ᐅ Solar energy output is not measurable

Washing machines and dishwashers are not worth connecting to hot water anyway.

Your heating engineer has already told you the truth, even if it’s for the first time now. These appliances are mainly important for building permit / planning permission purposes. Still, of course, they need to work properly ;-)

Whether the solar thermal system is working can be seen from the thermometers on the solar station.

As mentioned, the rest requires an additional charge. Turning off the heating system is not always possible, as the controllers often need to work together with the systems.

Even if you could read it, the values are useless (at least with our Vaillant). The only thing that matters to me is this: our gas boiler has been completely off for more than 4 weeks, meaning gas consumption is 0.0. When our buffer tank is full (95°C (203°F)), that is enough for about 5 days of hot water without any sun. So we are definitely saving. 🙂

Hello

Suppressing the reheating should generally always be possible.
If necessary, lower the storage temperature significantly.

Alex, why do you think supplying the washing machine and dishwasher with solar thermal is not worthwhile?
The numbers are certainly not precise, but:
Electricity 0.30 € per kWh
Gas 0.08 € per kWh
Solar 0.00 € per kWh

Olli

wrobel schrieb:
Alex, how do you come to the conclusion that supplying the washing machine and the property with solar thermal is not worthwhile?
The numbers are certainly not precise, but:
Electricity €0.30 per kWh
Gas €0.08 per kWh
Solar €0.00 per kWh

Because dishwashers require cold water! Especially fats should first be treated with cold water before using warm water. The machines use cold and warm water alternately depending on the program to achieve cleaning results—for example, pre-rinse and intermediate rinses don’t need warm water at all. If you already have plenty of solar thermal, it doesn’t matter, but if your hot water costs money, especially in winter, you’ll end up paying more.

Furthermore, dishwashers use very little water, meaning the hot water line should ideally be connected to a circulation system so that cost benefits can actually be realized. Otherwise, the machine will heat electrically again if 2–3 liters (0.5–0.8 gallons) of cold water flow in first when hot water is actually needed.

About half of the thermal energy in the dishwasher is actually absorbed from the incoming wash water through the dishes, meaning the dishwasher will always need to reheat electrically. You should never assume that connecting the dishwasher to the washing machine will significantly reduce its energy demand.

The washing machine must have a separate connection, partly because wash cycles below the feed water temperature won’t work otherwise. It’s pointless to run a 30°C (86°F) gentle cycle and let 50°C (122°F) hot water flow in. Only a few models have a separate hot water connection, and they cost about €200–300 ($200–300) more with otherwise similar features.

Additionally, there’s the investment for piping and ideally circulation (if not already available).

You also have to consider that dishwashers and washing machines are rarely run more than once a day, meaning the hot water in the supply lines cools down regularly, which works against the idea of energy savings (yes, the heat remains in the insulated pipe, but it doesn’t reach the dishwasher or washing machine). Circulation helps here too, but that incurs investment and ongoing costs.

We decided against it. I don’t need a new washing machine, circulation is a hassle, and the savings on the dishwasher are close to zero with a water consumption of 10–12 liters (2.6–3.2 gallons), no matter how you calculate it, simply because the amount of hot water used is so low.

wrobel schrieb:

The figures are certainly not precise, but:
Electricity 0.30 € per hWh
Gas 0.08 € per kWh
Solar 0.00 € per kWh

I am not against solar systems, but the prices mentioned above are accurate only if you live in a rental property (though they are usually included in the rent). Otherwise, investment and maintenance costs come into play, which should not be overlooked when considering the overall price.