Air-water heat pump indoor installation experiences?

Hello all,

for our new building (125m^2 living space on 2 floors, plus basement) we are planning a air-to-water heat pump heating system in the technical room (basement). So indoor installation. A thermal calculation is not yet available, so it is not yet about the perfect device for the task (reference point: timber frame construction near KfW55, controlled residential ventilation with heat recovery).
The questions are rather: The basement should protrude about ~80cm out of the ground, so it partially has daylight. The system should be integrated at the northeast corner. Supply and exhaust air would presumably have to be routed outside via light/air shafts, since at least one heat pump provider requires an air duct cross-section of 85x85cm^2 external dimension, furthermore the inlet and outlet ducts will certainly not come out of the system at the room ceiling. Is such a solution still feasible without problems?
On which side do noise problems typically occur more - inlet or outlet side?

Which providers have well-functioning systems for indoor installation in their program?
And: Which providers describe the systems in such a way that a heating planner can actually plan with them?

An alternative might be a system with a deep probe - if this is worthwhile with the expected low heating demand and can be approved in the area. Gas is not planned (supply line length > 30m), wood neither...

Best regards
I.

85cm squared as an air duct. Then it is certainly not sensible to put a light well in front of it that obstructs the airflow. What does the manufacturer say about this?

Hello,

... we are planning an air-to-water heat pump heating system in the utility room (basement). So an indoor installation...

What is the actual demand (capacity, energy) for heating and hot water?
Air heat pumps are basically "misused" air conditioning units for heating purposes. The heating capacity is completely contrary to the actual demand (thermal building characteristic).
Therefore, fully modulating split units have proven to be necessary. Fully modulating indoor units are not known. How long the compressors will survive the forced cycling remains to be seen.

... An alternative might be a system with a deep borehole - if it is economical given the expected low heating demand, and can be approved in the area.

With moderate or low demand and not an extremely cold location, a brine heat pump with vertical probes will hardly be economical. For trench collectors with a lot of own work, it looks somewhat more favorable.

Best regards.

€uro, I keep reading it and now I have to ask. This "fully modular". What does it do, what is the difference from a system that is not fully modular. What makes these systems better?

A single source for further reading is enough for me, if there is something competent.

In which price ranges do such systems move in a (I'll just say) 150 sqm house (even without knowing exact loads now).
How does it look at outside temperatures below zero?

Thank you very much

€uro, I keep reading about it and finally have to ask. This "fully modular". What does it do, what is the difference compared to a system that is not fully modular?

Fully modulating means that both the fans of the evaporator (noise) and the compressor can be regulated according to actual demand.

....What makes these systems better?

They probably last longer, because instead of On/Off a performance modulation according to demand takes place, and the energy efficiency (annual performance factor) is significantly better.

The evaporators have to defrost in the main operating range, which is not necessary for e.g. brine heat pumps. This reduces the achievable annual performance factor because part of the already produced energy is needed for this and therefore is not available to the heating surfaces! This portion can be reduced by full modulation. Therefore, I always recommend external heat meters for air heat pumps, not the integrated ones.

....In which price ranges do such systems move in a (I’ll simply say) 150sqm house (even without knowing exact loads now).

Who should be able to answer this question?

....How does it look at outdoor temperatures below zero?

Very good with well-planned systems, poor with poorly planned ones, depending on where the bivalence point was determined!

Best regards.

Hi,

and thanks for the answers.

85cm square as an air duct. Then it certainly doesn't make sense to put a light well in front of it that obstructs the airflow. What does the manufacturer say about that?

That was the interesting part – he does allow it in his installation manual, requires one with a clear width of just over 40cm and air deflection (I don't have the picture available, but it would also be subject to his copyright. I can’t make a sketch here right now... the technology available to me here doesn’t support that).

Hello,
What is the actual demand (power, energy) for heating and hot water?
Air heat pumps are basically "misused" air conditioners for heating purposes. The heating capacity is completely contrary to the actual demand (thermal building characteristic curve).
Therefore, fully modulating split devices have proven to be necessary. Fully modulating indoor units are not known. How long the compressors survive due to forced cycling remains to be seen.
With moderate or low demand and not extremely cold locations, a brine heat pump with vertical probes is hardly economical. With trench collectors and a lot of own work, it looks somewhat more favorable again.

Best regards.

Thanks... as I said, the heat calculation is not yet available, and my own estimate is unsuitable to make an accurate selection. Therefore, it is not yet about manufacturer/model determination. The demand will certainly not be very high (this results already from building volume/surface/wall and ceiling structure), so a brine heat pump is probably not economical.
The location is in the flat borderline area Odenwald / Spessart, so also rather not extremely cold.
Reasons for the desire for indoor installation: noise nuisance in the neighborhood. The distances to the neighbors are manageable, and there are already people there who have had very negative experiences with outdoor units. Unfavorable selection, unfavorable installation, very unfavorable orientation of the units all came together. Therefore the question about manufacturers who even have reasonable systems in their program here. Whether these systems are suitable for our specific case must then be clarified later.

Unfortunately, you find very little about the systems that a possible heating installer in our area is considering – once 'inverter with 7 or 10 kW', once 'modulating with 3-9 kW', plus the CoP at A2W35. That is too little for me to even be able to compare anything, let alone ask sensible questions. Therefore, a market overview would be helpful – at least then you know where and whom to ask and consider.

Best regards
I.