ᐅ Challenges for MEP planners: underfloor heating flow temperature and wastewater ventilation
Created on: 15 Jul 2022 10:22
P
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?
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?
It was as expected: She proudly told me on the phone that all heating circuits are now between 70 and 100 meters (230 and 330 feet) long. Only the bathroom is different; its heating circuit is 159 meters (520 feet) long. My suggestion to simply divide this into two heating circuits is now going to be implemented.
R
RotorMotor14 Oct 2022 08:49bortel schrieb:
Morning,
wouldn't it still be possible to design the flow temperature lower?
There seems to be enough potential in the pipe spacing, right? And sometimes you might have to accept lower temperatures in the bathrooms or insulate the walls, because the distance is already at its limit there.
Yes, with 15cm (6 inches) on the ground floor and 10cm (4 inches) on the upper floor, I could accept that under the given circumstances, provided that there is an attempt to reduce it further in the bathroom (to 5 or 7.5cm (2 or 3 inches)). I did not understand whether that will also be done.
Whether it then calculates the supply temperature as 38 or 36 degrees is irrelevant; you can always lower it further yourself and balance it out. If in doubt, just place a fan heater in the bathroom.
Whether it then calculates the supply temperature as 38 or 36 degrees is irrelevant; you can always lower it further yourself and balance it out. If in doubt, just place a fan heater in the bathroom.
bortel schrieb:
There is still enough potential in the installation spacing, right?I am still missing some exact data for the new calculation. However, the supply temperature cannot be lowered further without a significant underheating in the main bathroom. The rest of the house still has some potential.If I wanted to reduce the supply temperature even more, I would first have to convince the HVAC planner to install wall heating, then the developer would have to include this in the planning and coordinate it with the general contractor. Surely, additional planning services would also be charged. I think this is unrealistic in this setup.
If it is done as last communicated, I am initially satisfied. Further optimization will probably have to be based on the existing system and with real measured values.
to @face26: In both bathrooms, there will be 5cm (2 inches) installation spacing. This sets the bathrooms to 23°C (73°F), although this leads to overheating in the guest bathroom. An electric towel warmer will also be installed in both bathrooms as an additional heat source.
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