ᐅ Cooling with a heat pump through underfloor heating?

Bookstar schrieb:

1. During those 3 months, it’s only hot for a maximum of 6 weeks. The rest of the time, you can ventilate naturally.
2. Even without air conditioning, the indoor temperature here maxes out at 26 degrees Celsius (79°F), even when it’s 40 degrees Celsius (104°F) outside.
3. Today’s youth vote Green but then install air conditioners so they don’t sweat.

Almost right:
Voting Green but installing air conditioners to make the damage caused by 20 years of voting Black bearable, and then running the air conditioner with solar panels on the roof. 😎

I would generally distinguish between "opinions" and "experiences" – unfortunately, this is not clearly evident in many statements in this thread.

Here is an EXPERIENCE report based on:
- own house: air-to-water heat pump (Viessmann) with active cooling function via underfloor heating
- parents' house: air conditioning system

• My conclusion from this specific example:
On a summer day without active cooling: temperature in the attic is 28°C (82°F). When I activate the cooling, it goes down to 24°C (75°F) (lower temperatures are difficult due to condensation on the pipes). For me, as someone sensitive to heat, this difference is just enough to sleep comfortably in the attic. The PERCEIVED reduction in heat stress is significant!
This function is therefore excellent for preventing indoor spaces from overheating despite high outdoor temperatures.
• Pro compared to air conditioning: very pleasant cooling, no dry air
• Con compared to air conditioning: the indoor spaces don’t get really cold/cool. On a typical summer day, 23/24°C (73/75°F) is the limit. Those who want lower temperatures need air conditioning.

Overall, a clear recommendation for the cooling function

Thank you! You describe your experience starting from 28°C (82°F). Do you also have experience with cooler starting temperatures (for example, how low can you go starting from 24°C (75°F))?

Strahleman schrieb:

We find summer especially unbearable when high temperatures are combined with high humidity. Whether it’s a brine-to-water heat pump or an air-to-water heat pump, the humidity that ultimately causes the muggy and uncomfortable feeling is not reduced by them. Only an air conditioning system can achieve that. Cooling with a heat pump is nice, but it’s not comparable to an air conditioner. ...

Unfortunately, the argument about muggy air is often omitted here, so thanks for pointing it out. We also decided against cooling with the summer bypass of the air-to-water heat pump and are now adding an air conditioning system as well. I see it the same way: on one hand, the extreme temperatures are rising, and on the other, even at "just" 28°C (82°F), there can already be very uncomfortable humidity. The summer bypass of the air-to-water heat pump doesn't help me at all in that situation.

kati1337 schrieb:

We chose air conditioning instead of the special cooling function of the air-to-water heat pump. From most sources I heard that on really hot days, when you want to cool, lowering the temperature by 2-3°C (4-5°F) through an air-to-water heat pump/floor heating pipes is not enough. For us, it was important to have a working cooling system especially on days over 35°C (95°F), and if it’s 37°C (99°F) outside, I don’t want it to be 34°C (93°F) inside.

That was exactly our reason not to go for it.

nordanney schrieb:

At some point, the heat gets into every house – planning or not. And then you get the unlucky case where not only does the cold stay outside, but the heat is trapped inside as well. At that point, only an air conditioning system helps.

That’s true, and in the long run, I can’t imagine it being comfortable to constantly walk or sit on cooled floors while it’s still muggy and warm upstairs.

Hangman schrieb:

Thank you! You describe your experience starting from 28°C (82°F). Do you also have experience with cooler starting temperatures (for example, how far can you lower it from 24°C (75°F))?

Unfortunately, I don’t have experience with lower temperatures because I see no need for cooling below 25°C (77°F).
The limiting factor is the dew point. With my cooling system, you can lower the room temperature to about 4°C (7°F) above the dew point; below that, the pipes—which have to be significantly cooler than the target temperature—start to sweat.
Specifically: the cooler it is outside, the more you can cool inside.

drno1234 schrieb:

• My conclusion based on this specific example:
Summer day without active cooling: temperature in the attic at 28°C (82°F). When I activate the cooling, it drops to 24°C (75°F) (lower temperatures are difficult due to condensation on the pipes). For me, as someone sensitive to heat, this difference is just enough to sleep comfortably in the attic. The perceived reduction in heat stress is significant!
This function is therefore excellent for preventing indoor spaces from overheating despite high outdoor temperatures.

Thanks for the experience report!

We are still waiting for the offer for the cooling function from our heating contractor.
A 3-4°C (5-7°F) difference already makes a big difference in our current apartment. When the bedroom has warmed up during the day despite all measures and you open the windows wide at night, I notice that a 3°C (5°F) cooling can be the difference between "barely bearable" and "comfortable for sleeping."

In the end, as always, it’s a matter of price. Air conditioning is clearly better.
But:
How many hot days per year are there when you personally just can’t tolerate the heat anymore?
And is that difference worth around 4000 euros to you?