Oil to Gas Conversion FAQ – Everything Massachusetts Residents Need to Know

November 25, 2025

Benefits & Basics

Why should I convert from oil to natural gas heating?

Converting from oil to natural gas offers several significant advantages for Massachusetts homeowners:

Cost Savings: Natural gas is typically less expensive than heating oil on a per-therm basis, potentially saving you hundreds or thousands of dollars annually on heating costs.

Convenience: Once connected to the natural gas pipeline, you’ll never have to schedule oil deliveries, worry about running out of fuel, or sign up for automatic tank refills. Your gas supply is continuous and reliable.

Environmental Benefits: Natural gas emits approximately 30% less carbon dioxide per therm compared to heating oil, significantly reducing your home’s greenhouse gas emissions and environmental impact.

Cleaner Operation: Unlike oil systems that can form sludge in storage tanks and produce soot throughout your home, natural gas burns cleanly with minimal residue or maintenance issues.

Improved Efficiency: Converting typically means upgrading to newer, more efficient equipment. Modern gas boilers and furnaces can achieve efficiency ratings of 90-95% or higher, compared to older oil systems that may only be 70-80% efficient.

Safety: Eliminate the risk of oil tank leaks (which can be costly environmental disasters) and the possibility of running out of heating fuel during a cold snap.

Is natural gas really more efficient than heating oil?

Yes, for two key reasons:

1. Equipment Efficiency: When you convert, you’re typically installing a brand-new, high-efficiency gas furnace or boiler. Modern gas heating equipment can achieve Annual Fuel Utilization Efficiency (AFUE) ratings of 90-98%, meaning 90-98% of the fuel is converted to heat for your home.

2. Cleaner Combustion: Natural gas burns more completely and cleanly than oil, producing more usable heat and less waste. Oil combustion can leave residue and requires more frequent cleaning and maintenance.

The combination of newer equipment and cleaner-burning fuel typically results in 20-40% better efficiency compared to older oil systems.

What’s the difference between atmospheric-venting and condensing boilers?

Atmospheric-Venting Boilers/Furnaces:

  • Vent hot exhaust gases directly outside through your existing chimney
  • Typically offer efficiency of 80-85% AFUE
  • May require chimney liner inspection or replacement during conversion
  • Usually cost less up-front

Condensing Boilers:

  • Extract additional heat by condensing water vapor from exhaust gases
  • Offer much higher efficiency: 90-98% AFUE
  • Are vented directly through the sidewall via PVC pipe (no chimney needed)
  • Require higher upfront investment but provide greater long-term savings

Most conversions today use condensing boilers due to their superior efficiency and flexibility in venting options.

How much money will I save each year after converting?

Annual savings vary based on your home size, current oil usage, and market fuel prices, but most homeowners save $800 – $2,500 per year.

Typical Savings Scenario:

  • Average home using 800 gallons of oil per year at $3.75/gallon = $3,000/year
  • Same heating needs with natural gas at current rates = approximately $1,400/year
  • Annual savings: $1,600

Additional Potential Savings:

  • Reduced maintenance costs (gas systems require less frequent service)
  • No emergency oil delivery premiums during cold snaps
  • Elimination of oil tank maintenance and potential cleanup costs
  • Lower homeowners insurance (removing oil tank risk)

Many homeowners see a full return on investment within 5-8 years, with continued savings for the life of the equipment.

Can I choose my natural gas supplier, or am I locked into one company?

In Massachusetts, you have choices! The natural gas delivery system works in two parts:

Delivery (Regulated):

  • Your local utility (National Grid, Eversource, etc.) maintains the pipes and delivers gas
  • Delivery rates are regulated by the Massachusetts Department of Public Utilities
  • This portion appears as “delivery charges” on your bill

Supply (Competitive):

  • You can choose your gas supplier from registered competitive suppliers
  • Prices and contract terms vary between suppliers
  • You can switch suppliers without changing delivery service
  • Some suppliers offer fixed-rate contracts for price stability

Find Suppliers: Visit the Massachusetts Department of Public Utilities website or Mass.gov for a list of registered natural gas suppliers in your area: https://www.mass.gov/info-details/competitive-supply-for-natural-gas

Tip: Compare your utility’s default supply rate with competitive offers annually to ensure you’re getting the best price.

The Conversion Process

What exactly is involved in an oil-to-gas conversion?

