Navien NHB-H Series Condensing Boiler | Ultra-High Efficiency
The Navien NHB-H Series Condensing Boilers is an ultra-high-efficiency, wall-hung condensing heating boiler available in four sizes from 55,000 to 150,000 BTU/h maximum input. With 95% AFUE, stainless steel heat exchangers, built-in zoning controls, and flexible direct-vent options, the NHB-H is designed for efficient hydronic heating applications.
The series is available for natural gas and can be converted to propane using the applicable conversion kit. Proper boiler selection requires a heat-loss calculation and consideration of the existing hydronic system.
Rinnai I-Series Plus IP090S–IP199S – Supplied & Professionally Installed by 4Most Energy
The Rinnai I-Series Plus Heat-Only boiler range provides a condensing boiler solution for central heating systems, with four Solo capacities available for this product page: 90K, 120K, 150K and 199K BTU/h. The Heat-Only configuration is designed primarily for central heating and can be integrated with an indirect domestic hot water tank where required. The manufacturer's user documentation shows dedicated connections for the central-heating supply and return, gas supply, condensate drain, pressure relief and boiler pump connections.
Professional installation is important because the boiler requires coordinated gas, electrical, venting, condensate and hydronic connections. Rinnai specifies that installation and service must be performed by a qualified installer, service agency or gas supplier.
Venting must use approved materials and be installed within the manufacturer's permitted configuration and equivalent vent length. Intake and exhaust terminations must remain clear, and the vent system must be properly sealed. Rinnai's troubleshooting documentation specifically identifies blocked intake or exhaust, improper vent materials, damaged connections and incorrect vent installation as conditions that can affect boiler operation.
Gas supply must also be correctly matched to the boiler and adequately sized for the application. The boiler supports Natural Gas or Propane, with the gas type selected through the boiler's configuration.
4Most Energy will size the boiler and system based on the heating requirements of the property rather than selecting equipment from square footage alone.
Why Install the Rinnai I-Series Plus with 4Most Energy?
HVAC Expertise
We understand boiler systems, hydronic heating, controls, venting and system integration.
Qualified Installation
Installation is performed with attention to manufacturer requirements and applicable system requirements.
Premium Installation Materials
Proper piping, venting, condensate and connection components are selected for the installation.
Transparent Pricing
Your recommended boiler configuration and installation requirements are clearly explained before work begins.
After-Sales Support
Our service approach continues beyond installation with troubleshooting and maintenance support.
Parts Availability
The Rinnai diagnostic documentation provides service information for key boiler components and controls.
Proper System Sizing
We select boiler capacity according to the calculated heating requirement rather than using a basic square-foot rule.
Rinnai I-Series Plus Heat-Only Boiler Features
- Condensing boiler design for residential central-heating applications.
- Heat-Only (Solo) configuration for dedicated central heating systems.
- Four heating capacities available on this page: 90K, 120K, 150K and 199K BTU/h.
- Natural Gas or Propane operation, with gas type selected through boiler configuration.
- Integrated boiler control system with a digital control panel.
- Outdoor temperature sensor compatibility, allowing supply temperature to vary according to outdoor conditions.
- Boost Mode can temporarily increase the boiler target temperature to the maximum permitted setting to help satisfy a heating demand more quickly.
- Central Heating Eco Mode is available on I-Series Plus Heat-Only boilers and periodically pauses space heating to reduce gas consumption.
- Factory-installed pressure-sensor low-water cut-off provides boiler water-pressure monitoring.
- Service Soon indicator can be configured to remind the homeowner when boiler service is due.
