Good evening, dear house building experts!
We are currently planning the construction of a house with a building company (prefabricated house provider), with construction starting in 2024. The detailed design is still pending. So far, we have not received a clear statement from the builder regarding the design of the underfloor heating system. There was mention of a flow temperature of "about 35°C (95°F)." The performance specification only states that the heating system will be executed according to the applicable technical regulations (aRdT). Of course, we want the underfloor heating to be designed as efficiently as possible. We hope that the builder is willing to discuss and agree on a straightforward design. Nevertheless, we would like to know what we are entitled to and where we depend on the builder’s willingness to accommodate us.
We are currently planning the construction of a house with a building company (prefabricated house provider), with construction starting in 2024. The detailed design is still pending. So far, we have not received a clear statement from the builder regarding the design of the underfloor heating system. There was mention of a flow temperature of "about 35°C (95°F)." The performance specification only states that the heating system will be executed according to the applicable technical regulations (aRdT). Of course, we want the underfloor heating to be designed as efficiently as possible. We hope that the builder is willing to discuss and agree on a straightforward design. Nevertheless, we would like to know what we are entitled to and where we depend on the builder’s willingness to accommodate us.
- How much freedom does the builder have in determining the flow temperature? We have read that DIN EN 1264 specifies a maximum flow temperature of 35°C (95°F) and a temperature difference of at least 5 K. Is this correct, and is this DIN standard part of the applicable technical regulations (aRdT) or otherwise binding for the builder? We would prefer a lower value if possible. We could not find any other DIN requirements regarding the flow temperature. Are there any others?
- We would like to be involved early in the planning and heating load calculation. According to what we have read, § 650n grants a right to obtain the room-by-room heating load calculation from the builder. Have we understood this correctly?
- DIN EN 12831 allows the setting of indoor temperatures according to the standard or by agreement (form V). Can the builder simply set the temperatures according to the standard, or must the owner be asked whether individual temperature settings are desired?
- If we have understood correctly, the owner can demand the desired design of the underfloor heating according to § 650b of the Building Code. The builder may then charge the additional costs. Is that correct?
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WilderSueden7 Dec 2023 10:06The 35 degrees is, of course, the maximum. Calculations based on 32 or 30 degrees are not prohibited but require more effort, so most construction companies will implement the project using 35 degrees accordingly.
You always have the option to withhold approval of the detailed construction plan until all your questions, requests, or corrections have been addressed and incorporated.
However, hardly anyone will implement flow30 voluntarily and free of charge, as it requires extra effort during planning and may also lead to additional installation costs. You will need to accept these extra costs—prefabricated house providers usually charge well for this (unless you have contractually agreed everything in advance).
It is also possible that they refuse and say it cannot be done. In that case, your chances are slim, because if you try to counter expert reports with other expert reports, you will eventually derail your schedule completely (price guarantees, etc.).
However, hardly anyone will implement flow30 voluntarily and free of charge, as it requires extra effort during planning and may also lead to additional installation costs. You will need to accept these extra costs—prefabricated house providers usually charge well for this (unless you have contractually agreed everything in advance).
It is also possible that they refuse and say it cannot be done. In that case, your chances are slim, because if you try to counter expert reports with other expert reports, you will eventually derail your schedule completely (price guarantees, etc.).
D
Daniel-Sp7 Dec 2023 11:24Hello
What is contractually agreed then?
What is contractually agreed then?
W
WilderSueden7 Dec 2023 11:30Pacmansh schrieb:
Sorry, I expressed myself unclearly. I meant whether the 35° limit is defined anywhere as a maximum. Unfortunately, I don’t have a primary source, but this should serve as a good starting point.
Maximum Supply Temperature of Underfloor Heating
According to DIN EN 1264, an underfloor heating system must not exceed a maximum surface temperature of 35°C (95°F). The average surface temperature is around 29°C (84°F). To achieve this temperature for an underfloor heating system designed according to DIN 4724 and 4725, the following system temperatures (supply/return temperature) are used for dimensioning the heating surface:
- 35°C/28°C (95°F/82°F)
- 32°C/28°C (90°F/82°F)
- 30°C/26°C (86°F/79°F)
- 45°C/35°C (113°F/95°F) (old standard)
Depending on whether the underfloor heating can operate with both low and higher supply temperatures, every installed system should not exceed the maximum temperature defined by the DIN standard. The supply temperature of the heating water is set at a maximum of 35°C (55°C (131°F) for older systems), with a temperature difference (delta T) of 5°C (9°F) between supply and return.
X
xMisterDx7 Dec 2023 18:58Be prepared for a significant price increase if you want the flow temperature set to 32 or 30°C (90°F or 86°F). Based on experience, this usually means a four-digit amount, so don’t be caught off guard.
The system needs to be recalculated, more heating circuits are required, which means larger manifolds, more tubing, more installation work, and so on.
The main costs come from labor and the technical components.
The system needs to be recalculated, more heating circuits are required, which means larger manifolds, more tubing, more installation work, and so on.
The main costs come from labor and the technical components.
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