Comparison of geothermal heat pump with LWW pump

That is wrong. Almost every manufacturer now offers an air-to-water heat pump with an annual performance factor >= 4.5 in most climatic conditions. Nibe, Wolf, Viessmann, Alpha Innotec/Novelan etc pp

Because he had bad experiences. A brine-water heat pump can be cheap if you source it yourself through a trench collector.

I am currently having a lot of difficulty estimating the financial effort for these trench collectors.

I wouldn't say bad experiences. It's just uneconomical if you don't install it yourself. I also learned that gas doesn't always require collectors. For a wooden house, you probably don't need them, and then gas is unbeatable cheap.

But even so, you save a good amount of money and have very reliable technology. Unfortunately, heat pumps are still a bit away from that.

With gas, you also don't have the legionella issue, always boiling hot water, and if the supply temperature needs to be a few degrees higher, it's no problem at all.

With heat pumps, good night!

I have Novelan, modulating device, very new and efficient, but it does not achieve 4.5 according to the manufacturer's specifications. Where is the mistake?