ᐅ Is a buffer tank useful for a heat pump?

For example, the Geisha is available up to 5kW, although the 7kW model can also modulate down to the same level. It’s not very expensive, but you still need someone to connect it.

RotorMotor schrieb:

Of course, you need a few minutes a day, but that’s not a problem if you use the 17,000 liters (4,500 gallons) as a buffer.

24 like the original poster? Otherwise, the consumption figures are absolutely fine.

RotorMotor schrieb:

But as I said, first tackle the control system.

No. Unfortunately, first you have to decide whether to spend 5,000 euros on a new compressor (the old one is already worn out after 7 years of starts) or get a new (better suited) heat pump. And if you decide to repair, there still remains the question whether you can adjust the control differently/better or have to accept setting aside around 100 euros per month besides heating costs for the new compressor in 2030.

bortel schrieb:

For example, the Geisha is available up to 5kW, although the 7kW model can modulate down to the same level. It’s not too expensive, but you still need someone to connect it.

Yes, but that’s an air-to-water heat pump. I’ve installed two myself – anyone with basic skills can handle the connection. However, it’s installed outside, not inside the house, so it involves more effort. But the original poster already has a borehole for a ground-source heat pump. It would be a waste not to take advantage of this huge benefit.

That's right, I overlooked that in the heat of the moment.

jens.knoedel schrieb:

To be honest? Install a heat pump that’s properly sized for your house.

Your situation is like driving a worn-out car with a residual value of €6,000. The engine breaks down, and instead of buying a brand-new car for €9,000, you put a new engine into the old gas-guzzler.
Spend €200 on a proper heating load calculation and have a new heat pump installed—brand doesn’t really matter. Even if the initial investment is higher. Heat pumps of this size should cost between €6,000 and €9,000 in materials plus installation (which should be more than just removing, storing, reinstalling, and fastening the unit).

Thanks again for your response!

Unfortunately, the heating system is currently broken, and a new heat pump probably won’t be available or installable quickly. How are we supposed to shower in the meantime?

What’s puzzling me is that the neighbors’ identical heat pump at a similar house cycles 5 times less often within the same period (12,000 vs. 60,000 starts). I hope that when the technicians replace the compressor on Monday, they’ll check the points I mentioned (heating circuit/ground loop strainers, temperature sensors, bypass valve), find an error, and then the heat pump will work like the neighbors’.

(Unfortunately, I can’t wait for these checks before deciding whether the compressor should be replaced.)

jens.knoedel schrieb:

If you decide to repair, the question remains whether the controls can be adjusted or improved, or if you’ll have to accept setting aside €100 per month alongside heating costs for a new compressor in 2030.

If no fault is found in those areas (heating circuit/ground loop strainers, temperature sensors, bypass valve) and no optimized control settings are possible (night setback, wide hysteresis, possibly blocking periods or variable speed control optimized for lower speeds, speed limits), then hopefully the buffer tank will help to ease the situation. That would also be cheaper than a new heat pump.

jx7 schrieb:

Thanks again for the reply!

Unfortunately, the heating system is currently broken, and a new heat pump probably won’t be available or installable anytime soon. How are we supposed to shower in the meantime?

What puzzles me is that the neighbors’ identical heat pump in a similar house and the same period cycles five times less often (12,000 vs. 60,000 starts). I hope the technicians find a fault during the compressor replacement on Monday in one of the areas I mentioned (check the dirt filter in the heating circuit/brine circuit, temperature sensors, bypass valve), so the heat pump will then operate like the neighbors’.

(Unfortunately, I can’t decide whether to replace the compressor only after these checks.)

Then let’s proceed step by step. Repair, adjust, test, and if necessary, consider the buffer tank.