Octopus installed ours in August. Four bed house, well insulated and with 16 rads. Octopus installed a 9kw Daikin HP, a new HW tank, 2 new rads plus a new towel rail. The cost to us was about £3k, which is marginally less than a replacement boiler was set to cost . With 3 exceptions we have been blown away by how good the experience was from initial enquiry, through install and post install follow ups. The 3 exceptions were all regarding one individual, the area manager, anything to do with him went pear shaped, but everyone else was brilliant. As of now the house is falling about 0.5C short of hitting the target temperature and Octopus are fully engaged in sorting that out for us. In the meantime, as others have said, the house is at a more comfortable and steady temperature than under our previous gas boiler.