Commercial Boiler Systems

Service, Repair, and Replacement for Commercial Hydronic Boilers

A surprising number of commercial properties across southeast Wisconsin run on hydronic boiler systems: schools, churches, multi-family buildings, restaurants, office buildings, and industrial facilities. When the boiler is doing its job, nobody thinks about it. When it stops, you have angry tenants, cold customers, and a fast-moving problem to solve.

Doro Plumbing services commercial boiler systems for property owners and managers across Washington, Dodge, Ozaukee, Waukesha, and Jefferson counties. Our Certified Master Plumber handles the plumbing side of the system, from the boiler itself to the manifolds, circulators, zone controls, expansion equipment, and distribution piping.

Where Commercial Boiler Systems Show Up

Commercial boiler systems are common in:

• Multi-family buildings with central heating plants serving multiple units
• Office buildings running hydronic baseboard, radiators, or fan-coil systems
• Restaurants and commercial kitchens that need heat plus high-volume hot water for sanitation
• Schools and churches with original boiler plants from the building’s construction
• Light industrial facilities with both space heat and process water needs
• Senior living communities where reliable heat is critical
• Car washes and laundromats that use boilers for high-volume hot water
• Greenhouses and agricultural buildings with radiant or unit heater distribution

Whether your boiler is a 1960s cast iron giant in the basement or a brand-new high-efficiency condensing unit, we can service it.

What We Service

We work on most major commercial boiler types and brands:

• Cast iron sectional boilers, the workhorse of older commercial buildings
• High-efficiency condensing boilers with stainless steel heat exchangers
• Combi boilers that handle space heat and domestic hot water in one unit
• Steel firetube boilers in larger facilities
• Modular boiler banks with multiple smaller units staging together
• Indirect-fired water heaters running off a boiler loop

If you have older equipment that nobody else wants to touch, we are still happy to take a look. Older cast iron boilers often have decades of service left in them with proper maintenance.

Common Commercial Boiler Service Calls

Commercial boilers fail in predictable ways once you know what to look for:

• Failed circulator pumps interrupting flow to entire zones or buildings
• Expansion tank failures causing pressure spikes and relief valve discharge
• Zone valve and zone control failures that leave parts of the building cold
• Failed combustion components on gas-fired units (ignition modules, gas valves, flame sensors)
• Air bound zones that need professional purging
• Pressure-reducing valve and backflow preventer issues on the auto-fill connection
• Glycol leaks and contamination in glycol-protected systems
• Aquastat and control failures
• Sectional gasket failures on older cast iron units
• Heat exchanger fouling from poor water quality or skipped maintenance

We carry common parts for major brands so we can usually finish a service call in a single visit. For specialty parts on older equipment, we will let you know up front about lead time.

Annual Service and Combustion Tuning

Commercial boilers reward annual service with reliable operation, longer service life, and lower fuel bills. A neglected commercial boiler can waste twenty percent or more on fuel compared to one that has been properly tuned. Our annual service includes:

• Combustion analysis and tuning on gas-fired units
• Burner cleaning and inspection
• Heat exchanger inspection and cleaning where accessible
• Pressure check and adjustment
• Circulator pump function tests
• Zone valve operation tests
• Air bleed of any zones showing trapped air
• Glycol concentration test on protected systems
• Pressure relief valve function test
• Visual inspection of vent piping, gas piping, and water connections
• Documentation of findings and recommendations for the building file

For property managers handling multiple buildings, we can set up coordinated annual service so all your boilers get attention in the same visit cycle.

Wisconsin Code and Compliance

Commercial boiler work falls under multiple Wisconsin codes depending on the equipment and use case. Plumbing code (SPS 382), HVAC requirements, and inspection schedules all apply. Boilers above certain size thresholds require state inspection on a fixed schedule.

We pull permits where required, coordinate with state inspectors when needed, and provide documentation for property records. If you have inherited a building with poor or missing boiler documentation, we can do a baseline inspection and put together the records you need.

Replacement and New Installation

When a commercial boiler is past saving or your operation has changed enough that the equipment is no longer the right fit, we handle replacement projects from sizing through commissioning:

• Heat loss calculation and equipment sizing
• Equipment selection based on the building, fuel availability, redundancy requirements, and budget
• Coordination with mechanical engineers where the project requires stamped drawings
• Demolition and rigging of old equipment
• Full piping including primary-secondary loops for high-efficiency units
• Circulator, manifold, and zone valve setup
• Controls, thermostats, outdoor reset, and BACnet integration where applicable
• Combustion air, venting, and gas piping per code
• Permits, inspections, and commissioning documentation

For larger projects, we work with engineers and general contractors to keep the project moving on schedule.

Emergency Service

When a commercial boiler fails in heating season, every hour matters. We respond fast for commercial boiler emergencies, prioritizing properties on preventive maintenance contracts. If you have a building full of cold tenants or a process line down because heat or hot water failed, we will be on the way as quickly as we can get the right truck on the road.

Doro Plumbing · (262) 229-5632 · Hartford, WI