ᐅ Using a geothermal basket to precondition the air for a mechanical ventilation with heat recovery system?
Created on: 22 Aug 2022 18:14
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Nixwill2
Hello everyone,
From the beginning, I’ve been thinking about how to keep the temperature at a comfortable level (24° to 25°C (75°F to 77°F)) in our new house during the summer. We will have underfloor heating with a heat pump and cooling function. At least, we want to have air conditioning provisioned.
Since we will have a mechanical ventilation system with heat recovery, I’m also wondering if it’s really ideal to have warm outdoor air blown into the house.
Today, by pure chance, I came across something called a ground heat exchanger.
Does anyone have any experience with whether this is effective for pre-cooling the air? Of course, it should also have the positive effect of pre-warming the air in winter.
It doesn’t seem very complex and is supposedly relatively uncomplicated even in a water protection area.
I have no knowledge about heating or anything like that, so I’m just asking openly…
Best regards,
Nixwill2
From the beginning, I’ve been thinking about how to keep the temperature at a comfortable level (24° to 25°C (75°F to 77°F)) in our new house during the summer. We will have underfloor heating with a heat pump and cooling function. At least, we want to have air conditioning provisioned.
Since we will have a mechanical ventilation system with heat recovery, I’m also wondering if it’s really ideal to have warm outdoor air blown into the house.
Today, by pure chance, I came across something called a ground heat exchanger.
Does anyone have any experience with whether this is effective for pre-cooling the air? Of course, it should also have the positive effect of pre-warming the air in winter.
It doesn’t seem very complex and is supposedly relatively uncomplicated even in a water protection area.
I have no knowledge about heating or anything like that, so I’m just asking openly…
Best regards,
Nixwill2
@TmMike_2
Thanks to your keywords, I think I’m getting closer to understanding.
Currently, a Zehnder ComfoAir system is planned. If I’m interpreting this correctly as an ABSOLUTE beginner, for the project with a ground heat exchanger coil, in addition to the ComfoAir, you also need the ComfoFond-L ground heat exchanger—so an additional pre-unit plus, of course, the ground heat exchanger coil with all the necessary components.
I believe that the air conditioning here will not only make more sense, as rick2018 explained (since photovoltaic panels will be installed), but overall could also be almost cost-equivalent with significantly higher efficiency. These are just my assumptions; it would be great if someone with expertise could confirm the need for the pre-installed ground heat exchanger and the ground heat exchanger coil.
Thanks to your keywords, I think I’m getting closer to understanding.
Currently, a Zehnder ComfoAir system is planned. If I’m interpreting this correctly as an ABSOLUTE beginner, for the project with a ground heat exchanger coil, in addition to the ComfoAir, you also need the ComfoFond-L ground heat exchanger—so an additional pre-unit plus, of course, the ground heat exchanger coil with all the necessary components.
I believe that the air conditioning here will not only make more sense, as rick2018 explained (since photovoltaic panels will be installed), but overall could also be almost cost-equivalent with significantly higher efficiency. These are just my assumptions; it would be great if someone with expertise could confirm the need for the pre-installed ground heat exchanger and the ground heat exchanger coil.
WilderSueden schrieb:
Underfloor cooling is especially useful when you can’t ventilate the heat out. Here in the office, we have the problem that no one is there between 7 p.m. and 7 a.m., so the heat can’t be aired out during that time. With underfloor cooling, the temperature in the morning starts at only 24°C (75°F) instead of 28°C (82°F).
The problem isn’t just the air but that a building made of reinforced concrete stores a huge amount of heat. Once it’s heated up, you can’t simply air out the heat in a few hours. Underfloor cooling removes heat from the walls, floors, and ceilings. Since underfloor cooling is definitely planned for our house, I thought that adding the “geothermal loop & controlled ventilation system” could help delay the use of air conditioning by several years. That might still work for quite a while, but since costs also matter and the air conditioning is going to be pre-installed anyway, this plan will probably fall through...
Nixwill2 schrieb:
@TmMike_2
I believe the air conditioning system here will not only make more sense, as rick2018 explained (since photovoltaic will be available), but overall it will also be almost the same price with significantly higher efficiency. These are just my assumptions; it would be great if someone with expertise could confirm the setup with the pre-installed ground heat exchanger and ground heat basket.Exactly. Since all other factors (climate preparation, photovoltaic system, etc.) are already in place, I would save the additional expenses for the ground heat basket and directly opt for the air conditioning system. In terms of cost, you probably won’t be worse off, but it will be much more effective for the desired cooling and dehumidification. Even a single unit on the upper floor should significantly contribute to cooling.
Since last year, we have been living in a KfW40 house built with a timber frame structure (with a solid basement). We can cool passively using the ground-source heat pump and have also prepared the system for air conditioning. We decided against using an air well or earth heat exchanger – that seemed like too much effort for too little expected benefit (as already mentioned, air is a poor medium for this).
This summer, we tested what is possible with shading and ventilation alone: ventilation set to minimal during the day, the second-highest setting at night, and the highest setting in the mornings and evenings.
With this approach, indoor temperatures mostly stayed between 22 and a maximum of 24°C (72 and 75°F) on the upper and ground floors, except for up to 26°C (79°F) in the open-plan living area with kitchen in the evenings, and 20-23°C (68-73°F) in the basement. At the moment, we have therefore postponed using cooling through the underfloor heating system.
So, if good shading and ventilation are possible, a house like this remains very comfortable.
This summer, we tested what is possible with shading and ventilation alone: ventilation set to minimal during the day, the second-highest setting at night, and the highest setting in the mornings and evenings.
With this approach, indoor temperatures mostly stayed between 22 and a maximum of 24°C (72 and 75°F) on the upper and ground floors, except for up to 26°C (79°F) in the open-plan living area with kitchen in the evenings, and 20-23°C (68-73°F) in the basement. At the moment, we have therefore postponed using cooling through the underfloor heating system.
So, if good shading and ventilation are possible, a house like this remains very comfortable.
@DaHias81
Thank you for sharing your experience; it gives hope...
I have a few more questions for you.
Let’s start with the simple ones 🙂. What exactly is an “Allraum”? Is it a combined kitchen and dining area?
And what does “hintengestellt” mean—does it mean turned off or deactivated?
May I ask who supplied your house? We are also building with a solid basement, and except for the Allraum, I find your temperatures really good! Who provides your mechanical ventilation with heat recovery system? Can you program it the way you described, or do you have to adjust it manually?
Why didn’t you turn on the underfloor cooling to lower the temperature in the Allraum a bit? So this year you are doing it completely without extra night ventilation through the windows?
May I also ask where you live? Just the region is perfectly fine… I’m in southern Germany, where it often gets noticeably warmer than in the north, for example.
Thank you for sharing your experience; it gives hope...
I have a few more questions for you.
Let’s start with the simple ones 🙂. What exactly is an “Allraum”? Is it a combined kitchen and dining area?
And what does “hintengestellt” mean—does it mean turned off or deactivated?
May I ask who supplied your house? We are also building with a solid basement, and except for the Allraum, I find your temperatures really good! Who provides your mechanical ventilation with heat recovery system? Can you program it the way you described, or do you have to adjust it manually?
Why didn’t you turn on the underfloor cooling to lower the temperature in the Allraum a bit? So this year you are doing it completely without extra night ventilation through the windows?
May I also ask where you live? Just the region is perfectly fine… I’m in southern Germany, where it often gets noticeably warmer than in the north, for example.
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