Switching from Natural Gas To Oil –
Is It Viable Now?

 It may be possible, here’s what you want to check first:

• The building’s oil tank is in good working condition and inspections up to date. That’s a positive starting point for using oil again.

• There is no blanket regulatory prohibition on a building using oil if it meets the rules for the fuel grade and tank/pipe safety (e.g., for certain fuel oil grades). For example: NYC has rules phasing out the use of No. 6 and No. 4 oil in certain buildings. 

• If the building is already served by oil equipment and is not subject to latest prohibitions (or uses No. 2 oil), then in principle you may continue.

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Key regulatory/practical hurdles and caveats

1. Fuel Grade & Phase-Out Rules – In NYC, there are specific rules around the phase-out of dirty/heavy fuel oils:

   • Buildings using No. 6 oil: phase-out was required under Local Law 43.

   • Buildings using No. 4 oil: there is an accelerated ban (e.g., buildings must cease use of No. 4 by July 1, 2027) in NYC.

   • Therefore, if the building wants to switch back to oil, one must check which grade of oil is intended, and whether that grade is still permissible under the local law.

2. Utility Service Classification & Contractual Obligations – When a building converts to natural gas (or added natural gas service), especially under a “firm gas” classification with the utility, there may have been commitments or infrastructure investments made that expect continued gas service. For example, a building may have firm gas service terms (or incentives were provided) that require gas usage for a certain period.

   • For instance, documents note that a building converting to firm gas service may be required to commit for five years. 

   • If you revert to oil, you might need to renegotiate service classification with Con Ed (e.g., return from “firm gas” to whatever oil classification).

3. Delivery Minimum or Service Minimum Charges – Utilities often charge minimum delivery fees (for gas) whether or not usage is high. If you stop using the gas service (or revert to oil) you’ll need to check how that affects your delivery minimum or service classification. Perhaps you could close the gas account or reduce the capacity; but if you keep gas service available (as backup) you may still incur delivery minimums.

   • There is no public document I found that says you may revert to oil and automatically avoid any delivery minimum or additional penalty; you’ll need to check what the service agreement is now with Con Ed.

4. Infrastructure / Metering / Line Capacity – If you revert the heating system to oil, you’ll need proper oil-burning equipment, tank/tank‐installation compliance, permit(s) and inspections. On the gas side, you may also need to adjust or close out gas meter/service if you’re reducing service.

   • Utility rules for restoring or altering service can involve inspections or licensed plumber involvement.

5. Cost and Incentives – When the building switched from oil to gas, it may have accessed certain incentives or rebates. Reverting may forgo those or have implications. Also, the economics of oil vs gas (and regulatory trends toward electrification/clean fuels) may weigh heavily.

   • Note: Many buildings converted from oil to gas in part because of regulatory pressure and cleaner fuel mandates. 

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Our interpretation for your case

Given that your building switched from oil to natural gas more than five years ago and you want to go back to oil, here’s how I see it:

• Yes, it appears possible, provided the oil tank and burner systems are compliant with current regulations (grade of oil allowed, inspections done, meet building code/DEP/DOH/ DOB as applicable).

• But you cannot assume there will be no implications. There may be adjustments needed to your gas service contract (e.g., closing or reducing gas service), which could affect delivery minimums. Con Ed may treat the building differently (e.g., convert from firm gas to interruptible service or to an oil-based service).

• If you continue to maintain gas service (even minimally, for cooking or backup), you may still be liable for the standard delivery minimum for that gas service. If you eliminate gas service entirely, you may avoid the gas delivery minimum—but you’ll need to work with Con Ed to terminate or reduce service (which may have fees).

• If the oil you intend to use is a grade that is banned or being phased out (for example No. 4 oil post-2027 for NYC), you’ll need to ensure you switch to an approved, compliant oil grade (e.g., No. 2 or biodiesel blends) to avoid fines.

• Because regulatory trends in NYC are toward phasing out fossil fuels and stiffening codes for older systems, reversing to oil may carry long-term risk (e.g., future regulations might restrict oil use).

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What we recommend you do next

• Contact Con Ed’s gas service department and ask: “If we cease using gas for heating and revert the building to oil heating, how will that affect our building account, delivery minimum charges, and service classification?”

• Review the building’s service contract with Con Ed (what kind of gas rate you have: firm, interruptible, etc.).

• Check with your mechanical engineer/building services consultant about the oil system (tank inspection, fuel grade compliance, permits) to ensure switching back is mechanically and legally feasible.

• Check local building code / DEP / DOB to verify that the oil grade you intend to use is permitted in your building type and area.

• Consider the long-term cost implications (fuel cost, maintenance, future regulations) of switching back to oil vs staying on gas or exploring other alternatives (like dual fuel, or even electrification).

• If the building is subject to any specific municipal or utility incentive or obligation tied to the original conversion, check whether those obligations impose any restrictions on switching back.