on average with minimal repairs outside basic component wear, twice as long as most tank heaters.
  • Precise Temperature Control: Sophisticated computer modules maintain exact outlet water temperatures down to the desired degree.
  • Peace of Mind: Some gas tankless water heaters offer stainless steel heat exchangers superiorly resistant to mineral buildup. Condensing models extract extra heat from exhaust gases, increasing efficiency over traditional venting.
Benefits of Tankless Water Heaters Installation

Ideal Indoor Tankless Locations

When selecting an installation site, key considerations include:
  • Proximity to Water Lines: Should be mounted as close as possible to the main water supply lines entering the house to avoid expensive rerouting.
  • Nearby Electrical: Electrical tankless water heaters require hardwired 220V connections able to supply 150-200 amps for higher end units.
  • Convenient Gas Lines: Gas-fired units need a large gas line (often 3/4”) supply that can provide 180,000 – 300,000 BTU depending on model.
  • Ventilation: Stainless steel category III or IV vent pipes carrying exhaust heat should have the most direct path possible to external ventilation.
  • Wall Space: Several models offering up to 9.8 GPM weigh over 100 lbs so require reinforced mounting on a sturdy concrete or block wall.
  • Freeze Protection: If installing outdoor units in colder climates, precautions must be taken to insulate all system components vulnerable to freezing.
Popular Indoor Mounting:
  • Garage near the water main and panel
  • Basement near floor drain and vent access
  • Utility room for ease of access
  • External house walls to simplify venting
Tankless Unit Size & Flow Rate Sizing

Tankless Unit Size & Flow Rate Sizing

Choosing the appropriate size tankless model to meet household demand comes down to determining peak simultaneous flow rate needs so the heater can fire up to full capacity at any given moment without shortages. As these heaters lack reservoirs, they cannot compensate for under capacity. Consider needs for:
  • Showers – seek 2.5 GPM per shower head x number running at once
  • Sinks – 1-2 GPM for bathroom faucets used together
  • Appliances – dishwasher 2-3 GPM, washing machine 4-9 GPM. See specs.
  • Outdoor spigots for gardening, pools, hot tubs – wide variability
Also factor in any future kitchen or bath remodels that may add high volume fixtures. When in doubt, size up for comfort and convenience. Insufficient flow capacity triggers the unit to self-limit the rise in temperature to prevent overheating damage, resulting in frustratingly tepid “hot” water.

Pre-Installation Requirements & Prep

Consult local jurisdictions regarding permits needed for gas line work, electrical upgrades or exhaust venting through walls and ceilings. Utilize professional tradesmen for specialized tasks. Shut off cold water valves and gas/electrical supply to the region and drain all pipes. Gather necessary gear: Tools – pipe wrenches, tube cutter, propane torch, flux brushes, soldering iron, plumber’s putty, Teflon tape Materials – category III stainless venting, insulation wraps, pipe sealants, pipe fasteners, wall brackets Costs – factor $500-2000 for parts like circuit upgrades or gas line installation plus $2000+ for professional unit installation unless highly skilled. Pre-Installation Requirements & Prep

Tankless Installation Step-By-Step

Follow these key phases to install a new gas-fired tankless water heater:
  1. Mount the Unit. Determine the ideal wall location to simplify venting and pipe runs. Check specs for weight limits and reinforce as needed. Use a level to properly affix mounting brackets, allowing rear access to ports.
  2. Install Venting. Venting length and elbow turns impact flow dynamics so minimize complex routing. Cut stainless vent tubes to size. Maintain prescribed upward pitch. Seal all interior slip joints with manufacturer approved tape or sealant to prevent exhaust leakage into living spaces.
  3. Connect Water Lines. Solder copper cold and hot water supply lines to unit inlet ports with gas torch observing local codes or utilize sharkbite push-to-connect fittings for ease. Deburr all cut tube ends. Ensure inlet/outlet valves bookend unit. Install insulation wrap.
  4. Install Gas Line. A 3⁄4” minimum black iron pipe supply line is typical to sustain high BTUs on larger models. Branch off nearest high capacity trunk line after whole-house shut off valve. Maintain the gas line at downward pitch back to supply without sags for condensate drainage in unit. Use thread sealant and test for leaks.
  5. Make Electrical Connections. Hardwire heater to a properly grounded 220v circuit able to provide ample amps for the model size without tripping. Outdoor units require weatherproof NEMA electrical enclosures. Make all wire terminations tightly and securely.
  6. Adjust Settings & Test. Bleed all air from the lines by opening hot water taps. Verify computer module settings for output temp and activation flow rate are appropriate to needs and local codes. Activate heater for at least 15 minutes across various fixtures to check for leaks, kinks, odd sounds or errors before enclosing unit.

