The useful comparison is the complete installed scope, not two pump prices. A compact unit using suitable existing connections, an accumulator installation and a tank-fed system serving several floors involve different work.
The main cost drivers are equipment and storage size, access, pipe alterations, electrical provision, noise-control measures and hot-water integration. Tank support, overflow routes, reinstatement and work involving communal services can change the scope significantly.
Our quotation distinguishes the included installation, optional improvements and work by others, with VAT treatment stated. Measurements help avoid buying more equipment than the property needs—or a smaller system that cannot meet the agreed demand.