ᐅ Potential-free switchable outlet for whirlpool – is it useful?

Created on: 8 Jun 2021 11:27
H
hampshire
H
hampshire
8 Jun 2021 11:27
Hello everyone,
to save energy, I want to prioritize heating the hot tub when the photovoltaic system is supplying power. This is no problem with a potential-free switched socket, which I can control from my system. At the same time, I want to prevent the temperature from dropping below 36°C (96.8°F) if the photovoltaic system does not provide enough energy for an extended period. This could be done with a water temperature sensor that sends a potential-free signal when the set temperature is undershot.

The idea now is to use a socket with two potential-free switching contacts that enable power either when enough energy comes from the photovoltaic system or when the water temperature falls below 36°C (96.8°F). Overheating is prevented by the built-in control system of the hot tub. The power consumption of the hot tub is a pleasantly low 1400W. I have not yet measured the heat loss overnight during summer.

Using another potential-free switch, I activate the heating element in the domestic hot water heat pump. This raises the temperature in the storage tank by up to 10K to 63°C (145.4°F) (alternatively, the heat pump can be set to a lower maximum value). In this setup, the hot tub would have priority over the domestic hot water heat pump.

What do you think of this idea? Who knows of a suitable socket? Does anyone have a better idea?
Z
Zubi123
8 Jun 2021 12:24
The idea is good! That’s how I had imagined it in theory as well, but I hadn’t yet looked into the technical implementation.
G
guckuck2
8 Jun 2021 13:44
Are you sure the hot tub only draws 1.4 kW? That’s not even enough for a heater; usually, hot tubs have 3 to 4 phases.

Completely cutting the power will also disable necessary circulation pumps. Not a good idea.
H
hampshire
8 Jun 2021 13:48
Yes, it is only 1400 watts. It takes a very long time to heat 900 liters (240 gallons), but the insulation is excellent, so maintaining the heat requires less energy. The circulating pump is off for a maximum of a few hours, which I don’t see as a problem. During normal operation, the circulating pump is not running continuously, only during heating periods. The manufacturer is Softub.
G
gmt94
8 Jun 2021 14:24
I would suggest installing a Shelly 1 with a temperature add-on in the room.
H
hampshire
8 Jun 2021 14:48
Thanks for the tip. I couldn't determine if the temperature sensor is suitable for water. However, this could be a good approach—if I can use the device without WiFi.

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