ᐅ Air-to-water heat pump + controlled indoor ventilation system (central ventilation unit)

Hello everyone,

Here are some brief details from our side:

- KFW 55 single-family house with 160m² (1,722 sq ft) and basement
- 2 full storeys with a hipped roof
- Currently 2 people – hopefully 4 people in a few years

We are close to signing the contract but still very uncertain about one topic because we have received very little input in this area.

It concerns the models and integration of our air-to-water heat pump and the mechanical ventilation system with heat recovery (central ventilation system):

The following options were offered by our general contractor:

Option 1:

- Compact unit – mechanical ventilation with heat recovery + air-to-water heat pump in one device --> Brand/Model: Tecalor THZ 504 SOL
--> The air-to-water heat pump is included in the house price --> additional costs of €8,000 (for the mechanical ventilation system) would apply if we choose this unit.

Option 2:

- Air-to-water heat pump installed outdoors + central ventilation system as a separate unit --> Brand/Model air-to-water heat pump: Tecalor TTL 7.6 ACS
--> The air-to-water heat pump is included in the house price --> additional costs of €12,000 (for the mechanical ventilation system) would apply --> Here we are apparently free to choose the ventilation model – we would have to see what the trade offers us.

Option 3:

- Air-to-water heat pump installed indoors + central ventilation system as a separate unit --> Brand/Model air-to-water heat pump: Tecalor TTL 9.5 I
--> The air-to-water heat pump is included in the house price --> additional costs of €12,000 (for the mechanical ventilation system) would apply --> Here we are apparently free to choose the ventilation model – we would have to see what the trade offers us.

Does anyone have experience with the general differences between indoor and outdoor installations? Which is better? Both models seem to be at the same price.
Both are supposed to achieve a seasonal performance factor (SPF) of 4.5 and are eligible for government subsidies under BAFA.
Does anyone have experience specifically with these devices?
Is €12,000 a reasonable estimate for the mechanical ventilation system? Will this get me a good system? Are there any recommended models or manufacturers for this?

Also the question arises:
--> Are these “compact units” actually any good? Does anyone know this device? Is this the “future”? This option would effectively save us €4,000.

I would never choose a compact unit, as it basically only has disadvantages.

Bookstar schrieb:

I would never choose a compact unit; it basically only has disadvantages.

Mine works fine. Tecalor THZ 504. To each their own.

Yes, but a mechanical ventilation system with heat recovery would be easy to replace if it breaks... if it is integrated into the heating system, it will probably be more expensive.

Snowy36 schrieb:

Yes, but a mechanical ventilation system with heat recovery, if it breaks down, would be easy to replace ... if it’s integrated into the heating system, it will probably be more expensive.

That’s the question I’m asking myself as well.

But where do you get this assumption from? Is it really like that? Is the repair effort higher for a compact unit? If the mechanical ventilation system breaks down, can I not just add a separate ventilation unit? Do I always have to stick with a compact system?

Bookstar schrieb:

I would never choose a compact unit; it basically only has disadvantages.

Since you say a compact unit has “only” disadvantages:
Could you list some other disadvantages here?

I find the input on these topics in this house building forum quite limited. Is that because the expertise required is really very specialized, or because home builders don’t really need to be knowledgeable about this? Is there more “trust” placed in the tradespeople or general contractor (GC) in this area? Do people just accept whatever the GC proposes?

I would like to know, as this topic concerns me a lot and I find it quite difficult to make a decision...

Compact units have poorer repairability. There are also frequent compromises because everything has to fit into a tight installation space. I also think it is more difficult to replace one of these units.