ᐅ Controlled Residential Ventilation with Cooling: Ground Source Heat Pump Using Brine Loop Instead of Air-to-Water Heat Pump?
Created on: 3 Jan 2019 22:37
C
Christian K.
Hello everyone,
So far, I assumed that cooling with a mechanical ventilation system with heat recovery is done using an additional device that can be retrofitted later. This seems to be only partially true, as it is indeed an additional device, but retrofitting it later is difficult. Or are there systems that operate purely electrically? In our case, a photovoltaic system would be available, so we could technically cool using electricity in the summer.
Cooling with a mechanical ventilation system with heat recovery is done either with an earth-to-air heat exchanger (EWT) or a ground heat exchanger (ground loop). Since we need to raise the ground level by about 1.5m (5 feet), we could save on excavation work. It would be interesting to know what a ground heat exchanger would cost. So far, I haven’t found any concrete information because frequently only ground-source heat pumps are mentioned and not ground heat exchangers for mechanical ventilation systems, or if so, usually together with excavation work.
In my research, I came up with the idea of replacing our planned air-to-water heat pump with a ground-source heat pump. After all, I would have to install a system for cooling the mechanical ventilation anyway, so I could just extend the installation somewhat and switch to a ground-source heat pump, right? Or is it not that simple, and what disadvantages would there be? The costs are, of course, also interesting here, especially considering that we wouldn’t have additional excavation work.
I wasn’t able to find clear answers to these three questions and hope someone here can provide some clarification.
Good luck, CK
So far, I assumed that cooling with a mechanical ventilation system with heat recovery is done using an additional device that can be retrofitted later. This seems to be only partially true, as it is indeed an additional device, but retrofitting it later is difficult. Or are there systems that operate purely electrically? In our case, a photovoltaic system would be available, so we could technically cool using electricity in the summer.
Cooling with a mechanical ventilation system with heat recovery is done either with an earth-to-air heat exchanger (EWT) or a ground heat exchanger (ground loop). Since we need to raise the ground level by about 1.5m (5 feet), we could save on excavation work. It would be interesting to know what a ground heat exchanger would cost. So far, I haven’t found any concrete information because frequently only ground-source heat pumps are mentioned and not ground heat exchangers for mechanical ventilation systems, or if so, usually together with excavation work.
In my research, I came up with the idea of replacing our planned air-to-water heat pump with a ground-source heat pump. After all, I would have to install a system for cooling the mechanical ventilation anyway, so I could just extend the installation somewhat and switch to a ground-source heat pump, right? Or is it not that simple, and what disadvantages would there be? The costs are, of course, also interesting here, especially considering that we wouldn’t have additional excavation work.
I wasn’t able to find clear answers to these three questions and hope someone here can provide some clarification.
Good luck, CK
S
Steffen8028 Jan 2019 12:13Christian K. schrieb:
I will stick with an air-to-water heat pump, but as far as I know, you could completely replace it with a ground source heat pump. With deep drilling, that's no problem. As for a ground collector, it’s possible as far as I know, but probably not feasible. You need really long pipes, which isn’t doable on today’s small plots.
Who says that? Define cooling. If you mean that it doesn’t replace an air conditioner, then that’s correct. A mechanical ventilation with heat recovery can lower the temperature by about 2–3 degrees, so it can provide some cooling. But yes, it’s not comparable to an air conditioner that reaches a specific temperature (e.g., 18°C (64°F)).
We are currently planning to install a cooling coil ahead of the mechanical ventilation, which will cool the air slightly in summer. A 2–3 degree drop is enough for us because there is a difference between having 26°C (79°F) or 24°C (75°F) in the room, and it’s also better for the immune system ;-)This is simply nonsense. A mechanical ventilation system with heat recovery might consume 60 watts and is supposed to reduce the indoor temperature in the entire house? Every person present generates about 60 watts of waste heat alone. The ventilation system does not reduce anything, at least not in a noticeable way. This is complete rubbish!
C
Christian K.28 Jan 2019 12:30What does the performance of the mechanical ventilation with heat recovery have to do with cooling? Of course, the ventilation system itself does not provide cooling; it distributes the cooled air. The air can be pre-cooled either through a ground heat exchanger or a cooling coil. For example, if the outdoor air temperature is 35°C (95°F) and the indoor temperature is around 28°C (82°F), it already helps if cooler air at 26°C (79°F) is drawn in through the mechanical ventilation system instead of 35°C (95°F) air. The cooling is not done by the mechanical ventilation system itself.
S
Steffen8028 Jan 2019 14:47This still has nothing to do with "cooling" but rather with preventing the mechanical ventilation system from "heating" the space 🙂 This is also called a summer bypass ..
S
Steffen8028 Jan 2019 14:48Another example: If we heat the living room to 25°C (77°F) using the fireplace while the bedroom is at 16°C (61°F) (this happened recently when it was minus 10°C (14°F) outside)... what do you think? Does the mechanical ventilation with heat recovery warm the bedroom even by 0.1 degrees? It does not..!
C
Christian K.28 Jan 2019 15:14Steffen80 schrieb:
This still has nothing to do with "cooling," but rather with preventing the mechanical ventilation system from "heating" 🙂 It’s also called a summer bypass .. You are mixing things up here. A summer bypass means that the heat recovery function is not activated during the night in summer, so that the cooler air goes directly into the house instead of being preheated like in winter. During the day in summer, the heat recovery can also be used to cool the incoming warm outside air by using the cooler indoor air—just the opposite of winter. That has nothing to do with active cooling, which is correct.Here, we are talking about a ground heat exchanger or a cooling coil that cools the outside air before it enters the mechanical ventilation system.
I also don’t understand what you mean with your example of the living room/bedroom. If you understand how a central mechanical ventilation system is set up, you know that the temperatures of individual rooms do not affect each other, since the air from one room is not blown into another. That would mean, for example, that the exhaust air from the kitchen heats the bedroom and the exhaust air from the guest bathroom heats the living room. But you have already acknowledged that the mechanical ventilation system does not raise the bedroom temperature by 0.1 degrees.
S
Steffen8028 Jan 2019 15:30Okay. Then I mixed that up. But I still stick to my opinion: cooling with the help of controlled mechanical ventilation doesn’t work... the air circulated by the controlled mechanical ventilation... it’s ridiculous. Everything else is mostly just marketing talk from the seller. If it’s hot for an extended period in summer (like last summer), your place will eventually get very warm. Whether it’s 26, 27, or 28 degrees Celsius (79, 81, or 82 degrees Fahrenheit) – it doesn’t matter. It’s very warm... and there’s only one solution: air conditioning!
Similar topics