A complete conversion involves several key steps:

1. Assessment & Planning:

  • Professional evaluation of your current system
  • Gas line availability check
  • Sizing new equipment for your home’s heating needs
  • Determining optimal boiler/furnace placement
  • Venting system design

2. Gas Line Installation:

  • Your gas utility runs a line from the street main to your home (if not already present)
  • Installation of gas meter
  • Running gas piping from meter to equipment location

3. Old System Removal:

  • Professional removal of old oil boiler or furnace
  • Disconnection of oil lines
  • Oil tank removal (underground or aboveground)
  • Proper disposal of old equipment

4. New Equipment Installation:

  • Installation of new gas boiler or furnace
  • Connection to existing distribution system (radiators or ductwork)
  • Venting system installation or modification
  • Thermostat upgrade (if needed)
  • System testing and startup

5. Final Steps:

  • City/town inspections and permits
  • System commissioning and efficiency verification
  • Homeowner training on new equipment
  • Chimney capping or liner removal (if applicable)

Do I need to replace my chimney when converting to gas?

It depends on the type of system you’re installing:

If Installing an Atmospheric-Venting System:

  • Your existing chimney may be used for venting
  • However, a chimney liner inspection is typically required
  • The liner may need replacement because:
    • Gas produces cooler, more acidic exhaust than oil
    • Your chimney may have been sized for oil system’s larger exhaust volume
    • The liner may be damaged from years of use

If Installing a Condensing System:

  • Chimney is NOT needed for venting
  • Exhaust vents directly through sidewall via PVC pipe
  • Existing chimney can be capped or used for other purposes
  • This often makes condensing systems more cost-effective despite higher equipment cost

Bottom Line: Many homeowners choose condensing systems specifically to avoid chimney work and ongoing chimney maintenance costs.

Can I keep my oil tank after converting, or must it be removed?

While not always legally required, removing your oil tank is strongly recommended for several important reasons:

Risk of Leaks:

  • Unused tanks can still leak, causing expensive environmental cleanup
  • Soil contamination cleanup can cost $10,000 – $50,000+
  • You remain liable for leaks even if not using the tank

Home Sale Issues:

  • Abandoned oil tanks can complicate home sales
  • Buyers often require tank removal or significant price reductions
  • Home inspections will flag abandoned tanks

Insurance Concerns:

  • Some homeowners insurance policies won’t cover properties with abandoned oil tanks
  • Leak cleanup is mostly likely not covered by insurance

Legal Requirements:

  • Some municipalities require tank removal upon conversion
  • Underground tanks especially are subject to strict regulations

Best Practice: Include tank removal as part of your conversion project. Many contractors offer package pricing.

Maintenance & Ongoing Considerations

Will my maintenance costs go down after converting to gas?

Yes, significantly! Natural gas systems require much less maintenance than oil systems. Although both systems require annual maintenance in order to perform their best and last their longest, oil systems require more involved maintenance.

What happens if there’s a natural gas outage?

Natural gas outages are extremely rare, but here’s what you should know:

Reliability:

  • Gas infrastructure is underground and protected from weather
  • Much more reliable than oil delivery during storms
  • No risk of running out between deliveries
  • System continues to work during power outages (with battery backup or generator)

In the Unlikely Event of an Outage:

  • Utilities prioritize restoration of gas service
  • Most outages are resolved within hours, not days
  • Your gas company will notify you of planned maintenance
  • You can’t “run out” of gas the way you can with oil

Emergency Preparedness:

  • Consider a backup heating source (space heaters, fireplace)
  • Same recommendation as for any heating system
  • Battery backup for your thermostat
  • Keep utility emergency numbers handy

Historical Data: Major natural gas outages affecting residential customers are far less common than oil delivery disruptions during severe weather.

Do gas systems work during power outages?

Most modern gas boilers and furnaces require electricity to operate, but you have options:

Standard Gas Systems:

  • Require electricity for blower fan, controls, and pumps
  • Will not operate during power outage without backup power

Backup Power Options:

  • Portable Generator: Can power your heating system during outages
  • Battery Backup System: Some newer systems offer battery backup for essential components
  • Whole-Home Standby Generator: Automatic backup power for entire home

Compared to Oil:

  • Oil systems also require electricity to run
  • Gas systems have no advantage or disadvantage in this regard
  • Both require backup power solutions for outage operation

Planning Tip: If power outages are common in your area, discuss backup power options with your contractor during the conversion planning phase.

Technical & Safety Questions

Will converting to gas affect my existing radiators or ductwork?