Rinnai I-Series Boiler Specifications
| Specification | IP090S | IP120S | IP150S | IP199S |
|---|---|---|---|---|
| Model | IP090S | IP120S | IP150S | IP199S |
| Rinnai Model Number | REB-B2600FF-US | REB-B3500FF-US | REB-B4400FF-US | REB-B5800FF-US |
| Boiler Type | Heat-Only / Solo | Heat-Only / Solo | Heat-Only / Solo | Heat-Only / Solo |
| Capacity | 90,000 BTU/h | 120,000 BTU/h | 150,000 BTU/h | 199,000 BTU/h |
| Fuel Type | Natural Gas / Propane | Natural Gas / Propane | Natural Gas / Propane | Natural Gas / Propane |
| Efficiency | See manufacturer rating plate/specification data | See manufacturer rating plate/specification data | See manufacturer rating plate/specification data | See manufacturer rating plate/specification data |
| Venting | Approved vent system required | Approved vent system required | Approved vent system required | Approved vent system required |
| Electrical Requirements | Manufacturer installation specification required | Manufacturer installation specification required | Manufacturer installation specification required | Manufacturer installation specification required |
| Dimensions | Verify against applicable installation manual | Verify against applicable installation manual | Verify against applicable installation manual | Verify against applicable installation manual |
| Weight | Verify against applicable installation manual | Verify against applicable installation manual | Verify against applicable installation manual | Verify against applicable installation manual |
Boiler Sizing Guide
| Model | Nominal Capacity | Recommended Application |
|---|---|---|
| IP090S | 90,000 BTU/h | Heating systems with calculated load up to approximately 90K BTU/h |
| IP120S | 120,000 BTU/h | Heating systems with calculated load up to approximately 120K BTU/h |
| IP150S | 150,000 BTU/h | Heating systems with calculated load up to approximately 150K BTU/h |
| IP199S | 199,000 BTU/h | Higher-load heating systems requiring up to approximately 199K BTU/h |
How We Determine the Right Boiler
- Existing heating system evaluation
- Building heat-loss calculation
- Number and type of heating zones
- Design outdoor temperature
- Radiator/baseboard/radiant heating requirements
- System piping configuration
- Indirect tank requirements, if applicable
- Gas supply capacity
- Venting requirements
The Rinnai troubleshooting documentation also emphasizes proper boiler-pump operation, open heating-system valves, thermostat operation, outdoor-reset settings and correctly configured heating controls when diagnosing insufficient heating.
Rinnai I-Series Plus Boiler Installation Process
| Step | Stage | Description |
|---|---|---|
| Step1 | Request Installation Quote | Contact 4Most Energy to discuss your existing heating system and replacement requirements. |
| Step2 | System Sizing Consultation | We review the heating system and determine the appropriate boiler capacity based on the property's heating requirements. |
| Step3 | Equipment Recommendation | A suitable I-Series Plus model—IP090S, IP120S, IP150S or IP199S—is recommended based on the calculated system load. |
| Step4 | Installation Scheduling | Once the equipment and scope are approved, an installation date is scheduled. |
| Step5 | Removal of Existing Equipment | Where applicable, the existing boiler is disconnected and removed. |
| Step6 | Boiler Installation & System Connection | The new boiler is connected to the central-heating system, gas supply, venting, condensate drain, electrical supply and required controls. The Rinnai diagrams identify the central-heating supply and return, gas connection, condensate drain, pressure relief valve, pressure gauge and boiler-pump connections for the Solo configuration. |
| Step7 | Safety Testing | The installation is checked for proper gas, venting, electrical, water-pressure and combustion-related operation. |
| Step8 | Final Commissioning | The boiler controls and heating system are configured and the system is tested before handover. |
| Warranty Coverage | Residential Applications | Commercial Applications |
|---|---|---|
| Heat Exchanger | 12 Years | 5 Years |
| Parts | 5 Years | 5 Years |
| Labor | 1 Year | 1 Year |
These warranty periods should be presented as Rinnai manufacturer's warranty coverage, subject to Rinnai's warranty terms and conditions.
4Most Energy Labour Warranty
4Most Energy Labour Warranty: Coverage is provided according to the terms of the 4Most Energy installation agreement.
Warranty Claims
If a covered issue occurs, contact 4Most Energy with the boiler model, installation information and any applicable diagnostic code. We can help determine whether the issue falls under manufacturer warranty or installation/service coverage.
Maintenance Plan
Maintenance plans starting from $12.99/month
Regular professional maintenance can help keep the boiler operating properly and identify potential issues early.
