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?
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?
Convincing a developer to consider wall heating is almost certainly impossible.
Move on and don’t waste more time. If you have the chance to inspect the installation in the bathroom, definitely do so and insist on corrections if anyone has defaulted to the standard method out of habit.
Move on and don’t waste more time. If you have the chance to inspect the installation in the bathroom, definitely do so and insist on corrections if anyone has defaulted to the standard method out of habit.
Maybe an option would be to only install the supply and return lines each and leave them “capped off” at the manifold (to retrofit yourself later)? We arranged it this way for a potential future heating system installation in the attic, but not through a general contractor or developer, rather as separate contracts.
R
RotorMotor14 Oct 2022 09:22Nice idea, but who would tear down an entire wall—removing tiles, stripping off plaster, handling the pipes, replastering, and reinstalling the tiles—just to save €2.95 in heating costs per year?
Pacmansh schrieb:
to @face26: In both bathrooms, there is then a 5cm (2 inch) installation spacing. This sets the bathroom floor heating to 23°C (73.4°F), although in the guest bathroom this results in some overlap. An electric towel warmer is also installed in both bathrooms.Thank you for the information. As I said, under these circumstances I would be more than satisfied.
You won’t reach the 23°C (73.4°F) later on if you turn down the supply temperatures. That’s why the overlap in the guest bathroom is actually useful. I’m not a big fan of towel warmers—they hardly provide any noticeable warmth. If you want to maximize efficiency, consider using a fan heater or something similar. If the bathroom temperature is around 22 or 21.5°C (71.6 or 70.7°F), you can turn the fan heater on for 2 minutes if you really feel cold and bring it up to 23°C (73.4°F). The energy consumption from that is almost negligible. A lot of this also depends on personal comfort. If you jump straight into the shower, you’ll feel warmer anyway...
After handover, it will be important to familiarize yourself with the system and optimize it. Maybe lower the supply temperature, disconnect all the room temperature sensors, balance the system, deactivate the overheating protection valve if present, and so on...
R
RotorMotor14 Oct 2022 09:28face26 schrieb:
You obviously won’t reach 23°C (73°F) later if you lower the supply temperatures. So some overheating in the guest bathroom is just right.
I’m not a big fan of towel radiators. They hardly have any warming effect. I completely agree. However, we still installed an electric towel warmer.
Without it, the shower towels just didn’t dry properly.
It also helps reduce humidity during the transition season because it gets warmer, and the moisture is better absorbed and ventilated by the air. It usually runs only at midday using free solar power from the photovoltaic system. 😉
RotorMotor schrieb:
I completely agree. However, we ended up installing an electric towel warmer. It was just impossible to get the shower towels properly dry without one. It also helps reduce humidity during the transitional seasons since it gets a bit warmer and the moisture is better absorbed and ventilated by the air. It usually only runs around midday using free solar power from the photovoltaic system.I understand your approach. I didn’t pay close attention to whether the original poster has a ventilation system (or you, @RotorMotor), but with proper ventilation, humidity shouldn’t be a problem.
I’m not sure what kind of high-capacity towel warmers you have, but typically, they don’t provide much real heating power, and if they do, they tend to consume a lot of energy.
And I hope you don’t really believe your last sentence about free photovoltaic electricity!? :p You at least have to account for the feed-in tariff and possibly sales tax, and in winter, whatever power the photovoltaic system produces (if any) is usually already used by your heat pump or base load.
Personally, I’d rather use a fan heater.
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