Replacing a furnace or boiler in Philadelphia is a job for a licensed contractor, and in the city it generally needs a mechanical permit from the Department of Licenses and Inspections (L&I); for a one- or two-family house, an appliance replacement usually qualifies for an EZ permit without plans. Before you sign anything, settle three questions: do you replace the same type of system or switch (furnace, boiler or heat pump), how will the new unit vent (a high-efficiency unit usually exits through the wall, which can leave your water heater alone in the old chimney), and which rebates apply (PGW pays rebates on high-efficiency gas furnaces and boilers; the federal tax credit ended after 2025). Get those right and the quotes you collect will be comparable.
This is general information. In the city, L&I has the final word on permits; in Bucks, Montgomery and Delaware counties, ask your township or borough.
Repair or replace?
A heating system doesn't come with an expiration date, but the Department of Energy's Energy Saver guide suggests considering a replacement when any of these are true:
- the furnace or boiler is more than 15 years old;
- it needs frequent repairs and your energy bills are going up;
- some rooms are too hot or too cold;
- the system is noisy, or the house has humidity or dust problems.
None of these means you must replace today. A 20-year-old boiler that fires reliably and passes its yearly check can keep going; a 12-year-old furnace with a cracked heat exchanger can't. The usual trigger in Philadelphia is a technician's finding during a fall tune-up or a no-heat call in January. If you're reading this before the cold sets in, you have the advantage: you can get several quotes instead of taking the first company that can come tomorrow. Our heating tune-up guide covers what that visit should include.
If you have no heat right now
- Check the basics: thermostat set to heat with fresh batteries, the furnace or boiler power switch on, the breaker not tripped. On a steam boiler, look at the water level in the sight glass.
- If you smell gas, leave the house and call PGW (or PECO in the suburbs) from outside. Don't flip switches on the way out.
- If your household is income-eligible, the City's Heater Hotline, run by the Energy Coordinating Agency at (215) 568-7190, makes free emergency repairs to home heaters. The City's Basic Systems Repair Program provides free repairs, including heating, to eligible owner-occupied homes. Both have income limits listed on those pages.
Your options in a Philadelphia house
Most Philadelphia rowhomes and twins have either a gas furnace that blows warm air through ducts, or a gas boiler that sends hot water or steam to radiators. If you're not sure which you have, our radiator troubleshooting guide explains how to tell steam from hot water.
Same type, same spot
Replacing a furnace with a furnace or a boiler with a boiler is the most common job, and usually the quickest, because the ducts or radiator piping stay. The choice is mostly about efficiency, measured as AFUE (annual fuel utilization efficiency): the share of the fuel that ends up as heat in the house. ENERGY STAR certified gas boilers are rated at 90% AFUE or higher. PGW's rebates, below, start at 95% AFUE for furnaces and 94% for boilers.
A steam system is its own trade. Ask whether the contractor regularly replaces steam boilers, and ask them to check the rebate threshold against the specific model they quote, because steam boilers are generally rated lower than the high-efficiency hot-water boilers the rebates are aimed at.
Combi boiler
If you have a hot-water boiler and an aging water heater, a combination boiler heats both the radiators and your tap water in one wall-hung unit and frees up basement floor space. It touches plumbing as well as heating; our water heater guide covers that side.
Heat pump
A heat pump heats and cools with electricity. The Energy Saver guide calls heat pumps an efficient option for all-electric houses or houses with central propane or oil heat. In a house with ducts, a ducted heat pump can replace or work alongside a furnace; in a radiator house, ductless units mounted on the walls are the usual route, with the boiler often kept for the coldest days. It's a bigger change than a like-for-like swap: you need space outside for the outdoor unit (on a rowhome, often the roof or a small rear yard) and usually electrical work, so ask for it as a separately priced option.
Venting, the chimney and the drain
This is where replacement quotes differ the most, and where an incomplete quote turns into a change order.
Older gas furnaces and boilers usually vent into the brick chimney, often sharing it with the gas water heater. A high-efficiency condensing furnace or boiler vents through the wall instead, with plastic pipe of a type the manufacturer specifies, and it produces condensate water that needs a drain. A DOE measure guideline for high-efficiency gas furnaces points out three things to plan for:
- The water heater left behind. When the furnace is removed from a shared vent, the vent for the remaining appliance has to be re-checked against the gas code's venting tables. The guide says exterior masonry chimneys will require relining, and that skipping this step underestimates the cost of the replacement. Our chimney inspection guide explains this "orphaned water heater" problem.
- The condensate drain. The unit needs a drain below its condensate trap or a condensate pump, and in cold climates the guide says condensate should go into the house's sanitary drain, never outdoors.
- The wall vent. Sidewall venting needs clearance to neighboring buildings. On a rowhome, the side and rear walls are often close to a neighbor's windows or a narrow walkway, so ask exactly where the pipes will come out.
