Rental Boilers: When You Need One and What to Expect

A rental boiler is a temporary boiler — usually trailer-mounted or skid-mounted — that provides heating or process steam while the permanent boiler is unavailable. Rental boilers serve four primary scenarios:

1. During a boiler replacement project:
Replacing a commercial boiler typically takes 4-12 weeks from the time the old boiler is removed until the new boiler is commissioned. In heating season, the building cannot go without heat for this period. A rental boiler provides uninterrupted heating while the permanent boiler is replaced. This is the most common and most plannable use of rental boilers.

2. Emergency failure:
When a boiler fails unexpectedly — cracked section, tube failure, failed inspection requiring immediate shutdown, electrical or control failure that cannot be repaired quickly — a rental boiler provides emergency heating while the permanent unit is repaired or replaced. Emergency rental deployments are the most expensive (rush delivery surcharges) but often the only option when a building is without heat in winter.

3. Seasonal peak demand:
Some buildings have heating loads that exceed permanent boiler capacity during extreme cold weather. Rather than installing additional permanent capacity that sits idle most of the year, a rental boiler can be brought in for the coldest weeks. This is common in buildings where occupancy has increased since the original boiler was sized, or where building additions have been made without upgrading the boiler plant.

4. Planned maintenance shutdown:
Internal inspections, refractory repairs, tube replacements, and other major maintenance require the boiler to be shut down for days to weeks. In single-boiler buildings during heating season, a rental provides continued heating during the maintenance period. Forward-thinking building owners schedule major maintenance for shoulder season (spring or fall) to minimize rental costs and weather risk.

The rental boiler industry offers a range of equipment to match virtually any temporary heating or steam need:

Trailer-mounted boilers:
The most common rental configuration. The boiler, burner, controls, and often the fuel connection are mounted on a highway-legal trailer that can be towed to the site and connected to the building's heating system. Sizes range from 50 HP (approximately 1.6 million BTU/hr) to 800 HP (approximately 27 million BTU/hr). Trailer-mounted boilers can be operational within hours of arrival — the primary setup tasks are connecting fuel, water supply, electrical power, and piping to the building system.

Skid-mounted boilers:
Mounted on a steel frame but not on a trailer. These are delivered by flatbed truck and lifted or rolled into position by crane or forklift. Skid-mounted boilers are used when the installation will last several months or when the trailer must be returned while the boiler remains. Size range is similar to trailer-mounted units.

Mobile steam plants:
For large industrial applications, rental companies offer complete mobile steam plants that include the boiler, feedwater system (deaerator, chemical feed, softener), fuel system, and controls — all containerized and ready to connect. These units can produce 20,000-100,000+ pounds per hour of steam and are used during refinery turnarounds, power plant outages, and major industrial maintenance shutdowns.

Hot water vs. steam:
Rental boilers are available in both hot water and steam configurations. For building heating, the rental boiler must match the permanent system — a hot water boiler cannot be substituted for a steam boiler or vice versa without significant temporary piping modifications. Specify the correct type when ordering.

Fuel types:
Most rental boilers are natural gas-fired, but oil-fired (#2 fuel oil / diesel) units are available for locations without natural gas service or as dual-fuel backup. Propane-fired rentals are available for locations with neither natural gas nor oil infrastructure. The rental company can usually provide temporary fuel oil storage tanks if needed.

Sizing considerations:
The rental boiler must match the building's heating requirements in three dimensions:

• BTU output: The rental must be capable of producing enough heat to maintain building temperatures during the expected weather conditions. Your boiler service company or engineer can calculate the required capacity from the design heating load and outdoor temperature data. For emergency replacements, a reasonable rule of thumb is to match the existing boiler's output — but verify, because the existing boiler may have been oversized or undersized.
• Pressure and temperature: The rental must operate at the same pressure and temperature as the permanent system. A building with a hot water heating system operating at 180 degrees F and 30 PSI needs a hot water rental at those parameters. A steam building at 15 PSI needs a low-pressure steam rental.
• Fuel type: Must match available fuel supply at the site. If the building has a 2-inch gas meter, the rental cannot exceed the meter's BTU capacity. Verify gas meter capacity with the utility before ordering a large rental.

