ᐅ Air-to-Water Heat Pump: Current Consumption and Data

Simply increase the hot water temperature when there is enough photovoltaic power, as long as the heat pump can manage without the electric heating element, in my case up to a maximum of 55°C (131°F). This way, you have a reserve...

The hot water circulation is definitely installed, and 46°C (115°F) is too low; increase it to 48°C (118°F) with a 6K hysteresis, deactivate the circulation, and only run it once for 15 minutes before you get up.

@berny absolutely not

Because it is unnecessary and efficiency decreases the more heating is required, especially since you don’t have sunshine every day. With circulation, you lose almost 2-3 degrees Celsius (3.6-5.4°F) of heat per hour, whereas without it, it’s about 3 degrees Celsius (5.4°F) over 10 hours. In my opinion, it is unnecessary since we try to use as little electricity as possible without losing comfort.

Above all, how do you plan to control this? Today you have output from photovoltaic panels, tomorrow you don’t.

You’re obviously right about the circulation pump; I didn’t install one at all. In a small detached house with short pipe runs, it’s pointless. As for the temperature control: I’m home every day and check the weather forecast, so I can quickly raise the hot water temperature if sunny weather is expected. And when I’m on vacation (last time was in autumn 2019!!!), no hot water is used anyway. For me, this is mostly just a toy (in my opinion, photovoltaics still don’t pay off these days), but I don’t like being taken advantage of by any grid operators. Feeding electricity back into the grid pays about 12 cents per kWh, while buying electricity costs well over 20 cents. So I try to use as much of the power generated by my “toy” at home as possible: 1. direct consumption for general electricity, 2. charging the battery, 3. heating up the hot water, 4. increasing the underfloor heating during the day as much as makes sense. This works particularly well on sunny winter and spring days. Underfloor heating acts as a large heat storage. Only what absolutely must be fed into the grid is sent back. Usually from mid or late March until the end of October, when it’s simply not possible to use all the energy yourself (unless you happen to have an electric forklift without forks in your garage) 🙂 🙂

It was about the significant heat loss during showering and the fact that the buffer tank sometimes runs empty. I gave him a few suggestions on what the cause might be. Since you don’t have a circulation system and have a photovoltaic system, you can consider yourself lucky that this is not the case for you.

What’s the bottom line for you? During the 2-3 weeks per year when the conditions prevail, you don’t even save enough for a small cheese pizza and a soft drink.

In December, January, and February, you typically use over 80% of the annual consumption. One load of hot water currently requires about 1.3 kWh here, and we usually have two loads within 24 hours. Whether I get that energy from the solar panels or from the grid makes no real difference.