ᐅ What supply water temperatures are you currently using?

Created on: 24 Oct 2021 10:27
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lesmue79
Just out of curiosity, to better understand the slope of the heating curve, what flow temperatures do you typically run at 0°C (32°F) outdoor temperature, given a certain indoor temperature and insulation level, when using a combination of underfloor heating and a heat pump?

Background of the question:

My logic tells me that if I want, for example, 22°C (72°F) room temperature, the flow temperature must be at least 22°C (72°F) or higher, since I learned that there needs to be a temperature difference for heat transfer to occur.

So if my heating system turns on at 12°C (54°F) outdoor temperature, my flow temperature should logically start somewhere around 22°C–25°C (72°F–77°F). Accordingly, at only 5°C (41°F) outside, it should be around 27°C (81°F), and at 0°C (32°F) close to 30°C (86°F).

The system design usually takes the location and outdoor temperature down to about –12°C (10°F). If at 0°C (32°F) flow temperature is already 30°C (86°F) according to my logic, then at –12°C (10°F) the flow temperature should be about 40°C (104°F). But most underfloor heating designs for heat pumps are based on a maximum flow temperature of 35°C (95°F).

Of course, the insulation of the house and the indoor temperatures still play a role. Or is the increase in flow temperature actually so gradual that it only rises by about 0.5–1°C (1–2°F) for outdoor temperature drops in 0–5°C (0–9°F) increments?
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Dennis89
22 Nov 2021 11:10
lesmue79 schrieb:

The electric power consumption at that time was, I believe, 400 watts.

I think I can also display the frequency somewhere...
Incredible how low your heat pump modulates at the current outdoor temperature. Is the 400 watts just the compressor or the entire system?
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lesmue79
22 Nov 2021 12:24
Dennis89 schrieb:

It's impressive how low your heat pump modulates with the current ambient temperature. Is the 400 watts only the compressor or the entire system?

I would say that's for the entire system.
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Oetzberger
22 Nov 2021 14:38
Alessandro schrieb:

Here, and especially in the other forum, optimization is always taken to the extreme. 🙄
It’s also a bit of a hobby...
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annab377
22 Nov 2021 20:19
Malz1902 schrieb:

I can't adjust this on my heat pump.
There are only heating curve slope and heating curve shift settings. The slope is set to 0.1 and the shift to 0.

How do you actually determine the slope?
With my ground source heat pump, I can only set the heating curve using three values:
23°C (73°F) / 21°C (70°F) / 0 K
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halmi
22 Nov 2021 21:43
The heat pump has been running for 52 hours now, and the temperatures here keep dropping.

Clear dashboard with tables showing temperatures, inputs, outputs, and run times.
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lesmue79
25 Nov 2021 19:49
What is the quickest way to identify a hydraulic short circuit (a short heating loop causing the return flow to rise too quickly)? I plan to take another look at it over the weekend since the weather is supposed to get colder and snowy. Since my heat pump modulates, it always adjusts the temperature difference, so I’ve usually had a relatively small temperature spread (~3°C (5°F)) except for a few exceptions. I hope that when the system is under higher demand, it will run with a larger temperature spread (e.g., 5°C (9°F)), making an excessively hot return flow easier to notice. Or is that nonsense?