ᐅ Air-to-water heat pump combined with underfloor heating is not functioning properly
Created on: 22 Sep 2021 15:34
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_Ugeen_
Hello everyone,
We moved into our single-family house in the middle of the year and are now using our air-to-water heat pump (Daikin Altherma 3 R ECH2O) for the first time. In the rooms, we decided against the standard analog controllers and chose digital controllers instead. After several discussions with Daikin and the controller manufacturer, I now understand that a valve is only opened or closed when I want to increase the temperature or not.
With the Daikin system, I can set a target room temperature. According to Daikin, this target value does not represent the minimum temperature per room but rather the "preheating value," if I understand correctly. This value was previously set at 23°C (73°F).
In the bedroom, I set the digital controller so that heating only starts when the temperature drops below 18°C (64°F). Despite this setting, the room temperature has always been 22-23°C (72-73°F), although the digital controller shows that heating is off. After changing the target room temperature from 23 to 21°C (73 to 70°F), it got a bit cooler. However, in the bathroom, heating is supposed to activate below 23°C (73°F). The temperature there is 22°C (72°F), and the digital controller indicates that heating is active. Yet, the room does not get warmer, and the floor heating does not noticeably warm up either.
Conclusion: I still have not understood the logic behind the target room temperature setting. In our previous apartment, we also had underfloor heating with analog controllers that I could adjust higher or lower. That worked wonderfully, and I felt like I could control the temperature. Here, with the air-to-water heat pump, I don’t have that feeling. Also, the towel warmers do not get truly warm (only lukewarm), which Daikin says is normal even when the dial is set to 5. This is apparently because it is a low-temperature heat pump. Without the electric booster to warm the towel warmers, they are essentially ineffective. Is this normal? Could there be an error, or do I need to use completely different settings?
If anyone has experience with this topic, I would greatly appreciate your feedback. At the moment, I feel a bit lost on this subject.
We moved into our single-family house in the middle of the year and are now using our air-to-water heat pump (Daikin Altherma 3 R ECH2O) for the first time. In the rooms, we decided against the standard analog controllers and chose digital controllers instead. After several discussions with Daikin and the controller manufacturer, I now understand that a valve is only opened or closed when I want to increase the temperature or not.
With the Daikin system, I can set a target room temperature. According to Daikin, this target value does not represent the minimum temperature per room but rather the "preheating value," if I understand correctly. This value was previously set at 23°C (73°F).
In the bedroom, I set the digital controller so that heating only starts when the temperature drops below 18°C (64°F). Despite this setting, the room temperature has always been 22-23°C (72-73°F), although the digital controller shows that heating is off. After changing the target room temperature from 23 to 21°C (73 to 70°F), it got a bit cooler. However, in the bathroom, heating is supposed to activate below 23°C (73°F). The temperature there is 22°C (72°F), and the digital controller indicates that heating is active. Yet, the room does not get warmer, and the floor heating does not noticeably warm up either.
Conclusion: I still have not understood the logic behind the target room temperature setting. In our previous apartment, we also had underfloor heating with analog controllers that I could adjust higher or lower. That worked wonderfully, and I felt like I could control the temperature. Here, with the air-to-water heat pump, I don’t have that feeling. Also, the towel warmers do not get truly warm (only lukewarm), which Daikin says is normal even when the dial is set to 5. This is apparently because it is a low-temperature heat pump. Without the electric booster to warm the towel warmers, they are essentially ineffective. Is this normal? Could there be an error, or do I need to use completely different settings?
If anyone has experience with this topic, I would greatly appreciate your feedback. At the moment, I feel a bit lost on this subject.
Snowy36 schrieb:
As a layperson, I’m always surprised that operating an air-to-water heat pump apparently requires a degree (-:
If I had known that, I would have chosen gas. I would have been willing to pay the extra 10 euros per month for the peace of mind and to just be able to turn up the heat during transitional seasons…. I am a woman, and it’s almost unbearable that the heating doesn’t turn on because of some hysteresis blabla (my husband says) … On the ground floor I turn on the stove, but I’m freezing in the bathroom (-: Women, right….Misunderstanding. You can also run an air-to-water heat pump without optimization, meaning it costs 10€ (about $) more per month and still provides heat. No problem at all. That’s probably the case for most systems.
As mentioned before, “just turning up the heat” is not a missing performance feature of the heat pump itself. It is rather the result of underfloor heating systems with low supply temperatures. It would be the same with a gas heating system.
If it gets as warm in the bathroom as on the ground floor with the stove, then you probably need a stove there too—or something similar.
Actually, you’re right, and it should be said that the heat pump manufacturers have really dropped the ball here.
Something like a hydraulic balancing is a prime example of what a relatively simple algorithm (it doesn’t even have to be machine learning) could automatically control.
With combustion engines, advances in control electronics have reduced fuel consumption by about 30% over the last 20 years. Why shouldn’t the same be possible for heat pumps...
@Alessandro: Didn’t you mention that you’re now working for a heat pump manufacturer? You might want to suggest this...
@guckuck2: That’s true, but what’s missing is that heat pumps have a much steeper efficiency curve. The coefficient of performance drops much more sharply with higher temperature differences than it does with a gas boiler.
