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
netuser schrieb:
Underfloor cooling does not replace air conditioning, of course. The full comfort benefit is ultimately only achieved with the latter.
However, underfloor cooling is indeed "effective" within its limited scope and still provides a noticeable increase in comfort. At least, that is our experience and that of all visitors who have come in...
We also don’t like cold floors, so there is only hardwood flooring throughout the house (except in the bathrooms).
The cooler wood usually feels pleasant and is rarely too cold. It’s ultimately a relative sensation because it really shouldn’t get too cold, at least not like in your example.
The floor temperature should not be more than 5-7°C (9-13°F) cooler than the room/air temperature to avoid condensation. So, if my set room temperature is, for example, 23.5°C (74°F) and the room heats up to 28°C (82°F), then the floor temperature is about 21°C (70°F), which helps with cooling. This obviously only works with continuous operation and proactive control, so that the room doesn’t heat up in the first place due to automatic temperature regulation. Ultimately, this method is also "limited," but with 23-25°C (73-77°F) indoor temperatures during current outside temperatures above 30°C (86°F), we are quite satisfied. That’s right; the risk of condensation caused by dew point shifts should not be underestimated. I wanted to cool my ceiling at the time as thermal building component activation (but several people advised against it, so I have no experience with it). However, as I said, I didn’t have indoor temperatures above 23°C (73°F) this summer even without cooling, so I will no longer buy the additional module for the brine-water heat pump for underfloor cooling.
RotorMotor schrieb:
Yes, you usually connect a ground heat exchanger to a brine-to-water heat pump, right? You are correct, but there are (although few) posts where it is used together with a mechanical ventilation with heat recovery system. And this is where my question comes from... As I said, I have no knowledge about this at all...
Nixwill2 schrieb:
You’re right, and yet there are (unfortunately few, but some) posts that discuss this in connection with a mechanical ventilation with heat recovery system. And that’s where my question comes from... As I said, I have no knowledge about this at all... The thermal reservoir would probably be a brine circuit and would cool the incoming air via a heat exchanger (cooling coil).
This would be my basic, non-professional idea of the system setup – as I said, I have no experience with this – but it should be more efficient than an earth tube system. I would be interested to know what something like this costs.
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WilderSueden23 Aug 2022 10:01netuser schrieb:
Underfloor cooling, of course, does not replace air conditioning. Full comfort can ultimately only be achieved through the latter. However, underfloor cooling is indeed "effective" within its limited scope and still provides noticeable comfort benefits. At least, that’s our experience and the feedback from all visitors who have been inside.... Underfloor cooling is especially useful when you can’t ventilate the heat out. Here in the office, we have the issue that no one is present between 7 p.m. and 7 a.m., so no one can ventilate the heat during that time. Thanks to underfloor cooling, the temperature starts at 24°C (75°F) in the morning instead of 28°C (82°F). The problem isn’t just the air temperature but also that a building made of reinforced concrete stores a huge amount of heat. Once it’s warmed up, you can’t simply ventilate the heat out within a few hours. Underfloor cooling draws heat from the walls, floors, and ceilings.
How large is the plot? If there is enough space, try to draw air from as far away from the house as possible.
Install the pipes as deep underground as possible (5m-10m (16-33 ft)). This way, the air is slightly preheated or precooled.
At night, set the ventilation to high with the bypass open, and during the day only to the lowest setting.
This is the typical design for a standard controlled mechanical ventilation system, just like with underfloor cooling—a buffer. The air is not dehumidified either.
With an air conditioning system, you cover all needs. If you require it, the sun is shining, and you can run it on your photovoltaic electricity.
Install the pipes as deep underground as possible (5m-10m (16-33 ft)). This way, the air is slightly preheated or precooled.
At night, set the ventilation to high with the bypass open, and during the day only to the lowest setting.
This is the typical design for a standard controlled mechanical ventilation system, just like with underfloor cooling—a buffer. The air is not dehumidified either.
With an air conditioning system, you cover all needs. If you require it, the sun is shining, and you can run it on your photovoltaic electricity.
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