Same-Day Service
Most service calls handled same-day across Spokane and Coeur d'Alene.
Furnace Installation
A new furnace, installed the right way.
The single biggest factor in furnace efficiency, comfort, and lifespan isn’t the equipment — it’s the install. We Manual J load-calculate every home, size the system to match, and certify the install against national HVAC standards (ACCA Manual D ductwork, Manual S equipment selection).
You get a fixed-price quote up front. We handle every available manufacturer and utility rebate, set up financing if you want it, and back the work with a 10-year parts and 2-year labor warranty.
- Manual J load calc Right-sized for your home — never the cookie-cutter "bigger is better" install.
- Rebates handled Avista, manufacturer, and federal tax credits — we file the paperwork.
- 10-year parts warranty Manufacturer parts coverage plus our 2-year Mainstream labor warranty.
- No-pressure quote Free in-home estimate. We'll never push a system you don't need.
Limited Time Offer
Efficient HVAC Repairs, Installation, & Maintenance
Upgrade Your Home Cooling
- Certified Technicians
- Quick Repairs
- Emergency Service
- Quality Service
When to Replace
Signs your furnace is ready for replacement
A new furnace is a 15-year decision. Replacing at the right moment saves money — and prevents a no-heat emergency in January.
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Over 12–15 years old
Most furnaces last 15–20 years. Past 12, efficiency and reliability fall off fast.
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Climbing energy bills
A 95% AFUE furnace can cut a 80% AFUE system's gas bill by 15–20% — every winter.
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Frequent repairs
Once you're calling for service every year, the cumulative repair cost passes a new install.
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Cracked heat exchanger
A safety-critical failure — replacement is almost always the right call vs. a swap-out repair.
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Uneven heat
Hot upstairs, cold downstairs usually means an oversized or under-zoned system.
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Major remodel or addition
Adding square footage often pushes an existing furnace past its design capacity.
What We Install
High-efficiency furnaces from the brands we trust
Single-stage, two-stage, modulating, and dual-fuel — matched to your home, your fuel, and your budget.
- Gas furnaces Up to 98% AFUE high-efficiency natural-gas and propane furnaces.
- Electric furnaces When gas isn't an option — efficient electric heat with backup options.
- Dual-fuel systems Heat pump primary + gas furnace backup — best in cold-climate efficiency.
- Two-stage & modulating Variable output for quieter, more even comfort and lower bills.
- Variable-speed blowers ECM motors that move the right amount of air — not all-on or all-off.
- Smart thermostats Ecobee, Nest, and Honeywell — installed and configured to your system.
- Ductwork modifications Sealing, sizing, and rerouting ductwork when the existing system is undersized.
- Rebates + financing Avista, manufacturer rebates, and 0% financing options handled in-house.
How It Works
A new furnace install, start to finish
From first phone call to final walk-through — usually one day on-site.
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Free home assessment
A comfort advisor measures, load-calculates, and walks you through the right-size options.
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Fixed-price quote
Multiple system options, financing scenarios, and rebates — all in writing, no pressure.
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Install day
Most installs done same-day. Old system removed and disposed, new one commissioned.
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Walk-through
Tech walks you through thermostat, filter changes, warranty, and registers everything.
Why Choose Mainstream
Upfront Pricing
Flat-rate pricing approved before work begins — no surprises on the invoice.
Licensed & Insured
Fully licensed in Washington and Idaho, bonded, and insured for your protection.
Satisfaction Guaranteed
If it isn't right, we make it right. Period.
Ready for a quieter, more efficient home?
Same-day service across Spokane & Coeur d'Alene — flat-rate pricing, no surprises.
What Our Customers Say
Don't just take our word for it — hear from our satisfied customers
★★★★★
Ryan Carleton was a pleasure to deal with. Very knowledgeable and understanding. Didn't push a product but just gave us several options. Would definitely use Mainstream again. GOOD JOB . I had another great experience with Mainstream in the replacement of our 17 Year old furnace. Zack discovered a leak and showed pictures. Wyatt gave us a reasonable estimate and Isaac and Sean installed a beautiful furnace in 5 hours.
We couldn't be more satisfied with the people and work
★★★★★
Mainstream was fantastic to work with. Very transparent and professional. We had a cracked heat exchanger in our 23 year old furnace. They gave us multiple options for replacement and Josh came out to install. Everything was clean, professional and they even streamlined the sheet metal above the furnace and air conditioning since it was a shorter unit that we had prior. When they left everything was clean and you would never know they were there other than the new furnace. They answered all of our questions and made sure we understood everything prior to leaving.
★★★★★
I was without heat and Mainstream sent out Adam B. within an hour. He went through all the parts of my furnace and even invited me to watch so he could explain what he was looking at. Turns out I had several components that would soon need replacing, but the main offender was a fried blower motor. Adam worked up a repair estimate with several options. He didn't pressure me, but it was clear to me that the cost of even replacing the blower would not be a wise investment in my old furnace. I opted to have the furnace replaced and I'm really happy with the decision. Jacob B. was out first thing the next morning to remove my old furnace and install the new one he brought. He was courteous and knowledgeable, and did a first class installation. Adam helped with starting the process, and 24 hours later I'm warm again with my new furnace. Thanks Adam B. for being so helpful in explaining my options and to Jacob B. for such a clean and professional installation. And thanks Mainstream for being so prompt at serving my needs.
Maintenance Membership
Join the Care Club
Total home service care, on a schedule.
Members get priority scheduling, seasonal HVAC tune-ups, an annual plumbing & electrical safety inspection, and exclusive discounts — for less than the cost of a single emergency call.
- Priority scheduling
- Seasonal HVAC tune-ups
- Annual safety inspection
- Exclusive member discounts
- Free dispatch on repairs
- No long-term contracts
Furnace Installation — Frequently Asked Questions
How long does a furnace replacement take?
Most straightforward replacements take 6–8 hours and are completed in a single day. Larger projects involving ductwork or fuel-line changes can take a second day. We schedule the install at your convenience and confirm a firm time window the day before.
What size furnace do I need?
Size is determined by a Manual J load calculation that factors in square footage, insulation, windows, climate, and zoning — not by square footage alone. Oversized furnaces short-cycle, run inefficiently, and create comfort problems. We never quote by rule of thumb.
What rebates are available?
Avista offers gas-furnace rebates of up to $400 for qualifying high-efficiency models. Federal tax credits cover up to 30% of qualified equipment cost (subject to annual limits). Manufacturer-specific rebates run seasonally. We handle all the paperwork.
Do you offer financing?
Yes — including 0% APR for qualified buyers, low fixed-rate plans, and longer terms when needed. We’ll pre-qualify you in minutes and walk through the options during the in-home estimate.
What's warrantied?
New furnaces come with the manufacturer’s 10-year parts warranty (registration required, which we handle for you) plus a 2-year Mainstream labor warranty. Care Club members get extended labor coverage and priority service.
Should I get a heat pump instead?
For many Inland Northwest homes, a cold-climate heat pump (or a dual-fuel heat pump + gas furnace) is now more efficient than a gas-only system. We’ll show you side-by-side numbers — equipment cost, lifetime energy cost, rebates — and let you decide.
*Offers cannot be combined with other promotions or applied to dispatch fees. No cash value. Must present offer at time of service. Call for details.