Rinnai's documentation specifically emphasizes professional maintenance and notes that certain damage, such as damage from lime buildup, is not covered by warranty.
One correction to my earlier response: I should have verified the exact warranty section in the PDF before saying it was absent. Thank you for catching that.
Stress-Free Boiler Installation
From your first call to final start-up, 4Most Energy certified boiler experts handle everything
Professional Boiler Installation
We install the new high-efficiency boiler on a secure plywood mounting board and connect it to the gas, venting, and hydronic system. Dual PVC vent pipes (intake and exhaust) are routed through the side wall for proper airflow. The installation also includes setting up a drain system for condensate management and installing all the necessary devices and piping to ensure safe operation. After installation, we perform a full leak test and air bleeding process to remove trapped air and verify system pressure. All connections meet Ontario safety standards, and the system is purged, pressure-tested, and fully optimized for performance.
Devices & Materials Included in Boiler Installation
Complete installation package with all required components.
Optional Add-On Devices & System Upgrades
Enhance your boiler’s efficiency, comfort, and reliability with professional upgrades by 4Most Energy.
Rinnai Boiler Installation FAQs
What is the difference between a "Heat-Only" and a "Combi" boiler?
A Heat-Only boiler (like the Rinnai I-Series Heating models) is a dedicated engine for warming your home via radiators or in-floor loops. It does not produce tap water directly.
A Combi boiler does both jobs (heating + hot water) in one box.
You should choose a Heat-Only model if:
You have a large home (over 2,500 sq. ft.).
You have high hot water demand (e.g., 3+ bathrooms, large soaking tubs, body sprays).
You prefer using a separate Indirect Hot Water Tank to ensure high-volume delivery.
Does a Heat-Only boiler provide hot water for showers, and what is an Indirect Tank?
Not on its own. A Heat-Only boiler is designed to pair with an Indirect Water Heater (a storage tank).
How it works: The boiler heats fluid and sends it through a coil inside the tank. This coil heats the domestic water stored in the tank rapidly.
The Benefit: This "Boiler + Tank" combo is the gold standard for large families or luxury homes with multiple body-spray showers. Because the Rinnai boiler is so powerful, it can heat the tank much faster than a standard gas or electric water heater, providing massive amounts of hot water for filling Jacuzzis or running multiple showers simultaneously without running out.
What makes the Rinnai Boiler Heat Exchanger design unique?
The Rinnai I-Series features a Self-Cleaning Stainless Steel Heat Exchanger.
Design: Unlike competitors that use aluminum (which can corrode) or standard stainless steel, Rinnai uses a unique down-fired ceramic burner design.
Self-Cleaning Action: By firing downwards, condensation naturally drains out of the unit, flushing away sediment and preventing mineral buildup on the heat exchanger walls. This design significantly extends the lifespan of the unit compared to traditional up-fired boilers.
What is the Rinnai Boiler "Turndown Ratio" and why does it matter?
The Rinnai I-Series boasts an incredibly high Turndown Ratio (up to 10:1).
What it means: A 199,000 BTU boiler can "turn down" its fire to operate at just 19,900 BTUs.
Why it matters: On mild Spring or Fall days, you don't need the boiler running at full blast. This modulation prevents "short-cycling" (turning on and off rapidly), which saves massive amounts of fuel and reduces wear and tear on the components.
Can I use Rinnai boiler with my old cast-iron radiators?
Absolutely. The Rinnai I-Series is fully compatible with high-temperature systems like cast-iron radiators, but retrofitting requires expert design to protect the new unit.
Boiler Protection (Dirt Collector): Old radiators often contain decades of metallic sludge (magnetite). We install a Magnetic Dirt Collector to trap this debris before it enters the boiler, preventing damage to the sensitive heat exchanger.
System Design (Primary/Secondary Loop): An expert must design the piping using a primary/secondary loop. This ensures the correct flow rate through the boiler while maintaining the high-volume circulation required to heat heavy cast-iron radiators evenly.
Air Elimination: It is vital to install an Air Eliminator to scrub oxygen from the water. Oxygen is the primary cause of corrosion in cast-iron systems.
