ᐅ Who should you entrust with the room-by-room heating load calculation?

Hello everyone,

Do heating system installers know that underfloor heating is best sized and planned using a room-by-room heat load calculation?

Is the room-by-room heat load calculation also important for selecting the heat pump (in our case either water-to-water or ground-to-water), or is the "overall heat load calculation" of the entire building according to DIN 12831 sufficient?

If my architect does not offer this, who should I turn to? What should I look for in the phone directory / on the Internet to find a professional who can assist me with this?

From what I have read here in the past months, a room-by-room heat load calculation is very important. A precise calculation can save money because the heat pump selected accordingly will operate more efficiently, allowing the house to be heated more effectively.

Thank you for your answers,
Greetings from BaWü
Ann.

PS: Am I mistaken, or can the overall heat load calculation according to DIN 12831 really be verified or recalculated by oneself (assuming you have all the U-values of the building envelope, of course)? Are there already ready-made templates available on the Internet for this? Maybe also for the room-by-room heat load calculation, or is that usually too complex for the homeowner?

I’m also currently working on this topic a bit ^^

So, if I understand correctly, you don’t initially need a room-by-room heating load calculation to select the heat pump.
It’s enough to know the total heating load of your entire house. The heat pump is supposed to heat the whole house, not each room individually.

However, when it comes to installing the underfloor heating, you do need a room-by-room heating load calculation so you know how many meters (feet) of heating pipe to lay in each room.

And then for setting up the heat pump, this calculation is probably useful again.

It’s best to avoid individual room control and keep the flow temperature as low as possible. A hydraulic and thermal balancing must also be done.

Alright, I hope this is correct—if not, please correct me.
I’m just starting to get into this topic.

What I’m wondering is: how do I find an installer who CAN do all this and actually WANTS to do it?
That seems really difficult. Maybe the HTD forum can offer some hints on suitable installers.
And how do I bypass the requirement for individual room control? Or will this probably not be checked anyway? So maybe it’s enough to agree with the installer and just not spread the word?

Are there people here who have implemented it this way?

I’ll be following along with interest and hope I haven’t said too many wrong things ^^

Best regards
Specki

Specki schrieb:

What I’m wondering is: how do I find a plumber who KNOWS how to do all this and actually WANTS to do it.

That’s exactly what’s bothering me too. Sure, the heating installer will probably handle it when installing the underfloor heating, but – without meaning to criticize all heating installers – usually it’s done quickly, roughly, and “good enough.” But the idea that a detailed room-by-room calculation could make the system more efficient and save energy is probably not a priority for them. So who do you bring on board if you want it done as precisely as possible (meaning efficiently and sparingly for the heating system)?

No, the way you described it with the underfloor heating and pipe length, that’s how I’ve summed it up here, too. I’ve also read a lot about the ERR (electronic room thermostat). If you want to do everything strictly according to regulations, you can apply for an exemption at the local authority. But it probably depends on the local officer whether they accept it or not (search online for the thread “Planning underfloor heating – completely without ERR?”). Or you might find a heating installer who then knowingly overlooks the rules. Or you install everything with the absolute minimum effort and then disconnect the ERR again.

The most professional and therefore also the most cost-effective way to carry out a heating load calculation according to DIN 12831 is to have it done by an engineering firm specializing in building services engineering (technical building systems), or more conventionally: building services. Occasionally, building energy consultants or energy advisors listed by KfW-dena are also qualified to perform this, but usually at significantly higher costs. Heating/plumbing companies generally do not offer this service because it is too complex. However, the architect overseeing your construction project should be able to refer you to a suitable firm if they are managing your build.

You can calculate the heating load using MH software (free freeware), but you’ll need to spend a couple of evenings working with it.

The result will never exactly match the calculation from your heating contractor, general contractor, or HVAC specialist. Even those professionals don’t produce identical results among themselves.

Nowadays, heating contractors usually don’t do this during the bidding phase. Instead, they get this calculation as a service from their preferred supplier of heat generators and underfloor heating systems. As a result, the calculations tend to be quite superficial, which may be due to the limited time available.

In the past, when I worked in the industry, heating companies did the calculations themselves, and apprentices were taught how to perform them in vocational school.

A heating engineer will be able to do this. I wouldn’t hire a specialized engineer (building services engineering) for it, unless you have plenty of money. Just don’t expect it to be done free of charge during the quotation phase. Have the calculation specifically included in the offer and request the documentation for it.