Resistance heat is simple
An electric boiler converts electricity to heat close to one-for-one at the point of use and can reach high temperatures. A heat pump can deliver several units of heat per unit of electricity but needs a source and is constrained by lift.
Use each where it is strongest
A heat pump may cover base load and preheat while an electric boiler supplies peaks or the final temperature step. This can reduce connection capacity compared with assigning the whole duty to resistance heat.
Grid and tariff consequences
Both technologies can require network work. The electric boiler's higher input for the same useful heat makes contracted power and operating periods especially important.
Electricity input separates the options
An electric boiler needs roughly one unit of electricity for one unit of useful heat at the point of use. A heat pump at system COP 3.0 needs about 333 kWh of electricity per MWh of useful heat. At COP 4.0 it needs about 250 kWh. Auxiliary loads and distribution losses should be added on the same boundary.
The difference affects operating cost, transformer loading and contracted power. It also means a simple electric boiler can be expensive for continuous base load even where its equipment cost is lower.
An electric boiler can serve the final step
Resistance heat does not require a recoverable source and can reach temperatures outside a heat pump's efficient envelope. It may suit short peaks, startup, backup or the final lift after heat-pump preheating. The heat pump can then be selected for the steadier part of the duration curve.
Series integration needs controls that protect heat-pump flow and return temperature while preventing the electric boiler from carrying base load unnecessarily. Parallel integration needs clear dispatch rules and a common measurement boundary.
Test the electrical connection at annual and peak level
Compare maximum demand as well as annual consumption. A one-megawatt useful heat duty may require close to one megawatt of electric-boiler input but materially less compressor power at a credible heat-pump COP. Starting method, harmonics, redundancy and future production loads still need review.
Tariff modelling should include time periods and capacity charges. Thermal storage may shift some operation, though it cannot compensate for an undersized connection during sustained demand.
Sources
General technical explanation. No specific external source claims are made on this page.