Furnace Replacement in Unionville, PA
The furnace is the easy part. The house is what makes it fit.
Unionville has 1700s stone farmhouses, 1970s to 1990s colonials and newer homes with attic air handlers, sometimes on the same road. Each needs a different replacement plan. This page covers sizing, efficiency, fuel choice, costs, rebates and what a good estimate looks like.
- Free referral service, not a contractor
- Independent local HVAC companies
- No obligation
How Unionville's housing changes a furnace replacement
A furnace replacement in Unionville depends more on the house than on the brand. Stone farmhouses bring chimney and duct limits, older colonials bring oversized original systems, and newer homes bring attic air handlers and multiple zones.
1700s and 1800s stone farmhouses
Thick walls, chimneys built for wood or coal, and ducts added long after the house went up. Many still burn oil. Venting, liners, tank condition and duct capacity drive the plan.
Heating old stone homes1970s to 1990s colonials
Usually a basement furnace with central air on the same blower. The original furnace was often sized generously, and insulation or window upgrades since then lowered the load. A right-sized replacement is often smaller.
Newer homes and large estates
Often a basement furnace for the first floor and an attic air handler or heat pump upstairs, sometimes with zones. Each system is its own replacement decision, and attic units need drain pans and float switches done right.
East Marlborough Township, which includes Unionville, had 7,305 residents in 2020, with very old and much newer homes side by side. Plan for your house, not the neighborhood average.
Signs your furnace needs replacing, not another repair
One sign alone rarely decides it. Two or three together usually do. Ask the technician to show you the reading or the damage behind any replacement advice.
| Sign | Why it matters | What to ask for |
|---|---|---|
| Cracked heat exchanger or failed CO test | Combustion gases can reach the airflow. This is a safety issue at any age. | A photo, camera image or written CO reading |
| Furnace near or past 20 years | Gas furnaces typically last 15 to 20 years. Parts get harder to find. | The model and serial number, which date the unit |
| Repairs in back-to-back winters | Paying for a new part every season adds up fast on an old unit. | A written repair quote next to a replacement quote |
| Rising oil, propane or gas use | Older furnaces from the 1980s and earlier often ran around 60% AFUE. | Your fuel delivery or PECO bill history |
| Rooms that never even out | Can be oversizing, duct problems or a single-stage furnace that runs full blast. | A load calculation and a duct check, not just a bigger furnace |
| You also need new central air | Furnace and AC share the blower and coil. Matching them can make sense. | A combined quote and a heat pump or dual fuel option |
Not sure whether to fix it? Furnace repair covers the common single-part failures.
Why a Manual J load calculation should come first
Manual J is the ANSI-recognized standard from ACCA for calculating a home's heating and cooling loads. It looks at the house itself, not the old furnace's label, so the new furnace matches what your home actually loses in winter.
According to ACCA, the calculation accounts for local design temperatures, windows and their orientation, walls and attics, air leakage, ducts and ventilation. ACCA also notes that building codes and most jurisdictions require a load calculation done to the standard.
A farmhouse may have new windows or a large addition since its last furnace. A 1980s colonial may have been oversized from day one. Oversized furnaces short cycle and leave rooms uneven.
Watch the input and output numbers. The label shows input BTUs. Output is input times efficiency. An 80,000 BTU input furnace at 80% delivers about 64,000 BTUs. The same input at 96% delivers about 76,800, so a straight swap to high efficiency adds heat you may not need.
AFUE, explained simply
AFUE means annual fuel utilization efficiency. It's the share of the fuel you pay for that becomes heat in the house. At 80% AFUE, 20 cents of each fuel dollar leaves through the flue. At 96%, about 4 cents does.
| AFUE | Typical equipment |
|---|---|
| About 60% | Many furnaces from the 1980s and earlier |
| 80% | Standard gas or propane furnace venting into a chimney or metal flue |
| 80% to 87% | Standard oil furnaces |
| 90% to 98% | Condensing gas or propane furnaces with PVC venting |
ENERGY STAR says its certified gas furnaces for northern states are up to 18% more efficient than baseline models, and its oil furnaces up to 4%.
80% vs 95% furnaces: venting, condensate and the water heater
A 95% furnace saves fuel but changes the installation. It vents through PVC pipe, makes condensate that needs a drain, and can leave a gas or oil water heater alone in the chimney. An 80% furnace keeps the existing flue but burns more fuel.
| Item | 80% furnace | 95% furnace |
|---|---|---|
| Venting | Chimney or metal flue. Old masonry chimneys may need a liner. | Two PVC pipes through a side wall or roof |
| Condensate | None to manage | Trap, drain line and often a condensate pump |
| Snow exposure | Not an issue at the chimney | Vent outlets must sit above typical drifts. West Chester averages about 28 inches of snow a year. |
| Water heater | Keeps sharing the flue | May be orphaned in an oversized chimney. Needs a draft check or a liner. |
| Fuel use | Higher | Lower, which matters most on propane |
| Historic homes | No new wall openings | New vent openings. Ask the township first in the historic district. |
The orphaned water heater
When the furnace leaves a shared chimney for PVC, the water heater's smaller, cooler exhaust may not draft well on its own. It can condense inside the chimney or spill back into the basement. A careful installer tests the water heater's draft after the install and quotes a liner if it's needed.
