Oil to gas conversion is two projects billed as one. There is the heating system, which an HVAC contractor quotes, and there is the tank in your yard, which usually nobody quotes until later. The second one is where the surprises live.
Published figures for the work run from roughly $3,800 to $22,000, and that spread is not regional variation. It is mostly the difference between quotes that carry the underground tank and quotes that stop at the burner. A component breakdown across the cost aggregators lands at $300 to $2,500 for a burner or conversion kit and $800 to $3,000 for labor and interior gas piping. Venting and controls add $200 to $1,200, and closing the tank adds $1,000 to $3,500 plus $250 to $600 for every soil sample.
Before any of that matters, one question decides whether you can convert at all: is there a gas main in your street. Homeowners who skip that call spend three weeks comparing equipment quotes for a fuel they cannot buy.
This directory lists tank contractors, not furnace installers, so what follows will not pick your equipment or tell you which brand of boiler to buy. What it covers is the half of the job an HVAC quote tends to leave out. You are converting. Here is what happens to the tank, and here is what the equipment quote is not telling you.
Start with whether gas reaches your street
One phone call outranks every other step in this project, and it goes to the gas utility. Two questions settle it: whether a main runs past your address, and what it would cost to bring a service line from that main to your meter. Utilities answer this for free and will usually walk the address on a map while you are on the phone.
Distance decides the number. Running gas line generally costs $15 to $40 per linear foot, and a service connection from an existing main in the street commonly lands between $2,000 and $10,000 depending on run length and what the trench has to cross. Where no main exists on the street, the utility prices a main extension separately. That work is widely reported at roughly $100 per linear foot, and the only number that matters is your utility's written quote. A few hundred feet of extension can cost more than the entire heating system.
Many utilities offer an allowance or contribution toward the service line for a new heating customer, sometimes covering the first stretch entirely. That allowance is the single most variable number in this whole calculation, it changes by utility and by year, and it is worth asking about explicitly rather than assuming. Converting from oil to gas heat pencils very differently at a free 60 foot connection than at a $14,000 main extension.
If the answer is no main and no reasonable extension, stop reading about gas. The rest of this page still applies, because the tank questions are identical whichever fuel you land on, and what changes when propane is the only option is covered below.
What an oil to gas conversion cost actually includes
Ask every bidder to price the tank as its own line, not as a footnote. The equipment side of the job is well understood and quoted competitively. The tank side gets quoted by a different trade, on a different schedule, and it is the line that moves a $9,000 project to $14,000 without anyone lying to you.
Chimney relining cost after a conversion
Chimney work catches people. A high efficiency gas unit vents through PVC out a sidewall and does not use the flue at all, which sounds like a savings until you remember the flue was also venting your water heater. Leaving a now oversized masonry chimney serving one appliance invites condensation and draft problems, and relining runs $1,500 to $4,000 installed. Confirm which appliances are left on the chimney before you accept a venting plan.
Oil furnace removal cost
The oil equipment does not disappear on its own either. An old boiler or furnace has to be disconnected, drained, cut up, and hauled, and interior fuel lines get capped or pulled. Oil furnace removal cost is a small line, a few hundred dollars in most quotes, and it belongs in writing anyway because it is the one item both trades assume the other is handling.
Then there is the tank, which is the real subject of this page. A sound aboveground tank in a basement is a straightforward removal. A buried tank is a permitted job with soil sampling attached, and the full removal cost breakdown prices it properly. Run your own numbers through the oil tank removal cost calculator before you accept anyone's allowance for it.
| Line item | Typical range | Who quotes it |
|---|---|---|
| Burner or conversion kit | $300 to $2,500 | HVAC contractor |
| Labor and interior gas piping | $800 to $3,000 | HVAC contractor |
| Venting and controls | $200 to $1,200 | HVAC contractor |
| Chimney relining, if the flue still serves an appliance | $1,500 to $4,000 | HVAC or chimney specialist |
| Gas service connection from an existing main | $2,000 to $10,000 | Gas utility |
| Gas main extension where no main serves the street | Widely reported near $100 per linear foot; get it in writing | Gas utility |
| Removing the old oil furnace or boiler | A few hundred dollars | HVAC contractor |
| Closing the oil tank: removal | $1,500 to $3,500 with no contamination | Tank contractor |
| Closing the oil tank: permitted fill in place | $1,000 to $3,000 | Tank contractor |
| Soil sampling required by either closure route | $250 to $600 per sample | Tank contractor |
Pulling the tank versus filling it, and why lenders care
Removing the tank ends the obligation. Filling it manages the obligation, and the difference surfaces when the property changes hands rather than on the conversion invoice. Both are legitimate closures, both are legal in most states with the right paperwork, and they are not equivalent assets afterward.
