ᐅ Where to install ducts for controlled residential ventilation in the ceiling of the top floor
Created on: 24 Feb 2016 19:21
W
world-e
Hello,
can someone briefly explain where the ducts for a mechanical ventilation system with heat recovery can be installed on the upper floor if the house has two full stories, the top ceiling is a beam ceiling, and the roof above is either uninsulated or has only 60mm (2.4 inches) of insulation above the roof deck? If the ducts are installed above the beam ceiling, they are outside the thermal envelope; if installed within the insulation, much of the insulation’s effectiveness is lost. Also, running ducts perpendicular to the beams is difficult. How is this usually done? Thank you.
can someone briefly explain where the ducts for a mechanical ventilation system with heat recovery can be installed on the upper floor if the house has two full stories, the top ceiling is a beam ceiling, and the roof above is either uninsulated or has only 60mm (2.4 inches) of insulation above the roof deck? If the ducts are installed above the beam ceiling, they are outside the thermal envelope; if installed within the insulation, much of the insulation’s effectiveness is lost. Also, running ducts perpendicular to the beams is difficult. How is this usually done? Thank you.
Hello!
@Sebastian79
My general contractor strongly advised against drilling holes in the upper floor ceiling because this interrupts the vapor barrier between the upper floor and the attic. Honestly, that made a lot of sense to me. How did you handle this?
Also, how do you prevent the ventilation system from freezing in winter? Your ventilation unit is located outside the building’s thermal envelope, right? In our attic (we currently live in a house with a very similar construction to the one we’re about to build), I’ve measured temperatures as low as minus 10°C (14°F) during winter.
Best regards,
Andreas
@Sebastian79
My general contractor strongly advised against drilling holes in the upper floor ceiling because this interrupts the vapor barrier between the upper floor and the attic. Honestly, that made a lot of sense to me. How did you handle this?
Also, how do you prevent the ventilation system from freezing in winter? Your ventilation unit is located outside the building’s thermal envelope, right? In our attic (we currently live in a house with a very similar construction to the one we’re about to build), I’ve measured temperatures as low as minus 10°C (14°F) during winter.
Best regards,
Andreas
S
Sebastian7925 Feb 2016 10:39By properly connecting the vapor barrier to the valves—those were installed before the vapor barrier—and considering that there are other penetrations which also need to be appropriately sealed.
I mentioned that the system in the attic will be insulated with 50mm (2 inches). We probably won’t experience temperatures as low as minus 10°C (14°F) – the exterior insulation above the rafters should keep the attic frost-free. But that wouldn’t matter anyway, since the system is insulated.
And it is designed to operate reliably down to minus 15°C (5°F) air temperature.
I mentioned that the system in the attic will be insulated with 50mm (2 inches). We probably won’t experience temperatures as low as minus 10°C (14°F) – the exterior insulation above the rafters should keep the attic frost-free. But that wouldn’t matter anyway, since the system is insulated.
And it is designed to operate reliably down to minus 15°C (5°F) air temperature.
Yes, if you do it yourself, the vapor barrier might actually be airtight... We are still debating this, and we haven’t fully decided yet. I would also prefer ceiling outlets on the upper floor instead of floor and wall outlets.
So far, apart from the empty conduit for the 4 satellite cables and one power cable, we haven’t made any other penetrations into the attic.
I just checked the specifications again. The operating range of a Helios controlled ventilation system for living spaces indeed goes down to -20°C (-4°F), but the installation temperature (meaning the ambient temperature for the unit) must be above 5°C (41°F). How else would you get rid of the condensate? So you really need to be sure that there’s no frost in your attic, right? Or have you heated the condensate drain?
Best regards,
Andreas
So far, apart from the empty conduit for the 4 satellite cables and one power cable, we haven’t made any other penetrations into the attic.
I just checked the specifications again. The operating range of a Helios controlled ventilation system for living spaces indeed goes down to -20°C (-4°F), but the installation temperature (meaning the ambient temperature for the unit) must be above 5°C (41°F). How else would you get rid of the condensate? So you really need to be sure that there’s no frost in your attic, right? Or have you heated the condensate drain?
Best regards,
Andreas
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