ᐅ Underfloor heating on the ground floor and upper floor, radiators in the basement?

Hi everyone,

We are planning to build a single-family house next year with about 170 sqm (1,830 sq ft) and a full basement. The basement will be constructed as a waterproof concrete structure (“WU slab”) with 100 mm (4 inches) perimeter insulation. Heating will be provided by a gas boiler (Vaillant Vitodens 300-W). Underfloor heating will be installed on the ground floor and upper floor, but the question is about the basement.

In the basement there will be an office (just for normal private use and occasionally working from home, so not permanent use), a workshop room, and a large room (40 sqm (430 sq ft)) used for general storage. This might eventually be divided to create a multipurpose room for the kids. So, a pretty normal basement.

I think equipping the basement fully with underfloor heating is excessive given the additional costs charged by several general contractors, with the highest quote being more than 50 euros per sqm (about $50 per sq ft) extra!

My plan is to install regular radiators on the walls in the basement, just one or two sizes larger than normal, and run them at a flow temperature of 35°C (95°F). That’s it. Is there any reason not to do this? It doesn’t need to be exceptionally warm down there—I just want to be able to raise the temperature from about 15°C up to 20-21°C (59-70°F).

One of the contractors keeps trying to push electric heaters on me (because it’s less work for him), but I definitely do not want electric heating. We currently live in a house with a waterproof basement. As the first occupants, we had to keep the basement gently heated to keep it dry, and without continuous low-level heating, the basement would never have dried out. Heating 85 sqm (915 sq ft) electrically for three years straight is not a smart idea in my opinion.

Another contractor says, “No, flow temperatures that low won’t work; you need a completely different heating system with two heating circuits, etc.” My parents’ house was built in 1971, and for 20 years, we hardly ever set the flow temperature above 38°C (100°F)... it worked perfectly and drove the heating technician crazy!

So, has anyone here implemented something similar (underfloor heating on ground and upper floors, and regular radiators in the basement) and can share their experience? Or does anyone have other suggestions? Maybe wall or ceiling heating?

Thanks and best regards,

Andreas

If they charge 50 euros per square meter in the basement, they should do the same upstairs since the effort is basically the same.

I would try to find someone who doesn’t want to overcharge you and can install underfloor heating – that makes the most sense. Although with the gas boiler, you could probably run it at 35°C (95°F) or higher flow temperature, radiators really aren’t state of the art anymore.

Our installer recommended radiators with built-in fans to distribute the warm air for this situation (my quick Google search just now led me to, for example, "Zehnder Nova Neo"). He said this would be absolutely sufficient for a basement room and would work well.

@Sebastian79

Sure, they will also charge the €50 per square meter (about $54 per square yard) for the basement. But I find the additional cost completely unreasonable. I’m open to discussing an extra €20-25 per square meter (about $22-27 per square yard), but that’s where the limit of extra effort lies. Even the €25 surcharge adds up to €2000 (about $2150) per floor given the house size.

For me, radiators still have a certain charm. I like their quick response time, and in winter I can dry my wet sports clothes on them. Also, in my basement room I’m a bit concerned about having too many items stored on the floor that could cover up the underfloor heating too much. Plus, the dry indoor air radiators produce is exactly what I want in the basement.

PS1: Just because a technology has existed for a long time doesn’t mean it’s inherently bad: The wheel was invented 5,000 years ago, and no one has come up with a better idea since then…

PS2: And by that logic, underfloor heating would have to be considered outdated since the Romans already used it, while radiators have only been around for about 150 years.

Okay, *smartass mode off*


@Robbaut

Thanks for the tip, I’ve considered things like those too. But unfortunately, they are so expensive that underfloor heating ends up being much cheaper. Depending on the size, those units cost between €700-900 (about $750-970), while a standard radiator is easily €150-200 (about $160-215). So we’re talking about roughly €600 (about $645) additional cost—without including the extra installation effort, since they also require an electrical connection. With five radiators in the basement, that’s easily €3,000 (about $3,220) extra. I might as well just go with underfloor heating then.

I think these devices are a great solution when renovating and installing a heat pump (for whatever reason), or if you simply need more heating capacity but can’t fit a larger radiator. But for new builds, I don’t really see a use case. Or am I missing something?

Best regards,

Andreas

Why should radiators with low flow temperatures respond quickly? How do you conclude that they produce drier air than a surface heating system?

You should understand what I meant by "old" – in a modern house with low flow temperatures, these units are simply outdated – the space requirement should not be underestimated either if they are to run efficiently.

I still don’t understand why there is an extra charge for the basement but not for the upper floors.

I think the additional cost comes from the fact that heating is usually not planned for the basement. How often will the room be used? Perhaps an electric solution could be considered, which is only turned on for short periods?