ᐅ What is currently the best heating system?

Hello,

K.Brodbeck schrieb:
...I wanted to explicitly point out that at -20° it probably heats purely electrically, so it is not a special performance of the heat pump to warm the house, .....

The respective contribution of the air-source heat pump and, if applicable, the electric heating element depends on the device’s performance curve in relation to the building’s demand.

Air-source heat pump B has a higher "own" output at the design point (-14°C (7°F)), yet its annual performance factor is worse.
It is fundamentally wrong to size an air-source heat pump so that it provides 100% of the heating capacity on its own at the design point. Why? Heating systems mostly operate under partial load conditions. The COP values determined on the manufacturer’s test bench assume that the generated output is fully utilized. This is reasonable since manufacturers cannot foresee every application scenario. The planner is responsible here. They must select the appropriate unit based on the manufacturer's performance curves (COP, heating capacity) that best matches the specific requirements.

What was done wrong in the past (undersizing, inadequate boundary conditions) is now also being done incorrectly today under the motto "more is better," with similarly unpleasant consequences.
Well-designed air-source heat pump systems can achieve an annual performance factor of about 3.5, or possibly better, for heating and domestic hot water. Poorly planned systems reach only 2.3 to 2.7, at best 3.0. What this means for the operator can be calculated through a depreciation period of 20 to 25 years, provided the actual energy demand for heating and domestic hot water is known.

Best regards.

Hi, that sounds interesting. Could you please write it in German? I don’t understand much of it. It would be great if you could explain it in a way that a layperson can understand. Also, it would be helpful if you could describe the process, the house planner, and so on—when they come into play and when something might be oversized. How can you tell if a poor-quality pump is being used? What do you think of the Proxon Plus air heat pump? Is the Proxon Komforttechnik recommended?

Thanks, and good luck.

It's quite straightforward German. Just look at the diagrams; they clearly explain the situation.
A pump that delivers too little output when it's cold = bad, because of the electric heating element,
A pump that delivers too much output when it's warmer = bad, excess output causing on-off cycling... operation.
In both cases, the annual performance factor is poor.

VanTide schrieb:
.... It would be great if you could also explain the process, the role of the house planner, etc., when they come into play and when something is oversized.

A house planner or architect is not a trained MEP (Mechanical, Electrical, and Plumbing) engineer! Their education does not cover this at all! A responsible architect will always involve an MEP specialist overall or at least consult one. Unfortunately, this is often not the case, which is very disadvantageous for the client.
A heating system, in this case an air-source heat pump, is oversized if it noticeably worsens the annual performance factor and the lifespan of the heating system.

VanTide schrieb:
.... How can you tell if you are using a substandard pump?

For a layperson, it is extremely difficult if not impossible.
You either decide on a comprehensive system design covering the essential and critical areas, or you expose yourself to uncertainty due to lack of training by relying on architects or salespeople.

Best regards.

Saruss schrieb:
....Pump that delivers insufficient output when it’s cold = bad, because of the electric heating element,

Correct! However, in the overall energy balance, this has relatively little impact if the system is properly sized and designed!

Saruss schrieb:
....Pump that delivers too much power when it’s warmer = bad, excess output/on-off cycling... operation

Also correct, which is why I recommend a fully modulating air source heat pump if an air source heat pump proves to be a suitable solution overall!

Saruss schrieb:
....In both cases poor seasonal performance factor.

What exactly is a poor seasonal performance factor? This can only be evaluated in the overall context.
With an actual total demand of 10,000 kWh (34,121,000 Btu) for heating and domestic hot water, it plays a completely different role than, for example, with 3,000 kWh (10,236,000 Btu). Here is where opinions diverge. The higher the actual total demand, the higher the seasonal performance factor requirements for a heat pump.
Quiz question: Who really knows the actual demand for heating and domestic hot water?

Best regards.

Especially since actual needs change over the years (family, children, etc. are not constant). But somehow, you still have to plan when building a new house. It would be easier in a renovation, as you already know your data from previous years.

Nevertheless, threads like "I’m building 140m² (1506 sq ft), which heating system is the best?" will not disappear. Or the mention of "KFW70," which doesn’t really provide clear information about the demand.

The annual performance factor (seasonal performance factor) is simply interesting as a comparative value, in my opinion, if you know your demand. After all, it allows you to estimate consumption costs and cost-effectiveness. (Is it worth investing an additional €5,000 (about $5,400) for a system with an estimated annual performance factor about 0.5 higher for a specific demand?). Ultimately, these are all just theories; for a definitive statement, you probably need a concrete building project with all details.