ᐅ Roof suddenly too small for mechanical ventilation system!

Created on: 24 Feb 2019 08:51
M
M4rvin
Hi everyone,
we are building a small solid house with a general contractor. Originally, the plan was to have a gas boiler with a controlled ventilation system.
Now that we finally have an installer assigned, he told us there is no space for controlled ventilation!
This is quite short notice since the excavator is already on site, and digging for the foundation will probably start on Monday.

The general contractor has presented us with the following options:

Option 1:
- Gas condensing boiler with solar thermal system
(Photovoltaic system does not make sense here!)

Requirements:
o Flue pipe (either on the exterior wall or in the cloakroom niche)
o Buffer tank
o Expansion vessel
o Condensing boiler
o Piping for solar system up to the roof

Requires a lot of space

Option 2:
- Gas condensing boiler with ventilation (just sufficient for energy saving regulation calculations)
(Photovoltaic system does not make sense here!)

Requirements:
o Flue pipe (either on the exterior wall or in the cloakroom niche)
o Buffer tank
o Expansion vessel
o Condensing boiler
o Ventilation system (ceiling-mounted)

Basically no space available

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

Requirements:

o Buffer tank
o Expansion vessel
o Outdoor unit for air-to-water heat pump
o Ventilation system (ceiling-mounted)
o 10cm (4 inches) build-up in the sloped roof area needed for ventilation ducts

Option 4:
- Air-to-water heat pump without ventilation
(Energy saving regulation compliance is technically not a problem, but mechanical ventilation should possibly be ensured by e.g. window frame ventilation)
(Photovoltaic system can be added later – empty conduit to the roof)

Requirements:

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

Unfortunately, the additional costs for these options have not been communicated to us.
We are currently leaning towards option 4, but we are quite uncertain about these window frame ventilation solutions...

Have a nice Sunday
Marvin
M4rvin25 Mar 2019 17:26
So, it won’t be decentralized either. They want €6000 net for 2 supply air and 1 exhaust air.

We will switch to window vents instead.

Regarding the ventilation concept, who is actually responsible for it? The general contractor or me?