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Community and Q&A

HRV/ERV Ventilation ducting embedded in floor EPS

Davor Radman | Posted in Mechanicals on

I have a proposed method to install flexible ventilation ducting embedded inside of EPS on the 1st floor (not ground floor, one above it, not sure what you call it in USA).

This is a brick and concrete house, so it’s not as easy as putting them through and between joists.

It would go like this:
– 3 inch diameter flexible plastic ducts would be laid on the reinforced concrete floor of the 1st floor (not sure if some sort of dampeners or something are used)
– holes would be left in the concrete for ducts to go to the ground floor rooms
– part of supply/exhaust pipes would go vertically through walls (supply on the bottom, exhaust higher on the wall), some would have grilles on the ceiling (kitchen..)
– between ducts, EPS would be laid
– over that, 3 inch screen with radiant heating would be laid

This is offered as an alternative to embedding pipes directly in the concrete floor, and suspended ceiling.
Suspended ceiling would add more to the house height, which is something we would want to avoid, and embedding in the concrete is problematic because the seller of the equipment is too far, so i would need to find someone local to do the installation, and there is nobody here who would know how to do the installation in the concrete. Apparently it’s a bit trickier than i had imagined.

Are there any possible negative sided against the proposed method of installing them on the floor of the 1st floor embedded in the EPS and covered by screed and radiant heat?

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  1. Davor Radman | | #1

    Here is an example of how it would look like, with just pipes laid on the concrete:

    (image of pipes laid can be found somewhere in the bottom third of the page)

  2. GBA Editor
    Martin Holladay | | #2

    1. I understand why installing ducts in a suspended ceiling will add to your house height. But if you install the ducts in a super-thick floor, you also will add to your house height. So you have the same problem with either installation.

    2. You forgot to tell us what you intend to install above the "3 inch screen" (which sounds like concrete reinforcing mesh to me). Will you install a concrete slab? A layer of plywood and finish flooring? Something else?

  3. Expert Member
    Malcolm Taylor | | #3

    What is the purpose of having 3" of rigid foam on the first floor? Is it just to make up the height for the duct work?

  4. Davor Radman | | #4

    1) in this case, it would only be 8cm, as opposed to ~34cm that would be needed for the suspended ceiling. This 8cm could be done with a concrete strip on the walls of the 1st floor.
    Or by cutting the 10 inch high clay blocks horizontally in 3 equal pieces, since there are no clay blocks of that height.
    2) as per google, I used the term "screed" for: "a leveled layer of material (e.g. cement) applied to a floor or other surface". It's a dry mortar with radiant heating PEX piping embedded. Than on top of that tiles and laminate flooring

    Usually, with radiant heating, it's just 1 inch of a kind of elastic EPS that serves as a dampener between the concrete floor and the cement screed, but in this case, 3 inches would be used to allow for the ducts.

  5. Expert Member
    Malcolm Taylor | | #5

    It's always fascinating to hear about construction techniques outside those we use here in North America. Unfortunately, it's so far outside my experience it's hard to be of much help with your questions.

  6. Davor Radman | | #6

    No problem :)

    I'm just trying to get different perspectives.

    I did get an advice that embedding is not a good option if ever there is a need to repair/replace ducts. Flexible plastic ducts on paper should be great, but they are not time proven. So there is that slight risk.

    In any case, suspended ceiling is the best solution, technically. But it would represent a significant investment, in the order of up to 2% of the whole house price.
    That on the account of drywall vs plaster price (drywall with metal carriers are ~50-70% more expensive than plaster), extra masonry work (having to cut and build in non standard size of clay blocks) and than extra facade for that extra wall.

  7. GBA Editor
    Martin Holladay | | #7

    If you need to create a suspended ceiling to hide 3-inch-diameter ducts, I don't know why you need a height of 34 cm (=13.5 inches). For example, you could use a commercial suspended ceiling system -- I imagine that about 5 or 6 inches would do it.

  8. Davor Radman | | #8

    I was under the impression that I would need to do suspended ceiling on both floors. So together that would add up to 12-13-ish inches

    But in the meantime, I have received further clarification from the seller, whose engineer is the one who will do the plan for installation :
    - suspended ceiling would only be on the ground floor, pipes for the 1st floor would go vertically from there
    - doing it on the 1st storey floor is the best and cheapest option

    I am still worried about the potential noise, so I will pester him some more.

  9. JaBK | | #9

    You should take into account the statics of the building (stability of the buliding). You cannot put the pipes into concrete floor if that was not taken into account when designing it. It would weaken it.

  10. Davor Radman | | #10

    Kolega Jabk, I will take the equipment and plans from a slovenian company you may know, e-netsi :)

  11. JaBK | | #11

    Of course I know it. Everyone installing HRV or ERV in Slovenia knows it. They know what they are doing. The proposed solution is also the most common one here. It is a legitamate solution and most often chosen because:
    - usually we do not concer ourselves with ERV/HRV so early during planing and the static design does not support it
    - suspended ceiling is OK but usually needs more height. It is also more expensive if the suspended ceiling is made for just that purpose. If you are planning on installing recessed lights throughout the house, then the price difference is negligable
    - very often the firms who offer heating and ventilation installations also install water pipes and such... If they put them on the floor they do their work at once and are not really dependent on any other construction work. So coordination is easier.

    That said, the proposed solution is also the one I opted for.

  12. GBA Editor
    Martin Holladay | | #12

    A meeting of the Balkan division of GBA International...

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