ᐅ Cooling with a heat pump through underfloor heating?

hanse987 schrieb:

Radiators no, but large-area heating and cooling ceiling systems are, for example, almost standard in high-end office buildings. The whole system works primarily through radiation rather than convection. So I think "Nobody" is not entirely correct!

Maybe the technology has advanced compared to a few years ago. But I once had an office like that, and it ended with the women sitting under their desks in winter with electric fan heaters, while the men were too proud to do so ;-) In short: it didn’t work at all. The architecture firm was also sued over this and other planning errors but eventually went bankrupt....

80% relative humidity is already clearly too high. Mold can develop at 60%, and at 70%, mold growth can be expected on most substrates.
A single sensor provides little useful information since different values can occur in different parts of the rooms.
Air conditioning systems cause more problems than benefits if you want to maintain a seasonally adjusted relative humidity range of 50-70%. This applies even to the expensive units.

drno1234 schrieb:

A dew point sensor is installed on the supply line between the heat pump and the heating distribution manifold. It measures the relative humidity directly at the pipe and disables the cooling function if a definable threshold is exceeded. Mine is set to 80% because mold can form above this relative humidity.
The threshold can be set higher, since the floor temperature will always be higher than the supply pipe temperature—so high humidity on the pipe does not necessarily mean that moisture is present on the floor. Since the effect is, as explained above, more than sufficient for me, I leave it at 80%.

Maybe the technology has advanced compared to a few years ago... sitting under the desk in winter with an electric fan heater... In short: it simply didn’t work at all.

Maybe the technology has improved, but the physics remain the same:

1. There is no such thing as "cold radiation." If you feel a spot in the room is colder, it is at most due to missing heat reflection. But in this case, that would come from below, which doesn’t help and only results in cold feet.

2. A large surface heat source on the ceiling (in a reversed setup) would have practically no radiant heat effect at the typically low supply temperatures of heat pumps. For that, the supply temperature would need to be well above 60°C (140°F). That is why hardly anyone uses this approach.

The fundamental design principle is therefore:
never work against natural convection, but always support it.
(This is why, in traditional building construction, radiators are always placed below window sills.)

Search for rooms where the heating is used for cooling; this is from the Fraunhofer Institute.

But the worst part is the electricity consumption of air conditioning units.

konibar schrieb:

2. A large-area heat source on the ceiling (in the case of reversed principle) would have practically no radiant heat effect at the typically low supply temperatures of heat pumps. For that, the supply temperature would have to be well above 60°C (140°F). That is why almost no one does it this way.

Such a system must run at a maximum of 40°C (104°F), otherwise it would be uncomfortably hot.

Myrna_Loy schrieb:

Air conditioning systems cause more problems than benefits,

Are you referring to conventional air conditioning units or the floor cooling system combined with underfloor heating?

konibar schrieb:

Never fight against natural convection; always work supportively with it.

That would also be my basic understanding, although I’m not a physicist. Based on my own experience with such a ceiling heating system, I still don’t understand why some people want to cool their floors while others want to heat the ceiling when warm air naturally rises from the bottom up.

I see two effective options: either endure the heat or use a real air conditioning system. The latter also dehumidifies the air, which underfloor heating cannot do. And even when I’m cooking or baking a pizza at 250°C (482°F) in summer, the AC keeps the room nice and cool. A floor that’s only 2-3°C (4-5°F) cooler doesn’t help me at all in that situation.