Cost is closer than most owners assume. Pulling a residential tank runs about $1,500 to $3,500 with no contamination, and filling one in place runs about $1,000 to $3,000. Two thousand dollars of difference is not what should decide this. What almost always settles it is whether there is room to get a machine to it at all. A tank under a patio, an addition, or a shared driveway is the classic case for leaving it.
Paperwork is what a buyer's lender actually reads. Either route requires a permit, soil samples, and a closure report that the state or municipality accepts, and the abandonment and closure-in-place guide walks the fill sequence and material choice in detail. Sampling is what turns a fill into a closure. Skip it and the tank is merely covered up, and the next soil test on the property is what surfaces the omission.
Lenders vary and they are not uniformly hostile to a filled tank. A documented in-place closure with clean sample results clears most conventional underwriting. What stalls files is a tank with no documentation at all, and government backed loans tend to be stricter than conventional ones. If a sale is on the horizon, the remove versus close comparison is the page to read before choosing.
| Factor | Removal | Permitted fill in place |
|---|---|---|
| Typical cost, no contamination | $1,500 to $3,500 | $1,000 to $3,000 |
| Time on site | Usually one day | Usually one to two days |
| Permit required | Yes | Yes |
| Soil sampling required | Yes | Yes, and it is the step most often skipped |
| What you end up holding | Closure report, tank gone from the record | Closure report, tank stays on the record |
| Lender acceptance later | Cleanest outcome, rarely questioned | Generally accepted with full documentation; stricter under government backed loans |
| When it is the right call | Anywhere an excavator can safely reach the tank | Under a patio, addition, driveway, or against a footing |
What an undocumented tank does to a future sale
Nothing about a conversion removes the tank from the property record. Switching fuel changes what you burn, not what is buried, and a tank that was never formally closed stays a disclosable condition for as long as it is in the ground. Owners who convert and forget are the ones surprised at closing.
Buyers ask a narrow question and it is always the same one: where is the closure paperwork. A permit, sample results below the state cleanup number, and a written closure determination make the tank a solved item that gets initialed and moved past. Absence of those documents makes it an open question, and open questions get settled with a credit big enough to stop the buyer worrying.
The gap is not small: a documented closure costs low four figures, while a tank found during diligence gets removed and tested on the buyer's schedule with the seller holding no room to negotiate and a contract clock running. That dynamic, and what contamination does to it, is covered in removing a tank before selling.
There is a real exception. If the property is heading for demolition or a gut renovation, closing the tank on the buyer's schedule can be the correct economic call, because the excavator is coming anyway. That is a decision to make deliberately with a contractor, not by default because the conversion invoice was already big enough.
Running the Btu math yourself instead of trusting a sales sheet
Fuel prices move, so what follows is a method rather than a number. Comparing oil to gas honestly requires three inputs: the energy content of each fuel, its current price in your area, and the efficiency of the equipment burning it. Skip any one of the three and the comparison is decoration.
Energy content is fixed and published. Federal energy data puts distillate fuel oil at 15 parts per million sulfur and under at 5.770 million Btu per barrel, which works out to about 137,380 Btu per gallon. A therm of natural gas is 100,000 Btu by definition, and delivered gas averaged roughly 1,037 Btu per cubic foot in 2025, so one Ccf is about 1.037 therms. Propane sits at roughly 91,450 Btu per gallon.
Efficiency is the input people forget. A boiler rated at 87 percent turns 87 percent of that Btu content into heat in the house and sends the rest up the vent. Certified equipment carries an AFUE rating for exactly this comparison. On boilers the ENERGY STAR threshold is 87 percent or better for oil and 90 percent or better for gas. On furnaces it is 85 percent for oil, and for gas 95 percent in the northern region against 90 percent in the southern one, so a furnace quote and a boiler quote are not measured against the same bar. The formula is your price per unit, divided by Btu per unit, times one million, divided by AFUE as a decimal.
