High-Efficiency Boiler Replacement
Boiler Replacement in Elgin & the Fox Valley
When your boiler is past the point of repair, we replace it with a right-sized 95% AFUE condensing or combination boiler, handle the piping, gas, venting and permit, and take the Nicor Gas instant discount straight off your invoice. Quotes are free and in writing.
- Free written quotes
- $350 or $500 Nicor Gas discount off the invoice
- Permits filed under our own license
- Old boiler hauled away
Signs It’s Time to Replace Your Boiler
Boilers are durable, which is why so many Fox Valley homes are still heated by one installed decades ago. Durable is not the same as efficient or reliable. Here is when replacement stops being optional.
- A cracked section or leaking heat exchanger. Water from the boiler body itself, not from a fitting. This is not a repair.
- Over 20 years old and facing a major repair. A circulator, gas valve or control on an old boiler is money that would be better spent on a new one.
- Repairs every winter. Two or three service calls in a couple of seasons means the boiler is failing as a whole.
- Kettling that is getting worse. Heavy scale on the heat exchanger cannot be cleaned out of an old cast-iron boiler.
- Failed combustion numbers or rust at the flue. A boiler that cannot be tuned to a safe combustion reading has to go.
- Gas bills that keep climbing. An old atmospheric boiler often runs at 60 to 80% AFUE. A new one is 95%.
- Parts are hard to find. Some older boiler lines have no factory parts left. Waiting weeks for a control in January is not a plan.
- Your water heater is dying too. If both are old, a combi boiler replaces them with one high-efficiency unit and earns the larger discount.
- A chimney or venting problem. A deteriorating chimney can cost more to repair than a side-wall-vented boiler that no longer needs it.
Smell gas? Leave the house right away, call 911 from outside, and call your gas utility’s emergency line from outside before calling us.
Repair or Replace? The Math
We will fix almost any boiler. The question is whether you should keep paying to fix this one. Here is how we help you decide.
Start with the 50% rule. If a repair costs more than half of what a new boiler would cost installed, replacement wins, because you are putting a large sum into equipment that is still old everywhere else. Under that line, look at age and history.
| Boiler age | Small repair | Major repair (circulator, gas valve, board) |
|---|---|---|
| Under 15 years | Repair | Repair; check parts warranty |
| 15 to 20 years | Repair | Weigh against condition and repair history |
| Over 20 years | Repair if safe | Get a replacement quote alongside the repair |
| Any age, cracked section or heat exchanger | Replace | Replace |
| Any age, unsafe combustion or venting | Replace | Replace |
Then add the efficiency side. A boiler that has been running at 70% AFUE burns roughly a third more gas than a 95% boiler to deliver the same heat. Over a Fox Valley winter, with the boiler running most of the day from November through March, that difference is not small, and it grows as the old boiler scales up.
If you land on repair, our boiler repair page shows how that visit goes. If you land on replace, keep reading.
What Changes With a New Boiler
Replacing a 25-year-old atmospheric boiler with a modern condensing unit changes more than the efficiency rating.
95% AFUE
Condensing heat exchanger
A condensing boiler pulls extra heat out of the flue gases by cooling them until water vapor condenses. That is where the jump from 70 or 80% to 95% comes from. It also means the boiler runs best at lower water temperatures, which suits baseboard and most radiator systems well.
Right-sized
Sized to the home, not the old label
Old boilers were often oversized. We measure the connected radiation and size the boiler to the house, not the old nameplate; a heat-loss calculation is available as needed, on request or where a program requires one, and it may carry an additional cost. A right-sized modulating boiler runs longer, gentler cycles instead of slamming on and off, and the house feels more even.
Modulating
Burner that turns down
A modulating boiler adjusts its flame to the load rather than running full blast or off. On a 35°F day it can run at a fraction of its capacity. Paired with outdoor reset, it heats the water only as hot as the weather requires.
Combi option
Heat and hot water in one
A combination boiler replaces the water heater too, making hot water on demand. One gas connection, one vent, one appliance to maintain, and the larger $500 Nicor Gas discount. It is a strong fit when the water heater is also near the end.
Side-wall vent
No chimney needed
A condensing boiler vents through PVC out the rim joist, the same way a condensing furnace does. If your chimney is deteriorating, that is one less thing to fix. If a water heater shares the chimney, we address its venting so it drafts safely on its own.
Quieter, cleaner
New near-boiler piping
A replacement usually includes new near-boiler piping, a new expansion tank, air separator, fill valve and relief valve. Air gets purged out of the system properly. Radiators that gurgled for years often go quiet on the first fill.
