ᐅ Heating System for New Construction – Which Is the Best Option?

Let’s get specific: what are some points a layperson can raise with a general contractor (GC), and how can a layperson recognize that the GC lacks proper knowledge?

It’s easy to say you should inform yourself beforehand, but what exactly should you research? Reading individual cases without knowing the specific conditions and that might not even be comparable? Or listening to statements from other laypeople who, apart from a strong opinion, neither have long-term experience nor appropriate training?

What exactly should you do when the GC says, “Based on the heating load calculation, we choose this or that system with so many kW and a buffer tank for these reasons”? Seriously, someone in a forum claimed this is nonsense and GCs have no clue about the topic?

So, what are concrete points—something like a checklist—that a homeowner can mentally run through to identify during discussions with the GC and/or planner that the project is being messed up?

And preferably something more concrete than “all GCs” don’t understand anything when buffer tanks are planned and “just inform yourself.” Ideally with sources or verifiable statements from professionals, because otherwise, it’s just an individual layperson’s opinion—who at best knows their own property—versus experts with experience from many projects, where the latter must also guarantee that the house will heat properly and maintain that heat over time. The former is in the comfortable position of remotely making claims about the local situation without any responsibility for the consequences of their statements.

Without concrete reference points, it’s really difficult, if not impossible, for the prospective homeowner to make a difference, isn’t it?

Joedreck schrieb:

What is needed here is a proper, precise design of the underfloor heating system; then you can efficiently heat with an air-to-water heat pump at a supply temperature of 30 degrees Celsius (86°F). And it only requires a bit more planning.

Where do you get that from? Certainly not from the general contractor, who already disqualified himself with his uninformed statement? A mechanical, electrical, and plumbing (MEP) planner? Many people (architects, general contractors, building inspectors, and even MEP planners themselves) say that such planning is overkill for a single-family house.

So how does a prospective homeowner obtain a "reasonable design," who carries it out, and how can they tell if the proposed solution is actually reasonable? What are the criteria for such a reasonable solution?

Don’t get me wrong, I’m not questioning your opinion, but for example, I’m right in the middle of heating system planning... but how am I supposed to know whether it might not be reasonable?

As an uninterested layperson, you simply can’t manage it either. I myself am nothing more than an interested layperson who has been dealing with this intensively for over 7 years.
The main contact is an engineering office. The floor plan and construction description are sent there. In theory, you could also do the heating load calculation yourself.
The engineer will then calculate the heating loads for you.
With that, you go to the HVAC professional. You tell them that at one of your design temperatures, you want a maximum supply temperature of 30°C (86°F), and that the room temperature should be, for example, 21°C (70°F).
Make sure to get this in writing.
This way, they size the underfloor heating system accordingly.

Regarding the other post: of course, it’s not wise to share an opinion online without understanding the background.
Not “all HVAC professionals” are incompetent, but a few simple questions can help reveal whether they are up to date or just follow a “we’ve always done it this way” approach.
Just ask for the room-by-room heating load calculation. Many won’t be able to provide that.
Or ask about the purpose of the buffer tank. With a properly designed underfloor heating system, you don’t need one because nearly all individual room controllers (except maybe two) are fully open most of the time, and the heat pump has the required flow rate.

The fact is that the rise of heat pumps has brought about different technical requirements to heat as efficiently as possible.
For an oil or gas heater, it didn’t really matter if you needed a few degrees higher supply temperature. Constant on/off cycles also didn’t bother them.
But these are exactly the efficiency killers for a heat pump.
I know that building a house involves a lot of planning and thinking, and it’s not something you do casually.
However, systems costing easily €30,000 are installed and cannot simply be changed afterward. So spending a couple of days researching online is worth it.

There are also very good HVAC professionals. I have had very good experiences with two myself.

Forgotten: warming up and staying warm... Yes, that's basically what the builder does in case of doubt. That is also the primary goal. But the efficient operation should not be neglected either. After all, you have to deal with the consequences of mistakes for the next 40 years.

I certainly do not claim to be an expert.
I am happy to give tips, if wanted.
Besides, everyone is able to compare TVs, cars, etc., and then make a choice. But when it comes to the final planning of a 400,000€ property, the current state of technology is not that relevant.
By the way, the heating installer is both a craftsman and a salesperson. Usually, they earned their master’s certificate many years ago. After that, they just worked.
Keeping up to date with rapid technical progress is not easy. And when it gets technically complicated, people tend to switch off.

In an older society where the Chancellor said around 2007 (I believe) something along the lines of “this internet is new for all of us,” nothing surprises me anymore. That’s why you really have to stay engaged yourself.

Joedreck schrieb:
As an uninterested layperson, you simply cannot do it either. I am also nothing more than an interested layperson who has been dealing with this intensively for over 7 years.
The point of contact is an engineering office. The floor plan and construction description are sent there. In theory, you can also do the heating load calculation yourself.
The engineer then calculates the heating loads for you.
You then take this to the builder. You tell them that for one of your design temperatures you want a maximum flow temperature of 30 degrees Celsius (86°F), for example, at a room temperature of 21 degrees Celsius (70°F).
Make sure to get this in writing.
That is how they size the underfloor heating.

Regarding the other post: of course, it is not wise to express an opinion on the internet without understanding the background.
Not "all builders" are incompetent, but with a few simple questions you can usually tell whether they are up to date or just follow a "we’ve always done it this way" approach.
Just ask for the room-based heating load calculation. Many builders won’t have one.
Or ask about the purpose of the buffer tank. If the underfloor heating is properly designed, you generally don’t need one, since all individual room controllers (except maybe 2) are fully open all the time and the heat pump has the necessary flow volume.

The fact is that with the introduction of heat pumps, different technical requirements have emerged for heating as efficiently as possible.
For an oil or gas heating system, it wasn’t very important if you needed a few degrees more flow temperature. Cycling on and off constantly didn’t really matter for these systems.
But those are exactly the efficiency killers for a heat pump.
I know home building involves a lot of planning and consideration, and it’s not a side job.
But systems are installed that easily cost €30,000 and cannot just be changed afterward. So it’s worth spending a couple of days doing some research online.

However, there are also very good builders. I have had very good experiences with two of them myself.

With gas and oil heating, it is definitely not insignificant to switch them on and off frequently. This can lead to condensate forming in the boiler, especially in condensing boilers, causing the boiler to corrode. It is even worse with oil heating because of the mixture of sulfur condensate.

The efficiency of oil or gas condensing boilers also suffers from this.

I deliberately chose the past tense. I probably should have been more specific. I also intentionally left out certain aspects here because this is not a technical discussion and I am only partially capable of addressing them.

And yes, efficiency and service life also suffer in that case. However, the heat pump is considerably more sensitive.