Furnace Service Maine

Overview

Propane (liquefied petroleum gas / LPG) is stored in pressurized tanks on the property and delivered by truck. Unlike oil, propane tanks are almost always owned or leased from the propane supplier and installed by them. However, understanding the requirements helps homeowners make informed decisions about tank size, placement, and service.

Propane tank installation in Maine is governed by NFPA 58 (Liquefied Petroleum Gas Code), Maine PUC regulations, and local codes. All gas line connections and final hookups must be performed by a licensed gas fitter — this is a legal requirement in Maine, not optional.

Tank Sizing

Residential propane tanks range from 100-gallon cylinders (short-term supplement) to 1,500-gallon tanks (large homes or homes in remote delivery areas). Typical Maine residential heating installations use:

• 500-gallon tank — most common for homes with propane as the primary heat source. Provides a buffer for winter deliveries and accommodates most residential furnace BTU draws.
• 1,000-gallon tank — for larger homes, homes in rural areas with infrequent delivery access, or homes using propane for heat, cooking, water heating, and a generator.
• Two-tank manifold systems — two 500-gallon tanks connected together, allowing one to be swapped while the other continues in service.

Above-Ground Tanks

Above-ground tanks are the most common for Maine residential installations. They are less expensive to install than buried tanks, easier to inspect, and accessible for delivery and service. White or silver paint reflects heat to minimize pressure rise in summer.

Setback Requirements (NFPA 58)

• Tanks 125–500 gallons: minimum 10 feet from any building, property line, or ignition source.
• Tanks 501–2,000 gallons: minimum 25 feet from buildings, 10 feet from property lines.
• Tanks must not be located below windows, near air intakes, or where propane could collect in a low area.
• Propane is heavier than air — it sinks to the lowest point. Tank placement should account for this; avoid placement near basement window wells or in low-lying areas adjacent to the house.

Tank Pad Requirements

Above-ground tanks rest on concrete pads or heavy-duty plastic pads. The pad must be:

• Level — so the tank's float gauge reads accurately.
• Sized to extend at least 6" beyond the tank's feet on all sides.
• Solid and stable — tank legs must not sink or shift over time.

Underground (Buried) Tanks

Underground propane tanks are chosen for aesthetic reasons (invisible from the property) or when above-ground placement would conflict with setback requirements or property use. They are more expensive to install and more difficult to inspect, but they are common in upscale applications and in areas where homeowners associations restrict visible tanks.

Underground Tank Installation Requirements

• The tank must be a purpose-built underground tank with appropriate cathodic protection or non-metallic construction to resist corrosion from soil contact.
• Tanks are typically set in a gravel bed and backfilled carefully to prevent damage to the tank and fittings.
• A concrete collar or dome protects the fitting access point at grade level.
• Buried tanks require a dedicated shutoff valve accessible at grade and a remote gauge readable from above ground.
• Minimum horizontal distance from the edge of the tank to any building foundation: 10 feet for tanks up to 2,000 gallons.

Propane Gas Line Installation

From Tank to Building

• The supply line from the tank to the house is typically 1/2" or 3/4" copper tubing or corrugated stainless steel tubing (CSST), buried below frost depth (at least 24" in most of Maine, 36" in northern Maine).
• The line enters the building through a sealed penetration below grade and transitions to the interior gas piping system.
• A manual shutoff valve must be located at the tank outlet and at the building entrance.

Regulator

Propane leaves the tank at tank pressure (up to 200 psi). A two-stage regulator system reduces this to usable pressure:

• First stage regulator — mounted at the tank, reduces pressure to approximately 10 psi.
• Second stage regulator — mounted at the house entry or near the appliances, reduces pressure to 11" water column (standard low-pressure service) for appliances.
• Some installations use a single integral two-stage regulator at the tank.

Interior Gas Piping

• Black iron pipe (schedule 40) is the traditional interior gas piping material and is still widely used.
• CSST (corrugated stainless steel tubing) is increasingly common — it can flex around framing and is faster to install, but requires bonding to the electrical grounding system to protect against lightning-induced damage.
• A manual shutoff valve must be located within 6 feet of every appliance.
• All joints are tested with a pressure gauge after assembly — no open-flame leak testing. Soap solution can be used to locate minor leaks at fittings.

Propane Safety

• Install a listed LP gas detector in the home, near the furnace and in the basement or lowest level. Unlike CO, propane/LP gas detectors must be positioned low (propane is heavier than air).
• Never store propane cylinders inside the home.
• If you smell propane (an "rotten egg" odor from the odorant added for safety): leave the building immediately, don't operate any electrical switches, and call the propane supplier from outside.
• Schedule annual inspections of the tank, regulator, and gas lines with your propane supplier or a licensed gas fitter.