A new boiler will not fix a radiator that is undersized for its room, a zone that was never balanced or pipes that are pitched wrong on a steam system. We tell you about those before the quote so you can decide whether to address them at the same time.
What a Boiler Replacement Costs and How Pricing Works
We do not publish a single installed price, because two boiler jobs on the same street can be very different. We do tell you exactly what drives yours.
Every replacement starts with a free, written quote after we have seen the boiler room. The price is flat and fixed once you approve it. It covers the boiler, the near-boiler piping and components, venting, gas connection, condensate drain, permit, start-up and combustion test, and removal of the old equipment. The Nicor Gas instant discount is shown as a line on the quote and subtracted on the invoice.
- Boiler type and size. A heating-only condensing boiler costs less than a combi. Output is set by the house and your radiation, not by the old nameplate.
- Venting path. A short PVC run through the rim joist is simple. A long run, a roof penetration or a chimney that needs a liner for the water heater adds work.
- Near-boiler piping. Most replacements include new piping, expansion tank, air separator, circulator and fill valve. Old, undersized or badly routed piping takes more time to correct.
- Water heater. A combi removes it and adds a domestic water connection. Keeping a gas water heater on the old chimney may mean lining that chimney.
- Steam. Steam boiler replacements involve skimming, header piping to the manufacturer’s diagram and setting the water line, which takes longer than a hot-water swap.
After the discount, if you want to spread the cost, prequalify in about 2 minutes with no impact to your credit score. The discount lowers the amount you finance.
How a Boiler Replacement Goes
Replacement means taking out what you have and putting in what fits. Here is the sequence from quote to first fire.
1. Free written quote. We come out, look at the boiler, the radiation, the piping, the venting, the gas line and the water heater. We measure the connected radiation and size the boiler to the house (a heat-loss calculation is available on request). You get a written quote with the Nicor Gas discount already subtracted, plus options if a combi or a different venting path makes sense. Request a quote online or by phone.
2. Permit and scheduling. We file the mechanical permit under our own license where required and schedule the job. Most straight changeouts are one day. A combi that also removes the water heater, or a job with new near-boiler piping, may run two. If you need to spread the cost, prequalify in about 2 minutes with no impact to your credit score.
3. Removal. We shut off the gas and water, drain the system, disconnect the venting and break the old boiler down. Cast-iron boilers come apart in sections. The old unit and any piping we replace go on the truck for recycling. Disposal is included.
4. Setting the new boiler. The new boiler is mounted or set, near-boiler piping is built with a new expansion tank, air separator, circulator, fill valve and relief valve, and the gas line is connected and leak-tested. Condensing boilers get PVC intake and exhaust run through the rim joist and a condensate drain with a neutralizer.
5. Fill, purge and fire. We fill the system, purge every zone, set the pressure and start the boiler. Combustion is tested with an analyzer and the burner is adjusted. We set the aquastat or the control’s outdoor reset curve, run every zone to temperature, and check each radiator or baseboard loop for flow.
6. Walk-through and paperwork. You get a walk-through of the controls, the invoice with the discount shown, the permit for inspection, and we register the warranty for you. The technical side of the install itself is covered in more depth on our boiler installation page.
Why Fox Valley Homeowners Choose Rest Assured for Boiler Replacement
Boiler replacement is piping, gas, venting and controls work, not a box swap. We do all of it under our own license.
Laars boilers, installed by our team.
- Laars high-efficiency condensing and combination boilers; every brand replaced
- Sized to the house and your connected radiation, not the old nameplate; heat-loss calculation available on request
- Owner Jeff Kerley is EPA 608 Universal and NATE certified in gas heating installation
- Permits filed under our own license; municipally licensed in Elgin, Aurora, Bartlett, Huntley and Streamwood
- Nicor Gas Contractor Circle Installing Member: $350 or $500 off the invoice
- BBB of Chicago & Northern Illinois Complaint Free Award, 2024 and 2025
- Old boiler and piping removed and recycled
Boiler home with no cooling? Pair the new boiler with a Daikin ductless mini-split. Keep the new boiler healthy with a fall boiler tune-up, or see the boiler services hub.
Save With Nicor Gas Instant Discounts
As a Nicor Gas Contractor Circle Installing Member, we take the discount right off your invoice: $350 on a qualifying 95% AFUE heating boiler, or $500 on a qualifying combination boiler. No application, no rebate check to wait for. See Nicor Gas instant discounts.
Paying over time? Prequalify in about 2 minutes with no impact to your credit score, or ask about on-bill financing.
Boiler Replacement Across the Fox Valley
Based in Elgin, we serve homes throughout Kane, McHenry, DuPage and DeKalb counties.
