The SEAI heat pump grant calculator can provide an indicative estimate based on details such as your home, system and heating requirements, but it is not a grant approval or eligibility decision. Generally, you apply through SEAI before starting work, using information from a registered heat pump contractor, and wait for approval before proceeding. The contractor must complete the installation and required assessments in line with SEAI rules, after which the grant claim is processed under the applicable scheme requirements. Check the latest steps on the official SEAI website and confirm the likely grant and paperwork with your registered contractor.