Different machines for different loads
Gas boilers make high-temperature heat quickly and are familiar to operate. Heat pumps are strongest on stable, moderate-temperature loads with a warm source. A hybrid system may be more credible than an all-or-nothing replacement.
Compare delivered heat cost
Use actual gas price, boiler efficiency, electricity tariff and seasonal heat-pump performance. Include auxiliary electricity, maintenance, capacity charges and carbon costs where applicable.
Emissions depend on the boundary
Operational emissions fall as electricity becomes lower carbon, but equipment refrigerant and embodied impacts still need management. Claims should state the electricity factor and baseline used.
Compare one megawatt-hour of useful heat
The useful comparison is the cost of heat delivered to the process. If gas costs €40/MWh and the measured boiler efficiency is 85%, fuel costs about €47/MWh of useful heat before fixed charges and maintenance. At an electricity price of €100/MWh and a system COP of 3.5, heat-pump electricity costs about €29/MWh of useful heat before the same additions.
Those prices are arithmetic examples rather than market assumptions. Use the site's invoices, contracted power, interval tariff, boiler test data and supplier performance map. A result based on a catalogue COP and an average gas price is too weak for an investment decision.
Temperature and flexibility favour different assets
A boiler reaches high temperatures quickly and is relatively insensitive to the availability of a waste-heat source. A heat pump becomes more attractive on stable duties with a warm source, moderate delivery temperature and long annual hours. Startup, steam peaks and short sanitation loads may remain with the boiler.
A hybrid concept can reduce fuel without forcing the heat pump to serve its least efficient hours. Define the boiler's retained duties, minimum heat-pump load, return-temperature limits and takeover sequence before estimating displaced gas.
Check the investment boundary
The boiler case may require fuel infrastructure, flue work and emissions compliance. The heat-pump case may require source capture, exchangers, grid reinforcement, storage and process changes. Compare complete installed systems with the same availability and backup requirement.
Emissions should use the same useful-heat boundary and stated factors. Report refrigerant leakage and retained boiler operation separately rather than treating equipment nameplates as an emissions result.
Sources
General technical explanation. No specific external source claims are made on this page.