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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HausbauFrage8 Dec 2023 14:33WilderSueden schrieb:
A supplier is not obligated to fulfill every customer request. Ask your representative how such change requests are handled. We will do that. We just wanted to know in advance which regulations apply. Apparently, the supplier has quite some freedom in the design.
Pacmansh schrieb:
Is that really the case? I’m familiar with the 20/24 degrees, but that 35 degrees supply temperature is fixed is news to me.
I wouldn’t look for any legal framework here. This topic is important to you in terms of efficiency and comfort, but for the homebuilder, it’s more of a burden they want to handle as cheaply as possible. Make sure to address it very early and insist on optimization. If necessary, have your own calculations done and try to enforce them. In the end, it usually means just laying some pipes closer together, creating a few more heating circuits, and in the worst case installing a larger manifold and using an additional wall in the bathroom. The first three points don’t really matter to the contractor, the last one is probably the most effective but also the most complicated to implement. Yes, there will be additional costs, but I don’t think anyone should object to that.
And don’t get too hung up on the calculation itself. I’d generalize that for most prefab home suppliers, a heat load calculation is just a document that has to be created at some point, but not much thought goes into it beyond that. We will try to do that. We are willing to accept reasonable surcharges. We just wanted to understand what is currently actually required and where additional costs for the company begin.
Harakiri schrieb:
You always have the option not to approve an execution plan until all questions, wishes, or corrections have been answered or incorporated.
However, almost no one will voluntarily and free of charge implement flow30 for you, as it involves some additional effort in planning and may also cause extra costs during installation. You will have to accept those additional costs – prefab home suppliers usually charge well for this (unless everything has been contractually agreed in advance).
It is also possible they refuse and say it is not possible. Then you will be in a tough spot, because if you fight expert reports with counter-expert reports, you will eventually blow your timeline (price guarantee, etc.). If we ultimately want a design that goes beyond the scope required by the DIN standard, we are also willing to pay for it.
Daniel-Sp schrieb:
Hi,
What is contractually fixed? So far, only underfloor heating according to aRdT.
xMisterDx schrieb:
Definitely expect a considerable surcharge if you want supply temperatures of 32 or 30°C (90°F or 86°F). From experience, we’re talking about a four-digit sum, so don’t be surprised.
It needs to be recalculated; more heating circuits are required, meaning larger manifolds, more piping, more installation effort, etc.
What’s expensive is mainly the labor and the technology. As mentioned above, we are basically willing to pay an extra price.
X
xMisterDx8 Dec 2023 21:38HausbauFrage schrieb:
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As mentioned above, we are basically willing to pay an additional price.That’s commendable. I just wanted to gently prepare you for the fact that construction companies often charge disproportionately high fees for change requests once the contract is signed, and especially once construction has already started.