The DOE 95% furnace rule, as of October 2026
DOE set December 18, 2028 for most new gas furnaces to reach 95% AFUE. On June 8, 2026, the Supreme Court sent the legal challenge back to the D.C. Circuit, and DOE has proposed a delay. For now, 80% furnaces can still be installed. Don't let anyone rush you with a deadline.
Fuel options when you replace a furnace in Unionville
Replacement is the one time switching fuels is practical. Around Unionville the realistic options are staying on oil, propane, PECO natural gas where lines run, a heat pump, dual fuel, or geothermal on larger lots.
| Option | Good fit when | Watch for |
|---|---|---|
| Stay on oil | The tank and chimney are sound and you're used to deliveries | Tank age, chimney liner, yearly cleaning. |
| Propane furnace | No gas main, and you want a gas-style furnace | Tank placement and ownership. Converting from oil means a new tank, lines and venting. |
| PECO natural gas | A PECO gas line reaches your road | Service line and meter work. Ask PECO about availability before planning on it. |
| Air-source heat pump | You also need central air, or heat with oil, propane or electric | Electrical service capacity, duct size. PECO electric rebates may apply. |
| Dual fuel | You want a heat pump for most of the season and a furnace for the deep cold | Controls that switch between the two at the right temperature |
| Geothermal | Larger lots and new construction with room for loops or wells | Loop design and a company experienced with ground-source service |
For a side-by-side look at running costs and trade-offs, see the oil vs propane vs heat pump guide. Already on propane or oil? See propane furnaces and oil furnaces.
Single-stage, two-stage or variable speed, and the AC question
Single-stage furnaces run full blast every cycle. Two-stage furnaces run on low most of the time, and variable-speed blowers fine-tune airflow. The upgrades pay off most in homes with uneven rooms, and they cost more up front.
Single-stage
Simplest and least expensive. Fine for a right-sized furnace in a compact, well-ducted house. Louder starts and bigger temperature swings.
Two-stage
Low fire for mild days, high fire for January. Quieter and more even, which helps in two-story colonials where the upstairs runs cold.
Variable speed
The blower adjusts in small steps. Better for filtration, zoning and long duct runs in larger East Marlborough homes.
Replacing the furnace and AC together
A furnace and central air share the blower, ducts and indoor coil. If both are old, one installation with matched parts often makes sense. A new furnace with a tired AC coil can choke airflow. A fairly new AC can usually stay if the new blower and coil match it.
R-454B and R-32 refrigerants
New AC and heat pump equipment made since January 1, 2025 uses lower-impact refrigerants, mainly R-454B or R-32. Existing R-410A systems can still be serviced. A new outdoor unit usually can't pair with an old R-410A indoor coil, so ask which refrigerant the estimate includes and whether the coil is new.
What a written furnace replacement estimate must include
A good estimate lists the exact equipment, the venting and drain work, every add-on, and who handles permits and warranty registration. If a line is missing, ask before you sign, not after the old furnace is out.
- Brand, model number, input BTUs and AFUE of the new furnace
- The load calculation result, or how the size was chosen
- Single-stage, two-stage or modulating, and blower type
- Venting: PVC route and termination, or chimney liner
- Condensate drain and pump, if needed
- Water heater draft test after the install
- Duct, return or plenum changes
- Thermostat, and whether it suits dual fuel or zones
- AC coil or outdoor unit, and the refrigerant type
- Permit, inspection and who pulls them
- Removal and disposal of the old unit
- Parts and labor warranty terms, and who registers the equipment
- Total price, deposit and payment schedule
- The company's HICPA registration number
Slow down if you hear
- "You'll get the federal tax credit." The 25C credit ended for equipment placed in service after December 31, 2025.
- "80% furnaces are already banned." They aren't. The 95% rule is unsettled.
- "Same size as the old one." With no load calculation, that may repeat an old mistake.
- "Sign today for this price." A fair price holds long enough to compare.
- A condemned furnace with no proof. Ask to see the crack or the CO reading.
Pennsylvania has no statewide HVAC license. Contractors doing $5,000 or more of home improvement work a year must register under HICPA. See Pennsylvania contractor rules.
What happens on furnace installation day
A straightforward swap is often finished in a day. Fuel changes, new venting, duct work or a combined AC install can take longer. The order of work is similar either way.
- The crew protects floors and the path to the basement or attic.
- Power and fuel to the old furnace are shut off.
- The old furnace is disconnected and removed.
- The new furnace is set, leveled and connected to the plenum and returns.
- Gas or propane piping is connected and leak-tested, or the oil line is connected.
- Venting is installed: PVC pipes outside, or a liner and connector to the chimney.