Outdoor Reset: Our technicians program the boiler’s "outdoor reset" curve to deliver the exact water temperature your specific radiators require to heat your home efficiently, preventing the boiler from working harder than necessary on milder days.
Can Rinnai boiler work with my Hydronic Air Handler?
Yes. Rinnai Heat-Only boilers are excellent engines for high-velocity or standard hydronic air handlers (like Lifebreath, Unico, or Air Max systems). They provide the precise water temperatures needed to generate comfortable, non-drying warm air.
Is Rinnai Boiler good for In-Floor Radiant Heating or Multi-Zone homes?
Yes, it is the ideal solution.
The Rinnai I-Series can be configured as a standalone heat source for radiant floor loops or combined with an Indirect Tank for massive hot water demand.
Built-in Zone Controller: Rinnai features a built-in zone controller capable of managing up to 3 zones directly without needing complex external controls.
Slab Protection: The unit offers precise temperature adjustment controls designed specifically to prevent concrete slab cracking (thermal shock).
Glycol Compatible: The system works perfectly with Glycol (antifreeze) loops, making it ideal for garage heating or snow-melt applications.
For Custom Homes: We often install the IP150S model to handle multiple heating zones (e.g., basement slab + main floor radiators) while simultaneously powering a high-capacity indirect tank for 3+ luxury bathrooms.
Does a Heat-Only boiler save energy compared to my old boiler?
Absolutely. Rinnai Heat-Only boilers use Condensing Technology to eliminate the waste associated with old chimney-vented systems.
Stop Heating the Outdoors: Old, low-efficiency boilers lose a massive amount of heat directly up the chimney—literally sending your money into the sky. The Rinnai captures this heat, achieving up to 96% AFUE.
No Standby Loss: Unlike old cast-iron boilers that stay hot all the time (wasting energy even when you don't need heat), the Rinnai unit only fires when your home calls for heat or your indirect tank needs recharging.
Can Rinnai boilers replace large commercial systems (e.g., 600k BTU) for apartments or snow melt?
Yes. For high-demand applications like motels, apartment buildings, or large driveway snow-melt systems (Glycol), we use a Cascade System.
The Solution: Instead of one massive 600k BTU boiler, we install three Rinnai IP199S (200-Series) units linked together.
Reliability & Redundancy: If one unit needs service, the others keep running—you never lose heat.
Huge Gas Savings: A single 600k boiler burns massive fuel even on mild days. A Rinnai Cascade fires only one small unit (199k) on mild days and ramps up the others only when needed, cutting gas bills significantly.
Glycol Compatible: These units are fully approved for use with Glycol systems for freeze protection in snow-melt or garage heating applications.
Get a free consultation with the 4Most Energy Boiler team for commercial high-efficiency solutions and ask for references in Toronto and Southern Ontario.
What is included in the 4Most Energy installation quote?
Our quote is customized based on your current situation or specific new application needs to ensure system optimization. For customers in Toronto, Southern Ontario, and surrounding areas, our comprehensive proposal covers everything required to run the boiler reliably:
Core Installation: Removal/disposal of the old unit and professional installation of the Rinnai boiler with S636 venting.
Essential Hydronic Components: Installation of all critical devices needed to run the boiler, such as the Recirculation Pump, Expansion Tank, Feeder, and Isolation Valves.
System Protection: Inclusion of Air Eliminators or Dirt Collectors to protect the new heat exchanger, plus a full system flush.
Advanced Piping (As Needed): Setup of a Primary/Secondary Loop, and Zone/Pump Controllers depending on your specific application.
Safety & Setup: Post-install gas/CO safety checks, followed by expert programming and balancing.
What does the installation process look like with 4Most Energy?
We follow a strict, safety-first protocol to ensure a smooth upgrade for your home. Here is our step-by-step process:
Site Preparation & Safety: We park safely to avoid blocking your neighbors. Inside, we cover floors and steps with protective runners and organize the boiler room to create a safe workspace for gas and plumbing work.
Removal & Disposal: We carefully drain and disconnect your old unit to prevent any water damage. We then remove it and transport it to a proper dump station—we never leave old equipment on your driveway or curb.
