Marin County HVAC System Replacement Case Study | Bellows Plumbing, Heating, Cooling & Electrical

Project Summary

Project Type

Furnace and AC Installation

Location

Marin County, CA

Duration

2 Days (Completed Ahead of Schedule)

Services Provided

High-Efficiency Furnace
AC Unit
Smart Thermostat
Ductwork Modification

When a Marin County homeowner needed an new HVAC system installed to replace their outdated furnace AC and old brown floor registers, they turned to Bellows Plumbing, Heating, Cooling & Electrical for a comprehensive HVAC upgrade. While the existing equipment was still functional, it lacked the energy efficiency, quiet operation, and smart technology that modern systems offer. Our mission: install a high-efficiency furnace and AC system that would deliver reliable year-round comfort, optimized performance, and full compliance with current building codes.

Project Scope & Key Components

This HVAC system replacement project involved removing and upgrading both the forced air unit (FAU) and the air conditioning system, along with turning the ductwork and controls:

Furnace Replacement:
- Removed existing 80% AFUE single-stage horizontal FAU from the crawl space
- Installed 3-ton Lennox ML196 high-efficiency furnace
- Added horizontal “B” cabinet coil and condensate pump
Air Conditioner Upgrade:
- Removed old AC and installed 3-ton ML17XC1 AC unit on the left side of the home
- Ran new 35-foot refrigerant lineset
- Integrated system with existing electrical
Ductwork & Controls:
- Replaced all 9 supply registers, tying to existing 9 supply ducts and 1 return duct
- Sealed system to pass HERS testing
- Installed new EcoBee smart thermostat

Installation Phases & Timeline

When evaluating the value of this HVAC system replacement, it’s clear that the benefits go far beyond just replacing old equipment. From improved comfort and energy efficiency to smarter home control and long-term reliability, this installation checked every box for performance and peace of mind. Here’s how this system made a meaningful impact:

Day 1: System Removal & Site Prep

Removed the old indoor and outdoor HVAC units
Prepped and attached most of the ductwork to the new supply plenum
Ran a new service light and fixed an electrical switch in the crawl space
Installed the new furnace and coil on stands
Prepped the gas trap and wiring
Sealed the new supply plenum
Cleaned the worksite and ensured it was safe for Day 2

Day 2: System Installation & Finalization

Completed installation of furnace and AC system
Ran a new lineset and drain line with pump
Installed new flue pipe using 2-inch PVC for proper venting
Fabricated and installed new return and supply plenums
Rerouted existing supply ductwork for improved efficiency
Replaced all floor registers
Installed new EcoBee thermostat and programmed settings
Added a plug-in fuse (SRU) and updated gas piping to meet current code

Final Results & Homeowner Feedback

This project was completed on schedule, thanks to our team’s efficiency and coordination. The new HVAC system passed all code requirements and HERS testing, and the customer reported immediate improvement in comfort and system performance.

The project was completed in just two days by a two-person crew, minimizing disruption to the household.
The homeowner was especially pleased with the upgraded thermostat, quieter system operation, and the clean, professional workmanship throughout the process.

Photo Highlights

Want to get a closer look at the craftsmanship behind this HVAC system replacement? Below are photos showcasing key moments from the installation process-from the crawlspace prep and furnace stand setup to the final thermostat configuration and outdoor AC unit placement. These images capture the attention to detail and professionalism that define every Bellows installation.

Outdoor Condenser with Window Trim Access Point

Tape Measure Showing Existing Furnace Height

Floor Register Scheduled for Replacement

Ceiling-Mounted Return Grille in Hallway

Exterior Wall Showing Planned New Changes

Access Path and Clearance Near Outdoor Unit

System Benefits & performance Impact

A high-efficiency HVAC system replacement provides substantial benefits for homeowners:

Improved comfort: The Lennox ML196 furnace and ML17XC1 AC unit deliver more consistent temperatures, which the customer noticed immediately.
Lower utility costs: The higher efficiency rating compared to the old 80% AFUE model reduces energy consumption during heating seasons.
Quieter home environment: The customer specifically noted reduced noise levels with the new system.
Smart temperature control: The EcoBee smart thermostat provides programmable settings for additional convenience and efficiency.
Safety and compliance: The system meets all current building codes and passed HERS testing.
Longer system life: Modern equipment with proper installation (new flue pipe, condensate pump, sealed ductwork) typically outlasts older units.

With reduced maintenance demands and significantly lower energy bills, the homeowners now enjoy a more comfortable, cost-efficient lifestyle year-round, thanks to our heating and cooling services.

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Staffan Lofgren

Cody was very professional and friendly. Bellows is the best HVAC installer we have encountered.

Cas Ellena

Bellows was great, thank you for coming so fast and fixing the problem!

Bacchus Ridge

Zach did a fantastic and determined job of conquering our leak from under our crawlspace. Bellows sent someone an hour after I called with a leak report, although it was the end of the day. He diagnosed the issue, got cold water working, and was back the next day with the parts for the hot. Great attitude and fabulous service. Thanks, team bellows!

Jason Barraca

I received great service for my water heater. Nate was very professional and thorough.

Tom Larter

Bellows is outstanding. Best communication and the techs are amazing. Polite and always stay until the Job is done. Scottie is our hero. He is so helpful, polite and fixes every thing we need. We have used Bellows for out home for the last 14 years and never had anything other than 6 star service.

Mark Scofield

I give high praise to Bellows for performing three different jobs in succession. First, after being called to have a look, a Bellows troubleshooter recommended we replace our 40-year-old central furnace. We opted to respect his professional judgement. A two-man crew came and got the job done efficiently and with little disturbance. We asked for someone to have a look at our equally old shower valve. A man came to estimate the job then returned to replace it another day. Perfect! We love that we no longer wrestle with the old valve. Last, we asked that someone come to look at our home lighting. A man came to help us formulate a plan. Another two-man crew came and began work. We discussed our needs and minor changes were made to improve our environment further. In every case, we were treated courteously. When they requested permission to make changes, they were forthright and benefitted our environment. A sticking point to me, a retired craftsman, is cleanliness. Every person entering our home was professionally neat and left not the slightest dust for us after they left. I am impressed. Overall, my wife and I spoke with many people from Bellows both in person and on the phone. We would like to stress our perception that in every case, we felt we were working with a family business. That is, we were addressed courteously, and as friends, not simply clients. A few weeks on and we still marvel that we waited so long to do this work. As you see, we're glad we chose Bellows. Thanks!