ᐅ How to Properly Adjust an Air-to-Water Heat Pump with Underfloor Heating

Created on: 15 Dec 2019 16:52
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M4rvin
Hello,
I have been searching around and reading the manual for my Elco air-to-water heat pump, but I haven’t fully figured it out yet...

I have a manifold on the ground floor and first floor; the recommendation is to fully open everything, set all thermostats to maximum, and then adjust the heating curve on the heat pump low enough to roughly achieve the desired temperature.
Is that more or less correct?

At the moment, every thermostat (except bathroom/bedroom) is set to 20°C (68°F), and the temperature in each room is about 20.9°C (70°F) (bathroom slightly warmer, bedroom slightly cooler).
However, I’m surprised by the high electricity consumption — it has been 800 kWh in just 2 months.

135 m² (1455 sq ft) living area
Elco Split 7 kW
Circulation pump not yet connected

Thanks in advance
M4rvin
M4rvin17 Dec 2019 15:27
So, I have now set all the thermostats to maximum on the ground floor, and the heat pump is running. Is the curve still too high then?

Several flow meters with red scales in a pipe distribution, cables lie above.
M4rvin17 Dec 2019 20:04
Hi, a brief update...

Since I lowered the heating curve to 0.4 and set the thermostats to max, the heat pump has been running continuously. The flow valves were fully opened everywhere. (Some don’t go lower than 1.5; I tried to manually open them further.)

The average temperature has risen by about 1 degree everywhere. On the ground floor around 21.8°C (71°F), on the upper floor slightly over 22°C (72°F), and in the bathroom 23°C (73°F). Current outside temperature is 3°C (37°F).

Should I take any action now to cool the house down? Or should I wait because of thermal inertia?

By the way, I also noticed that after I set the radiator in the bathroom to 5, nothing happens; the flow is at 0.
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guckuck2
17 Dec 2019 20:10
Lower the heating curve. Anything above 0.25 is unnecessary in new buildings. You would have to want 24 degrees Celsius (75°F) indoors or have a poorly designed system for that to be reasonable.
seat8817 Dec 2019 20:13
But 22 degrees Celsius (72 degrees Fahrenheit) on the ground floor is not too warm, right?
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guckuck2
17 Dec 2019 20:29
Take a look at a heating curve diagram.
A slope of 0.4 means that at an outdoor temperature of 3°C (37°F), the supply temperature is already around 34–35°C (93–95°F). That’s already pleasantly warm for your feet...
For a modern underfloor heating system, that should be the endpoint, not the supply temperature at 3°C (37°F) outside.
The endpoint at a slope of 0.4 and a standard outdoor temperature of -15°C (5°F) is over 40°C (104°F) supply temperature!

0.25 is the starting point with an endpoint of about 35°C (95°F) supply temperature. The underfloor heating system should be designed for this.
You’d rather want less, for example, an endpoint of 30°C (86°F). This saves real money on energy consumption.

The house will continue to warm up since it’s only been running for a few hours.
But you can already tell what kind of energy the heat pump is pushing into the underfloor heating system without being fully utilized because the energy recovery regulator (ERR) cuts back. Completely pointless. First, the water is heated properly, only to be dripped into the heating circuit. It just doesn’t make sense.
M4rvin17 Dec 2019 21:45
Ok, I have now lowered it to 0.2! By the way, it can only be adjusted in 0.1 increments.

22°C (72°F) is too warm for me... 21°C (70°F) is the maximum tolerable temperature.

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