Hello everyone,
we are building a KfW 40 house with a Viessmann Vitocal 200-S heat pump and an 8 kW photovoltaic system.
The heat pump is also capable of cooling. The upgrade would cost 1000 € (only the heating installer, thermostats extra).
Is it generally worthwhile to cool using the heat pump? Just because it can does not necessarily mean it is practical.
How fast does a room cool down? Underfloor heating systems are usually quite slow in response.
Or does it make more sense to invest in an air conditioning system and operate it with the photovoltaic system on hot days?
Thanks and best regards
Markus254
we are building a KfW 40 house with a Viessmann Vitocal 200-S heat pump and an 8 kW photovoltaic system.
The heat pump is also capable of cooling. The upgrade would cost 1000 € (only the heating installer, thermostats extra).
Is it generally worthwhile to cool using the heat pump? Just because it can does not necessarily mean it is practical.
How fast does a room cool down? Underfloor heating systems are usually quite slow in response.
Or does it make more sense to invest in an air conditioning system and operate it with the photovoltaic system on hot days?
Thanks and best regards
Markus254
moHouse schrieb:
Thanks for the detailed report!
We are still waiting for the quote for the cooling function from our heating engineer.
Even a 3-4°C (5-7°F) difference makes a big impact in our current apartment. When the bedroom has warmed up during the day despite all measures, and you open the windows wide in the evening, I notice that a 3-degree drop can be the difference between "barely bearable" and "comfortable enough to sleep."
In the end, it’s always a question of cost. An air conditioning system is obviously better.
But:
How many hot days per year does one experience when it really becomes unbearable?
And is that price difference of around 4,000 euros worth it personally? For us, temperature control via underfloor heating costs about 4,000 euros. The most expensive part seems to be the controls. This is included in our price. Also, we will handle it through BAFA. I think we should get 35% of that back.
konibar schrieb:
No one would think of installing radiators on the ceiling.
Really? When I search for ceiling heating on Google, there are lots and lots of examples and offers.
Myrna_Loy schrieb:
80% relative humidity is already clearly too high. Mold can develop from 60%, and at 70% mold growth is likely on most surfaces.
Also, a single sensor provides little insight since different readings can occur in various parts of the rooms.
Air conditioning units cause more problems than benefits if you aim for a seasonal relative humidity range of 50–70%. Even the expensive ones. How does the interaction between underfloor heating, the temperature setting of the underfloor heating, and the ventilation system work? Since the air, and thus also the humidity, is controlled by the ventilation system, is that correct?
Acof1978 schrieb:
So the air and therefore the humidity are gone because of the ventilation system, right?No, because in summer, fresh air with the same humidity level is brought back inside in equal amounts. In winter, it is different since dehumidification works then. In summer, however, it does not, as the (large) temperature difference is missing.Mycraft schrieb:
No, because in summer fresh air with the same humidity enters in equal amounts. In winter, it is different because dehumidification works then. In summer, however, it does not, since the (large) temperature difference is missing.Even with an enthalpy heat exchanger? That’s what we will have as well.
As far as I understand it as a layperson, it can regulate the humidity.
Acof1978 schrieb:
How does the interaction work between underfloor heating, underfloor heating temperature control, and the ventilation system? Isn’t the air—and therefore the humidity—basically controlled by the ventilation system? During the summer months, our ventilation system only runs at night. If I run it during the day, no matter how much I shade, it pumps warm outside air into the house. Then there’s the heat recovery in modern systems—you can sometimes switch it off via a bypass or summer cassette, but it doesn’t help much when it’s 30°C (86°F) outside.
The underfloor heating is completely off because the heating system is in summer mode. The air conditioning runs daily, cycling on and off, and dehumidifies and cools. I would never want to live without air conditioning again; it’s a quietly humming quality-of-life addition mounted on the wall.
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