ᐅ Heat pump with a special heat pump electricity tariff?

Hello.
I am planning to install a Vaillant ground source heat pump VWF 88/4.
We are considering installing a second electricity meter to benefit from a cheaper tariff for the heat pump.
However, this meter would be off for up to 6 hours per day.
As far as I know, we do not have a buffer tank integrated.
Alternatively, we could use the regular electricity supply (one meter). Overall, this would cost about €250-300 per year more than with the heat pump tariff.

I am concerned that during the off periods, the electric heating element might turn on, and we could end up spending much more than the €250-300 savings.

How does the electric heating element usually work – does it only activate in emergencies, or does it always come on when hot water is drawn?

I would appreciate any answers or experiences.

How much electricity should the heating system (including hot water) ideally consume per year?

In our case, the second meter (which we had for one year) was not worth it. Now, with photovoltaic panels on the roof, it definitely isn’t.

Even without the photovoltaic system, the savings per kWh were negated by the fixed basic charges...

=> Depending on your location and electricity provider, it’s purely a matter of calculation.

But be careful, not every supplier allows a heat pump to be connected to a standard household electricity supply.

We have an estimated 8000 kW per year. The network operator allows connection to household current. We compared and calculated a maximum saving of 300 € (euros). But as mentioned before... what about the heating element?

It always turns on when the heat pump’s capacity is not sufficient. Unfortunately, I can’t tell you when this happens in your case.

We had the heating element disconnected by the heating technician, but so far we have never missed it.

Just to understand: You expect the heat pump to require 8,000 kWh of electricity per year? Quick check: What type of house, what size, year of construction, and energy efficiency? Energy demand?

Note: What the grid operator allows does not matter. There are inexpensive electricity suppliers that forbid this regardless of the grid operator!

cumpa schrieb:
I’m worried that the heating element will turn on during the restricted hours and we’ll end up losing the 250–300€ savings many times over.

During the restricted hours, nothing will turn on because the electricity is blocked.

First, you should clarify whether you really cannot get a buffer tank for hot water.
Then, you should distinguish between hot water production and heating operation:
The underfloor heating with a maximum supply temperature of 35 degrees Celsius (95°F) should ideally run continuously. Some downtime due to restricted hours should not cause much harm. For the 35 degrees Celsius (95°F) supply temperature, your heat pump generally should not need the heating element—unless it’s around -20 degrees Celsius (-4°F) outside.
Hot water production requires higher temperatures because you likely want to shower at about 38 degrees Celsius (100°F). Our hot water production is set to 44 degrees Celsius (111°F) and runs once per day (between 4 and 6 pm, but this can be adjusted as needed). This fills part of the buffer tank. Here, the heating element support might be needed since the system must reach a higher temperature (50 degrees Celsius / 122°F or above) to heat the tank. However, this also only happens when it’s quite cold outside.
Of course, you should ensure that the hot water production time is not scheduled during your provider’s restricted hours.

And, to add to Jochen’s point, the heat pump must be sized large enough to produce the required heat during the remaining 18 hours. It can happen that you need to choose a unit one size larger.