Something like a hydraulic balancing is a prime example of what a relatively simple algorithm (it doesn’t even have to be machine learning) could automatically control.
With combustion engines, advances in control electronics have reduced fuel consumption by about 30% over the last 20 years. Why shouldn’t the same be possible for heat pumps...
@Alessandro: Didn’t you mention that you’re now working for a heat pump manufacturer? You might want to suggest this...
@guckuck2: That’s true, but what’s missing is that heat pumps have a much steeper efficiency curve. The coefficient of performance drops much more sharply with higher temperature differences than it does with a gas boiler.
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RotorMotor8 Oct 2021 09:48@Snowy36 As mentioned several times before, the inertia mainly comes from the insulation and mass of the underfloor heating rather than the heat source (heat pump, gas, district heating, etc.). A solution here could be an infrared or electric heater, or best of all, a sweater.
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Alessandro8 Oct 2021 10:29The problem is not the systems themselves, but the installers! It starts with the heating load calculation and ends with the hydraulic balancing.
No installer can afford to send their staff to training or further education due to time constraints.
90% still install gas and oil heating systems.
90% of homeowners are not interested in adjusting the heat pump settings either. As long as it gets warm, that’s what matters. They often run with supply temperatures of 40°C (104°F), cycle 30 times a day, and waste energy.
@Tolentino: Yes, I work for a heat pump manufacturer. There are now apps for heating load calculation, underfloor heating design, and hydraulic balancing.
But these are mostly used only by the younger installers.
You have to clearly tell the installer or the general contractor exactly what you want during planning and also document it contractually. But which homeowner actually does that?
For the efficient operation of a heat pump, only the minimum flow rate is important. Compressor starts can easily be around 20 times per day. The machines should still run smoothly for 20 years.
The average air-to-water heat pump cycle time per run is about 25 minutes, which is perfectly fine.
Actually, a heat pump should be part of the electrical engineering trade.
No installer can afford to send their staff to training or further education due to time constraints.
90% still install gas and oil heating systems.
90% of homeowners are not interested in adjusting the heat pump settings either. As long as it gets warm, that’s what matters. They often run with supply temperatures of 40°C (104°F), cycle 30 times a day, and waste energy.
@Tolentino: Yes, I work for a heat pump manufacturer. There are now apps for heating load calculation, underfloor heating design, and hydraulic balancing.
But these are mostly used only by the younger installers.
You have to clearly tell the installer or the general contractor exactly what you want during planning and also document it contractually. But which homeowner actually does that?
For the efficient operation of a heat pump, only the minimum flow rate is important. Compressor starts can easily be around 20 times per day. The machines should still run smoothly for 20 years.
The average air-to-water heat pump cycle time per run is about 25 minutes, which is perfectly fine.
Actually, a heat pump should be part of the electrical engineering trade.
Alessandro schrieb:
Do you have the lengths of the heating coils and the heat load for each room?
There are calculators or formulas online that allow you to roughly estimate the flow rates. This way, you can roughly check whether Homematic is functioning correctly. Unfortunately not, but I could probably find out.
face26 schrieb:
I know the company; we had their radiators equipped with wireless thermostats in our old apartment. That worked quite well.
I can’t judge how well the heating actuator works. I haven’t read it in detail, just saw something about continuous flow control. To achieve this, you would either need actuators capable of that (which is rare) or the actuator controls it by something like pulse modulation. I’m not really familiar with the technical details.
The question is: Do you actually need that?
To control the system with Homematic, you usually need an access point. That means spending another 300-400€ on devices that consume electricity and can break down. A hydraulic balancing is not complicated. It costs you some time during one winter, but that’s it. If done correctly, you should never have to adjust your room thermostats again.
I have KNX installed. I integrated the actuators into KNX (for various reasons, not because I wanted to). So I could program all sorts of details, like increasing the living room temperature by 0.5 degrees when there are more than 4 sunshine hours before 4 pm and wind speed is above 1.5 m/s (5 mph) from the southwest, but only if someone is home.
And you want to know what I actually did? One season of hydraulic balancing. All actuators are always fully open; the rest regulates itself. Maybe I will fine-tune it a bit this winter (second season in the house), but so far it’s been completely hassle-free. When it got colder recently, the heat pump switched on by itself, and as you can see, the temperatures are within ±0.3 degrees (0.5°F) of the balance I set last season.
Yes, there are some small details, like when the sun shines a lot, it’s very windy, etc. But you cannot control that because the system is too slow for such adjustments. So, after hydraulic balancing, I set the maximum heat per room and turn the temperature control fully up. Unless I want to keep a room cooler, then I lower the temperature control. Is that correct?
Honestly, I also find it quite unreasonable what has been imposed on builders here. I want to make my life simpler, not more complicated.
But just a quick question: which technology costs me more money when operating inefficiently?
I had the impression that 2°C (3.6°F) higher supply temperature or poorly adjusted settings in underfloor heating and air-to-water heat pumps have a bigger impact on costs than with gas?
I had the impression that 2°C (3.6°F) higher supply temperature or poorly adjusted settings in underfloor heating and air-to-water heat pumps have a bigger impact on costs than with gas?
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