Special Electric Model Considerations

Electric tankless water heater installation follows the same mounting, ventilation, and water line connection process but with key electrical variations:
  • Often require upgraded 200 amp panels or subpanels
  • Use condensed internal wiring schemes without complicated gas lines
  • Must program computer modules to modulate heating coils across variable currents and avoid trip risks
  • Requireleman or outdoor NEMA weatherproof power boxes
Maintenance Musts

Maintenance Musts

While tankless heaters require less routine maintenance than traditional models, annual inspections help sustain efficiency and lifespan:
  • Inspect heat exchanger fins for mineral buildup restrictions which reduces output. Descale annually.
  • Check computer panel for error codes hinting at part failures. Diagnose issues early before cascading damage results.
  • Examine all water and gas fittings for corrosion or leaks needing resealing.
  • For gas models, verify exhaust venting remains intact without blockage.
  • Evaluate anode rods and purge valves on applicable units.
  • Test pressure relief valves to ensure proper hot water discharge.
While complex repairs are best left to licensed professionals, properly maintained tankless units should outlast traditional models 2-to-1.

Reaping Hot Water Rewards

Tankless water heaters involve careful placement planning, electrical knowhow and plumbing finesse to install but yield endless on-demand hot water for improved convenience, lower utility bills, and space maximization for years to come. Consult licensed professionals when complexity exceeds DIY capabilities. Enjoy those long steamy showers guilt-free knowing your energy and cost savings earn back install expenses relatively swiftly. The comfort and reliability of instantaneous hot water makes tankless a top choice to consider when upgrading home water heating in the modern age. Still Debating Whether Tankless Is Worth It?

Still Debating Whether Tankless Is Worth It? Key FAQs Answered

Question: How do tankless water heaters work and why are they considered energy-efficient? Answer: Tankless water heaters, also known as on-demand water heaters, 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’s heated by either a gas burner or an electric element. This process eliminates the need to keep a large volume of water hot in a tank, leading to energy savings. They’re energy-efficient because they only heat water when needed, reducing the standby energy losses associated with storage water heaters. Question: What are the installation costs for a tankless water heater compared to traditional models? Answer: The installation cost of a tankless water heater is generally higher than that of a traditional tank model. This is due to the need for potential upgrades like larger gas lines, stainless steel vent pipes, or enhanced electrical circuits. However, these initial costs are often offset by the long-term energy savings and the longer lifespan of tankless models. Question: What should be considered when choosing the type of tankless water heater for a home? Answer: When choosing a tankless water heater, consider factors like the size of your home, the number of fixtures needing hot water, and your peak water usage. Gas-powered models can handle higher flow rates and are ideal for larger households. Electric tankless water heater, while more compact and easier to install, is better for smaller homes and lower usage. For whole-house systems, consider a model that can handle the combined flow rate of showers, sinks, and appliances used simultaneously. Question: How much can I expect to save on energy bills with a tankless water heater? Answer: Tankless water heaters can be 20-50% more energy-efficient than traditional tank water heaters, potentially saving hundreds of dollars a year. The exact savings depend on factors like water usage, heater efficiency, and energy rates. Additionally, the more hot water you use, the greater the savings, as tankless heaters are more efficient under higher usage. Question: What are some installation requirements and professional skills needed for tankless water heaters? Answer: Installing a tankless water heater requires professional plumbing and, depending on the model, electrical skills. Gas model needs a gas connector kit, proper venting with stainless steel vent pipes, and a suitable black pipe for gas supply. Electric tankless water heater requires a dedicated electrical outlet and possibly an upgraded electrical panel. Always hire professional plumbers for safe and efficient gas or electric unit installation, and ensure they adhere to local building codes and safety standards.
Peter, plumber

I bring over 9 years of dedicated plumbing experience to the table. As a seasoned professional in the plumbing industry, I've tackled a wide range of projects, from residential repairs to large-scale commercial installations.

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