Top 5 Questions to Ask Before Installing a New Furnace (and the Answers You Actually Need)
Thinking about a new furnace? Before you sign anything, ask the right questions. The goal isn’t just “more heat.” It’s quiet, even, efficient heat that keeps your Iowa home comfortable through subzero snaps without blowing the budget. Here are the five questions we want every homeowner in Ankeny, Des Moines, West Des Moines, Johnston, Urbandale, Waukee, and Altoona to ask—plus clear answers from the team at Obsidian Heating & Cooling.
1) What size furnace do I really need?
Short answer: The “right” size comes from a Manual J load calculation and a look at your ductwork and airflow—not a square-footage guess or “whatever’s in stock.”
Why it matters:
An oversized furnace short cycles, creates hot-and-cold swings, and wears out faster.
An undersized furnace runs nonstop and still can’t reach setpoint when the wind howls across the prairie.
What we do: We measure the home, check insulation and windows, evaluate duct static pressure, and factor in spaces like finished basements or rooms over the garage. Then we match equipment to the actual heat loss of your home and confirm the ducts can deliver. That’s how you get smooth, quiet, even heat (and fewer repair calls).
Ask your installer:
“Will you do a Manual J calculation and share the results?”
“Will you check static pressure and returns to ensure the new unit can breathe?”
2) Single-stage, two-stage, or variable-speed—what’s best for my home?
Single-stage: One speed—on or off. Lowest upfront cost, most temperature swing.
Two-stage: Low most of the time, high when it’s bitter outside. Better comfort and noise control.
Variable-speed (modulating): Widest range of heat output with variable-speed ECM blowers for ultra-smooth airflow. Best balance of comfort, efficiency, and noise.
Rule of thumb: In Central Iowa, two-stage or variable-speed furnaces shine. They run longer on lower output, which evens out temperatures between floors, reduces noise, and can improve filtration.
Ask your installer:
“Can you price single-stage vs. two-stage vs. variable-speed so I can compare?”
“Will you pair this with the right thermostat to unlock all the comfort features?”
3) How will this affect my energy bills and comfort in Iowa winters?
Look for AFUE (Annual Fuel Utilization Efficiency). Modern high-efficiency gas furnaces land in the 95–98% AFUE range. Efficiency matters, but so does runtime behavior and airflow.
Comfort factors that lower bills:
Right size + right ducts = fewer on/off cycles and less wasted fuel.
Tighter envelope (air sealing, insulation) can let you heat with a smaller unit.
Smart thermostats help stage the system efficiently and maintain steadier temps.
Zoning can calm the “sauna upstairs, igloo downstairs” problem in two-story homes.
Ask your installer:
“What’s the expected operating cost difference between these options?”
“Do I qualify for utility rebates or federal incentives with a higher-efficiency model?”
4) What’s included in the quote—and what isn’t?
A good quote should be unambiguous. Beyond the furnace itself, you’ll want to see line items for anything that affects performance, safety, and warranty.
Make sure your quote covers:
Removal and disposal of the old unit
New venting/condensate for high-efficiency models
Proper gas and electrical connections
New filter cabinet and right-sized filter (huge for airflow)
Ductwork adjustments if static pressure or returns are borderline
Thermostat (and whether it’s staging/variable-speed ready)
Startup, testing, and a full homeowner walkthrough
Permits and municipal requirements
Warranties (parts, heat exchanger, and workmanship)
Ask your installer:
“Can you show me what’s included versus optional upgrades?”
“If duct changes are recommended, can you explain the ‘why’ and the outcome?”
5) What warranties, rebates, and financing are available?
Warranties protect your investment; rebates and credits help offset the upfront cost. In our market, utility rebates for high-efficiency equipment are common, and federal incentives may apply depending on the model and your home improvements. Financing can spread the cost while you enjoy lower operating bills right away.
Ask your installer:
“What are the parts and heat-exchanger warranty terms?”
“What’s your workmanship or labor warranty?”
“Which rebates apply to these exact model numbers?”
“Do you offer financing, and are there prepayment penalties?”
Bonus: What about that funky smell when the heat kicks on?
“What’s that funky smell?” you ask. That’s for a different blog post.
Spoiler: the first-run “dusty” smell is normal; burning or electrical odors are not. We’ll break this down soon so you know when to shrug—and when to shut it down and call.
How Obsidian makes furnace installs simple (and solid)
Here’s our playbook for a no-surprises experience:
In-home assessment & Manual J
We measure, inspect, and listen. Sizing, airflow, and comfort goals drive the recommendation—not guesswork.Clear options & pricing
You’ll see a couple of right-sized models (often two-stage or variable-speed), with transparent pricing, rebate notes, and expected operating cost differences.Airflow plan
If returns are undersized or static pressure is high, we’ll explain the fix. A great furnace needs a duct system that keeps up.Professional installation
Licensed techs, manufacturer specs, and clean workmanship. We handle venting, condensate, gas/electric, filter cabinets, and code compliance.Startup, testing & walkthrough
We set thermostat staging, verify safe operation, balance airflow where possible, and show you how to run and maintain the system.Follow-up & support
Questions later? We’re local, veteran-owned, and always a phone call away.
Ready to compare options the right way?
If you’re in Ankeny, Des Moines, West Des Moines, Johnston, Urbandale, Waukee, Altoona, or nearby, we’ll size your system properly, lay out clear choices, and install it the right way.
Considering replacement? Book a free, no-pressure furnace installation estimate.
On the fence? We’ll show repair-vs-replace numbers so you can decide with confidence.
Obsidian Heating & Cooling — comfort you can count on when Iowa winter gets real.
