u/Unborn_Bones

We have a modern house, heat loss calcs via heatpunk and also by the installer show heat losses of 2.9kw.

My options are Grant Aerona 4kw or Vaillant Arotherm 5kw. I'd prefer to go for the Vaillant based on reviews but I'm worried it may be oversized with its max output actually closer to 7kw. On the overhand the Grant could be undersized once defrost cycles and DHW are taken into account.

The Vaillant can modulate down to 2.1kw, the Grant down to 1.25kw.

Anybody have a similar heat loss and either of these heat pumps?