Experiences with brine heat pump

From what has been posted here, I was probably not wrong in saying that geothermal energy with drilling is not economically feasible in southern Germany. Especially because modern air-to-water heat pumps now also achieve a COP of over 4, which further significantly worsens the amortization of geothermal energy. On top of that, the sound emissions of modern systems have been massively reduced. Even mine can only be heard when you stand right next to it.

A pity really, a great technology, but no longer simply usable!

It is still a bit too general. In particular, the COP says very little. For most air-to-water heat pumps, the value for A7W35 is often given, meaning the lift from 7 degrees outside temperature to 35 degrees water temperature. However, this is not particularly important for the annual performance factor, since hot water is warmer than 35 degrees, and at 7 degrees you still don't need to heat that much. The list from BAFA with air-to-water heat pumps, updated this March, with more than 500 models, has an average COP of under 4 for A2W35; only a few models are above 4, the maximum I have seen is 4.42, I believe (but for one with 13 kW, which is way too much for a single-family house nowadays—the smaller the output, the lower the COP tends to be).

Well, I don't know how it is in other federal states, but NRW has a worldwideweb.geothermie.nrw.de portal *cough* where you can check how likely the output at a drilling site will be. I guess there is something like this everywhere.

Honestly, I didn't know there were such maps, it's almost like mobile network coverage.....

I checked, there is this for our federal state too....ok doki, that's the reason: medium to rather bad......

Thanks for the info, I can now sleep peacefully knowing that geothermal energy probably doesn't make sense for me.....too baaaad

Well,


That is my layman's opinion, but if you need twice as many drilling meters for the same performance, it eventually becomes uneconomical. Would a trench collector possibly make sense?


The south is often colder in winter than, for example, here at the Lower Rhine. So I don't know if I would want an air-water heat pump in the deepest Allgäu. In contrast, the Rhine Graben should be quite lucrative for deep geothermal energy. The yield is not equally good or bad everywhere in any federal state. There can be significant differences in some cases.

And to round it off for everyone... if the groundwater is nearby, you can also check whether, for example, a groundwater heat pump makes sense. There are also nice concepts for that, provided the location is suitable.

It's still a bit general. In particular, the COP says very little. For most, the air-to-water heat pump value is often given for A7W35, meaning the lift from 7 degrees outside temperature to 35 degrees water temperature. But this is not particularly important for the annual performance factor, since hot water is warmer than 35 degrees, and at 7 degrees you don't need much heating yet. The BAFA list with air-to-water heat pumps, updated this March, with more than 500 models, shows an average COP of under 4 for A2W35, only a few models are above 4, the highest I have seen is 4.42 I believe (but for one with 13 kW, which is far too much for a single-family house nowadays; the smaller the capacity, the lower the COP tends to be).

I calculated it using the annual performance factor calculator from Novelan and with the latest generation with inverter technology you get 4.2. I assumed 25% hot water demand.

I calculated it using Novelan's annual performance factor calculator, and with the latest generation with inverter technology, you get 4.2. I specified 25% domestic hot water demand.

Well, that is theory, from a manufacturer of devices. The fact is otherwise that the basic concept and physics of air-to-water heat pumps and brine-to-water heat pumps are the same, only the heat source is different. Better heat pumps therefore do not fundamentally change anything, since there are now also brine-to-water heat pumps with variable output. Otherwise, I can hardly imagine a real annual performance factor that high for an air-to-water heat pump, since domestic hot water is prepared with very low COPs and—in this region and with my house—75% of the ANNUAL energy demand occurs during the 3 cold months, and the air there is cold enough for COPs well below 4 (with air). Currently, nighttime temperatures here are only about -5 degrees, but my brine-to-water heat pump operates with a COP of over 6 thanks to the low design temperature of the heating system (current value, I have the diagrams of the heat pump for that).

I calculated it using the annual performance factor calculator from Novelan, and with the latest generation featuring inverter technology, you get 4.2. I specified 25% hot water demand.

The annual performance factor calculators are nice... I would place more value on practical experience. There is a heat pump consumption database – there you can roughly compare. This also includes heat pumps that may not be optimally adjusted or installed. However, it reflects reality more than a manufacturer's own calculator.

For example, there are practical values with the currently very popular Panasonic Geisha (Aquaera). Interestingly, these are exactly the heat pumps that the operators installed themselves.

Therefore, today I would rather go to an HVAC technician than a heating engineer if you want a heat pump and do not want/cannot do any work yourself. For acceptance / BAFA funding, you need a specialist contractor declaration, and the BAFA application must be submitted before ordering.