Good news: Your existing heat distribution system usually works perfectly with gas!

Hot Water Radiators (Boilers):

  • Your radiators will continue to work exactly as before
  • Gas boiler heats water just like oil boiler did
  • No modifications needed to radiators
  • May actually heat more evenly with new high-efficiency boiler

Forced Air Ductwork (Furnaces):

  • Existing ductwork typically works with new gas furnace
  • May benefit from duct sealing during conversion
  • New furnace may provide more consistent airflow
  • Some homes see improved comfort from better equipment

Potential Upgrades to Consider:

  • Zone valves or thermostats for better control
  • Radiator replacement if very old or inefficient
  • Duct cleaning if switching from oil furnace
  • Adding air conditioning (if you have ductwork)

Bottom Line: The conversion focuses on the heating equipment itself. Your heat distribution system—whether radiators, baseboard, or ductwork—remains in place and functions normally.

Is natural gas safe? What about carbon monoxide?

Natural gas is extremely safe when properly installed and maintained:

Built-In Safety Features:

  • Natural gas is odorized (mercaptan additive) so leaks are immediately detectable
  • Modern equipment includes multiple safety shutoffs
  • Automatic gas valve closure if flame goes out
  • Regular utility inspections of gas infrastructure

Carbon Monoxide Safety:

  • Any fuel-burning equipment (oil, gas, propane) produces CO
  • Gas produces LESS carbon monoxide than oil
  • Modern gas equipment has sealed combustion (draws air from outside)
  • Proper venting eliminates CO concerns

Safety Measures to Take:

  • Install CO detectors on every floor (required by Massachusetts law)
  • Schedule annual professional maintenance
  • Never block vents or air intakes
  • Know gas smell and how to shut off gas in emergency

Statistics: Natural gas heating has an excellent safety record. Properly installed and maintained gas systems are statistically safer than many other heating methods.

What if natural gas isn’t available on my street?

If natural gas isn’t currently available at your property, you have several options:

Option 1: Gas Main Extension

  • Gas utilities may extend service to your street
  • Cost depends on distance and number of interested customers
  • Sometimes free if enough neighbors are also converting
  • Contact your local gas utility to inquire about extension timeline
  • Can take 6 months to 2 years for planning and installation

Option 2: Propane Conversion

  • Similar benefits to natural gas
  • Propane tank installed on your property
  • Slightly higher fuel cost than natural gas
  • Still cleaner and more convenient than oil
  • No dependence on gas main availability

Option 3: Heat Pump Installation

  • Modern heat pumps work effectively in Massachusetts winters
  • Provides both heating AND air conditioning
  • Eliminates need for any fuel delivery or gas connection
  • Highest efficiency of all options
  • Significant rebates available (often $10,000+)

Check Availability: Contact your local gas utility:

  • National Grid: 1-800-233-5325
  • Eversource: 1-800-592-2000
  • Unitil: 1-888-301-7700

They can tell you if/when gas service may be available in your area.

Timing and Planning

Should I wait for my oil system to die, or convert while it’s still working?

Generally, converting while your oil system still works is the better choice:

Advantages of Proactive Conversion:

1. No Emergency Pressure

  • Time to plan for the installation and choose your best replacement option

2. Financial Benefits

  • Avoid expensive emergency oil system repairs
  • Oil equipment has declining value—don’t invest in repairs
  • Can plan conversion into your budget

3. Better Installation

  • Time for inspections and permits without stress

4. System Value

  • Working oil equipment may have trade-in/removal credit value
  • Avoid catastrophic failure that could damage other components

When to Wait:

  • Your oil system is less than 5 years old
  • Recent major investment in oil equipment repairs
  • Gas service not yet available in your area
  • You’re planning to move within 2-3 years

Red Flags That Mean “Convert Now”:

  • Oil system is 15+ years old
  • Increasing frequency of repairs
  • Rising maintenance costs
  • Rust or corrosion on tank or boiler
  • Decreased efficiency (higher oil consumption)
  • Soot or oil smell in home

Bottom Line: Don’t wait for a breakdown in January. Plan ahead and convert on your terms.

Common Concerns & Misconceptions

I’ve heard gas bills can be higher than oil costs. Is this true?

