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?
As far as I know, yes, although it is unclear whether the developer has chosen a radiant floor heating installation pipe with poor bending properties due to cost constraints, and whether this is communicated in the technical datasheets that should be available to the HVAC engineer.
In this case, as mentioned, it would be important to inform the developer that you are willing to cover the additional effort and material costs.
Please note that many HVAC engineering firms can charge very high fees. Not every company bills as moderately as the widely recommended DI Heckmann, who charges just a few hundred dollars; many smaller or less specialized HVAC firms may charge between 2,000 and 4,000 USD for a simple single-family house design without compliance with DIN standards, possibly even more.
On top of that, the increased material costs would apply, which in the situation involving the developer and a subcontracted plumber would certainly not be less than 1,000 USD.
But give it a try, maybe it won’t be that bad.
In this case, as mentioned, it would be important to inform the developer that you are willing to cover the additional effort and material costs.
Please note that many HVAC engineering firms can charge very high fees. Not every company bills as moderately as the widely recommended DI Heckmann, who charges just a few hundred dollars; many smaller or less specialized HVAC firms may charge between 2,000 and 4,000 USD for a simple single-family house design without compliance with DIN standards, possibly even more.
On top of that, the increased material costs would apply, which in the situation involving the developer and a subcontracted plumber would certainly not be less than 1,000 USD.
But give it a try, maybe it won’t be that bad.
N
Neubau202215 Jul 2022 11:57Tolentino schrieb:
As far as I know, yes, although you never know if the developer has chosen a floor heating pipe with poor bending properties due to cost constraints, and this should be communicated in the technical datasheets, which should be available to the HVAC engineer.
As mentioned, it is important to inform the developer that you are willing to cover the additional effort and material costs.
Beware that many HVAC design offices can charge very high fees. Not everyone bills like the widely appreciated DI Heckmann, who charges a few hundred USD, but typical local HVAC offices may want 2,000–4,000 USD for a simple single-family house design without planning according to DIN standards, possibly even more.
Then there are the increased material costs, which in the scenario of a developer and subcontracted plumber will certainly not be less than 1,000 USD.
But give it a try; maybe it won’t be that bad. However, the savings should be taken into account. A flow temperature of 40 degrees Celsius (104 degrees Fahrenheit) versus 30 degrees Celsius (86 degrees Fahrenheit) is a significant difference in electricity costs.
I have already experienced this. The HVAC planner charges a significant amount of money for their so far extremely poor performance. Of course, the developer doesn’t really care since they don’t have to pay for it.
Let’s see if anything can still be done; it would just be a shame not to at least try.
And just to clarify:
Do you really think it’s possible to run 40°C (104°F) warm water through the pipes without the surface temperature exceeding 27°C (81°F)?
Let’s see if anything can still be done; it would just be a shame not to at least try.
And just to clarify:
Do you really think it’s possible to run 40°C (104°F) warm water through the pipes without the surface temperature exceeding 27°C (81°F)?
N
Neubau202215 Jul 2022 12:13Pacmansh schrieb:
I’ve had that experience already. The HVAC planner is asking for a lot of money despite delivering extremely poor performance so far. Of course, the developer doesn’t mind because they’re not the ones paying.
Let’s see if anything can still be done; it would be a shame not to at least try.
And just to clarify:
Do you really think it’s possible to run 40°C (104°F) water through the pipes without the surface temperature exceeding 27°C (81°F)?It all depends on how the underfloor heating is installed.
C
Costruttrice15 Jul 2022 12:39If you don’t trust him, have it calculated externally and then they can proceed based on that. That’s what we did now; for me, it was worth it because I didn’t want to take any risks.
Similar topics