Work one example and the method is yours. Heating oil at $3.50 a gallon through an 87 percent boiler comes to roughly $29 per million Btu delivered, and gas at $1.60 a therm through a 92 percent unit comes to roughly $17. Those are illustrative prices, not a forecast, and your own current numbers are the only ones that count. Your last twelve months of gallons, which the heating oil usage calculator converts from gauge readings, tells you how many million Btu you actually buy.
| Fuel | Energy content | ENERGY STAR AFUE threshold |
|---|---|---|
| Heating oil, No. 2 distillate | About 137,380 Btu per gallon | 87 percent on boilers, 85 percent on furnaces |
| Natural gas | 100,000 Btu per therm, and 1 Ccf is about 1.037 therms | 90 percent on boilers, 95 percent on northern furnaces and 90 percent on southern |
| Propane | About 91,450 Btu per gallon | Same thresholds as natural gas equipment |
Rebates and credits, and why the number you read is stale
Incentive pages age badly, and the one you are reading is no exception. Federal credits, state energy office programs, and utility rebates all run on their own calendars, get amended mid year, and are frequently written about long after the terms changed. A page quoting a specific dollar amount is quoting the day it was written.
Programs generally sort into three buckets. Federal tax credits attach to qualifying high efficiency equipment and are claimed at filing. State energy offices run rebates that often favor efficiency upgrades over fuel switching, which surprises people. Utilities run their own conversion incentives, sometimes as bill credits and sometimes as the service line allowance covered under whether gas reaches your street.
Tank work is usually the orphan. Equipment incentives rarely cover removing or closing an underground tank, and where any help exists it tends to come from a separate state cleanup or heating oil tank program with its own eligibility rules, deductibles, and application windows. Several of those programs condition eligibility on filing before work starts, which makes the order of operations financially load bearing.
Confirm three things in writing before you sign: what the incentive pays, what its deadline is, and whether it requires a specific contractor certification. That last one has killed more rebates than any other condition, because homeowners hire on price, complete the work, and then discover the installer was not on the approved list.
When there is no gas main, and what propane changes
Propane is the fallback when the street has no gas, and it is a genuinely different product. It arrives by truck instead of pipe, it is stored on your property in a tank you either own or lease, and its price behaves more like heating oil than like piped gas because you are buying a delivered commodity. The equipment overlaps heavily, which is why converting to it is usually cheaper than a main extension.
Storage is the trade you are making. You have spent this whole project getting a fuel tank off your property, and propane puts one back, either a cylinder pair against the house or a larger vessel set on a pad or buried. Leased tanks tie you to one supplier's pricing while owned tanks cost more up front and let you shop deliveries. A buried propane tank carries its own closure obligations at end of life, handled by the propane industry rather than by the oil tank trade.
Energy content is the other trade. At roughly 91,450 Btu per gallon against 137,380 for heating oil, propane delivers about two thirds the heat per gallon. A price per gallon comparison between the two is therefore meaningless, and only the per million Btu math is honest. Run it before committing, because the answer flips with local delivered pricing.
None of this makes propane the wrong call. For a rural property with no main in reach it is frequently the only practical path to a modern high efficiency system. Propane also sits outside what this directory covers. For tank siting, supply contracts, and eventually decommissioning a propane vessel, the calls to make are to an HVAC contractor and a propane supplier in your area. Staying on oil with a new tank and burner is the smallest project of the three. What propane does not do is remove the tank from your life, and the buried version brings back the exact documentation problem you just solved.
Sequencing the tank work, and getting quotes
Close the oil tank after the new system runs, not before. Heat is the constraint. Pulling a tank in February and discovering the gas connection needs another two weeks leaves a house with no heat source and an owner buying emergency electric, which is how a planned project becomes an unplanned one.
The sequence that works is boring on purpose. Confirm gas availability and the connection price, book the conversion, burn the oil down so nobody pays to pump and dispose of usable fuel, commission the new system, then close the tank once heat is proven. Burning the tank down is worth real money, since pumping and hauling residual oil is a line item on the closure quote.
One exception overrides the sequence. If the tank is already leaking, or the smell in the basement says it might be, closure stops being a scheduling question and becomes an emergency. The first hour of a heating oil release matters more than the conversion calendar. Contamination discovered mid project rewrites every number on this page.
Bid the two trades separately and compare them side by side. Get the equipment quote from an HVAC contractor and the closure quote from a tank contractor, because a single number covering both usually hides an allowance rather than a price. Ask the tank bidder for the permit, the sampling plan, and the closure report in writing, itemised separately rather than rolled into one number. Then request a quote with the tank size, location, and whether it is buried or in the basement. Check the boundary against above ground tank options if you are keeping oil after all, and in New Jersey the tank removal listings are where to begin.