- The condensate drain or pump is installed on a high-efficiency unit.
- Wiring and the thermostat are connected.
- The furnace is started and gas pressure, temperature rise and combustion are checked.
- CO is measured, and the water heater's draft is tested if it shared the flue.
- You get a walkthrough, the manuals and the warranty paperwork.
Permits
Permit rules depend on the job and the township. Ask the company whether your replacement needs a permit and who will get it, or check with the East Marlborough Township office if you live there.
Warranty registration
Many manufacturers require registration within a set number of days to get the full parts warranty. Ask who registers it, and keep the confirmation with your model and serial numbers.
The historic district
The Unionville Village Historic District joined the National Register in 1979 with 69 contributing buildings. If your home is in it, ask the township about any rules for outdoor units or wall vents before you choose PVC venting or a heat pump location.
Furnace replacement rebates and credits in 2026
There is no federal 25C tax credit for a furnace or heat pump placed in service in 2026. PECO electric customers may get up to $300 on a qualifying ENERGY STAR heat pump or ductless mini split and up to $50 on a smart thermostat.
- Federal 25C credit: ended for equipment placed in service after December 31, 2025. Some older articles and ads still mention it.
- PECO electric: heat pump and mini split rebates up to $300, smart thermostat up to $50. Apply within 90 days with a receipt showing the model number.
- PECO natural gas: gas furnace and boiler rebates exist for PECO gas customers. PECO lowered them for applications on or after October 1, 2026.
- Oil and propane homes: PECO's heat pump rebates apply to PECO electric customers whatever they heat with now.
PECO decides eligibility and amounts, so confirm on peco.com before you buy. Help paying for heat, including LIHEAP for eligible households, is covered in rebates and heating assistance.
Furnace replacement questions from Unionville homeowners
How do I know what size furnace I need?
Ask for a Manual J load calculation. It's the ACCA standard for sizing heating and cooling equipment, and it looks at your windows, insulation, air leaks and ducts. Matching the old furnace's label often repeats an old sizing mistake.
Is a 95% furnace worth it over an 80%?
It usually pays off faster on propane and in homes that burn a lot of fuel. It needs PVC venting and a condensate drain, and the water heater may need a liner. In a historic home, new wall vents may need a township conversation first.
Can I still buy an 80% gas furnace?
Yes, for now. DOE set December 18, 2028 for most new gas furnaces to reach 95% AFUE, but the Supreme Court sent the challenge back to the D.C. Circuit on June 8, 2026, and DOE has proposed a delay.
Should I replace my oil furnace with a heat pump?
Many oil homes compare a heat pump or a dual fuel setup, where the heat pump covers mild weather and the oil furnace covers the coldest days. Your duct size and electrical service decide whether it fits. PECO electric customers may qualify for heat pump rebates.
Do I have to replace my air conditioner too?
Not always. A fairly new AC can stay if the new furnace's blower and coil match it. If the AC is old, replacing both at once means matched equipment and one installation, and new outdoor units use R-454B or R-32.
How long does a furnace replacement take?
A straight swap is often done in a day. New venting, a fuel switch, duct changes or a combined AC install can add time. Ask the company for its schedule in writing.
Do I need a permit to replace a furnace in East Marlborough?
It depends on the job. Ask the company whether a permit is needed and who will get it, or call the township office. Put the answer in the written estimate.
Is there a tax credit for a new furnace in 2026?
No. The federal 25C credit ended for equipment placed in service after December 31, 2025. If a quote promises one for a 2026 install, ask the company to show you the current IRS rule.
Is this site a heating contractor?
No. UnionvillePAFurnaceRepair is a free referral service. It connects you with independent local HVAC companies, which set their own prices and terms. This site doesn't perform or guarantee any work and may be paid for referrals.
Sources
- ACCA: Manual J residential load calculation.
- ENERGY STAR: furnaces.
- Federal 25C credit ending for property placed in service after December 31, 2025: One Big Beautiful Bill Act, Section 70505.
- DOE furnace rule status, PECO rebates, refrigerant change, historic district and township figures, as summarized on the Unionville furnace guide. Confirm rebates at peco.com.
- Pennsylvania Attorney General: Home Improvement Contractor registration.
Written by Lawrence. Updated October 25, 2026. Facts on this page were checked against the public sources listed above.
This is general information from a free referral service, not a heating contractor. For gas smells or carbon monoxide alarms, leave the house and call 911.
Related furnace help
Planning a new furnace? Get connected with local installers.
Ask two or three companies for a written estimate with a load calculation. Tell them your fuel, the age of the house and whether you also need air conditioning.
One call to (724) 241-4851 connects you with independent local HVAC companies that serve Unionville and nearby Chester County communities. It's free, with no obligation.
Have this ready when you call
- Your town or road
- Your fuel: oil, propane, gas or electric
- What the system is doing, and any blinking light code
- Whether you smell gas or oil (if so, leave and call 911 first)
Free referral service. Not a heating contractor. Companies are independent and set their own prices.