Ceiling suddenly too small for controlled residential ventilation!

Hi everyone,
we are building a small solid house with a general contractor. Originally planned was a gas boiler with controlled residential ventilation.
After we finally got assigned an installer, he now said that we don’t have space for controlled residential ventilation!
It’s a bit short notice now, the excavator is already on the property, and excavation for the foundation slab will probably start on Monday.

From the general contractor, we have now received the following options to choose from:

Option 1:
- Gas condensing boiler with solar thermal system
(Photovoltaic system doesn’t make sense here!)

Required:
o Flue pipe (either on the house wall or in the cloakroom niche)
o Buffer tank
o Expansion vessel
o Condensing boiler
o Pipes for solar up to the roof

Needs a lot of space

Option 2:
- Gas condensing boiler with ventilation (barely sufficient for energy saving ordinance calculation)
(Photovoltaic system doesn’t make sense here!)

Required:
o Flue pipe (either on the house wall or in the cloakroom niche)
o Buffer tank
o Expansion vessel
o Condensing boiler
o Ventilation system (under the ceiling)

Actually no space

Option 3:
- Air-water heat pump with ventilation
(Photovoltaic system can be retrofitted later – empty conduit to the roof)

Required:

o Buffer tank
o Expansion vessel
o Outdoor unit air-water heat pump
o Ventilation system (under the ceiling)
o 10cm extension in the roof slope necessary for ventilation pipes

Option 4:
- Air-water heat pump without ventilation
(Energy saving ordinance technically no problem, but mechanical ventilation should possibly be given for example by window rebate ventilation)
(Photovoltaic system can be retrofitted later – empty conduit to the roof)

Required:

o Buffer tank
o Expansion vessel
o Outdoor unit air-water heat pump

Unfortunately, we were not informed about additional costs associated with the options.
We are currently leaning towards option 4, but we are very uncertain about these window rebate ventilations...

Have a nice Sunday
Marvin

Unfortunately, we were not informed about the additional costs associated with the options. We are now leaning towards option 4, but we are very uncertain about these window rebate ventilations...

Without having read the rest in detail...what is that? Are you going to decide on something without knowing the costs???

...yo...placing an order on the construction without an offer...living on the edge!

Variant 2! That's what you wanted - what do you mean now "actually" no space?

If the general contractor plans the air-water heat pump like the ventilation, then I would stick with gas. Solar thermal instead of ventilation as an alternative is surely a joke, or why was ventilation planned initially?

In addition, I would make him feel early on that this way won't work, otherwise it will merrily continue with lazy compromises.

Option 2! That’s what you wanted – so what does "actually" no space mean now?

If the general contractor plans the air-to-water heat pump like the ventilation, then I would stick with gas. Solar thermal instead of ventilation as an alternative is a joke, right? Otherwise, why was ventilation planned in the first place?

Also, I would make him realize early on that this doesn’t work, otherwise there will be more lazy compromises going forward.

“Actually no space” means that there is no longer room for a washing machine/dryer in the utility room...
Ventilation was an option in the contract that we wanted. The standard offer includes an air-to-water heat pump, but we then decided on gas with controlled residential ventilation (-4k gas, +11k controlled residential ventilation).

Without having read the rest in detail...what is this? Are you going to make a decision now without knowing the costs???

...yo...placing an order at the construction site without an offer...living on the edge!

You just don’t know exactly yet, it would be 4k more, as stated in the standard offer.
What could we have done better? Because we thought that once you sign the contract, everything works as specified!

Regarding your question about window rebate ventilation. We have the following concept: gas boiler, solar, window rebate ventilation, exhaust fan Helios in the bathroom. Works great. Gas: warm house, no adjustments. Solar: from now on hot water only via solar until the end of 10/19. Ventilation: works. No mold, nothing, good air. Exhaust fan because it sucks the air out of the house. Fresh air constantly flows in through the rebates. Simple but good. K.

Ah very good, that doesn't sound bad at all! You have a window rebate in every window/door and additionally an exhaust vent in the bathroom. Nowhere else?