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?
A
Axolotl-neu15 Jul 2022 12:47Pacmansh schrieb:
Do you think it’s possible to run 40°C (104°F) warm water through the pipes without the surface temperature exceeding 27°C (81°F)? There’s a calculator available online. It’s called Abakus, starts with a “u.”
I entered some general data. With a 40°C (104°F) supply temperature, the surface temperature comes out to 35.6°C (96°F) (60mm (2.4 inches) screed with 40mm (1.6 inches) coverage, 150mm (6 inches) pipe spacing, and 16mm (0.6 inches) pipe diameter). So no, that doesn’t work with my typical setup. I believe the construction details matter less, and even if you install floating parquet flooring, it will almost always exceed 27°C (81°F).
If you already have to pay the MEP planner a high fee now (according to HOAI?), you can also insist on the delivery of services. You are the client.
They are then required to implement your requests within the framework of the "recognized rules of technology and the relevant DIN standards." If they are unwilling or unable to provide this, I wonder why you should pay them at all. Is it really an MEP planning office or rather an employee of the sanitation trades?
What does the contract structure look like, and what options do you have to change the planner?
They are then required to implement your requests within the framework of the "recognized rules of technology and the relevant DIN standards." If they are unwilling or unable to provide this, I wonder why you should pay them at all. Is it really an MEP planning office or rather an employee of the sanitation trades?
What does the contract structure look like, and what options do you have to change the planner?
Axolotl-neu schrieb:
I think it hardly matters how the system is set up, and in case of doubt, floating parquet will be installed; it will almost always exceed 27 degrees. Thanks. I probably just barely passed thermodynamics with a D, but I had a similar suspicion.
i_b_n_a_n schrieb:
What is the contract setup, or what options do you have to change the planner? It’s a purchase from a developer. So I don’t really have any options and I don’t pay the MEP (mechanical, electrical, plumbing) planner fully myself. This is a small developer who was founded specifically for this project (and maybe a few others). I only directly pay the MEP planner for my change requests or get told by the developer how much I have to pay them for additional MEP planning. It’s a lot of money for little work, and even that work is flawed. Since they deliver such poor work, I have looked into other matters and came across the problem with the supply temperature.
It’s a medium-sized planning office with architects, structural engineers, etc. (around 40 employees).
There are also requirements (indoor temperatures, surface temperatures, etc.). I just want to avoid them messing up and me having to deal with the consequences or the extra effort afterwards.
I’m thinking maybe they’re talking about heating load (40 W/m²), but they can’t be that careless. I still have a small issue to clarify with the site manager (who, by the way, has been great so far). Maybe he can just tell me if he has something regarding the planning. I’ve asked the MEP planner for further information.
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Costruttrice15 Jul 2022 15:37Pacmansh schrieb:
Yes, I had thought about that as well. Was it a developer project for you too, and did you receive all the necessary data?No, we hired a general contractor, but we didn’t trust the plumber’s explanation that "we always did it this way," so we commissioned an engineering firm. It cost around 600€ (about $650), but now I feel confident that everything is correct. The general contractor and plumber looked a bit puzzled, but it will be implemented as planned.
As always, this is nonsense. There are no universal distances or heating circuit lengths. It always depends on the individual case: the ratio of envelope area to underfloor heating area, insulation standard, number of windows, floor covering, pipe diameter, room temperature, temperature difference between supply and return, electric bathroom heaters.
Then VA20 is also possible, or VA5 with 130 meters (426 feet) length, with acceptable pressure loss and low supply temperature.
Then VA20 is also possible, or VA5 with 130 meters (426 feet) length, with acceptable pressure loss and low supply temperature.
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