ᐅ Recommendation for Digital Heating Thermostat

motorradsilke schrieb:

Sure, basically yes. But if, over the next few years, I end up using more electricity with the heat pump than I did with gas, meaning I pay more for power, it might no longer be worthwhile. Those are my concerns.

Then just think about it rationally! What does a surplus of €15,000 mean for you? If you are currently spending €500 on gas and (unrealistically) €1,000 on electricity per year, you could easily cover the additional consumption for 30 years from the subsidy surplus. However, CO2 taxes will work against you. And with sensible planning, the "extra costs" will too, so you will always be the "loser" with a gas heating system.

motorradsilke schrieb:

Now there is an offer to pay about 3000 Euro more for the heat pump and thus achieve kfw55. That makes me think.

I would be very cautious here. The small additional cost suggests that the same assumptions and designs are being applied for both gas and heat pump, and that the extra charge is just the pure price difference for the heating source.

However, you cannot apply this 1:1, and no general contractor will spend more money than they have to. In other words, the heating system design may (possibly) still be intended for a gas boiler. For an extra 3,000 Euro, you get a heat pump but with the same hydraulics as for gas. From the contractor’s point of view, that’s fine—they just expect the builder to operate a higher supply temperature.

So I would ask very carefully and request to see the figures showing what kind of system would actually be installed for that extra 3,000 Euro.

Mycraft schrieb:

I would be very careful here. The small additional cost suggests that the same assumptions and designs are being used for both gas and heat pump systems, and the extra charge is just the pure difference for the heating source.

However, this cannot be directly transferred one-to-one, and no general contractor (GC) will spend more money than necessary. In other words, the heating system design will (possibly) be planned for a gas boiler. For 3,000 (currency unit) more, you might get a heat pump, but with the same hydraulics as for gas. From the GC’s perspective, that’s fine—they just expect the builder to run a higher flow temperature.

So I would ask very detailed questions and request the figures showing what kind of system you would actually get for 3,000 (currency unit) more.

I have the model names of the devices. What should I be paying attention to?
According to the company, the system is already designed for the heat pump. How can I verify if this is true?
And shouldn’t the energy consultant be responsible for that, especially since they would be involved for the KfW55 subsidy?

motorradsilke schrieb:

Well, as of today my gas will not get more expensive next year, I have already received confirmation for the next contract renewal.

Please note the disclaimers in the fine print regarding changing fees and taxes.
As far as I know, these should already be included if the contract start date is in 2021.

Your assumptions are contradicted by the new gas pipeline from Russia as well.

Let’s wait and see. That project was costly and needs to be paid for.
The issue with gas and electricity is usually not that wholesale prices rise or fall drastically, but that public fees and taxes change. Mostly in one direction, and these are clearly politically driven for fossil fuels.
We’ll see.

The problem with turnkey building is that you do not choose the heating installer yourself. I also didn’t want to study to decide on a heating system.

Still, you can clarify this in advance if you know it is an important area that, besides window film, requires a bit of extra attention.

motorradsilke schrieb:

I have the names of the devices. What should I pay attention to?
According to the company, the system is already designed for a heat pump. How can I tell if that is true?
And shouldn’t the energy consultant check this, since they are required for the KfW 55 subsidy?

You need to make sure the size of the heat pump matches the heating load calculation (which must be done, not just estimated). An oversized heat pump leads to unnecessary upfront costs and typically cycles on and off too frequently during operation. Ideally, it is a modulating unit.

If you just want to be “prepared” for a heat pump, the most important things are a close piping spacing of maximum 10cm (4 inches), less in bathrooms if possible, and avoiding additional radiators.
The whole system should be designed for a maximum supply temperature of 35°C (95°F).

In case of a retrofit, it is also practical to be able to easily install the outdoor unit of the heat pump—for example, by positioning the heating system on a floor plan so that it is on an exterior wall that can remain free or be cleared for the outdoor unit. Electrical power can be added afterwards.
The location should also minimize potential conflicts with neighbors (possible noise issues).
Alternatively, prepare the boiler room so that it can accommodate an indoor heat pump unit. This means ensuring adequate room size and the possibility for supply and exhaust air ducts with relatively large cross-sections. This also involves an exterior wall or, in the case of a basement, two shafts, and considering noise levels (I have a neighbor who directed both onto his own terrace. I’m curious how happy he will be …).

You are making an investment of several hundred thousand euros here, and you have to make decisions that cannot be changed later or can only be corrected at great expense.

I decided to familiarize myself with the trades of heating/insulation and electrical work at least enough to avoid major mistakes.

motorradsilke schrieb:

According to the company, the system is already designed for the heat pump. How can I verify if this is true?
And shouldn’t the energy consultant be responsible for checking this, since they need to be involved for the KfW55 subsidy?

The energy consultant is often just a rubber-stamper. I wouldn’t rely on statements from the general contractor. Only hard data counts—that means a complete heating load calculation and a detailed system design.