ᐅ BAFA Innovation Grant for Air Source Heat Pumps

United98 schrieb:
Why not use a buffer tank? I'm currently considering adding one to my Stiebel Eltron LWZ 504 to better utilize the SG Ready function and to store excess heat. Are there any drawbacks besides heat loss (which stays inside the house anyway) that I might be missing?

We operate the identical THZ 504, and honestly, what significant savings are you expecting? Our heating costs are around €60-70 per month. Just an energy management system (EMS) to better use photovoltaic energy costs about €450. How much can you really save? €10-20? In another forum, they were estimating more like €5-10 per month. A buffer tank with the necessary technology is not cheap either. It will take a long time to break even.

Kekse schrieb:
No, that would be (if the assumptions are correct, which I cannot and do not want to judge) roughly 11.9%. You can’t just add percentages.

I know that. Since the 2.5% is only an approximate guideline anyway, it is acceptable as a rough estimate. The efficiency loss depends on both the heat pump itself and the temperature range. In fact, for each heat pump, the specific performance curve would need to be analyzed separately. Then you could have temperature ranges with a 3% slope and others with only a 1.5% slope.

The 2.5% is an average empirical value that usually fits reasonably well. Whether it is actually only 2% or as much as 3% in reality is not particularly important. That’s why it is also okay to add the 2.5%. You can easily calculate that roughly in your head. I still can’t really do 0.975^5 = (100% - 11.9%) in my head.

Regards, Nika