Furnace Replacement in Des Moines: Permits, Sizing and Efficiency

Furnace replacement Updated 2026-10-22 · By Kasey, Waukee, Iowa · 8 sources

A furnace replacement is one of the bigger checks a Des Moines-area homeowner writes, and it often happens at the worst time: in January, after a repair visit ends with "it's not worth fixing." Knowing the basics ahead of time helps you compare quotes calmly instead of in a cold house.

This guide covers what the City of Des Moines' mechanical code says about permits and licenses, how the U.S. Department of Energy says equipment should be sized, what AFUE and the ENERGY STAR label mean, and the questions worth asking every contractor. We don't list prices. Quotes depend on your house, and we won't guess.

Repair or replace?

There's no single rule, but the federal guidance gives you a starting point. The Department of Energy's Consumer Guide to Home Heating and Cooling says that if your heating or cooling system is over 15 years old, you can save on electric bills and improve efficiency by investing in new equipment. It adds that the right system depends on your home's size, insulation, windows, how you use heating and cooling, and the local climate.

Safety matters too. ENERGY STAR's maintenance checklist warns that a cracked heat exchanger can make a furnace run less safely and efficiently. If a technician tells you that's the problem, ask them to show you the evidence and explain the risk. For a big decision like this, it's reasonable to get a second opinion.

Des Moines permits: what the city code says

Des Moines has adopted Iowa's state plumbing and mechanical code with local amendments in Chapter 26 of its municipal code. The city's published summary of those amendments (the 2021 "short version") says:

• A permit is required. Sec. 26-501: "Mechanical permits are required for any installation, alteration, repair, replacement, or remodel to a mechanical system regulated by the State Mechanical Code." A furnace replacement falls under "replacement."
• Small repairs are exempt. Sec. 26-502 exempts minor repair, cleaning, adjustment, or replacement of minor parts of heating, ventilating, cooling or refrigeration equipment where the total cost of the work does not exceed $100.
• Only state-licensed contractors pull the permit. Sec. 26-550: only individuals or businesses holding a mechanical or plumbing contractor license from the Iowa Plumbing and Mechanical Systems Board may apply for and obtain permits for mechanical work in the city.
• The installer needs a state license. Sec. 26-551: a person shall not install or repair HVAC, refrigeration or hydronic systems without a license issued by the State of Iowa for that trade.

In plain English, your contractor should be the one pulling the Des Moines permit, and that tells you they hold the state contractor license the city requires. The summary we read is dated 2021, so confirm current rules and fees with the city's Permit & Development Center (permits@dmgov.org, per the city's page).

Live in West Des Moines, Waukee, Ankeny or Urbandale? Each city runs its own permit office. See our town pages for links to each city's own permit pages, and ask your contractor who pulls the permit.

Sizing: insist on a load calculation

Bigger isn't better. The DOE guide says oversized cooling systems can cost too much, deliver poor comfort, and lead to mold and poor indoor air quality. It also says the old rule of thumb, one ton of cooling per 400 to 500 square feet, fails to account for local climate and the efficiency of a house. The DOE says your contractor should use the Air Conditioning Contractors of America (ACCA) Manual J to calculate the right size. ENERGY STAR gives the same advice: your contractor should verify system size with "Manual J."

A good question for every quote: "Did you do a Manual J load calculation for my house, and can I see it?" A furnace sized the same as the old one by default may or may not be right, especially if you've added insulation or new windows since it went in.

Efficiency: what AFUE means

The DOE explains that Annual Fuel Utilization Efficiency (AFUE) measures how much heat actually reaches your house compared with the fuel the furnace uses. The higher the AFUE, the more efficient the furnace.

On the ENERGY STAR label:

• ENERGY STAR uses different gas furnace requirements for different regions. Models certified for the northern half of the U.S., which includes Iowa, carry the standard ENERGY STAR logo. Southern models carry a separate "U.S. South" logo.
• The DOE guide (2021) says ENERGY STAR natural gas furnaces must reach 95% AFUE in northern climates.
• ENERGY STAR says certified furnaces have higher AFUE ratings and more efficient blower motors than standard models.

ENERGY STAR also points out that efficient furnaces can cost more up front and earn it back through lower energy bills over time. It suggests pairing a new furnace with home air sealing, insulation and duct sealing to get the most out of it.

Furnace, air conditioner or heat pump?

Replacing the furnace is a good time to think about cooling too. ENERGY STAR notes that if you have a newer furnace and an older central AC, or you're adding central AC, an ENERGY STAR heat pump can create a dual-fuel system "for a modest extra cost over an AC system." The heat pump handles heating part of the time and the furnace takes over at other times. See our heat pumps in Iowa cold weather guide.

If the work touches the air conditioner or heat pump, EPA's Section 608 rules forbid intentionally venting refrigerant while servicing or disposing of AC equipment, and EPA runs a technician certification program. It's fair to ask how the old refrigerant will be recovered.

Utility discounts

MidAmerican Energy and Alliant Energy both run instant discount programs for qualifying heating equipment, applied through participating contractors or dealers. Terms change every year, so we link to the utilities' own pages instead of quoting amounts. See our Iowa HVAC rebates guide.

Questions to ask every contractor

1. Who pulls the permit? In Des Moines, the city code says it must be a state-licensed mechanical or plumbing contractor.
2. Can you show me your Manual J load calculation?
3. What exact model and AFUE are you quoting? Get the model number in writing so you can look it up on ENERGY STAR.
4. Is ductwork, venting or gas piping work included? What about removing the old unit?
5. Do you participate in my utility's instant discount program?
6. What do the manufacturer's and your labor warranties cover, and for how long? Get it in writing.
7. What is your Iowa contractor registration number and Plumbing & Mechanical Systems Board license? The board requires contractors to carry at least $500,000 in public liability insurance and a $5,000 surety bond.

For a full hiring checklist, see how to choose an HVAC company in Iowa.

After the install

Check that the work passed the city's inspection. Then keep up with the basics: the CDC recommends yearly service of your heating system by a qualified technician and CO alarms near every sleeping area. The DOE says changing filters monthly during peak season and getting a fall furnace check can cut heating and cooling costs by 10% or more.

Frequently asked questions

Do I need a permit to replace a furnace in Des Moines?

Yes, according to the city's published Chapter 26 amendments: mechanical permits are required for any replacement of a mechanical system, with an exemption only for minor repairs costing $100 or less. Confirm current requirements with the Permit & Development Center.

Can a homeowner pull a mechanical permit in Des Moines?

The city's Chapter 26 summary says only individuals or businesses holding a mechanical or plumbing contractor license from the Iowa Plumbing and Mechanical Systems Board may obtain permits for mechanical work. Ask the city if you have a special situation.

What size furnace do I need?

The Department of Energy and ENERGY STAR both say your contractor should calculate it with ACCA Manual J, which accounts for your home's insulation, windows and climate. Square-footage rules of thumb aren't enough.

What AFUE should I look for in Iowa?

Iowa falls in ENERGY STAR's northern region, where certified gas furnaces carry the standard ENERGY STAR logo. The DOE's 2021 guide says those models must reach 95% AFUE. Check a specific model on ENERGY STAR's product finder.

When should I replace my furnace?

The DOE suggests considering new equipment if your system is over 15 years old. Safety problems like a cracked heat exchanger are another reason. Get a second opinion on big decisions.