Controlled residential ventilation with heat recovery or exhaust air heat pump

Hello,

we are building a Kfw70 house with a U-value insulation of 0.15.
We will then have 180m² of living space with a granny flat. The ventilation is only intended for the 140m² house without the granny flat.
We want to have the underfloor heating and hot water preparation handled by the Mitsubishi AlphaTherm Zero + Sunhybrid buffer.

For this, we have now been offered the exhaust air heat pump Nibe Fighter 120, which is supposed to heat the water from the exhaust air with a small heat pump. This for 8200 Eur.

Now, when I look, I have been offered the Vaillant recoAir 275 with cross heat exchanger and 95% heat recovery for 7780 Eur in another offer.

What is better now, which one needs less electricity?
Because with the exhaust air heat pump, a heat pump runs that consumes electricity. With the Vaillant, I think the cross heat exchanger needs no electricity.
So the supply air is almost as warm as it goes out of the house at 95%. For that, I would not need supply air ducts with the exhaust air heat pump and the hygiene is better.....

Can you help me here? I face a difficult decision.
I definitely don’t want to have high electricity costs afterwards.
What are your Nibe experiences?

Thank you
Regards Philipp

....we are building a KFW70 house with a U-value insulation of 0.15.

KFW 55 should actually be possible

.... let Mitsubishi AlphaTherm Zero + Sunhybrid buffer take over underfloor heating and domestic hot water preparation.

The Mitsu does not have full modulation. Below -15°C it stops operating, meaning no heating or hot water. For operational limits, the site-specific minimum temperature counts, not the heating load design temperature! No one knows what minimum temperatures to expect here
When using an air heat pump, a site-specific evaluation of the climate (AT) is indispensable.

.... We were now offered the exhaust air heat pump ...

Exhaust air heat pumps could become a money pit in a KfW 70.

.... What is better now, what needs less electricity?.... Can you help me here? Facing a difficult decision? Definitely don’t want high electricity costs afterwards.

Save yourself the trouble of pointless searching and initially have a solid and precise fundamental assessment carried out. If the actual demand (capacity, energy) for heating and hot water is known, a suitable solution can be found taking into account the location-specific conditions.
Anything else is groping in the dark, guessing. Probably not a suitable basis for a major investment decision

regards

The Mitsu also has a heating rod installed in the indoor unit for > -15°..... but that is actually not the issue. Of course, you have to calculate that precisely when I have the values.

But can’t one say what is better, how much electricity does the controlled residential ventilation use compared to the AWP? That is what would be important to me at first and what I can first prepare for in the heating pre-planning.... because I don't want to simply trust my heating installer blindly just because he prefers the AWP....

Of course you have to calculate it exactly when I have the values. But can't you say which is better, how much electricity does the controlled residential ventilation consume compared to the AWP?

Apparently not understood? Besides, you can't compare apples and oranges. The AWP is heating + ventilation, the controlled residential ventilation is only ventilation!

...That is what would be important to me first and what I can then prepare for first in the heating preliminary planning....

For this, the actual demand must be known! The first step to which everything else follows.

Regards

Hello Philipp,

that is an adventurous construction => take €uro's advice to heart and have a proper TGA planning done!

By the way, I always wonder why potential builders – basically complete laymen when it comes to house construction and new technologies anyway – seek advice in a forum like this, but then remain resistant to learning.

Definitely don't want to have high electricity costs afterwards

That’s understandable – but in my opinion, you shouldn’t forget that there is no heating system that works without a power connection! However, this

.... exhaust air heat pump NIBE Fighter 120 ...

ensures that your utility company will be happy at the beginning of the year. Even as a layman, it should be clear to you that

heating the water from the exhaust air

is not possible “without” an additional power source. Where do you have “usable” exhaust air besides the bathroom and kitchen?

can you help me here? Facing a difficult decision?

Search HBF or google and read!

There is a highly reputable competitor whom I appreciate overall; he often advertises with such funny tents. What I still don’t understand is that he heats his houses using exhaust air heat pumps, even though he mostly does not build passive houses.

Use Aunt Google regarding this and you will find plenty of posts about “fun with the utility company”...

Best regards

Hello construction expert,

.... What I still do not understand is that he heats his houses using exhaust air heat pumps, while he is mostly not currently building passive houses

The answer is probably simple, consumption is not part of the contract!

Best regards