Is the air-to-water heat pump expandable?

Hello,
my husband and I are looking at a penthouse apartment (140 sqm) in a five-family house this weekend. The house dates from 2009, the other 4 apartments are finished and already inhabited. Then the developer went bankrupt and left the penthouse apartment in a shell condition.
What I know so far is that a air-to-water heat pump with underfloor heating is used as heating there. The building is made of expanded clay/Estelit.
Does this building material actually fit with an air-to-water heat pump?
I also read now that the electricity costs are supposed to be very high. If that is the case, can we add another form of heating to reduce the electricity costs?
What should we pay attention to when we meet the current developer on Saturday? My head is really spinning after reading up on this topic.

Best regards
sevenofnine

Hello,

...The house dates from 2009, ....
What I know so far is that an air-to-water heat pump with underfloor heating is used for heating. The building is made of expanded clay/Estelit.
Does this building material actually match with an air-to-water heat pump?

This question does not arise at all, because there is no direct connection here! The decisive factor is always the overall complex of the unit to be heated => external envelope, climate location, user behavior...etc..

...Also, I have now read that the electricity costs are supposed to be very high.

That is relative. Well-designed air heat pump systems achieve seasonal performance factors around 3.5.
Poorly, incorrectly or insufficiently planned systems (unfortunately very often) achieve an annual performance factor of just 2...2.7 in operation, with accordingly high consumption costs.

...What should we pay attention to when we meet the current developer on Saturday?

Quite simple, have all calculation documents for the system presented and have them checked by an MEP planner.

- Ventilation calculation, if controlled residential ventilation with/without heat recovery
- Heating load calculation according to DIN 12831, => nominal heating load, room heating loads
- Heating surface dimensioning (underfloor heating)
- Pipe hydraulics

If none of this is available, the risk is quite high that it could be a botched system!

In addition, it is unusual that there is no common heating center for all usage units!

Best regards.

Hello building expert,
by expanded clay I meant estepor wall elements from the company Estelit. In the research it says that this building material has good thermal insulation properties.

@ €uro
Thank you very much for your answer. What is meant by user behavior? I like it warm, 20 degrees is too cool for me and I work from home. So the heating would be on all day. Would the heating costs then be too high?

There must be a common heating center. We first looked at the whole building area to estimate whether we like it there. We can already say yes to that and when I called the responsible employee, she gave information about underfloor heating with an air-water heat pump in answer to my question about the type of heating. Tomorrow we will meet there and look at the house.
It is already finished and some owners moved in last year. The first developer there went bankrupt and the current one is basically continuing the rest of the construction. That means the penthouse apartment is still in shell condition and we can plan all interior walls etc. ourselves. Only the heating not.

Could a wood-burning stove be installed? Does something like that fit with an air-water heat pump? Surely we also have to check whether it is even allowed or whether other owners have objections.

Best regards
sevenofnine

Good morning!

Over the weekend we looked at the apartment. It is actually very nice, but the interior finishing is our responsibility after the insolvency of the developer.
The air-to-water heat pump is a Siemens LI26ML type 2WP3 167-25, with the possibility of switching on 3, 6, or 9 kW. Operating range from minus 20 to plus 35 degrees with heating element. Now I have researched on the internet and on the technical data sheet of the system it states a COP of 3.1. Isn’t that too low?
What we have received so far are the construction description, a list of the remaining interior works with cost estimate, the minutes of the owners’ meetings, the utility cost statement, the business plan.
The building was constructed according to the 2002 Energy Saving Ordinance. It is located on a slope and is oriented to the south along the broad side. According to the other owners, the heating costs in recent years have been very low.
So far the heating costs for the entire building (2 garden-level apartments with 60 sqm, 2 upper floor apartments with 109 sqm, and the uninhabited penthouse with 139 sqm) have been 4,832 euros per year for all.
I am still waiting for the heat demand calculation etc. When I inquired this morning, this lady really had no idea about it.
Are Siemens pumps reliable?

Best regards
sevenofnine

... and the unoccupied penthouse with 139 sqm) at 4832 euros per year for all.

Which is likely to change significantly! ;)
Also, are the figures climate-adjusted? How were the figures substantiated? Heating only or including hot water?

... I'm still waiting for the heat demand calculation etc.. When I inquired this morning, that lady didn't really have a clue about it.

Anything else would have surprised me a lot. ;)

... Are Siemens pumps decent?

Decent is relative! However, this device cannot modulate. A COP of 3.1, presumably for A2/35, is also relative, since for the actual consumption the entire characteristic curve is relevant (annual performance factor!)

best regards

Dear €uro,

thank you for the quick and knowledgeable response :)
I have found items to clarify in the construction description and the invoices anyway, so I have now sent the lady a list of questions. I am curious whether I will now receive the technical data, annual performance factor, etc.

Best regards
sevenofnine