ᐅ Challenges for MEP planners: underfloor heating flow temperature and wastewater ventilation

Created on: 15 Jul 2022 10:22
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Pacmansh
Hello,

we are at the beginning of the construction phase for our development project with the builder, and I am having some disagreements with the MEP planner. To be better prepared for the discussion, I would appreciate your assessment.

Point 1) Supply temperature of underfloor heating, new building, KfW55 standard, air-to-water heat pump
The supply temperature of the underfloor heating (end-terrace house on both floors) was stated to me as 40°C (104°F) after inquiry. This seems absurdly high to me. Additionally, I was informed that the surface temperature is designed to a maximum of 27°C (81°F) due to the flooring materials. Somehow, this does not seem consistent. When I asked about lowering the supply temperature, the response was: "A general reduction is not feasible with the underfloor heating without reducing the pipe spacing to an unacceptable level."

Do you have any ideas how I can respond to this in a reasonably professional way? Are there any documents or sources I could refer to, or information I should request?

Point 2) Wastewater venting
Contrary to earlier agreements, this has been planned in a rather unfavorable location. The reason given is "because the wastewater vent and the residential ventilation (exhaust air) must be routed over the roof with a certain separation according to flat roof guidelines." What distance should be maintained here? A quick online search only showed a 30cm (12 inches) distance to other building components. Basically, this is about the roof penetrations and their distance from each other, correct?
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Pitiglianio
14 Oct 2022 12:30
bortel schrieb:

Alternatively, install the chicken ladder electrically.
What speaks against connecting the chicken ladder directly to the heat pump from the start instead of operating it electrically?
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RotorMotor
14 Oct 2022 12:32
A chicken ladder with a 25-degree incline is basically useless and only introduces rust into the underfloor heating system!
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Pitiglianio
14 Oct 2022 13:51
The flow temperature is fixed at 35 degrees Celsius (95 degrees Fahrenheit) for the original poster, right, or have I missed something in the meantime?
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Pacmansh
14 Oct 2022 13:53
It is now at 36° Celsius (97°F), but at a correspondingly low temperature. Throughout the year, it should actually be lower, right?
face2614 Oct 2022 14:10
Pacmansh schrieb:

It is now set to 36° Celsius (97°F). But that is at a correspondingly low temperature. During the year, it should actually be lower, right?

That is the design temperature... if it is currently 8°C (46°F) outside, the flow temperature would only be around 26°C (79°F). (An arbitrarily chosen number, meant just as an example).
This is the heating curve that shows how it works.
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Pacmansh
14 Oct 2022 14:15
Exactly, that’s how I understood it as well.