From Steam to Electric: Why Manufacturers Are Replacing Boiler Systems with Decentralised TCUs

The Real Cost of Steam Is Not the Gas Bill

When manufacturers think about the cost of steam-based process heating, they focus on gas prices. And gas prices have given them plenty to worry about — European TTF natural gas traded above €47/MWh in early March 2026, roughly double pre-2021 levels. But gas is only part of the story.

A central steam boiler system loses energy at every stage between the burner and the process. The boiler itself converts gas to steam at 80–85% efficiency. Then the real losses begin: distribution piping radiates heat despite insulation (6–8% loss), steam traps fail at rates of 10–20% in most plants (adding another 5–10% loss), condensate that is not fully recovered wastes both heat and treated water (3–5% loss), and blow-down procedures discharge hot water to maintain water chemistry. By the time steam energy reaches the mould, die, or reactor, a typical plant delivers only 50–65% of the fuel energy to the process. The rest heats the factory ceiling.

An electric temperature control unit eliminates this entire chain. An immersion heater in a TCU converts electricity to heat at 98–99% efficiency. The heated fluid — water or thermal oil — flows directly to the process through a short, closed circuit. There is no boiler, no steam distribution network, no condensate system, no water treatment plant, and no blow-down losses.

TCO Comparison: Steam vs. Electric TCU

The following comparison is based on a realistic scenario: a single process heating point requiring 18 kW of continuous thermal energy at 140°C, operating 6,000 hours per year. This is typical for a mid-size injection moulding, die casting, or chemical process application.

Steam System (Gas-Fired Boiler)

With an overall system efficiency of 55% (accounting for boiler efficiency, distribution losses, trap failures, and condensate losses), the gas consumption is 18 kW ÷ 0.55 = 32.7 kW of gas input. At 6,000 hours and a gas price of €45/MWh (current European range), the annual gas cost is approximately €8,836. Add annual boiler maintenance, water treatment, and steam system upkeep of approximately €3,000–5,000 per heating point (allocated share of central system maintenance), and the operating cost reaches €11,800–13,800 per year. This excludes the capital cost of the boiler plant itself, which typically runs €150,000–400,000 for a complete installation.

Electric TCU (Oil-Based, 150°C)

An electric TCU delivering 18 kW with an efficiency of 98% requires 18.4 kW of electricity input. At 6,000 hours and an industrial electricity price of €0.18/kWh (typical for EU mid-size industrial consumers, 2025/2026), the annual electricity cost is approximately €19,850. Annual maintenance is minimal — an oil analysis, filter check, and general inspection — typically €300–500 per unit. Total operating cost: approximately €20,150–20,350 per year.

At first glance, electricity loses. The energy cost per unit is higher. But this comparison changes significantly when you include the full picture.

Where Electric Wins: The Hidden Costs of Steam

Infrastructure. A central boiler plant requires a boiler room, gas supply infrastructure, chimney, water softening system, condensate return network, and certified boiler operators in many jurisdictions. An electric TCU plugs into a standard industrial power supply and a cooling water connection. Installation cost for a new TCU: €5,000–8,000 including the unit. Installation cost for a new steam system: €150,000–400,000.

Regulatory compliance. Gas boiler systems in the EU require regular inspections (typically annual), certified boiler attendants in many member states, emissions reporting, and compliance with increasingly strict emissions regulations. Electric systems have no combustion, no emissions at point of use, and no specific operator certification requirements.

Maintenance burden. Steam systems require continuous attention: daily water chemistry checks, weekly trap inspections, monthly safety valve tests, and annual pressure vessel inspections. A TCU requires an annual service visit and periodic fluid checks.

Temperature precision. Steam provides heat at the saturation temperature corresponding to its pressure — typically delivered at a fixed temperature with limited controllability. A TCU controls process temperature to ±0.1°C with PID control, responding in real time to process demand. For applications where temperature precision affects product quality — injection moulding, pharmaceutical processing, composites curing — this difference directly reduces scrap and rework.

Flexibility. Steam is a central utility. Adding or relocating a process heating point means extending the steam network. A decentralised TCU can be moved, reconfigured, or replaced independently — a significant advantage in facilities that change products or layouts frequently.

When the Numbers Flip

The economic comparison shifts further toward electric in several common situations. When the steam system serves only a few heating points, the fixed costs of the boiler plant are spread across fewer users, making per-unit steam cost very high. When the factory is replacing an aging boiler, the capital cost of a new boiler plant versus multiple TCUs often favours the decentralised approach. When gas prices are volatile — as they have been since 2021 — electricity contracts offer more stability and predictability. And when industrial electricity prices continue to fall with the growth of renewable generation, the long-term trajectory favours electric heating.

For existing plants with an efficient, well-maintained steam system serving dozens of heating points, the central boiler may still make economic sense. The transition typically happens one machine at a time — as old steam connections are retired and new production lines are installed with their own TCUs.

Water or Oil?

If your process runs below 90°C, a pressureless water TCU is the simplest and most efficient choice. Between 90°C and 160°C, pressurised water systems offer excellent heat transfer. Above 150°C, thermal oil systems operate without pressure and handle temperatures up to 350°C — covering the full range that steam typically serves in industrial applications.

What This Means for Your Plant

If you are operating a central steam system and facing a boiler replacement decision, rising gas costs, or increasingly burdensome boiler compliance requirements, it is worth calculating the total cost of ownership for decentralised electric TCUs as an alternative. The energy cost per kWh is higher for electricity, but the total system cost — infrastructure, maintenance, compliance, precision, and flexibility — often favours the electric approach.

Boe-Therm manufactures both water TCUs (90–160°C) and oil TCUs (150–350°C), configured to your exact process requirements and delivered in 3–4 weeks. If you want to calculate what TCU configuration your process needs, try our free online configurator — it takes about two minutes and requires no registration.