ᐅ Air-to-Air vs. Air-to-Water Heat Pump for a KfW55 House – Importance of Cooling Function
Created on: 26 Jun 2023 14:32
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nanella
Hello everyone,
we are currently deciding between several prefab house suppliers, and a major difference is the heating system offered. Some suppliers install an air-to-air heat pump as standard (cooling available at extra cost), while others provide an air-to-water heat pump with underfloor heating and a ventilation system with heat recovery (an air conditioning unit can be added). Geothermal or groundwater as a heat source will likely not be an option for the plot we are currently considering. It will be a KFW 55 house, initially without photovoltaics for cost reasons, but solar panels are planned to be added later.
We have already read quite a bit on the topic, but as laypeople, we find it difficult to make a decision regarding the heating system. It is important to know that we are very sensitive to heat and want to include active cooling right from the start. In the worst case, we would need to heat/cool only individual rooms.
These are the advantages and disadvantages we know so far:
In principle, this results in 3 options that we are currently considering (we were advised against underfloor heating with cooling function for the reasons mentioned):
Which option would you prefer, or do you see another solution? Do you have any ideas which option would be better in terms of running costs? Because we probably have a rather expensive plot and need to watch costs during construction, air-to-air currently sounds like the better solution to us.
We would appreciate your assessments.
we are currently deciding between several prefab house suppliers, and a major difference is the heating system offered. Some suppliers install an air-to-air heat pump as standard (cooling available at extra cost), while others provide an air-to-water heat pump with underfloor heating and a ventilation system with heat recovery (an air conditioning unit can be added). Geothermal or groundwater as a heat source will likely not be an option for the plot we are currently considering. It will be a KFW 55 house, initially without photovoltaics for cost reasons, but solar panels are planned to be added later.
We have already read quite a bit on the topic, but as laypeople, we find it difficult to make a decision regarding the heating system. It is important to know that we are very sensitive to heat and want to include active cooling right from the start. In the worst case, we would need to heat/cool only individual rooms.
These are the advantages and disadvantages we know so far:
| Heat Pump | Advantages | Disadvantages |
| Air-to-Air with Cooling Function |
|
|
| Air-to-Water with Underfloor Heating + Air Conditioning |
|
|
| Air-to-Water with Underfloor Heating with Cooling Function |
|
|
In principle, this results in 3 options that we are currently considering (we were advised against underfloor heating with cooling function for the reasons mentioned):
- Install air-to-air heat pump with cooling function
- Install air-to-water with underfloor heating, add air conditioning when photovoltaics are installed, and live with the heat until then
- Install air-to-water with underfloor heating and air conditioning, tolerate high cooling costs until photovoltaics are added
Which option would you prefer, or do you see another solution? Do you have any ideas which option would be better in terms of running costs? Because we probably have a rather expensive plot and need to watch costs during construction, air-to-air currently sounds like the better solution to us.
We would appreciate your assessments.
R
RotorMotor5 Jul 2023 09:28In my opinion, with an air-to-water heat pump, it is always just a "software update" or simply a license key. The licensing models are determined individually by each manufacturer or heating specialist. Whether it involves one or two devices does not initially affect this.
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WilderSueden5 Jul 2023 09:33I think the tail is wagging the dog here. Whether to use one device or two is a matter of personal preference. Personally, I would prefer to have two devices so they can be replaced independently. Then you can address the cooling issue.
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KatlarOne5 Jul 2023 09:42Okay, interesting, that’s how the consultant explained it to us in the customization area.
However, we only have these two heating systems to choose from – maybe the key is simply more expensive with Viessmann.
What is the search term for the cooling system? I would check directly with the manufacturer for both models.
However, we only have these two heating systems to choose from – maybe the key is simply more expensive with Viessmann.
What is the search term for the cooling system? I would check directly with the manufacturer for both models.
KoalasAreCute5 Jul 2023 09:44WilderSueden schrieb:
Personally, I would prefer to have two separate units so they can be replaced independently. A small real-life example. Our solar technician in the old house probably caused a short circuit during the installation of the photovoltaic system. This damaged the circulation pump in the heat pump. We didn’t notice anything until the day after moving in, when we realized the house was quite cold. Customer service couldn’t fix it; the manufacturer’s service had to handle it. They could be there as soon as three days later. We bridged those three days by heating with the air conditioner. It was very expensive, but better than freezing in a cold house with a small baby.
Since my plumber is still on vacation this week, I turned to the internet for help. Perhaps someone here has the same heat pump and can confirm this information. In advance, we are having a Vaillant VWL 75/6 installed. It is an air-to-water heat pump with underfloor heating.
According to my research, activating the cooling function only requires the appropriate coding resistor (costs around 30-60€) and that should be it.
I’m quoting ChatGPT here, as it summarized my entire research very well:
According to my research, activating the cooling function only requires the appropriate coding resistor (costs around 30-60€) and that should be it.
I’m quoting ChatGPT here, as it summarized my entire research very well:
To install the coding resistor, you must first switch off the power to the heat pump or the hydraulic station. Then, remove the cover of the heat pump or the hydraulic station. Next, insert the coding resistor into the designated socket or terminal. The exact location of the socket or terminal depends on your model. You can refer to the quick installation guide for installers.
After installing the coding resistor, replace the cover and turn the heat pump or the hydraulic station back on. Then you can activate the cooling function via the control panel or remote control.
Please note that installing the coding resistor must only be done by a qualified professional. If you are unsure about how to install the coding resistor, please contact a Vaillant service partner near you.
I hope this guide was helpful. If you need further assistance, please let me know.
jrth2151 schrieb:
According to my research, only the appropriate coding resistor is needed to activate the cooling function.That was also my understanding, so I was surprised by the cost. I will probably be back at our construction site tomorrow. My plan is to ask the plumber (from the general contractor) if I can order it and if he can simply install it. Let’s see what he says and if he would need to do anything else for it. If I get the right person, he is actually quite competent and goal-oriented.Similar topics