Separate a mode from a modification
Ask the provider whether the proposed heater has a manufacturer-approved operating mode that meets your goal, and what that mode does during faults, low air temperature, or high demand. An owner setting does not establish that internal wires may be disconnected or the circuit reduced.
Request the manufacturer's written direction if a provider proposes a special configuration. The applicable listing, installation instructions, and electrical requirements must support the actual equipment, not an online description of another model.
Do not remove covers, disconnect elements, bypass controls, or perform live measurements yourself. If wires have already been changed, keep the heater out of use and tell the qualified providers exactly what was altered before anyone restarts it.
Compare purpose-built options
Have the installer and electrician compare suitable listed lower-demand products, required circuit work, and the household's hot-water needs. Ask about room conditions, recovery, outage recovery, and the performance tradeoffs of the selected option.
Request complete costs and the operating assumptions. A heater that draws less power may still be unsuitable for the planned use or location; the providers should explain the whole fit.
Verify before use
Ask who restores any altered equipment, verifies approved parts and wiring, checks the supply, and confirms safe startup. Keep the written finding with the model's service record.
Your next step is to obtain a listed-equipment and electrical comparison from qualified providers. Preserve the approved design rather than treating disconnected backup wires as a capacity solution.