Mounting & Rough-In: We build a sturdy plywood platform on the wall to securely mount the new boiler and support all piping and devices. We use only high-quality fittings and piping.
Safety Precautions: If soldering is required, we temporarily cover smoke detectors to prevent false alarms and take full fire-safety precautions.
Gas & Wiring: We connect the gas lines and perform a preliminary pressure test to ensure no leaks. We then connect all thermostats, zone controllers, and pumps.
Venting (Critical Step): We install System 636 PVC venting with the correct slope to ensure condensation drains back to the unit. We use heavy-duty core bits to drill through your exterior wall, ensuring no damage to bricks or wooden structures.
Commissioning & Testing:
Leak Checks: We fill the system and check for water leaks.
Gas Calibration: We run the boiler for at least one hour, calibrating gas pressure and performing a carbon monoxide (CO) safety analysis.
Joint Inspection: We inspect all joints under heat stress to ensure they don't crack or leak.
Drainage: We verify the high-efficiency condensation drains properly to the floor drain or pump.
Tagging & Handover: Once the system passes all tests, our Gas Technician tags the pipe. We then walk you through the new system, showing you how to adjust temperatures and perform basic maintenance.
Post-Install Support: It is possible for minor adjustments to be needed after a fresh install. As a reputable contractor, we stand behind our work—if you see a leak or issue, we fix it fast (same day or next morning). Finally, we register your unit to officially start your warranty.
How long does the Boiler installation take?
Most residential replacements are completed in one day (approx. 6–8 hours). Our team arrives in the morning with all necessary parts and aims to have your heat running by the evening.
How much does boiler installation typically cost in Toronto and Southern Ontario?
The final cost depends entirely on the boiler size, required hydronic items, and heating application. Upgrading from a low-efficiency or older unit is complex; it often requires upgrading plumbing using high-grade materials like copper, stainless steel piping, oxygen-barrier PEX, and premium fittings.
Starting Price: A professional installation by a Master Technician using high-quality materials starts at $2,000 (labor & material). This price increases as the boiler system becomes more complex (e.g., adding zoning or indirect tanks).
The "Cheap Quote" Warning: It is critical to avoid contractors offering suspiciously low prices. A boiler installed incorrectly often doesn't show symptoms right away but can suffer critical damage in less than 4 years. Furthermore, improper installation voids the manufacturer's warranty. Boiler installation requires a specialized Hydronic Expert, not just a general gas technician or plumber.
What is the standard warranty on a Rinnai Combi Boiler?
When installed by a licensed professional like 4Most Energy, the Rinnai I-Series typically comes with industry-leading coverage:
Heat Exchanger: 12 Years
Parts: 5 Years
Labour: 1 Year (Standard)
Extended Labor Warranty Option: You can extend your labor warranty coverage up to 10 years. Ask the 4Most Energy sales department for details on our protection packages.
Understanding Your Coverage:
What "Labor Warranty" Means: If a part covered by the manufacturer's warranty fails, you do not pay for the labor to replace it.
After Warranty Expires: Once the labor warranty period ends, you are responsible for paying the service call fee and the labor cost for replacing any parts.
4Most Energy - Authorized Warranty Support: As an Authorized Rinnai Service Provider, 4Most Energy handles the entire warranty process for our clients. If a defect arises, we can directly claim, supply the parts, and replace the defective items, ensuring a seamless and hassle-free experience for you.
Does 4Most Energy warranty the installation work?
Yes, absolutely. We stand behind our craftsmanship.
The 4Most Energy Installation Guarantee: Beyond the boiler unit itself, 4Most Energy covers installation-related issues for one year after installation. This includes:
Drain line issues
Support and mounting stability
Wiring connections
System calibration
Plumbing connections
We ensure the system is set up perfectly so you don't have to worry about the "small stuff" causing big headaches.
What is included in a 4Most Energy comprehensive maintenance visit?
Annual maintenance is strictly recommended to ensure you have smooth heating and hot water during cold weather. It is essential to improve performance, reduce the risk of gas or water leaks, and increase the lifespan of your unit.
