4Most Energy is a top choice for Navien and Rinnai installations because:

• 10+ years of boiler & tankless experience

• Fully manufacturer-trained and certified installers

• Authorized to claim Navien & Rinnai warranty

• Experts at fixing installation errors from other companies

• Same-day emergency support across the GTA

• Honest, brand-neutral recommendations based on your home

• Proper solutions for any water-heating system, regardless of brand availability

Professional installation, fast service, and full warranty protection make 4Most Energy one of Ontario’s most trusted tankless specialists.

4Most Energy checks current factory promotions, supplier discounts, and in-stock models before giving you a quote. We always recommend the option with the best performance at the lowest cost at that moment.

Gas line upgrade (if needed)

Venting system

Condensate pump/drain

Isolation valves

Stainless steel flex lines

Commissioning & system testing

Warranty registration

1-year labour coverage

No hidden add-ons.

4Most Energy’s licensed technicians have 15+ years of combined experience installing boilers, tankless water heaters, and heat pumps across Ontario. Our service is backed by hundreds of 5-star Google Reviews.

Both Rinnai and Navien are top-performing tankless brands, but each has unique advantages:

Rinnai (Premium Reliability)

• Industry-leading Japanese engineering

• Longest lifespan in the market

• Extremely low failure rate

• Quieter operation

• Best choice if long-term durability is your priority

Navien (Best Features & Value)

• Built-in recirculation on many models (faster hot water)

• Stainless steel heat exchanger

• Strong performance for multi-bathroom homes

• Often more cost-effective

4Most Energy installs both brands based on the size of your home, hot-water demand, and venting/gas requirements—not upselling.

Tankless sizing depends on:

• Number of bathrooms

• Shower flow rates

• Peak hot-water usage (GPM)

• Winter inlet temperature in Ontario

• Home layout

General guideline for Ontario homes:

• 1 bathroom / condo → 120,000–150,000 BTU

• 2 bathrooms / townhome → 150,000–180,000 BTU

• 3+ bathrooms / detached home → 180,000–199,000 BTU

• Large homes / multi-showers → 199,000 BTU or dual tankless in parallel

4Most Energy provides the correct GPM calculation and recommends the ideal Navien or Rinnai model for your home.

All 4Most Energy installations include:

• 1-year labour warranty (extendable to 10 years)

• Up to 10-year manufacturer parts warranty

• Heat exchanger warranty:

  • Rinnai → up to 15 years

  • Navien → up to 15 years

• Full warranty registration by our team

• Priority support & service across the GTA

Your system is fully protected long-term.

Rinnai performs best with air handlers and hydronic coils.
It provides:

• Stable hot-water supply

• Consistent flow

• High reliability for heating systems

If your home uses an air handler for heating, Rinnai is usually the better choice.

Navien is the best option for homes with:

• Long plumbing runs

• Slow hot-water delivery

• Multiple bathrooms

• Need for faster recirculation

Many Navien units include a built-in recirculation pump, giving quicker hot water at remote taps.

Maintenance needs depend on Ontario water quality and usage.

Recommended Schedule:

• Descaling every 3–5 years (hard water = every 3 years)

• Annual system check including:

  • Vent inspection

  • Air intake filter cleaning

  • Cold-water inlet filter cleaning

  • Gas pressure testing

  • Condensate drain inspection

  • Ignition system cleanup

  • Checking for restrictions or leaks

This ensures maximum performance and extends lifespan.