ᐅ LWZ 504 with or without buffer tank

Created on: 2 Oct 2018 07:54
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Roppo
Hello everyone,

I am planning to equip our new build with an LWZ 504.
I have noticed that opinions about buffer tanks vary quite a bit.

Currently, I am leaning towards leaving out the buffer tank, since we don’t necessarily need the cooling function through the underfloor heating (it has worked well without it for the past 30 years), and these tanks generally tend to reduce efficiency.
However, I have also read—though not specifically about Stiebel Eltron—that some heat pumps can have issues when using ERR (which is basically required) if there is no buffer tank installed.

What are your experiences and opinions on this?

Best regards,
Roppo
seth04874 Oct 2018 15:30
As far as I remember, only very few air-to-water heat pumps are eligible for subsidies. Air-to-air heat pumps are not supported at all. Most ground-source heat pumps are generally eligible. There was also a list of approved models somewhere.

If we had been able to, I would have chosen a ground-source heat pump as well... but at some point, the budget was spent...
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werners81
28 Oct 2018 10:37
Regarding funding, feel free to contact me. I successfully obtained the Thz 504 grant a few months ago. Just send me a private message if you’re interested.
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United98
10 Apr 2019 13:09
We also installed the LWZ 504. It should actually qualify for subsidies because of the inverter, but in our case, it was rejected due to the too low annual performance factor. To be honest, I then forgot to look into it more thoroughly or had other priorities, and so the appeal deadline passed...