- Elgin
- South Elgin
- St. Charles
- Aurora
- Bartlett
- Streamwood
- Huntley
- Plato Center
- Sycamore
- Carpentersville
- West Dundee
- East Dundee
- Algonquin
- Gilberts
- Hampshire
- Pingree Grove
- Campton Hills
- Geneva
- Batavia
- Barrington
- Hoffman Estates
- Schaumburg
- Burlington
- Marengo
- Wayne
- Sleepy Hollow
Don’t see your town? Call (847) 224-2420. View all service areas.
Boiler Replacement FAQs
How long does a residential boiler last?
A cast-iron hot-water or steam boiler often runs 20 to 30 years with annual maintenance. Condensing boilers typically last 15 to 20 years. Age alone is not the reason to replace, but past 20 years the combination of efficiency loss, parts availability and repair frequency usually is.
Should I repair or replace my boiler?
Use the 50% rule: if the repair costs more than half of a new boiler, replace. Under that line, replace if the boiler is over 20 years old and needs a major part, has a cracked section or leaking heat exchanger, or has needed a repair every winter. Otherwise, repair it.
How much does a new boiler cost?
It depends on the boiler type, size, venting and the condition of your piping, so we do not publish a single number. Quotes are free, written, and include the Nicor Gas instant discount. Request a free quote and you will have a real price, not a range.
What is the Nicor Gas discount on a new boiler?
$350 off a qualifying 95% AFUE heating boiler, or $500 off a qualifying combination boiler. As a Nicor Gas Contractor Circle Installing Member we take it right off the invoice. See Nicor Gas instant discounts.
What is a combi boiler and should I get one?
A combination boiler heats your home and makes domestic hot water on demand in one unit, so you can remove the separate water heater. It is a good fit when your water heater is also near the end of its life, space is tight, or you want a single high-efficiency appliance. It carries the larger $500 Nicor Gas discount.
Will a new boiler work with my old radiators?
Yes. Cast-iron radiators and baseboard work with a new boiler. What changes is the water temperature the boiler is designed for. We size the new boiler to the home and set it up so your existing radiators deliver full heat, and with outdoor reset the boiler runs cooler on mild days and saves gas.
Can a new boiler vent through my old chimney?
A condensing boiler vents through PVC out the side of the house and does not use the chimney. If a gas water heater was sharing that chimney, it is now the only appliance on it and the chimney may need a liner or the water heater may need its own vent. We check that before the quote so there are no surprises.
How long does a boiler replacement take?
Most straight changeouts are done in one day. A combi boiler that also replaces the water heater, a steam-to-hot-water conversion or a job that needs new near-boiler piping can run two days. Heat is back on before we leave each day whenever possible.
Do I need a permit to replace a boiler?
In most Fox Valley municipalities, yes. A boiler replacement is a mechanical permit, and gas and venting work is inspected. We file the permit under our own license where required and meet the inspector.
What happens to my old boiler?
We drain it, disconnect the gas and venting, break it down if it is cast iron, and haul it away for recycling along with the old piping we replaced. Disposal is included in the quote.
Can I replace a steam boiler with a hot-water boiler?
Sometimes, but it is a bigger project than a boiler swap because steam piping and radiators are not designed for pumped water. Usually the right answer is a new steam boiler sized correctly to the radiation. We will tell you which applies to your house.
How much more efficient is a new boiler?
An old atmospheric boiler is typically in the 60 to 80% AFUE range as it ages. A new condensing boiler is 95% AFUE, and with outdoor reset it runs at lower water temperatures where it condenses most of the time. The gas savings are real, and larger the older your current boiler is.
Do you replace boilers you didn’t install?
Yes. We replace every brand of residential hot-water and steam boiler. We install Laars boilers and can match a replacement to your existing radiation, piping and venting.
Can I finance a new boiler?
Yes. You can prequalify in about 2 minutes with no impact to your credit score, and the Nicor Gas discount lowers the amount you need to finance.
Will I get a warranty on the new boiler?
Yes. The manufacturer’s parts and heat exchanger warranty applies, and we register the boiler for you so the full term is in effect. Your invoice lists the equipment and warranty terms.
Ready to Replace Your Boiler?
Request a free written quote with the Nicor Gas discount already figured in, or call to talk it through.
Not sure yet? See boiler repair or see financing options.
Discount amounts reflect the 2026 Nicor Gas Energy Efficiency Program for qualifying equipment installed January 1 through December 31, 2026, and are subject to change or cancellation due to funding limits. Rest Assured HVAC LLC is an independent contractor and is not affiliated with or endorsed by Nicor Gas.
