Is a buffer tank useful in a heat pump?

And on the topic of better energy efficiency: well, I don't have to be a great clairvoyant to know that if I install a modern pump by today's standards, it will be more effective than a 7-year-old box.

You won't notice a real difference. Especially not with brine heat pumps. An annual performance factor of 4.6 is effective; just because the devices have more colorful screens for the settings today doesn't mean you have a serious difference inside. In fact, the switch from the bad CFCs to the "good" ones actually costs efficiency in the devices.

If the new one is also properly sized (starting at 1 kW, not at 3), then I am definitely even more efficient.

That is true, a better-sized heat pump runs more efficiently. Unfortunately, that is not enough for KfW funding. It would be nice—then I would throw away all my Geishas every 10 years and install new (better?) devices and still get 30-40% funding. Because funding will continue for a long time.

I have a first offer for the installation of a new heat pump: €36,000!

. Even if the initial investment is more expensive. WPs of that size should cost between €6,000 and €9,000 in materials + installation (but more than dismantling, storing away, repositioning and screwing in is not necessary).

That's how it is, but 36 is really outrageous. I'll take a German manufacturer, where an inverter machine has a list price(!) of 15. It ranges from 1-6 kW, then add a bit of small stuff like MAG etc. so my 18 wasn't so bad after all.

That's how it is, but 36 is really cheeky. I'll take a German manufacturer, there an inverter machine has a list price(!) of 15. It ranges from 1-6 kW, now add a bit of small stuff like MAG etc. I wasn't that far off with my 18.

An offered was a Viessmann Vitocal 200 G 201.B08 for €16,600. On the internet, you can buy this heat pump for €9,500. Furthermore, the offer included 104 working hours worth €9,000. Optionally, passive cooling was offered for an additional €6,300.

So, if I have read the data sheet correctly: R 410 a, refrigerant, FGases, that's where the next danger lurks. Heat pump from the clearance sale, that's why it's so cheap on the internet, nobody wants it anymore. No inverter, you'll go from the frying pan into the fire. 104 hours. So two people want to work on it for over a week? Oh man, I'm doing something wrong...

A Viessmann Vitocal 200 G 201.B08 was offered for €16,600. On the internet, this heat pump can be purchased for €9,500.

Furthermore, the offer included 104 working hours worth €9,000.

Optionally, passive cooling was offered for an additional €6,300.

A sample example of a defensive offer. That a craftsman wants to earn money is okay. But needing 1.5 weeks with 2 people for the replacement (!!!) of a heat pump and not a complete new installation of the heating system is quite audacious. I seriously wonder what the guys are doing there.