The same guide recommends sizing the new unit with ACCA Manual J or an equivalent load calculation, and suggests a lower-capacity unit when the old one cycles on and off too often. Ask whether the contractor ran a load calculation or simply matched the old unit's size. If you've added insulation or new windows since the old system went in, the house may need less heat than it used to.
What the City requires
L&I's mechanical permit page says a mechanical permit is needed to install equipment regulated by the Philadelphia Mechanical and Fuel Gas Codes, including heating and gas piping. Ordinary repairs and maintenance don't need one. The key points for a replacement:
- EZ permit. Replacing appliances in one- or two-family dwellings is eligible for an EZ permit, which doesn't require plans.
- Licensed contractor. The page says a licensed contractor must perform all work, with an active license, current City taxes and insurance on file with L&I.
- Fees. As of October 2026 the page lists a $100 nonrefundable filing fee and $69 per appliance in one- or two-family dwellings, plus small surcharges. Fees change, so check the page.
- Inspection. A Certificate of Approval is issued after the required inspections pass. Ask for a copy.
- Boilers. The City notes that boiler installations are regulated by the Pennsylvania Department of Labor and Industry. The state's boiler program exempts boilers in single-family homes (with no business in the home) and in buildings with four or fewer units from its inspections, while noting that such work may still fall under the building code. In practice, ask the contractor which permits they will pull for the boiler, the gas piping and the venting, and get the answer in the quote.
A contractor who suggests skipping the permit is telling you how they work. For the general checks, including Pennsylvania Home Improvement Contractor registration, see how to check a contractor in Philadelphia.
Rebates and tax credits
- PGW customers (Philadelphia): PGW's EnergySense residential rebates, listed for September 2024 through August 2027, include $400 for a 95% AFUE furnace, $1,000 for a 94% AFUE boiler and $1,400 for a qualifying combi boiler, with higher amounts ($800, $1,400 and $2,000) for customers who enrolled in PGW's Customer Responsibility Program or received a LIHEAP or hardship grant in the past year. Rebates are first-come, first-served while funds last, apply only to homes on PGW firm rates, and require the invoice, the AHRI certificate, manufacturer specs and a copy of your PGW bill. The page also warns that check processing is currently delayed. Confirm the amounts before you buy; PGW can change the program.
- PECO customers in the suburbs: rebates change by program year, so check PECO's Ways to Save for your home page, especially if you're considering a heat pump.
- Federal tax credit: the energy efficient home improvement credit that covered furnaces, boilers and heat pumps ended for equipment placed in service after December 31, 2025, according to the IRS. Don't count on it for a 2026 installation.
What drives the price
We don't publish a single number, because two replacements on the same block can be very different jobs. What moves the price:
- the type of system and its efficiency (a standard unit versus a condensing one, or a switch to a heat pump);
- venting: a new wall vent, a chimney liner for the water heater, or both;
- the condensate drain or pump;
- changes to gas piping, ducts or radiator piping;
- steam versus hot water, and the condition of the existing pipes;
- access: narrow basement stairs and tight utility rooms are common in rowhomes;
- removal and disposal of the old unit (an old boiler can be very heavy);
- the permit, and whether it's an emergency replacement in the middle of winter.
Checklist before you hire
- Photograph the old unit's label (make, model, age), the vent connection and the space around it.
- Write down what you have: furnace or boiler, steam or hot water, and whether the water heater shares the chimney.
- Note problem rooms, high bills and anything you've changed, such as new insulation or windows.
- Decide whether you want a like-for-like swap or prices on alternatives (combi boiler, heat pump).
- Ask each contractor for a written quote that names the model and its AFUE, the venting plan, the condensate drain, chimney work for the water heater, the permit and removal of the old unit.
- Ask whether they ran a load calculation.
- Confirm the City license (or township requirements) and the PA Home Improvement Contractor registration.
- Check rebate requirements with PGW or PECO before you buy, and keep the invoice, the AHRI certificate and the permit papers.
- After the install, make sure you have working carbon monoxide alarms; see our smoke and CO detector guide.
When to call a pro
For a replacement, always. Gas piping, venting, combustion and the boiler's safety controls are licensed work, and the City requires a licensed contractor and a permit. Call right away if you smell gas, a CO alarm goes off, you see soot or scorch marks around the unit or vent, water is leaking from a boiler, or the system won't fire in cold weather.
When you're ready for quotes, you can post your heating project on HomeKept. Describe the system and what you want once, with the photos from the checklist above, and compare up to 3 estimates from local pros. It's free for homeowners.
HomeKept is a brand of FalconAI LLC, 331 E Street Rd, Feasterville-Trevose, PA 19053.
HomeKept needs JavaScript. Please enable it and reload the page. ·
HomeKept necesita JavaScript. Actívalo y vuelve a cargar la página. ·
Для работы HomeKept нужен JavaScript. Включите его и обновите страницу.