This is a common misconception based on comparing bills incorrectly. Here’s the reality:

Why People Think Gas Costs More:

  • Monthly gas bills vs. sporadic oil deliveries
  • Psychological impact of regular bills vs. occasional large payments
  • Not accounting for equipment efficiency differences
  • Comparing old vs. new pricing

Actual Cost Comparison (Per Therm of Heat):

  • Heating oil: $3.50/gallon ÷ 138,500 BTU = ~$2.53 per therm
  • Natural gas: $1.50/therm (typical Massachusetts rate)
  • Natural gas provides same heat for 40% less cost

Real-World Example:

  • Home using 800 gallons of oil @ $3.50 = $2,800/year
  • Same home with gas @ 1,400 therms × $1.50 = $2,100/year
  • Annual savings: $700
  • Add in efficiency gains from new equipment: Total savings ~$1,000+/year

Additional Cost Factors:

  • Gas: Consistent monthly bills easier to budget
  • Oil: Emergency delivery premiums during cold snaps
  • Oil: Maintenance costs are higher
  • Gas: More stable pricing (less market volatility)

Truth: When comparing equivalent heat output and accounting for equipment efficiency, natural gas is significantly less expensive than oil in Massachusetts.

Will converting to gas increase my home’s value?

Yes! Converting from oil to gas heating typically increases home value and marketability:

Market Value Impact:

  • Homes with natural gas typically sell for 2-5% more than comparable oil-heated homes
  • Gas heat is seen as more desirable by buyers
  • Modern, efficient equipment adds value
  • Eliminates oil tank liability concern

Faster Sales:

  • Gas-heated homes often sell faster
  • Fewer buyer objections and concerns
  • No oil tank inspection complications
  • Appeals to environmentally conscious buyers

Appraisal Considerations:

  • New high-efficiency equipment adds measurable value
  • Removal of oil tank eliminates potential liability
  • Lower operating costs make home more attractive
  • Modern HVAC system is a strong selling point

Real Estate Agent Perspective:

  • Gas heat is a positive selling point
  • Oil heat can be a negotiating liability
  • Buyers often request oil tank removal anyway
  • Modern heating system sells the home

Bottom Line: If you’re planning to sell within 5-10 years, conversion can be a smart investment that pays off at closing.

Can I do a partial conversion to save money?

While technically possible, partial conversions are generally not recommended:

What People Consider:

  • Keep oil tank “just in case”
  • Install gas boiler but delay tank removal
  • Use gas as primary, oil as backup

Why This Doesn’t Work:

1. Safety & Liability:

  • Abandoned oil tanks continue to pose leak risk
  • You remain liable for any environmental damage
  • Homeowners insurance issues

2. No Cost Savings:

  • Must maintain both systems
  • Dual inspections and maintenance
  • Keeping oil tank has ongoing costs

3. Home Sale Issues:

  • Abandoned tank complicates future sale
  • Buyers will require tank removal anyway
  • May need to remove tank to sell home

4. No Real Benefit:

  • Gas supply is extremely reliable
  • “Backup” oil system likely won’t be maintained or operational
  • False sense of security

Better Approach:

  • Do complete conversion at once
  • If concerned about backup heat, consider:
    • Generator for power outages
    • Electric space heaters
    • Woodstove or fireplace

Bottom Line: Do it right the first time. Complete conversion provides best value, safety, and peace of mind.

Next Steps

Why should I choose McMahon Plumbing & Heating for my oil-to-gas conversion?

McMahon Plumbing & Heating has been helping Greater Boston homeowners convert from oil to gas for over 70 years. Here’s what sets us apart:

Experience & Expertise:

  • 70+ years serving Greater Boston
  • Hundreds of successful oil-to-gas conversions completed
  • Mass Save qualified contractor
  • Licensed, insured, and fully qualified

Complete Service:

  • Gas line coordination with utilities
  • Professional oil tank removal
  • High-efficiency equipment installation
  • Venting system design and installation
  • All permits and inspections handled
  • System commissioning and homeowner training

Quality Equipment:

  • We install leading brands: Viessmann, Burnham, Weil-McLain, Rinnai
  • High-efficiency options available
  • Equipment backed by manufacturer warranties
  • Proper sizing and selection for your home

Rebate Assistance:

  • Help you identify all available rebates
  • Assist with Mass Save paperwork
  • Coordinate utility incentives
  • Maximize your savings

Customer Service:

  • Detailed written estimates
  • Transparent pricing, no surprises
  • Clean, professional installation
  • Ongoing service and maintenance available
  • 24/7 emergency service

Ready to Convert?

Categories: Heating