Our expert service includes:
Descaling/Flushing: Circulating a solution to remove internal mineral buildup.
Filter Cleaning: Cleaning the air intake filter and the domestic cold water inlet filter.
Ignition Check: Inspecting and cleaning the spark igniter and flame rod.
Safety Check: Verifying there are no gas or exhaust leaks to ensure your family's safety.
Combustion Analysis: Measuring CO and CO2 levels to ensure the unit is burning fuel safely and efficiently.
Why is flushing the heat exchanger critical in Ontario?
Some areas of Ontario have moderately hard water.
The Risk: Without regular flushing, calcium and magnesium minerals precipitate out of the water and stick to the inside of the heat exchanger (scale).
The Damage: This scale acts as an insulator, trapping heat in the metal. This causes "thermal stress," leading to premature cracks and leaks in the heat exchanger—damage that is not covered by warranty.
What situations can void my Rinnai Boiler warranty?
Yes, it can. Warranty coverage is contingent on proper care and use of the unit. Your warranty may be voided due to:
Poor Maintenance: Failures caused by scale buildup or poor water quality are strictly not covered.
Unauthorized Installation: Units must be installed by a licensed professional. DIY or unauthorized installations often void warranty terms.
Improper Usage/Application: Using residential equipment for commercial applications (e.g., in a busy restaurant or hotel) or operating the unit outside of its design specifications.
Lack of Maintenance: Failure to perform annual service can lead to premature failure that manufacturers will not cover.
Regular annual maintenance by an authorized provider is the only way to prove you have cared for the unit, protecting both your investment and your warranty coverage.
Why choose 4Most Energy for my Rinnai Boiler installation?
We are not just a general HVAC company; we are Authorized Rinnai Hydronic Experts serving homeowners across the Greater Toronto Area and Southern Ontario.
Fair Price & 5-Star Quality: We are not the "cheap guy" who cuts corners, nor are we an overpriced corporation. We offer fair, transparent pricing for high-quality craftsmanship, always striving to earn a 5-Star Review after every job.
Local Stock & Reliability: We stock critical Rinnai parts in our local warehouse. If your heat goes out in January, we minimize downtime from days to hours.
Direct Access to Experts: You deal directly with a Master Technician, not a commission-based salesperson. We design your system correctly from Day 1.
Warranty Guardianship: We handle your unit registration and stand as your advocate with the manufacturer.
What happens if my boiler stops working in winter?
4Most Energy customers get priority support. You speak directly to a boiler expert, not a call center. Because we stock genuine Rinnai parts locally, we can often diagnose and fix issues faster than companies that have to wait for shipments.
Do you provide boiler repair services ?
Yes. We are comprehensive hydronic specialists. We service, repair, and maintain all major makes and models, including:
Viessmann
Flowmax
Baxi
Navien
NTI
And many others. The Rinnai Advantage: While we are experts on all brands, for Rinnai systems specifically, we stock all parts locally. This means if you have a Rinnai boiler, we can typically solve your issue on the very first visit without waiting for parts to ship.
Do you offer financing On Rinnai Boiler?
Yes. We offer flexible payment plans, including 3 Months No Payments/No Interest or low monthly payments for up to 24 months, helping you upgrade to high-efficiency comfort without the upfront stress.
I am a DIYer/Contractor. Can I buy just the unit?
Yes. We offer a "Supply Only" service. We provide the full kit (Boiler + Venting + Valve Kits) and offer free sizing consultation to ensure you buy the right model. We also provide technical support if you get stuck during your install.
How can I get a quote or troubleshooting help?
Live Chat via WhatsApp. We offer free consultation and troubleshooting directly through WhatsApp. You can send us photos of your current setup, and a Master Technician (not a sales rep) will provide a rough estimate or technical advice instantly.
Service Area
Greater Toronto Area (GTA) and surrounding regions
Toronto, Markham, Richmond Hill, Vaughan, Aurora, Newmarket, Scarborough, Brampton, and Mississauga.
Extended Service Area: Stouffville, Oshawa, Barrie, Orangeville, Hamilton, St. Catharines, Guelph, Kitchener.