Setup requirements:

• Location: The rental boiler is typically positioned outdoors near the building's mechanical room, with temporary piping running through a wall or window penetration. A level, load-bearing surface (parking lot, concrete pad, or compacted gravel) is required. Allow space for fuel connections and service access.
• Fuel connection: A licensed plumber or pipefitter must connect the fuel supply. For natural gas, this typically involves a temporary gas line from the meter to the rental boiler. For oil, a temporary fuel tank and supply line are installed.
• Water supply: The rental needs a makeup water connection — typically a garden hose connection to a domestic water line.
• Electrical power: Most rental boilers require 120V or 208/240V single-phase power for burner controls and pumps. Larger units may require 480V three-phase. A temporary electrical connection or extension cord from the building's electrical system is needed.
• Piping tie-ins: Temporary piping (supply and return) must be connected from the rental boiler to the building's heating system. This is typically done at a point near the permanent boiler using temporary fittings and flexible connectors. Insulate temporary outdoor piping to prevent heat loss and freezing.

Lead time:

• Emergency delivery: Major rental boiler companies (Nationwide Boiler, Power Mechanical, Carrier Rental Systems) maintain fleets of ready-to-ship boilers. Emergency delivery is typically 24-48 hours from order to on-site delivery, with an additional 4-12 hours for setup and commissioning. Availability is not guaranteed during peak demand periods (December-February).
• Planned rental: For replacement projects or scheduled maintenance, arrange the rental 2-4 weeks in advance to ensure the right size and type is available. Plan delivery 1-2 days before you need it to allow for setup and testing before the permanent boiler is shut down.

Rental costs:
Rental boiler pricing is based on boiler size, rental duration, and market conditions. Typical monthly rental rates:

• 50-100 HP (1.6-3.3 million BTU/hr): $2,000-$4,000/month
• 100-200 HP (3.3-6.7 million BTU/hr): $4,000-$7,000/month
• 200-400 HP (6.7-13.4 million BTU/hr): $7,000-$10,000/month
• 400-800 HP (13.4-27 million BTU/hr): $10,000-$15,000/month

Additional costs beyond the monthly rental rate include:

• Delivery and pickup: $1,500-$5,000 each way depending on distance
• Setup and commissioning: $2,000-$5,000 (may be included in rental agreement)
• Temporary piping materials and installation labor: $3,000-$10,000 depending on complexity
• Fuel connection: $1,000-$3,000 for temporary gas or oil piping
• Electrical connection: $500-$1,500
• Rush delivery surcharge (emergency): 25-50% premium on the monthly rate

Rental company vs. building owner responsibilities:

• Rental company provides: A tested and certified boiler in operating condition, delivery and pickup, technical support and 24/7 emergency phone line, boiler insurance and registration (in most cases), and often operator training for building staff.
• Building owner provides: A suitable location for the boiler, fuel supply and connection, water supply, electrical power, piping tie-ins to the building system, and any required permits from the local authority. The building owner is also typically responsible for fuel costs during the rental period.

Permits for temporary installations:
Most jurisdictions require a permit for a temporary boiler installation, even if the boiler itself is already registered and inspected. The permit may be a mechanical permit, a temporary boiler installation permit (issued by the state boiler division), or both. Some states have expedited permitting processes for emergency boiler rentals. The rental boiler company can usually advise on local permitting requirements — they deal with them regularly.

Insurance coverage:
Verify that the rental boiler is covered under the rental company's boiler and machinery insurance policy — most reputable rental companies include this in their rental agreement. Additionally, confirm that your building's general liability and property insurance covers the temporary installation, including the temporary piping and connections. Notify your insurance carrier of the temporary boiler installation to avoid any coverage gaps.